Total phenolic content, antioxidant, anti-inflammatory and anti-microbial potentials of Bambara groundnut (Vigna subterranea L.) seed extract

Abstract

PurposeBambara groundnut is a hard-to-cook grain and this has limited its utilisation to some extent. However, the grain is a good source of phytochemicals with antioxidant properties. This study investigated the total phenol content, antioxidant, anti-inflammatory and anti-microbial potentials of hot-water extract of four Bambara groundnuts differentiated by their seed coats (cream, black, maroon and brown).Design/methodology/approachBambara grains were heated in water at a ratio 1:20 (w/v) and the grains brought to boiling in a controlled water bath. As soon as boiling started, the temperature was reduced to 90 °C to reduce the evaporation rate. The extracts were withdrawn within 30 min, which was chosen from a preliminary study where beyond this time, the extract was drying off and the amount of solution obtained was not sufficient for the initial run. Grain colour and composition and antioxidant, antimicrobial and anti-inflammatory properties of the extract were determined using standard methods.FindingsProtein (20.57–26.31%) and carbohydrate (55.43–61.09%) were the major components of the grain. Grain type and boiling time generally affected the total phenolic content of the extract. Cream Bambara displayed substantially lower total phenolic content at all boiling times compared with the maroon, brown and black Bambara groundnuts. The total flavonoid contents and total phenolic contents of the Bambara groundnut extracts were dependent on the boiling time and type of grain. The extracts showed no activity against Candida albicans, but the maroon coat Bambara demonstrated a peak inhibition of 6.00 mm against Escherichia coli. The total phenolic, flavonoid contents and the antioxidant properties of the grains generally followed the order Maroon > Black > Brown.Originality/valueThis study has demonstrated the possibility of promoting the use of Bambara groundnut beyond the current level of usage by using simple processing method of boiling to extract phytochemicals with medicinal properties.

Effect of partial mutton meat substitution with Bambara groundnut (Vigna subterranea (L.) Verdc.) flour on physicochemical properties, lipid oxidation, and sensory acceptability of low‐fat patties

“…Similarly, Oyeyinka et al. ( 2021 ) found higher moisture in cream BGN flour than in red and brown BGN flours. The ash content of all BGN flours was not significantly ( p < .05) different from each other, with values varying from 2.89% to 3.39%.…”

“…disparity in TPC(Oyeyinka et al, 2021). Therefore, BGN grains that are darker in coat colors possess higher TPC than those with lighter coat colors(Adedayo et al, 2021;Parikh & Patel, 2018) Oyeyinka et al (2017).…”

Phytochemical composition and antioxidant properties of methanolic extracts of whole and dehulled Bambara groundnut (Vigna subterranea) seeds

“…The black whole seed had the highest (p < 0.05) antioxidant activity (84.4 μmol AAE/g) followed by red (64.9 μmol AAE/g), mixture (52.4 μmol AAE/g), brown (50.5 μmol AAE/g), brown-eye (37.9 μmol AAE/g) and black-eye whole seed (34.5 μmol AAE/g). Oyeyinka et al 37 reported black and maroon BGN seed hot-water extracts showing the highest FRAP values when compared to brown and cream BGN seed hot-water extracts. Oyeyinka et al 37 further noted that high antioxidant activities in black and brown BGN seed extracts when compared to other seeds, could be as a result of increased concentration of protic flavonoids in the BGN seed coats.…”

“…Oyeyinka et al 37 reported black and maroon BGN seed hot-water extracts showing the highest FRAP values when compared to brown and cream BGN seed hot-water extracts. Oyeyinka et al 37 further noted that high antioxidant activities in black and brown BGN seed extracts when compared to other seeds, could be as a result of increased concentration of protic flavonoids in the BGN seed coats. A significant difference (p < 0.05) in FRAP existed between black and red whole seed, red, mixture and brown as well as brown-eye and black-eye seed extracts.…”

“…Bambara groundnut seed coats extracted with acetone at different temperatures of 30, 60 and 90 ℃ as well as ethanol at 90 ℃, were reported to possess high TPC among the different solvents and temperatures used for extraction 42 . Klompong and Benjakul 42 and Oyeyinka et al 37 further postulated that recoveries of phenolics in plants are mostly reliant on the type of solvent used, solvent polarity, legume variety and method of extraction. Significant differences (p < 0.05) existed in the TPC among the black, red, brown, mixture, black-eye and brown-eye seeds.…”