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

<p>The present study was designed to conduct the bioassay-guided isolation of possible bioactive compound(s) responsible for the antidiabetic action of <i>Xylopia aethiopica</i> (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 (<i>p</i> < 0.05) lower IC<sub>50</sub> 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 <i>X. aethiopica</i> fruit through the inhibition of α-amylase and α-glucosidase enzyme activities.</p>