Phytochemical Analysis and Antioxidant Study of Methanolic Extract of Leaves of Alstonia scholaris R. Br.

Alstonia scholaris R. Br. (Apocynaceae), commonly known as “devil tree” is a glabrous, evergreen, perennial herbaceous plant. According to the Ayurvedic system of medicine, the plant is used as potent blood purifier. Traditionally the leaves are used in conditions like cough, chronic bronchitis, asthma, fever and other respiratory diseases. The juice obtained from its leaves is also used to cure ulcers, wounds, rheumatism etc. Literature review suggests the presence of various phytoconstituents like Alstonlarsine A, an alkaloid which shows anti-diabetic activity, 12-ursene-2, 3, 18, 19-tetrol, 28 acetates -triterpenoid esters and glycosides as anti-inflammatory agents, Scholarisine T -alkaloid, for anti-bacterial activity and Akuammidine an indole alkaloid responsible for anti-spasmodic activity. Apart from this, diseases resulting from oxidative stress like cancer, rheumatoid arthritis, respiratory diseases etc. are very common nowadays and is on the rise which can be treated by free radicals present in plants. The aim of the present study is therefore to determine in vitro antioxidant activity and also to ascertain the qualitative and quantitative estimation in the leaf extracts of Alstonia Scholaris R. Br. The plant material after authentication was dried and extracted with methanol as the solvent. Different qualitative and quantitative estimations including the total alkaloid, flavonoid and Phenolic content were determined followed by antioxidant activity by DPPH radical scavenging method. Preliminary phytochemical studies confirmed the presence of Alkaloids, Flavonoids, Tannins and Steroids. The total alkaloid content was found to be 6.77±1.09mg/g in gravimetric method where total flavonoid and phenolic content was found to be 24.83±0.21mg QE/g of the sample by using quercetin as standard and 42.19±0.43mg GAE/g of the sample by using gallic acid as standard respectively. The IC₅₀ values of the methanolic extract of Alstonia scholaris and Ascorbic acid were 57.19±0.64pg/ml and 46.88±0.53pg/ml respectively. This shows that the methanolic extract of Alstonia scholaris possess strong antioxidant property which is comparable with the standard ascorbic acid.