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Journal articles on the topic 'Lactone reduction'

Author: Grafiati

Published: 4 June 2021

Last updated: 17 February 2022

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1

Plutno, A. B., I. D. Sham'yanov, and G. G. Galust'yan. "Reduction of the natural sesquiterpene lactone leucomisin." Chemistry of Natural Compounds 31, no. 1 (1995): 58–62. http://dx.doi.org/10.1007/bf01167572.

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2

Ishii, Hideki, Sergei V. Dzyuba, and Koji Nakanishi. "Lactone-free ginkgolides via regioselective DIBAL-H reduction." Organic & Biomolecular Chemistry 3, no. 19 (2005): 3471. http://dx.doi.org/10.1039/b509129b.

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3

Huneck, Siegfried, Jürgen Schmidt, and Andrea Porzel. "Zur Chemie der Roccellsäure / On the Chemistry of Roccellic Acid." Zeitschrift für Naturforschung B 49, no. 4 (1994): 561–68. http://dx.doi.org/10.1515/znb-1994-0420.

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The isomerization of roccellic acid to threo-roccellic acid has been investigated. Reduction of dimethyl roccellate with LiAlH4 gave the corresponding diol which yielded on oxidation with Jones' reagent two isomeric γ-lactones. 1-Methyl roccellic amide has been transformed by a photochemical reaction to the δ-lactone acaranoic acid. Two copper complexes of roccellimide have been prepared.

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4

Kataoka, Michihiko, Sakayu Shimizu, and Hideaki Yamada. "Stereospecific conversion of a racemic pantoyl lactone to D-(-)-pantoyl lactone through microbial oxidation and reduction reactions." Recueil des Travaux Chimiques des Pays-Bas 110, no. 5 (2010): 155–57. http://dx.doi.org/10.1002/recl.19911100504.

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5

Liu, Zhengchun, Alessandro Granata, Xinhua Shen, and Arthur S. Perlin. "Reactions of hydriodic acid with aldonolactones and n-alkanolactones. Interconversions between lactones and iodocarboxylic acids." Canadian Journal of Chemistry 70, no. 7 (1992): 2081–88. http://dx.doi.org/10.1139/v92-264.

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Aldonolactones containing from four to eight carbon atoms, and lactones of the related monohydroxy-n-alkanoic acids, were subjected to reaction with 57% hydriodic acid at 125 °C. As in the classical studies of Kiliani, the reduction of D-glycero-D-ido-heptono-1,4-lactone yielded mainly γ-heptanolactone. Analogously, the corresponding γ-alkanolactones were obtained as major products from the 1,4-lactones of the D-xylono-, D-allono-, and D-erythro-L-talo-octono configuration. Monoiodo-n-alkanoic acids were also formed in admixture with the lactones in all of these reactions. D-Erythrono-1,4-lactone was unique among the aldonolactones in that it led only to an acid, i.e., 3-iodo-n-butanoic acid. The latter was also the product of the non-reductive reaction of hydriodic acid with β-butyrolactone whereas, by contrast, γ-butyrolactone afforded 4-iodobutanoic acid. Among compounds in the five to eight carbon series, it was found that under conditions close to equilibrium the ratio of lactone to iodoacid decreased progressively with the length of the carbon chain; e.g., in the 4 h reactions of γ-valero-, γ-capro-, γ-heptano-, and γ-octanolactone, the ratios were 2.4, 1.2, 0.2, and 0.1, respectively. An accompanying characteristic of these reactions is a progression in the number of isomeric iodoacids formed. Whereas γ-valerolactone was accompanied by 4-iodopentanoic acid, there were two isomers (4- and 5-) of iodohexanoic acid, three monoiodo- (including 6-iodo-) heptanoic acids, and four (including 7-iodo-) octanoic acids. In all instances, the isomer substituted at the penultimate carbon was major. An interplay of several individual reactions, including ring-opening displacements, eliminations–additions, and rearrangements, as well as a probable influence of entropy changes on the lactone-acid equilibria, appear to account largely for these observations.

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6

Kolt, R. J., D. Griller та D. D. M. Wayner. "Unsaturated spiro-γ-lactone formation by the dissociative reduction of bromoacetates". Tetrahedron Letters 31, № 52 (1990): 7539–40. http://dx.doi.org/10.1016/s0040-4039(00)97292-7.

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7

Xie, Minhui, Jianping Gao, Huiying Kang, et al. "Fabrication of effective oxygen reduction catalysts using lactone tofu as precursor." Journal of Electroanalytical Chemistry 850 (October 2019): 113395. http://dx.doi.org/10.1016/j.jelechem.2019.113395.

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8

Brito, Maria V., Ricardo A. Marques, Marcos C. Mattos та ін. "Semisynthesis and absolute configuration of a novel rearranged 19,20-δ-lactone (9βH)-pimarane diterpene". Acta Crystallographica Section C Structural Chemistry 74, № 8 (2018): 870–75. http://dx.doi.org/10.1107/s2053229618009452.

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Annonalide (3β,20-epoxy-3α,16-dihydroxy-15-oxo-7-pimaren-19,6β-olide, C20H26O6, 1) is the major (9βH)-pimarane diterpene isolated from tubers of Cassimirella ampla, and it exhibits cytotoxic properties upon interaction with ctDNA. We have prepared new derivatives of 1 by modification of the (9βH)-pimarane backbone and report here the semisynthesis and absolute configuration of a novel rearranged 19,20-δ-lactone (9βH)-pimarane. Our approach was the reduction of the carbonyl groups of 1 with sodium borohydride, at positions C15 (no stereoselectivity) and C3 (stereoselective reduction), followed by rearrangement of the 6,19-γ-lactone ring into the six-membered 19,20-δ-lactone ring in 4a (3β,6β,16-trihydroxy-7-pimaren-19,20β-olide monohydrate, C20H30O6·H2O). The absolute structure of the new compound, 4a, was determined unambiguously with a Flack parameter x of −0.01 (11), supporting the stereochemistry assignment of 1 redetermined here. Besides the changes in the pattern of covalent bonds caused by reduction and lactone rearrangement, the conformation of one of the three fused cyclohexane rings is profoundly different in 4a, adopting a chair conformation instead of the boat shape found in 1. Furthermore, the intramolecular hydrogen bond present in 1 is lost in new compound 4a, due to hydrogen bonding between the 3-OH group and the solvent water molecule.

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9

Levine, Stewart J., Barbara Adamik, Feras I. Hawari, et al. "Proteasome inhibition induces TNFR1 shedding from human airway epithelial (NCI-H292) cells." American Journal of Physiology-Lung Cellular and Molecular Physiology 289, no. 2 (2005): L233—L243. http://dx.doi.org/10.1152/ajplung.00469.2004.

