Exploration of potential antidiabetic and antioxidant components from the branches of Mitragyna diversifolia and possible mechanism

In this study, sixteen compounds were isolated from the branches of Mitragyna diversifolia, including twelve triterpenes (1–12), a phenolic compound (13), and three flavonoids (14–16). Among them, compounds 1–7, and 10–16 were reported for the first time from this plant. Compounds 7, 14, and 15 exhibited significant inhibitory activities against α-glucosidase, with IC50 values of 18.48 ± 2.74, 12.14 ± 1.58 and 35.77 ± 4.52 µM, respectively. Furthermore, the inhibitory kinetics of α-glucosidase revealed that all fractions, active compounds 7, 14, and 15 belong to the mix inhibition type. In molecular docking, the analysis showed that compounds 13, 14, 15, and 16 possessed superior binding capacities with α-glucosidase (−8.3, −9.6, −9.9, and −9.2 kcal/mol, respectively). The results of the glucose uptake experiment indicated that only compound 14 showed a significant promotion effect on the glucose uptake rate of 3T3-L1 adipocytes (P < 0.05). Meanwhile, compounds 13, 14, 15, and 16 possessed potent antioxidant abilities with DPPH, ABTS, and FRAP. In DNA and protein oxidative damage assays, compound 15 had a stronger effect than the positive control Vc. The network-based pharmacological analysis platform was used to predict the diabetes-related target proteins of active compounds 7, 13, 14, 15, and 16, and two candidate targets (ALB and PPARG) related to their therapeutic effects on diabetes were identified.