Academic literature on the topic 'Carpobrotus rossii'

"Metabolic syndrome" refers to the triumvirate of obesity-related, cardiovascular diseases such as hyperlipidaemia, type 2 diabetes, atherosclerosis and hypertension. The worldwide prevalence of these diseases have increased to such an extent that they are now the leading cause of human morbidity and mortality. Metabolic syndrome is characterised by elevated levels of plasma lipids, hyperglycaemia, compromised insulin signalling, excessive production of reactive oxygen species (ROS) and a vasculature that is in a persistently inflamed state. Because of the increasing prevalence of these diseases, considerable research effort has gone into understanding the disease processes and developing appropriate therapies. Two metabolic syndrome targets which have been identified and for which therapeutics have been successfully developed are hyperlipidaemia and hyperglycaemia. A common target of the lipid-lowering therapies is the HMG-CoA reductase enzyme which catalyses the rate limiting step in the cholesterol synthesis pathway namely the conversion of 3-hydroxy-3-methylglutaric acid coenzyme-A (HMG-CoA) to mevalonate. Statins are the primary class of drugs with this HMG-CoA inhibiting ability. Polyphenolic compounds produced by plants have also been shown to have hypolipidaemic activity by inhibiting HMG-CoA as well as other enzymes involved in the processes of lipid manufacture and delivery to cells. Polyphenolic compounds have also been shown to improve the glucose status of diseased subjects by improving vascular health, improving insulin signalling and glucose uptake into muscle. Of these plant-derived polyphenolic compounds, members of the flavonoid sub-family been shown to be particularly successful in treating both hyperlipidaemia and hyperglycaemia. Carpobrotus rossii (CR) is a succulent halophyte native to Australia and commonly found growing along the coastal margins of southern Australia. The plant has a history of use by both the indigenous aboriginal population and early Tasmanian settlers. CR was reportedly consumed as a food, to treat gastrointestinal upsets, and applied topically for the treatment of bites and scratches. Preliminary investigations conducted at the University of Tasmania have shown that crude extracts from its leaves inhibit platelet aggregation, inflammatory cytokine release (interleukin-1-beta, tumour necrosis factor-alpha) and lipid oxidation in vitro (Geraghty et al., 2011). This activity is believed to be due to the flavonoid compounds that the plant produces in its leaves. Several of these flavonoids have a known HMG-CoA inhibitor 3-hydroxy-3methylglutaric acid (HMG) present as a substituent (Jager, 2009).The presence of this moiety, in conjunction with the known hypoglycaemic and hypolipidaemic activities of other flavonoids, mean that the consumption of CR flavonoids could potentially improve endothelial health, cardiovascular function and health via a combination of effects related to both their flavonoid and statin properties. In planta, the primary function of flavonoids appears to be as antioxidants, and their production has been shown to be induced under a suite of conditions which cause the plant to experience oxidative stress. The ROS generation and signalling process in planta are complex, and the effect of environmental conditions on a plant's redox status, and hence flavonoid production, is likely to vary between species. The effects of environment on flavonoid product has not been previously investigated for CR. The flavonoid structures described in chapter 4 are extremely complex, and based on informal discussions with an organic chemist familiar with similar compounds, not easily amenable to synthesis. As such, the ability to produce sufficient material and improve the efficiency of their production e.g. increasing biomass or increasing flavonoid concentration by the modification of environmental parameters is a key component of overall CR pharmaceutical and nutraceutical investigations. This thesis has involved using techniques relevant to the disciplines of pharmacology, organic chemistry and plant physiology. The primary aims were to investigate the pharmaceutical and nutraceutical potential of the flavonoids derived from CR leaves. To do this, several basic questions were addressed, namely: 1. What effect do environmental conditions have on metabolite production, 2. What is the structure of the CR flavonoids, 3. Is the consumption of CR leaf derived extracts safe, and, 4. Do the CR leaf flavonoids possess pharmacological activity in metabolic syndrome, specifically an improvement in either glycaemic or lipid profile. A suite of novel findings which pave the way for further study of this plant are the result of this research. The body of the thesis is presented as a series of articles for publication, of which three are published at the time of thesis submission.

Type 2 diabetes mellitus (T2DM), driven by overweight and obesity linked to unhealthy diets, is the fastest-growing non-communicable disease in Australia. Considering that food is an important parameter in the regulation of blood glucose response, replacing ‘junk food’ with products that are good regulators of postprandial blood glucose (PPG) may go a long way to reduce the rate of T2DM in Australia. This study was designed to develop new food products that have the potential for use as nutritional preventatives against escalating levels of T2DM within the Australian Indigenous community. Edible portions of eight Australian native plant species namely; Leucopogon parviflorus, Arthropodium strictum, Carpobrotus rossii, Rhagodia candolleana, Typha orientalis, Correa alba, Dianella revoluta and Acacia longifolia were collected from the coast of Warrnambool, Victoria Australia. The plant species were analysed for proximate, minerals, fatty acids and phenolic composition following the methods of the Association of Official Analytical Chemistry (AOAC), Inductively Coupled Plasma Spectometry (ICP), High performance liquid chromatography (HPLC) and gas chromatography/Mass spectrometry analysis (GCMS). Plant species that exhibited significantly high amounts of nutrients, antioxidants and antidiabetic polyphenols were selected for development of potential antidiabetic food preventatives. The developed food products (Acabungi flakes and crackers) were evaluated for acceptability and the cracker was further studied for stability and microbiological load. Its Glycaemic index (GI) was estimated by in-vitro enzymatic starch hydrolysis. All eight plant species were found to be sources of carbohydrates (39.7 - 65.5%), proteins (2.6 - 15.1%), fats (1 - 14.3%), total dietary fibre (1.5 - 17.2%) and contained Ca, Mg, Na and K. The species exhibited consistent antioxidant activity with phyto-components of gallic acid (GA), epigallocatechin (EPC), catechin (CH), epigallocatechingallate (EPG), dihydroquinidine (DHQ), ρ-coumaric acid (PCA) and luteolin (LT). The betacyanin, betanidin 5-O-β-glucoside (BT) was detected in R. candolleana (700 mg/kg) and C. rossi (244 mg/kg) while the alkaloid, Dihydroquinidine (DHQ) was detected in D. revoluta (101 ± 5.7 mg/kg) and T. orientalis (17 ± 7.1 mg/kg). However, not all the compounds were isolated from a single plant species and except for BT, higher quantities of components were extractable in methanol than water (P<0.05). Palmitic, oleic and linoleic acids were the dominant of 10 fatty acids detected in the native species with record quantities of 4.2 - 39%, 12.3 - 39% and <0.5 - 44% respectively. No single species had all 10 fatty acids. The cracker, with a record overall consumer acceptability of 70.5% remained stable and unchanged with no microbial growth after 35-days storage at room temperature under light and in the dark. The cracker contained significant amounts of total dietary fiber, proteins, complex carbohydrates and exhibited a low GI of 47.7. R. candolleana and A. longifolia were found to have high contents of betanin and linoleic acid respectively, two components with potentially wide industrial application. Further studies to determine the antidiabetic mechanism of action of the cracker would shed more light on its potential application.