Effects of seasonal variation on antioxidant potential and metabolite contents of Spilanthes acmella Hutch and Dalz

Spilanthes acmella Hutch and Dalz is being used as food supplement and important traditional medicine for the treatment of numerous ailments and diseases. In the present study, the effects of seasonal variation on the antioxidant potential and metabolite contents in different parts of the plants have been analyzed by collecting samples during pre-and post-monsoon periods. Methanol extracts of leaves and flowers of S. acmella collected during pre-monsoon period showed the highest antioxidant potentials (IC₅₀ of 13.67 and 14.09 μg/ml) respectively. Phenolic and flavonoid contents in the leaves, flowers and stems were significantly higher during pre-monsson period (p<0.001). Similarly, protein and carbohydrate contents in the leaves and stems of the plant were significantly higher during pre-monsoon period (p<0.001). However, the leaves of the plant collected during pre-monsoon period were recorded with the highest phenolic (360.53±4.96 mgGAE/g), flavonoid (227.04±7.25 mgQE/g) and proteins (495.19±31.34 mgBE/g) contents. The carbohydrate content was maximum in the stem (465.89±16.55 mgDE/g) of the plant. The results indicated strong influence of seasonal changes on the metabolite profile and defensive activities of S. acmella. The antioxidant potential and metabolite (phenolic, flavonoid, protein and carbohydrate) contents in different parts of the plant were significantly higher during pre-monsoon period as compared to those collected during postmonsoon period.