Kaurane Diterpenoids from <i>Xylopia aethiopica</i> Inhibits Alpha-Amylase and Alpha-Glucosidase: A Combined in Silico and in Vitro Approach

Background/Objectives Diabetes mellitus is among the leading cause of death worldwide. This study evaluated the alpha amylase and alpha glucosidase inhibitory properties of kaurane diterpenoids (kauran-13-ol (D1), xylopic acid (D2) and kauran-16α-ol (D3)) from the fruit of X. aethiopica. Methodology In vitro alpha amylase and alpha glucosidase inhibitory assays were performed on D1, D2 and D3 (0.03125, 0.0625, 0.125, 0.25, 0.5, 1.0 and 2.0 mg/mL) and acarbose (0.003125, 0.00625, 0.0125, 0.025, 0.05 and 0.1 mg/mL) followed by molecular docking studies, molecular dynamics simulation and MMPBSA to examine their mode of interaction, binding affinity, binding mode and binding energy established with the enzymes. Also, ADMET properties of the studied diterpenes were examined to explain their druggability potential. Result The in vitro alpha-amylase and alpha-glucosidase studies identified D3 as the most promising inhibitor among the kaurane diterpenes with lower IC 50 values of 0.65 and 0.17 mg/mL. The molecular docking analysis showed that D1, D2 and D3 established vital hydrogen bond, hydrophobic and pi-interaction with the receptors, while the molecular dynamics simulation showed the kaurane diterpenes exhibited good stability at the enzymes’ binding pocket. The MMPBSA binding energy values showed the diterpenes had good binding energies that corroborated that of molecular docking. The ADMET properties identified the compounds as promising drug candidate. Conclusion The study demonstrated that the kaurane diterpenoids have good inhibitory effect on the diabetes enzymes. Further comprehensive investigation into the antidiabetic properties of the diterpenes may lead to the identification of new hit molecule.