Oleanolic acid as a potential antidiabetic component of Xylopia aethiopica (Dunal) A. Rich. (Annonaceae) fruit: bioassay guided isolation and molecular docking studies

Abstract

The present study was designed to conduct the bioassay-guided isolation of possible bioactive compound(s) responsible for the antidiabetic action of Xylopia aethiopica (Dunal) A. Rich. fruit. The isolation of compound was guided by α-glycosidase and α-amylase inhibitory activities. Molecular docking with Autodock Vina was used to decipher the mode of interaction and binding affinity of the possible compound(s) with the selected enzymes. A pentacyclic triterpene, oleanolic acid (OA) was isolated from fruit and exhibited significantly (p < 0.05) lower IC₅₀ values (α-amylase: 89.02 ± 1.12 µM, α-glucosidase: 46.05 ± 0.25 µM) than other fractions and the acarbose. Interestingly, OA was found to bind to the α-amylase and α-glucosidase with minimum binding energy values of -0.9 and -1.2 kcal/mol respectively and none of the interactions involved hydrogen bond formation. Data of this study suggest that OA is responsible for the antidiabetic action of X. aethiopica fruit through the inhibition of α-amylase and α-glucosidase enzyme activities.

Keywords:

• Oleanolic
•  acid
• α-amylase
• α-glucosidase
• molecular docking

Disclosure statement

No conflict of interest was reported by the authors. This study was supported by a Competitive Research Grant from the Research Office of the University of KwaZulu-Natal, Durban; and a Grant Support for Young and Women Researchers from the National Research Foundation (NRF), Pretoria, South Africa.

Additional information

Funding

This study was supported by a competitive research grant from the Research Office, University of KwaZulu-Natal (UKZN), Durban; an incentive grant for rated researchers and a grant support for women and young researchers (Grantno.7429/2012) from the National Research Foundation (NRF), Pretoria, South Africa.