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The type 1 55-kDa TNF receptor (TNFR1) is an important modulator of lung inflammation. Here, we hypothesized that the proteasome might regulate TNFR1 shedding from human airway epithelial cells. Treatment of NCI-H292 human airway epithelial cells for 2 h with the specific proteasome inhibitor clasto-lactacystin β-lactone induced the shedding of proteolytically cleaved TNFR1 ectodomains. Clasto-lactacystin β-lactone also induced soluble TNFR1 (sTNFR1) release from the A549 pulmonary epithelial cell line, as well as from primary cultures of human small airway epithelial cells and human umbilical vein endothelial cells. Furthermore, sTNFR1 release induced by clasto-lactacystin β-lactone was not a consequence of apoptosis or the extracellular release of TNFR1 exosome-like vesicles. The clasto-lactacystin β-lactone-induced increase in TNFR1 shedding was associated with reductions in cell surface receptors and intracytoplasmic TNFR1 stores that were primarily localized to vesicular structures. As expected, the broad-spectrum zinc metalloprotease inhibitor TNF-α protease inhibitor 2 (TAPI-2) attenuated clasto-lactacystin β-lactone-mediated TNFR1 shedding, which is consistent with its ability to inhibit the zinc metalloprotease-catalyzed cleavage of TNFR1 ectodomains. TAPI-2 also reduced TNFR1 on the cell surface and attenuated the clasto-lactacystin β-lactone-induced reduction of intracytoplasmic TNFR1 vesicles. This suggests that TNFR1 shedding induced by clasto-lactacystin β-lactone involves the zinc metalloprotease-dependent trafficking of intracytoplasmic TNFR1 vesicles to the cell surface. Together, these data are consistent with the conclusion that proteasomal activity negatively regulates TNFR1 shedding from human airway epithelial cells, thus identifying previously unrecognized roles for the proteasome and zinc metalloproteases in modulating the generation of sTNFRs.

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10

Satō, Tsuguo. "Synthesis of optically active forms of the δ-lactone of 3,5-dihydroxydecanoic acid". Canadian Journal of Chemistry 65, № 12 (1987): 2732–33. http://dx.doi.org/10.1139/v87-454.

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11

Shimizu, Sakayu, Shizuo Hattori, Hiroyuki Hata, and Hideaki Yamada. "Stereoselective enzymatic oxidation and reduction system for the production of d(−)-pantoyl lactone from a racemic mixture of pantoyl lactone." Enzyme and Microbial Technology 9, no. 7 (1987): 411–16. http://dx.doi.org/10.1016/0141-0229(87)90136-0.

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12

Muskal, Steven M., Joe Sliman, John Kokai-Kun, Mark Pimentel, Vince Wacher, and Klaus Gottlieb. "Lovastatin lactone may improve irritable bowel syndrome with constipation (IBS-C) by inhibiting enzymes in the archaeal methanogenesis pathway." F1000Research 5 (April 8, 2016): 606. http://dx.doi.org/10.12688/f1000research.8406.1.

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Methane produced by the methanoarchaeonMethanobrevibacter smithii(M. smithii) has been linked to constipation, irritable bowel syndrome with constipation (IBS-C), and obesity. Lovastatin, which demonstrates a cholesterol-lowering effect by the inhibition of HMG-CoA reductase, may also have an anti-methanogenesis effect through direct inhibition of enzymes in the archaeal methanogenesis pathway. We conducted protein-ligand docking experiments to evaluate this possibility. Results are consistent with recent clinical findings.METHODS: F420-dependent methylenetetrahydromethanopterin dehydrogenase (mtd), a key methanogenesis enzyme with a known sequence but no tertiary protein structural information, was modeled for two different methanogenic archaea:M. smithiiandMethanopyrus kandleri. Once protein models were developed, ligand-binding sites were identified. Multiple ligands and their respective protonation, isomeric and tautomeric representations were docked into each site, including F420-coenzyme (natural ligand), lactone and β-hydroxyacid forms of lovastatin and simvastatin, and other co-complexed ligands found in related crystal structures.RESULTS: 1) Generally, for each modeled site the lactone form of the statins had more favorable site interactions compared to F420; 2) The statin lactone forms generally had the most favorable docking scores, even relative to the native template PDB ligands; and 3) The statin β-hydroxyacid forms had less favorable docking scores, typically scoring in the middle with some of the F420 tautomeric forms. Consistent with these computational results were those from a recent phase II clinical trial (NCT02495623) with a proprietary, modified-release lovastatin-lactone (SYN-010) in patients with IBS-C, which showed a reduction in symptoms and breath methane levels, compared to placebo.CONCLUSION: The lactone form of lovastatin exhibits preferential binding over the native-F420 coenzyme ligandin silicoand thus could inhibit the activity of the keyM. smithiimethanogenesis enzymemtdin vivo. Statin lactones may thus exert a methane-reducing effect that is distinct from cholesterol lowering activity, which requires HMGR inhibition by statin β-hydroxyacid forms.

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13

Muskal, Steven M., Joe Sliman, John Kokai-Kun, Mark Pimentel, Vince Wacher, and Klaus Gottlieb. "Lovastatin lactone may improve irritable bowel syndrome with constipation (IBS-C) by inhibiting enzymes in the archaeal methanogenesis pathway." F1000Research 5 (April 28, 2016): 606. http://dx.doi.org/10.12688/f1000research.8406.2.

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Methane produced by the methanoarchaeonMethanobrevibacter smithii(M. smithii) has been linked to constipation, irritable bowel syndrome with constipation (IBS-C), and obesity. Lovastatin, which demonstrates a cholesterol-lowering effect by the inhibition of HMG-CoA reductase, may also have an anti-methanogenesis effect through direct inhibition of enzymes in the archaeal methanogenesis pathway. We conducted protein-ligand docking experiments to evaluate this possibility. Results are consistent with recent clinical findings.METHODS: F420-dependent methylenetetrahydromethanopterin dehydrogenase (mtd), a key methanogenesis enzyme was modeled for two different methanogenic archaea:M. smithiiandMethanopyrus kandleri. Once protein models were developed, ligand-binding sites were identified. Multiple ligands and their respective protonation, isomeric and tautomeric representations were docked into each site, including F420-coenzyme (natural ligand), lactone and β-hydroxyacid forms of lovastatin and simvastatin, and other co-complexed ligands found in related crystal structures.RESULTS: 1) Generally, for each modeled site the lactone form of the statins had more favorable site interactions compared to F420; 2) The statin lactone forms generally had the most favorable docking scores, even relative to the native template PDB ligands; and 3) The statin β-hydroxyacid forms had less favorable docking scores, typically scoring in the middle with some of the F420 tautomeric forms. Consistent with these computational results were those from a recent phase II clinical trial (NCT02495623) with a proprietary, modified-release lovastatin-lactone (SYN-010) in patients with IBS-C, which showed a reduction in symptoms and breath methane levels, compared to placebo.CONCLUSION: The lactone form of lovastatin exhibits preferential binding over the native-F420 coenzyme ligandin silicoand thus could inhibit the activity of the keyM. smithiimethanogenesis enzymemtdin vivo. Statin lactones may thus exert a methane-reducing effect that is distinct from cholesterol lowering activity, which requires HMGR inhibition by statin β-hydroxyacid forms.

