Isolation, identification and characterization of gallic acid derivatives from leaves of Tapinanthus bangwensis

Gallic acid and its derivatives are widely present in the plant kingdom and are known to display antioxidant activity by the ability to counteract the damaging effects of free radicals in tissues and thus are believed to protect against cancer, arteriosclerosis, heart disease, and several other diseases. Hence, the present work describes the isolation of gallic acid derivatives from the ethyl acetate fraction of leaves of T. bangwensis. The structures of three phenolic acids of gallic acid derivatives namely; Methyl syringate (1), 3,4,5triomethyl gallic acid (2) and 3, 4dimethoxy-5hydroxyl benzoic acid (3) were determined using data obtained from FAB-MS, H and C NMR spectra as well as by various correlation experiments (COSY, NOESY, HMQC and HMBC). The result corroborates the therapeutic potential of T. bangwensis. The possible mechanisms of action may be attributed to the presence of these polyphenolic compounds isolated from the leaves of T. bangwensis. Keyword: Gallic acid derivatives; T. bangwensis; Fractionation; Phenolic compounds. INTRODUCTION The search for antioxidants from natural products is on the increase as against antioxidants of synthetic origin. It has been reported that reactive oxygen species (ROS) readily attack and induce oxidative damage to various biomolecules including proteins, lipids, lipoproteins and DNA (Faber, 1994; Heikal, et al., 2012). Therefore, the need to develop natural antioxidants that will aid in the slowdown of the oxidative damage caused by oxidation is of primary concern. Antioxidant has been defined as any substance that delays, prevents or removes oxidative damage to a target molecule’’ (Halliwell, 2007). Halliwell and Gutteridge (1995) also defined antioxidants as any substance that when present at low concentrations compared with that of an oxidizable substrate significantly delays or inhibits oxidation of that substrate. Gallic acid (GA, 3, 4, 5-trihydroxybenzoic acid) and its derivatives are widely present in the plant kingdom and represent a large family of plant secondary Journal of Natural Products