Radical scavenging activity and phenolic components in different plant parts of Saraca asoca

The therapeutic properties of herbal drugs depend on certain chemical constituents (secondary metabolites) which varies according to age and maturity of the plant. Phenolic compounds have multiple biological properties and also act as antioxidants. They protect the human body against damage by reactive oxygen species. Medicinal plants have been focused for antioxidant compounds because of safety concerns associated with synthetic antioxidants. Saraca asoca (Roxb.) Wilde (Fabaceae) an important medicinal tree has been well known for its effectiveness in menorrhagia and dysmenorrhea. Its bark has stimulating effect on the endometrium and ovarian tissue and has been used traditionally for gynecological disorders. Different plant parts: bark, leaves and twigs of various aged group trees of Saraca asoca were evaluated for their total phenols (TP), total flavonoids (TF), tannins (T), phenolic acids contents and radical scavenging activity. TP varied from 5.27–8.65%, TF from 0.16–0.28%, T from 20.88–51.17%. This is the first study in which different phenolic acids were estimated in Saraca asoca; vanillic acid varied from 2.34–5.07%, caffeic acid from 1.37–7.15%, chlorogenic acid from 8.51–25.59%, gallic acid from 0.17–0.46% and catechin from 4.78–7.95mg/100g. Radical scavenging activity showed significant variation among different girth classes and IC₅₀ values ranged between 2.29–4.82mg/ml. Bark was found to contain maximum concentration of active ingredients. The results revealed that the optimum girth class to obtain quality produce is 61–90cm as it contains maximum concentration of active ingredients and possess high radical scavenging activity. Thus it can be used for making various formulations containing natural antioxidants.

Keywords: Antioxidants, phenolic acids, harvesting age, Saraca asoca

Acknowledgement: The authors are thankfull to the Director, Tropical Forest Research Institute for providing neccessary facilities to carry out the research work. The work was supported by a grant from the National Medicinal Plant Board (NMPB), Govt. of India, New Delhi.