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14

Muskal, Steven M., Joe Sliman, John Kokai-Kun, Mark Pimentel, Vince Wacher, and Klaus Gottlieb. "Lovastatin lactone may improve irritable bowel syndrome with constipation (IBS-C) by inhibiting enzymes in the archaeal methanogenesis pathway." F1000Research 5 (June 22, 2016): 606. http://dx.doi.org/10.12688/f1000research.8406.3.

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Methane produced by the methanoarchaeonMethanobrevibacter smithii(M. smithii) has been linked to constipation, irritable bowel syndrome with constipation (IBS-C), and obesity. Lovastatin, which demonstrates a cholesterol-lowering effect by the inhibition of HMG-CoA reductase, may also have an anti-methanogenesis effect through direct inhibition of enzymes in the archaeal methanogenesis pathway. We conducted protein-ligand docking experiments to evaluate this possibility. Results are consistent with recent clinical findings.METHODS: F420-dependent methylenetetrahydromethanopterin dehydrogenase (mtd), a key methanogenesis enzyme was modeled for two different methanogenic archaea:M. smithiiandMethanopyrus kandleri. Once protein models were developed, ligand-binding sites were identified. Multiple ligands and their respective protonation, isomeric and tautomeric representations were docked into each site, including F420-coenzyme (natural ligand), lactone and β-hydroxyacid forms of lovastatin and simvastatin, and other co-complexed ligands found in related crystal structures.RESULTS: 1) Generally, for each modeled site the lactone form of the statins had more favorable site interactions compared to F420; 2) The statin lactone forms generally had the most favorable docking scores, even relative to the native template PDB ligands; and 3) The statin β-hydroxyacid forms had less favorable docking scores, typically scoring in the middle with some of the F420 tautomeric forms. Consistent with these computational results were those from a recent phase II clinical trial (NCT02495623) with a proprietary, modified-release lovastatin-lactone (SYN-010) in patients with IBS-C, which showed a reduction in symptoms and breath methane levels, compared to placebo.CONCLUSION: The lactone form of lovastatin exhibits preferential binding over the native-F420 coenzyme ligandin silicoand thus could inhibit the activity of the keyM. smithiimethanogenesis enzymemtdin vivo. Statin lactones may thus exert a methane-reducing effect that is distinct from cholesterol lowering activity, which requires HMGR inhibition by statin β-hydroxyacid forms.

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15

Eltom, Salah E. M., Ahmed A. H. Abdellatif, Hamzah Maswadeh та ін. "The Anti-Inflammatory Effect of a γ-Lactone Isolated from Ostrich Oil of Struthio camelus (Ratite) and Its Formulated Nano-Emulsion in Formalin-Induced Paw Edema". Molecules 26, № 12 (2021): 3701. http://dx.doi.org/10.3390/molecules26123701.

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The ostrich oil of Struthio camelus (Ratite) found uses in folk medicine as an anti-inflammatory in eczema and contact dermatitis. The anti-inflammatory effect of a γ-lactone (5-hexyl-3H-furan-2-one) isolated from ostrich oil and its formulated nano-emulsion in formalin-induced paw edema was investigated in this study. Ostrich oil was saponified using a standard procedure; the aqueous residue was fractionated, purified, and characterized as γ-lactone (5-hexyl-3H-furan-2-one) through the interpretation of IR, NMR, and MS analyses. The γ-lactone was formulated as nano-emulsion using methylcellulose (MC) for oral solubilized form. The γ-lactone methylcellulose nanoparticles (γ-lactone-MC-NPs) were characterized for their size, shape, and encapsulation efficiency with a uniform size of 300 nm and 59.9% drug content. The γ-lactone was applied topically, while the formulated nanoparticles (NPs) were administered orally to rats. A non-steroidal anti-inflammatory drug (diclofenac gel) was used as a reference drug for topical use and ibuprofen suspension for oral administration. Edema was measured using the plethysmograph method. Both γ-lactone and γ-lactone-MC-NPs showed reduction of formalin-induced paw edema in rats and proved to be better than the reference drugs; diclofenac gel and ibuprofen emulsion. Histological examination of the skin tissue revealed increased skin thickness with subepidermal edema and mixed inflammatory cellular infiltration, which were significantly reduced by the γ-lactone compared to the positive control (p-value = 0.00013). Diuretic and toxicity studies of oral γ-lactone-MC-NPs were performed. No diuretic activity was observed. However, lethargy, drowsiness, and refusal to feeding observed may limit its oral administration.

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16

Largeron, Martine, Nicolas Auzeil, Bouria Dakova, Eric Bacqué, Jean-Marc Paris, and Maurice-Bernard Fleury. "Incidence of the peptidic lactone opening on the electrochemical reduction of pristinamycin IA." Tetrahedron Letters 37, no. 42 (1996): 7499–502. http://dx.doi.org/10.1016/0040-4039(96)01729-7.

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17

KOLT, R. J., D. GRILLER та D. D. M. WAYNER. "ChemInform Abstract: Unsaturated Spiro-γ-lactone Formation by the Dissociative Reduction of Bromoacetates." ChemInform 23, № 14 (2010): no. http://dx.doi.org/10.1002/chin.199214188.

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18

Uroz, Stéphane, Siri Ram Chhabra, Miguel Cámara, Paul Williams, Phil Oger, and Yves Dessaux. "N-Acylhomoserine lactone quorum-sensing molecules are modified and degraded by Rhodococcus erythropolis W2 by both amidolytic and novel oxidoreductase activities." Microbiology 151, no. 10 (2005): 3313–22. http://dx.doi.org/10.1099/mic.0.27961-0.

