Abstract
Background: Type 2 diabetes mellitus (T2DM) is a global health challenge characterized by chronic hyperglycemia and oxidative stress. Pithecellobium dulce root has long been recognized for its antidiabetic potential; however, its specific bioactive constituents and mechanisms of action remain poorly defined. This study aimed to evaluate the antidiabetic and antioxidant properties of extracts and isolated molecules from P. dulce root bark. Methods: The DCM/MeOH crude extract of P. dulce root bark was fractionated with n-hexane (PDEH) and ethyl acetate (PDAE), followed by chromatographic purification and spectroscopic characterization, yielding seventeen compounds (1–17). The antioxidant activity (DPPH, ABTS, FRAP) and antidiabetic potential of PDEH, PDAE, and 1–17 were assessed in vitro using yeast-derived enzymes and in silico (targeting human α-glucosidase [PDB: 2QLY] and human α-amylase [PDB: 4GQR]). The in vitro α-glucosidase experiments used saccharomyces cerevisiae enzyme, which varies from the human target. Therefore, these results should be taken as preliminary screening data that needs confirmation with human enzymes. Results: Compound 1 was identified as new, while 2 was isolated for the first time from a natural source. The cell-free chemical tests DPPH, ABTS, and FRAP measured antioxidant capability. These tests quantify radical-scavenging and electron-transfer capabilities in vitro and are preliminary chemical screening methods. They do not directly represent biological antioxidant activity in cells or organisms. PDEH demonstrated strong radical scavenging against DPPH (IC50 = 15.30 μg/mL) and ABTS (IC50 = 12.80 μg/mL), while pristriol (16) showed ferric reducing power (EC50 = 4200 μM FeSO4/g). Enzyme inhibition assays demonstrated activity against α-amylase (IC50 53.88–112.24 µg/mL; acarbose IC50 = 91.20 µg/mL) and α-glucosidase (IC50 18.38–136.88 µg/mL; acarbose IC50 = 11.31 µg/mL). Compounds 15, 1, and 2 showed superior activity compared to acarbose for α-amylase, with effect sizes (Cohen’s d) of 2.15, 0.94, and 0.82, respectively, and IC50 values of 53.88, 88.15, and 92.62 µg/mL; for α-glucosidase, IC50 values were 18.38, 39.25, and 36.40 µg/mL, respectively. Docking studies supported these findings, revealing binding energies of −9.08, −8.34, and −7.22 kcal/mol for compounds 1, 2, and 15 with α-amylase, and −10.35 and −9.79 kcal/mol for compounds 1 and 2 with α-glucosidase. ADME profiling further identified 1 and 2 as promising lead candidates for dual-enzyme inhibition. Conclusions: P. dulce root bark represents a potent source of bioactive molecules with both antioxidant and dual-enzyme-inhibitory properties. These findings validate its traditional use and highlight its potential in the development of multitarget therapies for T2DM management.