Total Phenolics and In-vitro Antioxidant Activities in Methanol Extracts of Raw, Ripe and Overripe Neem (Azadirachta indica A. Juss) Seeds

Abstract

The harvesting of fruits at different developmental stages until maturity may influence their antioxidant activities. Therefore, the
present study aimed to investigate the changes in total phenolics, flavonoid contents, and in-vitro antioxidant activities in methanol
seed extracts of Azadirachta indica A. Juss at different maturity stages (raw, ripe and overripe). All the tested biochemical parameters
varied significantly with maturity stages (p < 0.05%). Total phenolics [mg gallic acid equivalent (GAE)/g dw] and flavonoids contents
[mg quercetin equivalent (QE)/g dw] were highest in ripe (33.7 and 0.28, respectively) followed by raw (19.4 and 0.16, respectively)
and least in overripe seeds (12.9 and 0.15, respectively). 2, 2-Diphenyl-1-picrylhydrazyl (DPPH), 2, 2-Azino-bis 3-ethylbenzthiazoline-
6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) activities in methanol seed extracts [μM ascorbic acid equivalent
(AAE)/g dw] varied between 83.6–106.5, 68–93.8 and 44.8–177.9, respectively. IC50 values (mg/mL) for overripe, raw and ripe seed
methanol extract were 0.60, 1.11, and 2.10, respectively. The study concludes that seeds of A. indica were rich in natural phenolics and
also possess significant antioxidant activities. Thus the present study suggested that fruit industries should harvest ripe fruit seeds of
A. indica to meet out the need of natural phenolics for health benefits of local people.