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The Rhodococcus erythropolis strain W2 has been shown previously to degrade the N-acylhomoserine lactone (AHL) quorum-sensing signal molecule N-hexanoyl-l-homoserine lactone, produced by other bacteria. Data presented here indicate that this Gram-positive bacterium is also capable of using various AHLs as the sole carbon and energy source. The enzymic activities responsible for AHL inactivation were investigated in R. erythropolis cell extracts and in whole cells. R. erythropolis cells rapidly degraded AHLs with 3-oxo substituents but exhibited relatively poor activity against the corresponding unsubstituted AHLs. Investigation of the mechanism(s) by which R. erythropolis cells degraded AHLs revealed that 3-oxo compounds with N-acyl side chains ranging from C8 to C14 were initially converted to their corresponding 3-hydroxy derivatives. This oxidoreductase activity was not specific to 3-oxo-AHLs but also allowed the reduction of compounds such as N-(3-oxo-6-phenylhexanoyl)homoserine lactone (which contains an aromatic acyl chain substituent) and 3-oxododecanamide (which lacks the homoserine lactone ring). It also reduced both the d- and l-isomers of n-(3-oxododecanoyl)-l-homoserine lactone. A second AHL-degrading activity was observed when R. erythropolis cell extracts were incubated with N-(3-oxodecanoyl)-l-homoserine lactone (3O,C10-HSL). This activity was both temperature- and pH-dependent and was characterized as an amidolytic activity by HPLC analysis of the reaction mixture treated with dansyl chloride. This revealed the accumulation of dansylated homoserine lactone, indicating that the 3O,C10-HSL amide had been cleaved to yield homoserine lactone. R. erythropolis is therefore capable of modifying and degrading AHL signal molecules through both oxidoreductase and amidolytic activities.

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19

Sefkow, M., M. Raschke, and C. Steiner. "Enantioselective synthesis and biological evaluation of a-hydroxylated lactone lignans." Pure and Applied Chemistry 75, no. 2-3 (2003): 273–78. http://dx.doi.org/10.1351/pac200375020273.

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A short and efficient synthesis of enantiomerically pure α-hydroxylated lactone lignans starting from commercially available diisopropyl malate is presented. Stereoselective alkylation with various benzyl bromides and saponification yielded the corresponding succinic acids. Acetalization afforded the dioxolanones, which were stereoselectively alkylated. Reduction (and deprotection, where required) yielded the lactone lignans in up to 30 % overall yield. The inhibition of the proliferation of HT29 colon cancer cells was investigated. One lignane, bis-2,4,6 trimethylbenzyllactone lignan, was active (IC50 = 35 μM), whereas all other tested lignans were inactive within the investigated concentration range.

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20

Swift, Simon, Martin J. Lynch, Leigh Fish, et al. "Quorum Sensing-Dependent Regulation and Blockade of Exoprotease Production in Aeromonas hydrophila." Infection and Immunity 67, no. 10 (1999): 5192–99. http://dx.doi.org/10.1128/iai.67.10.5192-5199.1999.

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ABSTRACT In Aeromonas hydrophila, the ahyI gene encodes a protein responsible for the synthesis of the quorum sensing signal N-butanoyl-l-homoserine lactone (C4-HSL). Inactivation of the ahyI gene on the A. hydrophila chromosome abolishes C4-HSL production. The exoprotease activity of A. hydrophila consists of both serine protease and metalloprotease activities; in theahyI-negative strain, both are substantially reduced but can be restored by the addition of exogenous C4-HSL. In contrast, mutation of the LuxR homolog AhyR results in the loss of both exoprotease activities, which cannot be restored by exogenous C4-HSL. Furthermore, a substantial reduction in the production of exoprotease by the ahyI + parent strain is obtained by the addition of N-acylhomoserine lactone analogs that have acyl side chains of 10, 12, or 14 carbons. The inclusion ofN-(3-oxododecanoyl)-l-homoserine lactone orN-(3-oxotetradecanoyl)-l-homoserine lactone at 10 μM in overnight cultures of A. hydrophila abolishes exoprotease production in azocasein assays and reduces the activity of all the exoprotease species seen in zymograms.

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21

Janků, Josef, Sergei D. Isaev, Leonid V. Cybulskii, Luděk Vodička, and Alexander G. Yurchenko. "Reactions of isomeric oxo-2(3)-oxahomodiamantanes. Dehydration of tetracyclic diols with concentrated phosphoric acid." Collection of Czechoslovak Chemical Communications 55, no. 10 (1990): 2475–80. http://dx.doi.org/10.1135/cccc19902475.

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Reduction of 11-oxo-10-oxapentacyclo[7.4.1.14,13.02,7.06,12]pentadecane (lactone I) and 10-oxo-11-oxapentacyclo[7.4.1.14,13.02,7.06,12]pentadecane (lactone II) with lithium aluminium hydride afforded 4-hydroxymethyl-12-hydroxytetracyclo[7.3.1.02,7.06,11]tridecane (diol III) and 4-hydroxy-12-hydroxymethyltetracyclo[7.3.1.02,7.06,11]tridecane (diol IV). Diol III reacted with concentrated phosphoric acid to give 3-methyltetracyclo[6.4.1.02,6.05,10]tridecanone-9 (V) as practically the sole product. Diol IV afforded a complex mixture of products in which were identified 2-methyl-3-oxadiadamantane (VI; 57%), 10-oxa-2(3)-homodiadamantane (VII; 20%), 3-hydroxydiadamantane (VIII; 3%), diadamantane (X; 7%) and diadamantanone (IX; 2%).

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22

Bazhenov, Sergey, Uliana Novoyatlova, Ekaterina Scheglova, et al. "Influence of the luxR Regulatory Gene Dosage and Expression Level on the Sensitivity of the Whole-Cell Biosensor to Acyl-Homoserine Lactone." Biosensors 11, no. 6 (2021): 166. http://dx.doi.org/10.3390/bios11060166.

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Aliivibrio fischeri LuxR and Aliivibrio logei LuxR1 and LuxR2 regulatory proteins are quorum sensing transcriptional (QS) activators, inducing promoters of luxICDABEG genes in the presence of an autoinducer (3-oxo-hexanoyl-l-homoserine lactone). In the Aliivibrio cells, luxR genes are regulated by HNS, CRP, LitR, etc. Here we investigated the role of the luxR expression level in LuxI/R QS system functionality and improved the whole-cell biosensor for autoinducer detection. Escherichia coli-based bacterial lux-biosensors were used, in which Photorhabdus luminescensluxCDABE genes were controlled by LuxR-dependent promoters and luxR, luxR1, or luxR2 regulatory genes. We varied either the dosage of the regulatory gene in the cells using additional plasmids, or the level of the regulatory gene expression using the lactose operon promoter. It was shown that an increase in expression level, as well as dosage of the regulatory gene in biosensor cells, leads to an increase in sensitivity (the threshold concentration of AI is reduced by one order of magnitude) and to a two to threefold reduction in response time. The best parameters were obtained for a biosensor with an increased dosage of luxRA. fischeri (sensitivity to 3-oxo-hexanoyl-l-homoserine lactone reached 30–100 pM).

