Academic literature on the topic 'Blackcurrant leaves'

Abstract The blackcurrant gall mite (Cecidophyopsis ribis) is the most important pest of blackcurrant crops. Over recent years withdrawal from plant protection programmes of chemical products (endosulfan and amitraz) used for the control of this pest in Poland, has led to an observed increase in population numbers. In 2013, fenpiroxymate (Ortus 05 SC) became registered for control of this pest. It is deemed best that chemical protection should be used during the migration period; when big gall mites emerge from buds in search of new buds. The studies were carried out in a plantation of blackcurrants during 2011-2013. The assessment of migration of the blackcurrant gall mite was carried out on the cultivars ‘Ben Hope’, ‘Ben Alde’r, ‘Ojeby’n and ‘Ruben’. Every year, from selected cultivars buds were collected. They were then placed on blackcurrant leaves within Petri dishes. After one, three and five days of placing buds on the leaves, the estimated number of eriophyid mites on the leaves was calculated. The data has shown a very useful method for monitoring blackcurrant gall mite, which can be used in calculating the treatment dates for this pest. Also, the data has shown that differences in the periods of migration of the mite are dependent on the cultivar and time of flowering. Among the cultivars observed the least susceptible to colonization by the blackcurrant gall mite was a Polish cultivar ‘Ruben’, while the most susceptible cultivar was ‘Ben Hope’.

The aim of this study was to determine the basic chemical composition, the content of bioactive compounds and antioxidant activity in currant leaves. The leaves of black, red and white currant shrubs were collected in May, and in the beginning of June, July and August, for two years between 2018 and 2019. The proximate analysis, including dry matter, protein, fat, ash and total carbohydrates, was determined. In addition, the content of the polyphenols and the total antioxidant activity using ABTS, DPPH and FRAP assays were conducted. The highest concentration of protein was detected in the whitecurrant leaves harvested in May in both years, while the highest content of crude fat was found in the blackcurrant leaves harvested in both years, with the exception of the August harvest. Extracts from the blackcurrant leaves collected in June/July 2019 had the highest antioxidant activity that was measured by the ABTS method (about 7000 µmol Trolox/g DM) and confirmed by other methods, while extracts from the whitecurrant leaves produced from the August 2018 collection had the lowest antioxidant activity (1884 µmol Trolox/g DM). Currant leaves are a rich source of bioactive compounds and contain higher amounts of polyphenols as compared with currant fruits. These compounds may play a very important role in the risk reduction and even prevention of the most chronic non-communicable diseases. Therefore, further research is needed to identify currant leaves as a source of bioactives for functional foods and natural health products. The highest antioxidant activity was in the redcurrant leaves from all the harvest times in 2018 as measured by the ABTS and FRAP methods. On the contrary, blackcurrant leaves from all the harvest times in 2019 had the highest antioxidant activity.

Antioxidant potentials of polyphenolic extracts from leaves of trees and fruit bushesThe aim of the work was to determine the antioxidant potential of extracts from leaves of strawberry, blackcurrant and apple in relation to lipids contained in the erythrocyte membrane. The studies performed have shown that the substances used protect membrane lipids against oxidation, clearly reducing the level of free radicals in erythrocyte ghosts suspension. The antioxidant activity of the substances studied follows the sequence: strawberry leaves > apple leaves > blackcurrant leaves. The results of the research on the antioxidant activity when confronted with the contents of polyphenols in the extracts indicates that the antioxidant potentials of the extracts depend both on the quantity and kind of individual polyphenols; in particular, on the kind and quantity of quercetin derivatives that constitute over 60 % of all the phenolic compounds. Moreover, the high antioxidant activity of the extracts may be also due to other, nonphenolic substances that occur in leaves. The extracts exhibit very good properties as free radical scavenges, and can thus be used as cheap, easily available, natural antioxidants in the industries where natural antioxidants in the form of fruit extracts have been used for long.

