Effect of Geographical and Seasonal Variations on Phenolic Contents and Antioxidant Activity of Aerial Parts of Urtica diocia L.

Background: Environmental conditions affect the biosynthesis of secondary metabolites as a result of biotic and abiotic factors. In the present study, the effect of different geographical locations and season was studied on total phenolic and flavonoid contents extracted from Urtica dioica Linn. Methodology: The aerial parts of U. dioica collected from Palampur, Shimla and Dharamshala in different seasons were subjected to hydro-alcoholic extraction. Quantitative estimation of total phenolic and flavonoid contents in various extracts was carried out spectrophotometrically. Results: The highest amount of total phenolic (3.987 +/- 0.130) and flavonoid contents (2.847 +/- 0.341) was found in Palampur sample collected in summer season whereas sample collected from Dharamshala in spring season showed the least phenolic contents. In vitro antioxidant activity of all the samples was evaluated by DPPH, NO scavenging and FRPA method. The antioxidant potential was found maximum in the sample collected from Palampur in the summer season, however, the sample collected from Dharamshala in spring season showed the least antioxidant potential. Conclusion: The present study confirms that altitude and seasonal variations significantly affect the levels of secondary metabolites in plant parts.