Phytochemical Screening, GC-MS Analysis and In vitro Antioxidant Studies of Ethanol Extract of Icicinia mani (Earth Balls) Tubers

Abstract

Introduction: Icicinia mani also known as Efik-isong in Ibibio is a potential feed material for animals including humans. There are reports that commercial producers of garri, a major staple food in Southern Nigeria combine large quantities of Icicinia mani tubers with cassava to increase their production. In this study, we conducted the phytochemical screening, GC-MS analysis and in vitro antioxidant activity of Icicinia mani (Earth balls) tubers using standard methods to ascertain the safety or otherwise of this plant material. Methodology: Finely ground Icicinia mani tubers (1000 g) was extracted with 80 % ethanol and the filtrate was concentrated using a rotary evaporator (LabTech EV400H). The dried extract was refrigerated at 4 oC until required for use. Qualitative and quantitative phytochemical screening were conducted using standard protocols. Analysis of the extract was by gas chromatography-mass spectrometry (GC-MS) to identify the important functional groups and phytochemical constituents. In vitro antioxidant activity of the extract was evaluated using ferric-reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, and nitric oxide (NO) scavenging assays. Results: The results of phytochemical screening indicate the presence (g/100 g) of alkaloids (29.703), flavonoids (8.911), tannin (5.455), steroids (0.007), saponin (13.269), cardiac glycosides (18.889), cyanogenic glycosides (0.002), oxalate (0.0004) and anthocyanin (10.00). GC-MS analysis revealed the presence of one hundred and five (105) compounds of which 1,2-Benzisothiazole, 3-(hexahydro-1H-azepin-1-yl)-, 1,1-dioxide had the highest retention time (23.712), Ethyl 2-(2-chloroacetamido)-3,3,3-trifluoro-2-(4-fluoroanilino) propionate had the highest molecular weight (356.70), while n-Hexadecanoic acid the highest peak area (4.92). The FRAP, DPPH, and NO scavenging assays indicated that the extract was capable of neutralizing free radicals. Conclusion: Ethanol extract of Icicinia mani tubers contains useful phytochemicals which synergistically confers strong antioxidant potentials on it, hence, the extract may be considered a potential natural source for developing additives in the food and pharmaceutical industries, offering an alternative to synthetic compounds for enhancing health benefits and mitigating oxidative stress. Further investigations on the minerals and proximate analysis as well as the effects of the extracts on biochemical parameters are on-going in our laboratory.