Ice formation and movement in stems, leaves, and flowers of blackcurrant were observed by infrared video thermography. Stem sections bearing leaves and racemes were cooled slowly to as low as -6.4 °C and allowed to freeze without artificial nucleation. Ice formed in stems first, then moved from stems into leaves and racemes. Patterns of ice movement were complex and depended upon the temperature of the initial nucleation event. Individual flowers froze between -1.6 and -5.5 °C. Survival of flowers after a cooling treatment depended upon whether they froze and the amount of freezing that occurred in the peduncles to which they were attached. Some flowers survived the initial freezing treatments but later died because of peduncle damage. Movement of ice from stems into peduncles sometimes was observed to occur in discrete steps, separated by time and temperature. Several independent freezing events were often observed in a peduncle, rather than one continuous event. Pedicels attached to frozen peduncles often remained supercooled for several minutes to over an hour before freezing. No consistent pattern was evident during freezing of individual flowers in an inflorescence. The range of temperature over which flowers in a single inflorescence froze was in some instances over 4 °C. Both mature and immature flowers supercooled. Barriers to movement of ice appeared to exist at certain anatomical junctions within the plant, notably where the peduncle of an inflorescence attaches to a stem and where a flower pedicel joins a peduncle. The time required for ice to pass through these barriers was inversely related to the degree of supercooling that had occurred prior to freezing.

Abstract The antioxidant capacity is the combined free radical scavenging effect of all antioxidant compounds found in the studied system. There is a growing need for accurate, numerical determination of this capacity (for easier comparison), so there are many analytical procedures, methods, and measurement systems available to researchers. Neither one is able to model the totality of real, naturally occurring reactions; therefore, conclusions about the antioxidant power of the studied sample can be drawn only after using several methods. In this work, the total phenolic content (TPC) of blackcurrant leaves and buds was determined, and the antioxidant capacity was tested using the DPPH and FRAP assays. 80% methanol was the most effective in the extraction of phenolics followed by 80% ethanol, while for the antioxidant capacity the acetone (50%)/water/acetic acid (2%) mixture proved to be the best. Significant differences were observed between cultivars and sampling dates, but the pattern of variation during the harvest period was similar for all cultivars.

Compounds contained in fruits and leaves of blackcurrant (Ribes nigrumL.) are known as agents acting preventively and therapeutically on the organism. The HPLC analysis showed they are rich in polyphenol anthocyanins in fruits and flavonoids in leaves, that have antioxidant activity and are beneficial for health. The aim of the research was to determine the effect of blackcurrant fruit and leaf extracts on the physical properties of the erythrocyte membranes and assess their antioxidant properties. The effect of the extracts on osmotic resistance, shape of erythrocytes and hemolytic and antioxidant activity of the extracts were examined with spectrophotometric methods. The FTIR investigation showed that extracts modify the erythrocyte membrane and protect it against free radicals induced by UV radiation. The results show that the extracts do not induce hemolysis and even protect erythrocytes against the harmful action of UVC radiation, while slightly strengthening the membrane and inducing echinocytes. The compounds contained in the extracts do not penetrate into the hydrophobic region, but bind to the membrane surface inducing small changes in the packing arrangement of the polar head groups of membrane lipids. The extracts have a high antioxidant activity. Their presence on the surface of the erythrocyte membrane entails protection against free radicals.

