Phytochemical analysis, and antioxidant and antibacterial activities of Alstonia scholaris from Mizoram, India

Abstract

The Devil’s tree (Alstonia scholaris (L.) R.Br.), a member of the Apocynaceae family, is recognised in various traditional systems for its efficacy in treating several diseases. In the Mizo traditional medicines of India, the bark extract is utilised as a remedy for bacterial and parasitic infections, among other ailments. To validate the therapeutic claim of the Mizo people, a methanolic extract of the bark was prepared and its chemical composition was analysed. The extract was found to contain alkaloids, carbohydrates, flavonoids, glycosides, phytosterols, saponins, tannins, and reducing sugars. The antioxidant components of the extract were quantified, revealing a phenolic content of 13.563±0.09 mg/g quercetin equivalent, a flavonoid content of 31.64±2.50 mg/g gallic acid equivalent, and a total antioxidant of 10.48±0.84 mg/g ascorbic equivalent. These findings underscore the plant’s cellular protective capacity. Furthermore, the antioxidant activities were assessed using 2,2-diphenyl-1-1-picryldrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. The plant extract exhibited significant antioxidant properties, with a half-maximal inhibitory concentration (IC50) value of 11.01 against free radicals generated from the DPPH reaction. Notably, the extract demonstrated broad-spectrum antibacterial activity against Gram-negative bacteria, including Escherichia coli and Salmonella typhi, as well as Gram-positive species such as Bacillus cereus, Enterococcus faecalis and Staphylococcus aureus. This study establishes A. scholaris as a medicinal plant with promising antimicrobial and pharmacological properties, containing chemical components that can be harnessed for therapeutic purposes.