Comparative evaluation of in vitro antioxidant and antidiabetic potential of five ethnomedicinal plant species from Punjab, India

Abstract

• Quantitative analysis of total flavonoid and phenolic contents of selected plant species. • HPLC analysis of leaf extracts of selected plant species for detection of polyphenols. • To evaluate and compare antioxidant and antidiabetic potential of selected plant species • Leaf extracts of B. variegata and S. cumini showed better antioxidant and antidiabetic potential. Plant species like Azadirachta indica (locally known as ‘neem’) , Bauhinia variegata (locally known as ‘kachnar’), Dalbergia sissoo (locally known as ‘tahli’), Psidium guajava (locally known as ‘amrood’) and Syzygium cumini (locally known as ‘jamun’) are known for their role in traditional systems of medicine for treatment of diabetes and other diseases in India and other countries. The present study was designed to compare antioxidant and antidiabetic potential among methanolic leaf extracts of A. indica, B. variegata, D. sissoo, P. guajava and S. cumini employing in vitro assays. In addition, this study also deals with quantitative analysis of total flavonoid and phenolic contents in the extracts. In vitro evaluation of antioxidant activities of leaf extracts of above five plant species were determined by 2,2′-azino-bis 3-ethylbenzthiazoline-6-sulfonic (ABTS ) , 1, 1-Diphenyl-2-picrylhydrazyl (DPPH), and superoxide radical scavenging assays whereas the antidiabetic potential of all the extracts was determined using α-amylase and α-glucosidase inhibitory assays. On the basis of EC50 values of different leaf extracts analysed for their antioxidant activity in three assays, leaf extracts of B. variegata and S. cumini were shown to present better antioxidant activity mainly in ABTS and superoxide radical scavenging assays. EC50 values for leaf extract of B. variegata were 31.19 ± 4.15 and 28.82 ± 4.42 and for S. cumini were 13.64 ± 10.39 and 30.19 ± 6.82 in ABTS and superoxide radical scavenging assays respectively. Similarly, these extracts also demonstrated better antidiabetic activity in both α-amylase and α-glucosidase inhibitory assays with IC50 of 27.28 ± 6.11 and 24.69 ± 0.91 for B. variegata and 48.34 ± 1.62 and 30.15 ± 0.80 for S. cumini in respective assays. The study demonstrated that leaf extracts of B. variegata and S. cumini showed better antioxidant potential than other plant species studied in ABTS and superoxide radical scavenging assays. These extracts also showed better antidiabetic potential in both α-amylase and α-glucosidase inhibitory assays as compared to other extracts.