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Dennettia tripetala fruit is a popular Nigerian fruit from the family of plant known as Annonaceae. The whole fruit (flesh and seed) is usually consumed as snacks and it is oftentimes consumed with local gin (ufofop in Ibibio or kaikai in Igbo) or added to dishes as spice due to its peculiar strong pepperish taste and sweet aroma. The present study is aimed at evaluating the antioxidant potentials of ethanol extract of ripe and unripe DT fruit in vitro. The antioxidant activity of the ethanol extract of DT was evaluated spectrophotometrically using various in vitro models like 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) and hydrogen peroxide scavenging activity; metal chelating activity and reducing power. Vitamin C was used as the standard antioxidant. Unripe and ripe DT fruits, as well as vitamin C showed a competitive inhibition of DPPH and H2O2 free radicals. As concentration of the extracts increased from 20 to100 µg/ml, the % scavenging activity for vitamin C increased from 87.86 ± 0.11 to 90.66 ± 0.07 and for ripe DT fruits from 15.15 ± 0.24 to 25.52 ± 0.23, while for unripe, fruits values increased from 12.09 ± 0.35 to 23.06 ± 0.12. The IC50 values was highest in unripe (549.23) followed by ripe (276.63) and lowest in vitamin C (12.92) indicating that vitamin C was the best scavenger of DPPH radical. Similar trend was obtained for H2O2 scavenging activity as well as reducing power. Unripe DT fruit extract was more potent at chelating metal ions (IC50 was 95.38), followed by the standard ascorbic acid with IC50 of 97.03 and was lowest in ripe DT fruit extract with IC50 value of 124.66. Unripe and ripe DT are potent antioxidants in nature and may be used to supplement our diets as rich sources of natural antioxidants for health protection.
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