Antioxidant Capacity, Inhibitor of Alpha-glucosidase and DPP-IV of Kesambi (Schleichera oleosa) Leaf Extract and their Compound Profiles Based on LC-ESI-MS Analysis: In vitro and In silico Study

Kesambi leaves (Schleichera oleosa (Lour.) Oken) are endemic plants spread across Indonesia. Kesambi leaves are empirically used in various traditional medicines. This study aims to evaluate the antioxidant and antidiabetic activities in vitro and in silico. The dry powder of Kesambi leaves was extracted by sonication using n-hexane, ethyl acetate, acetone, and methanol solvents. The extract was evaluated for its antioxidant capacity using total antioxidant capacity (TAC), cupric ion power reduction (CUPRAC), and ferric reduced antioxidant power (FRAP). The active extract was continued by identifying the compound profile using the LC-ESI-MS approach. The results showed that acetone and ethyl acetate extracts consistently provided strong antioxidant capacity on TAC (478.78 ± 9.48 and 455.44 ± 10.72 mM QEAC/g), CUPRAC (2526.57 ± 23.54 and 1585.15 ± 29.85 mM GAEAC/g), and FRAP (532.99 ± 3.64 and 499.14 ± 7.91 mM QEAC/g). Its alpha-glucosidase and DPP-IV inhibitor activity showed that ethyl acetate and acetone extracts provided significant activity compared to other extracts, with categories ranging from moderate to very strong. Twenty-one compounds were identified in the acetone extract, and eight were identified in the ethyl acetate extract using the LC-ESI-MS approach. Compounds 5, 12, 13, and 14 from acetone extract and compounds 24, 25, and 26 from ethyl acetate extract showed strong interactions with target proteins alpha-glucosidase (2QMJ) and DPP-IV (5T4B) through molecular docking and dynamic approaches. This study provides a scientific description of the ability of Kesambi leaf extract, which has the potential to be an antioxidant and antidiabetic in vitro and in silico.