Ce travail aborde la question de la standardisation, de la répétabilité et de l'optimisation de l'extraction des plantes médicinales dans l'eau. Trois plantes ont été sélectionnées, pour lesquelles les activités pharmacologiques complémentaires reposent sur les différents flavonoïdes, dont deux sont bien documentées (sommités fleuries d'aubépine et feuilles de cassis) avec des propriétés bien connues, et la troisième a été peu étudiée (Chrysanthellum americanum). Nous avons établi un protocole d'extraction général dans l'eau basé sur l’infusion pour ces trois plantes, utilisable par chacun de nous, qui peut permettre une absorption quotidienne standardisée et reproductible de composants bioactifs (phénols, flavonoïdes, oligomères proanthocyanidines) à une température buvable. La granulométrie est le facteur le plus important pour obtenir les meilleurs rendements d'extraction (environ 22% pour l'aubépine, 26% pour le Chrysanthellum americanum et 28,5% pour le cassis). La composition chimique de ces plantes a été étudiée par des méthodes colorimétriques, ainsi que par des instruments analytiques performants et complémentaires (UHPLC-ESI-MS et FT-ICR MS). Les extraits de cassis contiennent beaucoup plus de composés phénoliques (les principaux composants détectés en UV étant les flavonols) que les deux autres plantes. Les extraits d'aubépine contiennent beaucoup plus d'oligomères de proanthocyanidines (les principaux composants détectés en UV étant les flavanols, les flavonols et les flavones) que les deux autres plantes. Les extraits de Chrysanthellum americanum et de cassis contiennent des quantités similaires de flavonoïdes, le premier contenant essentiellement des dérivés d'acide hydrocinnamique, des flavones, des flavanones et des aurones comme composants détectés en UV. Environ 2500 molécules ont été détectées pour chaque plante, parmi lesquelles environ 25% sont communes aux 3 plantes et environ 15% sont spécifiques à chaque plante. Des dérivés de quercétine et de kaempférol ont été identifiés dans les extraits de feuilles de cassis, tandis que la vitexine-2-O-rhamnoside, l'hyperoside et l'isoquercétine ont été identifiés dans les extraits de sommités fleuries d'aubépine, et des dérivés de flavanomaréine et de martitimeine, ainsi que l'acide oléanolique ou ursolique ont été identifiés dans les extraits de Chrysanthellum americanum. Une inhibition intéressante de la hyaluronidase (≥ 90%) a été rapportée pour les extraits d'aubépine, bien supérieure à celle des deux autres extraits de plante. Quant à l'activité anti-hypertensive, les extraits de Chrysanthellum americanum ont démontré une inhibition de l'ECA plus élevée que les deux autres extraits de plante. Concernant l'activité antioxydante, les extraits de feuilles de cassis ont montré la capacité antioxydante la plus élevée. Enfin, la formation de nanoparticules dans les infusions (appelées teacreaming) a été étudiée d'un point de vue cinétique et rayon hydrodynamique en fonction de la température
This work deals with the question of standardization, repeatability and optimization of medicinal plant extraction in water. Three plants were selected, for which the complementary pharmacological activities are based on different flavonoids, two of which are well documented (hawthorn flowering tops and blackcurrant leaves) with well-known properties, and the third one has been little studied (Chrysanthellum americanum). We established a general extraction protocol in water for these three plants that can be used by each of us, based on infusion that can afford a reproducible daily uptake of bioactive components (phenols, flavonoids, proanthocyanidin oligomers) at drinkable temperature. Granulometry was the most important factor to get the best extraction yields (about 22% for hawthorn, 26% for Chrysanthellum americanum and 28.5% for blackcurrant). Chemical composition of these plants was investigated by colorimetric methods, and also using performant and complementary analytical instrumentations (UHPLC-ESI-MS and FT-ICR MS). Blackcurrant extracts contained much more phenolic compounds (the main UV-detected components detected in UHPLC being flavonols) than the two other plants. Hawthorn extracts contained much more proanthocyanidin oligomers (the main UV-detected components in UHPLC being flavanols, flavonols and flavones) than the two other plants. Chrysanthellum americanum and blackcurrant extracts contained similar amounts of flavonoids, the former one containing essentially hydrocinnamic acid derivatives, flavones, flavanones and aurones as UV-detected components. About 2500 hints were obtained for each plant, among which about 1100 are common to all 3 plants and about 700 are specific to each plant. Quercetin and kaempferol derivatives were identified in blackcurrant leaves extracts, while vitexin-2-O-rhamnoside, hyperoside and isoquercetin were identified in hawthorn flowering tops extracts and flavanomarein and martitimein derivatives, and Oleanolic or Ursolic acid were identified in Chrysanthellum americanum extracts. A significant inhibition of hyaluronidase (≥ 90%) was reported for hawthorn extracts, much higher than that of the other two plant extracts. As for the anti-hypertensive activity, the Chrysanthellum americanum extracts demonstrated higher ACE inhibition than the other two plant extracts. Regarding antioxidant activity, blackcurrant leaf extracts showed the highest antioxidant capacity. Finally, the formation of nanoparticles in the herbal tea infusions (also known as tea creaming), was studied from a kinetic and size-distribution point of view as a function of temperature

