Comparative determination of antioxidant activities and phytochemicals from fractions of ethanol extract of Senna occidentalis using GC-MS

Medicinal plants have been the mainstay of traditional herbal medicine. Their medicinal properties are due to the presence of phytochemicals which exert pharmacological effects on the body. In this study, phytochemicals from partially purified fractions of ethanolic extract of Senna occidentalis leaf were comparatively determined using GC-MS. Fractionation was carried out using solvents of different polarities, namely n-Hexane, Chloroform, Ethyl acetate, Ethanol, Methanol and water. The total phenolic content (TPC), Total flavonoids content, metal chelating activity of the fractions were determined. The result for Total Anti-Oxidant Capacity (TAC) showed that fractions 2a and 6a have the highest capacity (128.8µg/ml), followed by 6b (112µg/ml), 4a (86.8 µg/ml), 7a (84 µg/ml) and lastly 9a&2b (81.2 µg/ml). The decrease in the TAC of the fractions was in the order: 2a&6a>6b>4a>7a>9a&2b>3a&10a, with 3a and 10a having the lowest TAC. The result for Total Phenolic Content (TPC) showed that fraction 1b had the highest concentration of total phenol content (97.5mg/ml), followed by F9b (78mg/ml). F6b has the lowest concentration (1.95mg/ml). The result for Total Flavonoids Content (TFC) shows that fraction 1a had the highest concentration (2373mg/ml), followed by F3a (2226mg/ml). Fractions F8a, 8b, F9a, F9b, and F10b had the lowest concentration (21.0mg/ml). The fractions with higher TAC, TPC and TFC were subjected to GC-MS analysis, revealing compounds of diverse pharmacological and industrial applications. The fraction eluted with ethyl acetate + chloroform contained fatty acid esters with %Area ≥ 1(Heptanoic acid octyl ester 55.42%), the fraction eluted with ethyl acetate + methanol contains both fatty acid esters and glycosides presented as % Area ≥1 (Cyclononene 23.70 %). The fraction eluted with Methanol showed high concentrations of essential oils presented as % Area ≥1 (Oleic Acid 59.57%). These properties of Senna occidentalis revealed that the fractions contain the active ingredients that are the major targets for drug development. The presence of high concentrations of flavonoids, phenolic compounds, fatty acids and essential oils in this plant does not only predispose it to a very good antioxidant property but can also can be used as a natural source of antioxidants towards the prevention of disease progression.