Characterization of the Phenolic Constituents in Mauritian Endemic Plants As Determinants of Their Antioxidant Activities in Vitro

ARTICLE IN PRESS

Journal of Plant Physiology 163 (2006) 787—799

www.elsevier.de/jplph

Characterization of the phenolic constituents in Mauritian endemic plants as determinants of their antioxidant activities in vitro

Vidushi S. Neergheena, Muhammad A. Soobratteea, Theeshan Bahoruna,Ã, Okezie I. Aruomab,ÃÃ aDepartment of Biosciences, Faculty of Science, University of Mauritius, Re´duit, Republic of Mauritius bFaculty of Health and Social Care, London South Bank University, Borough Road, London SE1 0AA, UK

Received 22 May 2005; accepted 26 September 2005

KEYWORDS Summary Mauritian endemic The phenolic constituents of Mauritian endemic plants from the Rubiaceae and plants; Myrtaceae family were assessed and correlated with their potential antioxidant African medicinal activities in vitro. The antioxidant activities of the plant extracts ranged from 0.27 plants; to 1.49 mmol Trolox equivalent/g FW and from 0.20 to 1.39 mmol Fe(II) equivalent/g Myrtaceae genus; FW in the TEAC and FAP assays, respectively, with Syzygium commersonii showing the Rubiaceae genus highest activity in these two systems. Eugenia orbiculata and all the Syzygium species were effective scavengers of hypochlorous acid while Monimiastrum acutisepalum was the most potent inhibitor of deoxyribose degradation. The plant extracts inhibited microsomal lipid peroxidation with low IC50 s ranging from 0.02 to 1.75 mg FW/mL when reaction was initiated with Fe3+/ascorbate and from 0.093 to 1.55 mg FW/mL in the AAPH-dependent lipid peroxidation. The potential prooxidant nature of the plant extracts was compared with ascorbate (250 mM) using copper–phenanthroline assay. The plant extracts at concentrations up to 5 g FW/L were not prooxidant. However, Myonima nitens, Syzygium commersonii, Syzygium glomeratum and Syzygium mauritianum at concentrations of 10 g FW/L had potency approaching 50% of the prooxidant activity of ascorbic acid in vitro, suggesting relative safeties. The total phenolics inﬂuenced the antioxidant activities in the TEAC, FRAP and HOCl scavenging assays whereas a negative correlation was observed with the deoxyribose assay. The high levels of polyphenolic compounds and the

Abbreviations: AAPH, 2, 20-azobis(2-amidinopropane) hydrochloride; FRAP, ferric reducing antioxidant power; TEAC, Trolox equivalent antioxidant capacity ÃCorresponding author. ÃÃAlso for correspondence. E-mail addresses: [email protected] (T. Bahorun), [email protected] (O.I. Aruoma).

788 V.S. Neergheen et al.

Introduction levels of phenolic compounds in endemic plant species previously studied (Toyokuni et al., 2003). There is a growing body of evidence suggesting Several of these endemics have already been that free radicals play an important role in the reported in the traditional pharmacopoeia against development of tissue damage and pathological a wide range of disorders including bronchitis, events in living organisms (Aruoma, 1998; Lefer and diabetes, asthma and inflammatory diseases (Gur- Granger, 2000; Smith et al., 2000; Bhatia et al., ib-Fakim, 1996). The antioxidant activity of some 2003; Olinski et al., 2003; Peuchant et al., 2004). Mauritian endemic plants of the Rubiaceae and Lipid peroxidation of fats and fatty acids in foods Myrtaceae family comprising the Myonima, Ferne- results not only in their spoilage but is also a source lia, Eugenia, Monimiastrum and Syzygium species of peroxyl and hydroxyl radicals that are associated (Table 1) were examined using the antioxidant with carcinogenesis, mutagenesis and aging (Yagi, assays Trolox equivalent antioxidant capacity 1987; Finkel and Holbrook, 2000). Therefore, (TEAC), ferric reducing antioxidant power (FRAP), antioxidants that scavenge reactive oxygen species hypochlorous acid (HOCl) scavenging, deoxyribose, (ROS) and reactive nitrogen species (RNS) may be of copper–phenanthroline and lipid peroxidation. The major importance in preventing the onset and/or antioxidant potency was then related to their total the progression of oxidative pathologies and pro- phenolic, proanthocyanidin and flavonoid content. vide protection to foods. This study is the first of its kind to report the Many health-related properties including antic- antioxidant effectiveness of some selected Mauri- ancer, antiviral, antimicrobial, anti-inflammatory tian endemic plants. Thus the endemic plants from activities, antioxidant properties, effects on capil- the Rubiaceae and Myrtaceae family could be lary fragility, and an ability to inhibit human potential sources of dietary polyphenolic antiox- platelet aggregation have been ascribed to pheno- idant compounds that may have potential benefits lics (McGregor et al., 1999; Spignoli, 2000). The in health and disease management. physiological benefits of the plant phenolics have been attributed to their potential role in inhibiting lipid peroxidation, modulating cell signal transduc- tion pathways and inducing apoptosis (Lin et al., Materials and methods 1999; Hou et al., 2004; Wiswedel et al., 2004). The tropical island of Mauritius is endowed with a Plant material unique flora, resulting from colonization and adaptive radiation of plant species from different Mature leaves of Syzygium commersonii, Syzy- sources. Tropical plants are generally tolerant of gium glomeratum, Syzygium mauritianum, Eugenia high levels of environmental stress induced by pollicina were obtained from Brise Fer forest ultraviolet radiation thereby explaining the high (centre of Mauritius). Fernelia buxifolia, Syzygium

Table 1. Endemic plants used in this study

Family Plant species Common name Traditional use

Rubiaceae Fernelia buxifolia Bois Chauve souris, Bois de buis Rubiaceae Myonima nitens Petit bois de pintade Rubiaceae Myonima obovata — Myrtaceae Eugenia elliptica — Myrtaceae Eugenia orbiculata — Myrtaceae Eugenia tinifolia Bois de neﬂes Purgative Myrtaceae Monimiastrum acutisepalum Bois de Clous Myrtaceae Syzygium commersonii Bois de Pomme Myrtaceae Syzygium glomeratum Bois de Pomme Use in the treatment of migraine Myrtaceae Syzygium mauritianum — Myrtaceae Syzygium venosum — Download English Version: https://daneshyari.com/en/article/2057343

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