Natural products and derivatives thereof have contributed significantly to drug discovery and development and have also been used in traditional medicine for the treatment of various disease states. Sometimes, the use of such traditional medicines may be based upon many hundreds, if not thousands, of years of human experience. An advantage of drugs derived from natural products compared to synthetic drugs is their availability and the likelihood of reduced side effects. Drugs and drug leads derived from natural products may also be less time consuming and expensive to develop and may be more accessible to developing countries. An exciting advance in this area is the application of computational chemistry to potentially bioactive molecules that can be identified in such natural products. Thus, the structural and physicochemical properties of such molecules can be reconciled with current theories on the molecular aspects of a given disease and/or be used to improve upon such theories or to develop new ones. Computed properties may also be benchmarked to experimental data for isolated molecules of interest that can lead to improved molecular design. In this context, two different strategies have been devised and implemented for the identification and development of potentially bioactive compounds from medicinal plant materials whereby reliable molecular structures and experimental data, that have been previously reported in the peer reviewed scientific literature, have been reconciled with carefully designed computational chemistry calculations and/or further experimentation - with a view to (I) developing improved antioxidants as potential anti-inflammatory drugs and (II) to identify small molecule potential metal chelators that may pass through the blood brain barrier and potentially ameliorate neurodegenerative diseases such as Alzheimer’s or Parkinson’s disease. Thus two bioactive products derived from medicinal plants, namely Ribes nigrum (Blackcurrant leaves) and Bacopa Monnieri (Brahmi tea), that are traditionally employed to treat rheumatic disease and neurodegenerative symptoms, respectively, have been chosen for investigation under these strategies. These plant materials have been extensively investigated in the scientific literature in terms of the identification of the structures of their potentially bioactive molecules and also with respect to experimental and biological investigations. For the former material, the purported anti-inflammatory effects of the component poly phenolic molecules, in terms of their reported experimental radical scavenging propensities, have been reconciled with their computed antioxidant capacities. These have also been related to a range of computed qualitative and quantitative structural and physicochemical properties. This is with a view to optimizing their antioxidant potential and possibly designing anti- inflammatory drug candidates. For the latter material, a screening of the reported molecular structures of potentially bioactive components has identified two smaller molecular fragments, namely the isomers jujubogenin and pseudojujubogenin, that may also be present in the plant extract and that are deemed capable of passing through the blood brain barrier and complexing transition elements within the brain, specifically copper and/or zinc, that are associated with stabilizing the amyloid plaque of Alzheimer’s disease, or iron, that may over-load the substantial nigra in Parkinson’s disease. In this thesis, the metal complexes of these two molecules have been modelled utilizing semi-empirical quantum chemistry and density functional calculations and the characteristics of the copper, zinc and iron complexes have been described. These studies clearly show that the diaquo, square planar copper complex of jujubogenin is the preferred structure, revealing that jujubogenin is an excellent bidentate ligand for this particular transition metal. The corresponding zinc complex was also shown to be feasible, but less likely to form; whereas the iron complex was shown not to be accommodated at all. To complement these studies, the Brahmi tea material was extracted with a range of solvents, and fractions were systematically subjected to ESI- MS. Scrutiny of the resultant spectra revealed the presence of the protonated jujubogenin moiety in one of the ethyl acetate fractions. Subsequent spiking of this fraction with copper, zinc and iron revealed the presence in the spectra of the diaquo copper complex of jujubogenin, exactly as predicted from the computer modelling. Notably, no zinc or iron complexes could be detected and competition experiments only revealed the presence of the copper complex - also consistent with the computer modelling. Subsequent MS/MS experiments on the copper complex yielded the free ligand. In summary, for possible anti-inflammatory agents, these investigations show that the computed homolytic bond dissociation energies of the component poly phenolics, by themselves, are not sufficient to explain enhanced antioxidant activity and suggest that other properties such as molecular conformation, steric effects and, in particular, the magnitude and direction of the dipole moment also have important roles to play. In relation to possible drug leads for the treatment of neurological conditions, the discovery of the extraordinary copper specificity of the jujubogenin molecule, both computationally and experimentally, makes this molecule a candidate for a BBB penetrating chelating agent that could be active towards the amelioration of Alzheimer’s disease and possibly other conditions. This is an exciting discovery and warrants the isolation of jujubogenin and its derivatives in for further testing. Thus, the design and implementation of the key strategies devised and described within this thesis and their respective application to two selected traditional medicines relating to specific disease states, is demonstrably useful in the rational design of drug candidates and suggest new avenues for future research.