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23

Ouazzani-Chahdi, Jamal, Didier Buisson, and Robert Azerad. "Preparation of both enantiomers of a chiral lactone through combined microbiological reduction and oxidation." Tetrahedron Letters 28, no. 10 (1987): 1109–12. http://dx.doi.org/10.1016/s0040-4039(00)95923-9.

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24

KATAOKA, Michihiko, Sakayu SHIMIZU, and Hideaki YAMADA. "Novel enzymatic production of D-(-)-pantoyl lactone through the stereospecific reduction of ketopantoic acid." Agricultural and Biological Chemistry 54, no. 1 (1990): 177–82. http://dx.doi.org/10.1271/bbb1961.54.177.

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25

Parmar, Dixit, Lorna A. Duffy, Dhandapani V. Sadasivam, et al. "Studies on the Mechanism, Selectivity, and Synthetic Utility of Lactone Reduction Using SmI2and H2O." Journal of the American Chemical Society 131, no. 42 (2009): 15467–73. http://dx.doi.org/10.1021/ja906396u.

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26

Kataoka, Michihiko, Sakayu Shimizu, and Hideaki Yamada. "Novel Enzymatic Production of D-(–)-Pantoyl Lactone through the Stereospecific Reduction of Ketopantoic Acid." Agricultural and Biological Chemistry 54, no. 1 (1990): 177–82. http://dx.doi.org/10.1080/00021369.1990.10869925.

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27

Eck, Richard, and Helmut Simon. "Synthesis of (R)-pantoyl lactone by reduction of ketopantoate with formate and Proteus species." Tetrahedron: Asymmetry 5, no. 8 (1994): 1419–22. http://dx.doi.org/10.1016/0957-4166(94)80100-2.

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28

Ponsard, Louise, Emmanuel Nicolas, Ngoc Huan Tran, et al. "Coupling Electrocatalytic CO 2 Reduction with Thermocatalysis Enables the Formation of a Lactone Monomer." ChemSusChem 14, no. 10 (2021): 2198–204. http://dx.doi.org/10.1002/cssc.202100459.

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Val, Dale L., and John E. Cronan. "In Vivo Evidence that S-Adenosylmethionine and Fatty Acid Synthesis Intermediates Are the Substrates for the LuxI Family of Autoinducer Synthases." Journal of Bacteriology 180, no. 10 (1998): 2644–51. http://dx.doi.org/10.1128/jb.180.10.2644-2651.1998.

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ABSTRACT Many gram-negative bacteria synthesize N-acyl homoserine lactone autoinducer molecules as quorum-sensing signals which act as cell density-dependent regulators of gene expression. We have investigated the in vivo source of the acyl chain and homoserine lactone components of the autoinducer synthesized by the LuxI homolog, TraI. In Escherichia coli, synthesis ofN-(3-oxooctanoyl)homoserine lactone by TraI was unaffected in a fadD mutant blocked in β-oxidative fatty acid degradation. Also, conditions known to induce the fadregulon did not increase autoinducer synthesis. In contrast, cerulenin and diazoborine, specific inhibitors of fatty acid synthesis, both blocked autoinducer synthesis even in a strain dependent on β-oxidative fatty acid degradation for growth. These data provide the first in vivo evidence that the acyl chains in autoinducers synthesized by LuxI-family synthases are derived from acyl-acyl carrier protein substrates rather than acyl coenzyme A substrates. Also, we show that decreased levels of intracellularS-adenosylmethionine caused by expression of bacteriophage T3 S-adenosylmethionine hydrolase result in a marked reduction in autoinducer synthesis, thus providing direct in vivo evidence that the homoserine lactone ring of LuxI-family autoinducers is derived from S-adenosylmethionine.

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Yamauchi, Satoshi, Kenji Takeda, Makoto Ganaha, and Yoshiro Kinoshita. "Synthesis of (R)-6,7-dihydro-5-HETE lactone and (S)-6,7-dihydro-5-HETE lactone by using novel yeast reduction as a key reaction." Journal of the Chemical Society, Perkin Transactions 1, no. 19 (August 30, 2002): 2156–60. http://dx.doi.org/10.1039/b206843p.

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31

Lumjiaktase, Putthapoom, Stephen P. Diggle, Suvit Loprasert, et al. "Quorum sensing regulates dpsA and the oxidative stress response in Burkholderia pseudomallei." Microbiology 152, no. 12 (2006): 3651–59. http://dx.doi.org/10.1099/mic.0.29226-0.

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Burkholderia pseudomallei is the causative agent of melioidosis, a fatal human tropical disease. The non-specific DNA-binding protein DpsA plays a key role in protecting B. pseudomallei from oxidative stress mediated, for example, by organic hydroperoxides. The regulation of dpsA expression is poorly understood but one possibility is that it is regulated in a cell population density-dependent manner via N-acylhomoserine lactone (AHL)-dependent quorum sensing (QS) since a lux-box motif has been located within the dpsA promoter region. Using liquid chromatography and tandem mass spectrometry, it was first established that B. pseudomallei strain PP844 synthesizes AHLs. These were identified as N-octanoylhomoserine lactone (C8-HSL), N-(3-oxooctanoyl)homoserine lactone (3-oxo-C8-HSL), N-(3-hydroxyoctanoyl)-homoserine lactone (3-hydroxy-C8-HSL), N-decanoylhomoserine lactone (C10-HSL), N-(3-hydroxydecanoyl) homoserine lactone (3-hydroxy-C10-HSL) and N-(3-hydroxydodecanoyl)homoserine lactone (3-hydroxy-C12-HSL). Mutation of the genes encoding the LuxI homologue BpsI or the LuxR homologue BpsR resulted in the loss of C8-HSL and 3-oxo-C8-HSL synthesis, demonstrating that BpsI was responsible for directing the synthesis of these AHLs only and that bpsI expression and hence C8-HSL and 3-oxo-C8-HSL production depends on BpsR. In bpsI, bpsR and bpsIR mutants, dpsA expression was substantially down-regulated. Furthermore, dpsA expression in Escherichia coli required both BpsR and C8-HSL. bpsIR-deficient mutants exhibited hypersensitivity to the organic hydroperoxide tert-butyl hydroperoxide by displaying a reduction in cell viability which was restored by provision of exogenous C8-HSL (bpsI mutant only), by complementation with the bpsIR genes or by overexpression of dpsA. These data indicate that in B. pseudomallei, QS regulates the response to oxidative stress at least in part via the BpsR/C8-HSL-dependent regulation of DpsA.

