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Title : Antioxidant Polyphenolics : Common factors of prophylaxis in Mauritian plant based foods and the endemic flora T. Bahorun1, V.S. Neergheen1, V. Luximon-Ramma1, M.A, Soobrattee1, A. Crozier2 and O.I.Aruoma3 1 Department of Biosciences, Faculty of Science, University of Mauritius Plant Products and Human nutrition Group, Graham Kerr Building, Division of Biochemistry and Molecular Biology, Institute of Biomedical and life Sciences, University of glasgow, Glosgow G128QQ, UK 3 Department of pharmaceutical and Biomedical Sciences, Touro College of Pharmacy, 230 West 125th Street, New York, NY 10027, USA 2 Abstract : A large number of studies provide convincing evidence of the beneficial role of plant foods and their nutraceuticals for the maintenance of health (Kris-Etherton et al, 2002) Epidemiological studies show a protective effect of fruits, vegetables, plant preparations and beverages like teas against the risk of development of chronic diseases such as cancer, atherosclerosis, cardiac dysfunctions, diabetes, hypertension and neurodegenerative disorders (Bazzano et al, 2001 ; Singh et al, 2002) . The benefits that plant rich diets confer are believed to be ascribed to various antioxidants, especially carotenoids and antioxidant vitamins including ascorbic acid and tocopherols. However the antioxidant capacity of a particular plant extract may originate from compounds other than ß-carotene, vitamin C or vitamin E. The significance of phenolics such as catechins, phenylcarboxylic acids, phenylpropanoids, anthocyanins and proanthocyanidins as dietary antioxidants in fruits, vegetables, medicinal plant extracts and teas is being, in this respect increasingly suggested (Bahorun et al, 2004 ; Vági et al, 2005) . The antimutagenic, antibacterial, anti-inflammatory, antithrombotic and vasodilatory actions of polyphenolics are well characterized (Middleton et al, 2000) and accumulating chemical, biochemical, clinical and epidemiological evidence supports the chemopreventive effects of phenolic antioxidants against oxidative stress-mediated disorders (Mandel and Youdim, 2004). The pharmacological actions of phenolic antioxidants are strongly suggested to stem mainly from their free radical scavenging and metal chelating properties as well as from their effects on cell signaling pathways and on gene expression (Toyokuni et al 2003, Soobrattee et al, 2005). Mauritius is a tropical island in the Indian Ocean with a relatively high prevalence of cardiovascular diseases ( 51% of total annual deaths), cancers ( 11% of total deaths and diabetes ( 20% of the Mauritian population affected). Dietary nutraceuticals from food and medicinal plants are widely suggested to have prophylactic effects against reactive oxygen and nitrogen species ( ROS and RNS) mediated pathologies. This has triggered interest in the role of natural antioxidants as a therapeutic strategy for the management of diseases in many countries. In this regard, the biopotency and antioxidant prophylactic properties of Mauritian plant based foods and endemic plant species were investigated (Mersch-Sundermann et al, 2006 ; Neergheen et al, 2006 ; Bahorun et al, 2007 ; Soobratee et al, 2008). Furthermore the protective effects of black tea infusates on a number of markers of oxidative stress indicative of ischaemic heart diseases among the Mauritian population was assessed in a clinical trial. 17 commonly consumed exotic fruits were analysed for their antioxidant capacity, total phenolics, proanthocyanidins, flavonoids and vitamin C content. The antioxidant activities of the fruits ranged from 1 to 47 μmol Trolox equivalent (TEAC) g –1 fresh weight and from 11 to 360μmol ferric reducing antioxidant power (FRAP) g-1 fresh weight. Total phenolics in the fruits ranged from 118 to 638 μg g-1 fresh weight, proanthocyanidins from 7 to 2561 μg g-1 fresh weight, flavonoids from 21 to 712 μg g-1 fresh weight and vitamin C content from 8 to 1426 μg g-1 fresh weight. There were strong correlations between antioxidant activity (assessed by both TEAC and FRAP) and total phenolics and proanthocyanidins. Flavonoids seemed to contribute less to the antioxidant potential of the fruits, while very poor correlations were observed between ascorbate content and antioxidant activity. The highest antioxidant capacities were observed in red and yellow Psidium cattleianum Sabine ‘Chinese guava’, sweet and acid Averrhoa carambola L ‘starfruit’, Syzygium cumini L Skeels ‘jamblon’ and white Psidium guajava L ‘guava’. These fruits were also characterised by high levels of total phenolics. Antioxidant activities of the 10 vegetables analysed ranged from 0.43 to 3.68 μmol g-1 fresh weight Trolox equivalent antioxidant capacity (TEAC) and from 0.60 to 8.47 μmol g-1 fresh weight ferric reducing antioxidant power (FRAP). Levels of total phenols in the vegetables varied between 132 and 1189 μg g-1 fresh weight and those of total flavonoids between 45 and 944 μg g1 .fresh weight, while proanthocyanidins were detected at very low levels in only a few vegetables. Vitamin C contents varied between 25 and 748 μg g-1 fresh weight. Quercetin was the dominant flavonoid aglycone in the hydrolysed vegetable extracts, with values in the range of 15-390 μg g-1 fresh weight. There were strong correlations between antioxidant capacity and total phenols (TEAC, r = 0.91 ; FRAP, r = 0.83) and total flavonoids (TEAC, r = 0.89 ; FRAP, r = 0.82). Vitamin C contents showed