Total phenolics, total flavonoids, antioxidant capacities, and volatile compounds gas chromatography-mass spectrometry profiling of Moringa oleifera ripe seed polar fractions

Background: Academic reports have confirmed Moringa oleifera leaves to possess significant antioxidant capacities; however, such studies are unavailable for its ripe seeds even though they are more desirous for consumption due to their sweet taste. Objective: In this study, we investigated antioxidant capacities of four polar extracts (crude water, ethanol, butanol, and aqueous residue) from the plant's ripe seeds. Materials and Methods: Phytochemicals were extracted from the ripe seeds of M. oleifera using ethanol and water solvents at initial stage. Butanol and aqueous residue were then subsequently fractioned out from the ethanol extract. Phenolic and flavonoid contents of the polar extracts were determined. Then, their antioxidant capacities were quantified by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. Finally, gas chromatography-mass spectrometry (GC-MS) analyses of the extracts were performed. Results: DPPH and ABTS tests showed that the polar extracts possess significant antioxidant capacities that ranged from 29 to 35.408 μM Trolox equivalence antioxidant capacity (TEAC)/mg sample and 7 to 29 μM TEAC/mg sample, respectively. The antioxidant capacities of the extracts corresponded to their phenolic and flavonoid contents that varied from 13.61 to 20.42 mg gallic acid equivalence/g sample and 0.58 to 9.81 mg quercetin equivalence/g sample, respectively. Finally, GC-MS analyses revealed antimicrobial phenolic compounds, 4-hydroxybenzaldehyde in crude water extract and 4-hydroxybenzene acetonitrile in the ethanol and butanol extracts, and aqueous residue. Conclusion: Our results established that M. oleifera ripe seeds have significant antioxidant activity which may be due to its phenolic and nonphenolic compounds content.