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Sha, Jian, Lakshmi Pillai, Amin A. Fadl, Cristi L. Galindo, Tatiana E. Erova, and Ashok K. Chopra. "The Type III Secretion System and Cytotoxic Enterotoxin Alter the Virulence of Aeromonas hydrophila." Infection and Immunity 73, no. 10 (2005): 6446–57. http://dx.doi.org/10.1128/iai.73.10.6446-6457.2005.

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ABSTRACT Many gram-negative bacteria use a type III secretion system (TTSS) to deliver effector proteins into host cells. Here we report the characterization of a TTSS chromosomal operon from the diarrheal isolate SSU of Aeromonas hydrophila. We deleted the gene encoding Aeromonas outer membrane protein B (AopB), which is predicted to be involved in the formation of the TTSS translocon, from wild-type (WT) A. hydrophila as well as from a previously characterized cytotoxic enterotoxin gene (act)-minus strain of A. hydrophila, thus generating aopB and act/aopB isogenic mutants. The act gene encodes a type II-secreted cytotoxic enterotoxin (Act) that has hemolytic, cytotoxic, and enterotoxic activities and induces lethality in a mouse model. These isogenic mutants (aopB, act, and act/aopB) were highly attenuated in their ability to induce cytotoxicity in RAW 264.7 murine macrophages and HT-29 human colonic epithelial cells. The act/aopB mutant demonstrated the greatest reduction in cytotoxicity to cultured cells after 4 h of infection, as measured by the release of lactate dehydrogenase enzyme, and was avirulent in mice, with a 90% survival rate compared to that of animals infected with Act and AopB mutants, which caused 50 to 60% of the animals to die at a dose of three 50% lethal doses. In contrast, WT A. hydrophila killed 100% of the mice within 48 h. The effects of these mutations on cytotoxicity could be complemented with the native genes. Our studies further revealed that the production of lactones, which are involved in quorum sensing (QS), was decreased in the act (32%) and aopB (64%) mutants and was minimal (only 8%) in the act/aopB mutant, compared to that of WT A. hydrophila SSU. The effects of act and aopB gene deletions on lactone production could also be complemented with the native genes, indicating specific effects of Act and the TTSS on lactone production. Although recent studies with other bacteria have indicated TTSS regulation by QS, this is the first report describing a correlation between the TTSS and Act of A. hydrophila and the production of lactones.

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Zhang, Bao, Xiyi Zhuang, Liyun Guo, Robert J. C. McLean, and Weihua Chu. "Recombinant N-acyl homoserine lactone-Lactonase AiiAQSI-1 Attenuates Aeromonas hydrophila Virulence Factors, Biofilm Formation and Reduces Mortality in Crucian Carp." Marine Drugs 17, no. 9 (2019): 499. http://dx.doi.org/10.3390/md17090499.

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Quorum quenching (QQ) is a promising alternative infection-control strategy to antibiotics that controls quorum-regulated virulence without killing the pathogens. Aeromonas hydrophila is an opportunistic gram-negative pathogen living in freshwater and marine environments. A. hydrophila possesses an N-acyl homoserine lactone (AHL)-based quorum-sensing (QS) system that regulates virulence, so quorum signal-inactivation (i.e., QQ) may represent a new way to combat A. hydrophila infection. In this study, an AHL lactonase gene, aiiA was cloned from Bacillus sp. strain QSI-1 and expressed in Escherichia coli strain BL21(DE3). The A. hydrophila hexanoyl homoserine lactone (C6-HSL) QS signal molecule was degraded by AiiAQSI-1, which resulted in a decrease of bacterial swimming motility, reduction of extracellular protease and hemolysin virulence factors, and inhibited the biofilm formation of A. hydrophila YJ-1 in a microtiter assay. In cell culture studies, AiiAQSI-1 decreased the ability of A. hydrophila adherence to and internalization by Epithelioma papulosum cyprini (EPC) cells. During in vivo studies, oral administration of AiiAQSI-1 via feed supplementation attenuated A. hydrophila infection in Crucian Carp. Results from this work indicate that feed supplementation with AiiAQSI-1 protein has potential to control A. hydrophila aquaculture disease via QQ.

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de Oliveira, Luciane F., та Valentim E. U. Costa. "Unexpected formation of a chiral δ-lactone by reduction of the 1,3-dicarbonylic cyclopentanoid derivatives". Tetrahedron Letters 47, № 21 (2006): 3565–67. http://dx.doi.org/10.1016/j.tetlet.2006.03.062.

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Ghosh, Arun K., and Hui Lei. "Chelation-Controlled Reduction: Stereoselective Formation ofsyn-1,3-Diols and Synthesis of Compactin and Mevinolin Lactone." Journal of Organic Chemistry 67, no. 25 (2002): 8783–88. http://dx.doi.org/10.1021/jo020402k.

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36

Yates, Edwin A., Bodo Philipp, Catherine Buckley, et al. "N-Acylhomoserine Lactones Undergo Lactonolysis in a pH-, Temperature-, and Acyl Chain Length-Dependent Manner during Growth of Yersinia pseudotuberculosis and Pseudomonas aeruginosa." Infection and Immunity 70, no. 10 (2002): 5635–46. http://dx.doi.org/10.1128/iai.70.10.5635-5646.2002.

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ABSTRACT In gram-negative bacterial pathogens, such as Pseudomonas aeruginosa and Yersinia pseudotuberculosis, cell-to-cell communication via the N-acylhomoserine lactone (AHL) signal molecules is involved in the cell population density-dependent control of genes associated with virulence. This phenomenon, termed quorum sensing, relies upon the accumulation of AHLs to a threshold concentration at which target structural genes are activated. By using biosensors capable of detecting a range of AHLs we observed that, in cultures of Y. pseudotuberculosis and P. aeruginosa, AHLs accumulate during the exponential phase but largely disappear during the stationary phase. When added to late-stationary-phase, cell-free culture supernatants of the respective pathogen, the major P. aeruginosa [N-butanoylhomoserine lactone (C4-HSL) and N-(3-oxododecanoyl)homoserine lactone (3-oxo-C12-HSL)] and Y. pseudotuberculosis [N-(3-oxohexanoyl)homoserine lactone (3-oxo-C6-HSL) and N-hexanoylhomoserine lactone (C6-HSL)] AHLs were inactivated. Short-acyl-chain compounds (e.g., C4-HSL) were turned over more extensively than long-chain molecules (e.g., 3-oxo-C12-HSL). Little AHL inactivation occurred with cell extracts, and no evidence for inactivation by specific enzymes was apparent. This AHL turnover was discovered to be due to pH-dependent lactonolysis. By acidifying the growth media to pH 2.0, lactonolysis could be reversed. By using carbon-13 nuclear magnetic resonance spectroscopy, we found that the ring opening of homoserine lactone (HSL), N-propionyl HSL (C3-HSL), and C4-HSL increased as pH increased but diminished as the N-acyl chain was lengthened. At low pH levels, the lactone rings closed but not via a simple reversal of the ring opening reaction mechanism. Ring opening of C4-HSL, C6-HSL, 3-oxo-C6-HSL, and N-octanoylhomoserine lactone (C8-HSL), as determined by the reduction of pH in aqueous solutions with time, was also less rapid for AHLs with more electron-donating longer side chains. Raising the temperature from 22 to 37°C increased the rate of ring opening. Taken together, these data show that (i) to be functional under physiological conditions in mammalian tissue fluids, AHLs require an N-acyl side chain of at least four carbons in length and (ii) that the longer the acyl side chain the more stable the AHL signal molecule.