poor correlation with TEAC values (r = 0.33), while no correlation was observed with FRAP values. Highest antioxidant capacities were observed in Chinese cabbage (Brassica chinensis L), onion (Allium cepa L), mugwort (Artemisia vulgaris Cantley) and broccoli (Brassica oleracea L var botrytis L subvar cymosa). Mauritian endemic plants from the Celastraceae, Erythroxylaceae, Ebanaceae, Rubiaceae, Sterculaceae, Myrtaceae family were assessed and correlated to their in vitro antioxidant propensities. A multi-antioxidant assay approach (8 independant assays) was employed to evaluate the antioxidant capacity of the plant extracts. The data indicate that Eugenia pollicina, E. orbiculata, S. commersonii, S. glomeratum, S. mauritianum from the Myrtaceae family and Diospyros species from the Ebenaceae family had important levels of phenolics and were potent antioxidants. Levels of total phenol ranged from 1 to 103 mg gallic acid equivalent/g fresh weight while the flavonoid content was estimated between 1 to 16 mg quercetin equivalent/g fresh weight. HPLC analyses indicated the presence of significant amounts of catechins and their derivatives, procyanidin dimers and flavonol aglycones. Since plant-derived natural phytochemicals have shown great potential in the fight against cancer, this research work has been geared towards the evaluation of the chemopreventive potential of the Mauritian endemic plant extracts against human cancer cell lines. Leaf extract of Monimiastrum globosum at low concentrations (98 and 195 μg FW/ml) protected benzo[a]pyrene- dependent DNA damage in human hepatoma cells, thus exhibiting anti-genotoxic effects. In the same vein, plant extracts from the genus Eugenia, Syzygium and Myonima (concentration range of 0.05-4 mg FW/ml) showed promising anti-proliferative activities against MDAMB 231 and MCF-7 human breast cancer cell lines. Apoptosis has been proposed as a potential target in chemoprevention and in this study E. pollicina (concentration of 0.5 mg FW/ml) was shown to induce apoptosis of MCF-7 breast cancer cells. The in vivo investigation of black tea consumption in a randomised clinical trial revealed that daily consumption of a Mauritian black tea infusate (9 g daily) had a reducing effect on high fasting serum levels of glucose (> 140 mg/dl: 20%), cholesterol (> 220 mg/dl: 16 %), triglycerides (> 200 mg/dl: 56%), LDL/HDL ratio (> 3: 37%), uric acid (> 7 mg/dl: 8.5 %), creatine kinase MB (> 200 U/L: 33%), C-reactive protein (> 4 μg/L: 77%) and GOT/GPT ratio (> 2: 35%) while blood plasma showed an increase in antioxidant status as evaluated by the FRAP assay (0.2-0.8 mmol/L: 175%) and TEAC assays (1-2 mmol/L: 32%). The above collective data clearly indicate that Mauritian fruits, vegetables and black tea represent rich sources of prophylactic antioxidant nutraceuticals that could used as supplements in a balanced diet within existing programs in the management of chronic diseases. It can also be envisaged that Mauritian endemic plant extracts with their high levels of phenolic antioxidants can offer a realistic promise to reduce the incidence of cancer and other oxidative stress mediated disorders including cardiovascular disorders and neurological diseases. References : Bahorun, T.; Luximon-Ramma, A.; Crozier, A.; Aruoma, O.I. Total phenol, flavonoid, proanthocyanidin and vitamin C levels and antioxidant activities of Mauritian vegetables, J Sci Food Agric. 2004, 84, 1553-1561. Bahorun, T, Neergheen, V.S., Soobrattee, M.A., Luximon-Ramma, A. and Aruoam, O.I. Prophylactic phenolic antioxidants in functional foods of tropical Island States of the Mascarene Archipelago (Indian ocean). In : J. Losso, F. Shahidi and D. Bagchi, eds Marcel Decker Incorporation, New York, 2007 149-176 Bazzano, L.A.; He, J.; Ogden, L.G. Legume consumption and risk of coronary heart disease in US men and women: NHANES I epidemiologic follow-up study. Arch Intern Med. 2001, 161, 2573-2578. Kris-Etherton, P. M.; Hecker, K. D.; Bonanome, A.; Coval, S. M.; Binkoski, A. E.; Hilpert, K. F.; Griel, A. E.; Etherton, T. D. Bioactive compounds in foods: their role in the prevention of cardiovascular disease and cancer. Am J Med. 2002,113, 71S-88S. Mandel, S.; Youdim, M.B.H. Catechin polyphenols: neurodegeneration and neuroprotection in neurodegenerative diseases. Free Rad Biol Med. 2004,37, 304 Mersch-Sundermann V., Bahorun T, Stahl T., Neergheen V.S., Soobrattee M.A, Wohlfarth R., Sobel R., Brunn H.E., Schmeiser T., Lamy E. and Aruoma O.I. Assessment of the DNA damaging potency and chemopreventaive effects tpwards BaP-induced genotoxicity in human derived cells by Monimiastrum globusum, an endemic Mauritian plant, Toxicology in Vitro, 2006, 1427-1434 Middleton, E.Jr.; Kandaswami, C.; Theoharides, T.C. The effects of plant flavonoids on mammalian cells: implications for inflammation, heart disease and cancer. Pharmacol Rev. 2000, 52, 673-839. Neergheen V.S., Soobrattee A.A., Bahorun T. and Aruoma O.I. Characterization of the phenolic constituents in Mauritian endemic plants as determinants of their antioxidant activities in vitro, Journal of Plant Physiology, 2006, 787-799. Singh, R.D.; Dubnov, G.; Niaz, M.A.; Ghosh, S.; Singh, R.; Rastogi, S.S.; Manor, O.; Pella, D.; Berry, E.M. Effect of an Indo-Mediterranean diet on progression of coronary artery disease in high risk patients (Indo-Mediterranean Diet Heart Study):a randomized single-blind trial. Lancet. 2002,360, 1455-1461. 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