Day time trend in the phytochemical constituents and antioxidant activity of Azadirachta indica leaves

Background & Aim:Medicinal plants have been of immense therapeutic values to many communities, some traditional folklore places emphasis on collecting plants during the day for medicinal purpose. This study examined the effect of collection time on the phytochemical composition and antioxidant activity of Azadirachta indica leaves. Experimental: Leaves samples were collected at six hour intervals between 6AM to 6PM, phytochemical quantification was done using standard methods; antioxidant assays were done after ethanol extraction via reducing power and nitric oxide scavenging assay (NO). Results: Saponin concentration ranged from 1.08-1.24%, Tannin 0.22-0.31%, Steroid 0.08-0.14%, Glycoside 0.090-0.104%, Alkaloids 3.88-4.27%, Flavonoids 0.050-0.080% and 1.16-1.32% for Phenolics in the leaves of A. indica collected at different time of the day. The effect of time of sample collection on the phytochemical constituents shows that phytochemicals such as saponin, tannin, glycoside, alkaloids and phenolics are significantly (p<0.05) more concentrated in the leaves in the evening time (6PM) compared to other time period while steroid and flavonoid are also significantly more concentrated in the noon time (12PM). Reducing power assay shows that leave samples collected at 12PM exhibited the highest reducing power which is comparable with the samples collected at 6PM. The early morning samples showed the least reducing power while the standard antioxidant had higher reducing power than the three sample extracts. The highest percentage NO inhibition was observed in leave samples collected at 12PM (72.40%), but this is less than the ascorbic acid (standard antioxidant) which shows 84.47% inhibition. Analysis of the IC50 revealed that the afternoon sample (12PM) had the least value (23.29 μg/ml) thus, possessing better antioxidant capacity with respect to the NO scavenging; this is to a lower extent than the IC50 value (12.71 μg/ml) of the standard antioxidant.Recommended applications/industries: From the foregoing, variation exists in daytime concentrations of phytochemical in A. indica leaves which may impact on its pharmacological actions.