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37

Ombwayo, Faraja, Zahilis Mazzhichette, and Amos Mugweru. "Electrochemical reduction of artemisinin: Chromatographic identification of bulk electrolysis products." Journal of Electrochemical Science and Engineering 9, no. 3 (2019): 165–74. http://dx.doi.org/10.5599/jese.652.

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Artemisinin is a naturally occurring sesquiterpene lactone with an endo-peroxide bond. This drug is used for treatment of many diseases including malaria. The reduction of this molecule on an electrode surface was carried out by cyclic voltammetry as well as amperometry. Cyclic voltammetry of artemisinin generated one prominent peak wave at -1.0 V and another, smaller one at -0.3 V vs Ag/AgCl reference electrode. The bulk electrolysis of artemisinin on a carbon electrode generated two other irreversible peak waves at around -0.7 and -0.1 V. The concentration of the products was dependent on the time of electrolysis. LC-MS was used to determine the bulk electrolysis products of artemisinin. Initially dihydroartemisinin was generated as the main reduction product. Other reduction products were formed after further reduction of dyhidroartemisinin.

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38

Yu, Haitao, Xiaohang Tang, Le Tong, Mengyi Yao, Qiaoli Liang, and Xiaolong Wang. "A New Process for the Total Synthesis of Sparstolonin B." Synlett 28, no. 10 (2017): 1187–90. http://dx.doi.org/10.1055/s-0036-1588723.

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A novel and simple route was developed that gives sparstolonin B in high yields from affordable commercial compounds. A Diels–Alder strategy was used for the facile construction of the multisubstituted diphenyl ether. The xanthenone segment was obtained by cyclization in an intramolecular Friedel–Crafts reaction, followed by selective reduction of a ketone group and a transformation from a hydroxy group into a cyano group. The final part of the lactone was directly derived by the reduction of the cyano group with Raney nickel.

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Venkatanarayana, Muvvala. "Identification and Efficient Synthetic Method for Preparation of Cyclopentane-1,3-diol Impurity in Tafluprost Drug." Asian Journal of Chemistry 33, no. 1 (2020): 210–14. http://dx.doi.org/10.14233/ajchem.2021.22934.

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In present work, the isolation, synthesis and characterization of the identified triol impurity present in tafluprost is described. This investigation helps to avoid formation of impurity by control the reaction and its leads to improving high yields of tafluprost. The source of impurity was identified, due to over-reduction of lactone with diisobutyl aluminum hydride (DIBAL-H).

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40

Piatak, David M., and Pui-Fun Louisa Tang. "Notes on the directed aldol synthesis and reduction of some compounds related to cycloheximide." Canadian Journal of Chemistry 65, no. 6 (1987): 1327–31. http://dx.doi.org/10.1139/v87-222.

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Several N-phenylcycloheximide analogues were prepared by TiCl4-promoted aldol condensation between trimethylsilyl enol ethers of cyclic ketones and (N-phenylglutarimide)-β-acetaldehyde. Favored stereoisomers were isolated in several instances and identified from nuclear magnetic resonance data. Only for the analogue from 4-tert-butylcyclohexanone was it possible to obtain both erythro and threo isomers. Catalytic reduction of the β-hydroxyketone system overPtO2 gave dihydrocycloheximide analogues possessing an axial ring hydroxyl group. Reduction in glacial HOAc was noted as promoting fission of the glutarimide ring with formation of lactone amides and, in several instances, concomitant reduction of the phenyl ring to a cyclohexyl group.

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41

Sautier, Brice, Karl D. Collins, and David J. Procter. "Development of an additive-controlled, SmI2-mediated stereoselective sequence: Telescoped spirocyclisation, lactone reduction and Peterson elimination." Beilstein Journal of Organic Chemistry 9 (July 18, 2013): 1443–47. http://dx.doi.org/10.3762/bjoc.9.163.

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Studies on SmI2-mediated spirocyclisation and lactone reduction culminate in a telescoped sequence in which additives are used to “switch on” individual steps mediated by the electron transfer reagent. The sequence involves the use of two activated SmI2 reagent systems and a silicon stereocontrol element that exerts complete diastereocontrol over the cyclisation and is removed during the final stage of the sequence by Peterson elimination. The approach allows functionalised cyclopentanols containing two vicinal quaternary stereocentres to be conveniently prepared from simple starting materials.

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Das, Biswanath, G. Satyalakshmi, Nisith Bhunia, K. Ravider Reddy, V. Saidi Reddy, and G. Mahender. "Chemical Transformations of Parthenin, a Natural Bioactive Sesquiterpenoid [1]." Natural Product Communications 4, no. 1 (2009): 1934578X0900400. http://dx.doi.org/10.1177/1934578x0900400104.

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Chemical modifications of parthenin, a naturally occurring bioactive sesquiterpenoid, were carried out in regio- and stereoselective manners using various inexpensive reagents to form different natural and unnatural analogues. Reactions including dehydration, reduction, alkylation, addition and hydroxylation have been studied. In some of the analogues, the α-methylene-γ-lactone moiety, which plays a vital role for bioactivity of parthenin, remained intact.

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43

Alhariri, Moayad, and Abdelwahab Omri. "Efficacy of Liposomal Bismuth-Ethanedithiol-Loaded Tobramycin after Intratracheal Administration in Rats with Pulmonary Pseudomonas aeruginosa Infection." Antimicrobial Agents and Chemotherapy 57, no. 1 (2012): 569–78. http://dx.doi.org/10.1128/aac.01634-12.

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ABSTRACTWe sought to investigate alterations in quorum-sensing signal moleculeN-acyl homoserine lactone secretion and in the release ofPseudomonas aeruginosavirulence factors, as well as thein vivoantimicrobial activity of bismuth-ethanedithiol incorporated into a liposome-loaded tobramycin formulation (LipoBiEDT-TOB) administered to rats chronically infected withP. aeruginosa. The quorum-sensing signal moleculeN-acyl homoserine lactone was monitored by using a biosensor organism.P. aeruginosavirulence factors were assessed spectrophotometrically. An agar beads model of chronicPseudomonaslung infection in rats was used to evaluate the efficacy of the liposomal formulation in the reduction of bacterial count. The levels of active tobramycin in the lungs and the kidneys were evaluated by microbiological assay. LipoBiEDT-TOB was effective in disrupting both quorum-sensing signal moleculesN-3-oxo-dodeccanoylhomoserine lactone andN-butanoylhomoserine lactone, as well as significantly (P< 0.05) reducing lipase, chitinase, and protease production. At 24 h after 3 treatments, the CFU counts in lungs of animals treated with LipoBiEDT-TOB were of 3 log10CFU/lung, comparated to 7.4 and 4.7 log10CFU/lung, respectively, in untreated lungs and in lungs treated with free antibiotic. The antibiotic concentration after the last dose of LipoBiEDT-TOB was 25.1 μg/lung, while no tobramycin was detected in the kidneys. As for the free antibiotic, we found 6.5 μg/kidney but could not detect any tobramycin in the lungs. Taken together, LipoBiEDT-TOB reduced the production of quorum-sensing molecules and virulence factors and could highly improve the management of chronic pulmonary infection in cystic fibrosis patients.

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Robin, Sylvie, François Huet, Annie Fauve та Henri Veschambre. "Microbiological reduction of keto-sulfones. Application in a three-step synthesis of (S)-(+)-β-angelica lactone". Tetrahedron: Asymmetry 4, № 2 (1993): 239–46. http://dx.doi.org/10.1016/s0957-4166(00)82344-7.

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45

Depré, Dominique, András Horváth, Walter Snissaert, Leo Van Den Bergh, and Wim Dermaut. "Implementation on Pilot-Plant Scale of the Titanocene-Catalyzed Reduction of a Lactone with Poly(methylhydrosiloxane)." Organic Process Research & Development 12, no. 1 (2008): 96–100. http://dx.doi.org/10.1021/op700207m.

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Nakamura, Yutaka, Seiji Takeuchi, Yoshiaki Ohgo, Makoto Yamaoka, Akihiro Yoshida та Koichi Mikami. "Enantioselective protonation of samarium enolates derived from α-heterosubstituted ketones and lactone by SmI2-mediated reduction". Tetrahedron 55, № 15 (1999): 4595–620. http://dx.doi.org/10.1016/s0040-4020(99)00143-x.

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47

ECK, R., and H. SIMON. "ChemInform Abstract: Synthesis of (R)-Pantoyl Lactone by Reduction of Ketopantoate with Formate and Proteus species." ChemInform 26, no. 3 (2010): no. http://dx.doi.org/10.1002/chin.199503128.

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48

FERNANDEZ, PABLO S., MARIA J. OCIO, TOMAS SANCHEZ, and ANTONIO MARTINEZ. "Thermal Resistance of Bacillus stearothermophilus Spores Heated in Acidified Mushroom Extract." Journal of Food Protection 57, no. 1 (1994): 37–41. http://dx.doi.org/10.4315/0362-028x-57.1.37.

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The thermal resistance of Bacillus stearothermophilus spores was studied in bidistilled water as the reference medium, mushroom extract and acidified mushroom extract. Citric acid and glucono-δ-lactone were used as acidulants. Results indicated that mushroom extract affects the heat resistance of spores; D values were lower than for those in bidistilled water. The pH effect was lower with higher treatment temperatures. Acidification reduced the thermal resistance of spores, the reduction being similar for both types of acidulants, and in general it also had the effect of increasing the z values. It has been confirmed that acidification of the canned mushrooms could actually help to control the thermophilic spoilage. This acidification could also be obtained by the use of glucono-δ-lactone, which has been shown to be as effective as citric acid in reducing the heat resistance of spores.

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Dunstall, George, Michael T. Rowe, G. Brian Wisdom, and David Kilpatrick. "Effect of quorum sensing agents on the growth kinetics of Pseudomonas spp. of raw milk origin." Journal of Dairy Research 72, no. 3 (2005): 276–80. http://dx.doi.org/10.1017/s0022029905000713.

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Psychrotrophs, particularly strains of Pseudomonas fluorescens, dominate the microflora of refrigerated raw milk and secrete heat-stable extracellular enzymes (proteases and lipases) which survive pasteurisation and even UHT heat treatments and degrade the casein and fat components of raw milk causing a reduction in cheese yield, gelation of UHT milk and off flavours in many dairy products. These enzymes are usually produced in the late log/early stationary growth phases when the cell density is high. This fact indicated that induction of these enzymes may be a candidate for quorum sensing, a phenomenon by which bacteria can sense and respond to cell population size by means of chemical signals based on the homoserine lactone molecule. It is assumed that the production of these enzymes contributes to the selective advantage of psychrotrophs and hence have a significant effect on their growth kinetics. In the work reported here nine proprietary homoserine lactone compounds were screened, using water as a control, for their effect on the lag phase duration (LPD) and exponential growth rate (EGR) of three strains of Pseudomonas fluorescens isolated from refrigerated raw milk after 1, 3 and 5 days storage. Two compounds viz. N-benzoyloxycarbonyl-L-homoserine lactone and N-3-oxyhexanoyl-DL-homoserine lactone were found to significantly (P<0·001) reduce the LPD and increase the EGR of the three strains. Further work with these compounds is warranted, monitoring growth in parallel with enzyme production, to determine the extent to which extracellular enzyme production is mediated by the quorum sensing phenomenon in this species.

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Evans, Kelly, Luciano Passador, Ramakrishnan Srikumar, Eric Tsang, Jonathon Nezezon, and Keith Poole. "Influence of the MexAB-OprM Multidrug Efflux System on Quorum Sensing in Pseudomonas aeruginosa." Journal of Bacteriology 180, no. 20 (1998): 5443–47. http://dx.doi.org/10.1128/jb.180.20.5443-5447.1998.

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ABSTRACT Pseudomonas aeruginosa nalB mutants which hyperexpress the MexAB-OprM multidrug efflux system produce reduced levels of several extracellular virulence factors known to be regulated by quorum sensing. Such mutants also produce less acylated homoserine lactone autoinducer PAI-1, consistent with an observed reduction inlasI expression. These data suggest that PAI-1 is a substrate for MexAB-OprM, and its resulting exclusion from cells hyperexpressing MexAB-OprM limits PAI-1-dependent activation of lasI and the virulence genes.

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