Alpha-Glucosidase Inhibitory Assay-Screened Isolation and Molecular Docking Model from Bauhinia pulla Active Compounds

Abstract

The aim of this research was to establish the constituents of Bauhinia pulla as anti-diabetic agents. A phytochemistry analysis was conducted by chromatographic and spectroscopic techniques. The alpha-glucosidase inhibitory assay screening resulted in the isolation of eight known compounds of quercetin, quercitrin, luteolin, 5-deoxyluteolin, 4-methyl ether isoliquiritigenin, 3,2',4'-trihydroxy-4-methoxychalcone, stigmasterol and β-sitosterol. Ethanol leaf extracts showed potential effects, which led to a strong inhibitory activity of isolated quercetin at 138.95 µg/mL and 5.41 µg/mL of IC₅₀, respectively. The docking confirmed that flavonoids and chalcones had the same potential binding sites and responsibilities for their activity. This study was the first report of Bauhinia pulla chemical constituents and its alpha-glucosidase inhibition.

Keywords: Bauhinia pulla; alpha-glucosidase inhibition; anti-diabetic; molecular docking.

Figure 1

The chemical structure of Bauhinia pulla isolated compounds.

Figure 2

The molecular interaction between amino acids in the active site of glucosidase (Ivory) and glucose as a native ligand (White) and isolated flavonoids, luteolin (Blue), 5-deoxyluteolin (Pink), quercetin (Green), quercitrin (Yellow), chalcones, 3,2’,4’-trihydroxy-4-methoxychalcone (Red) and 4-methyl ether isoliquiritigenin (Cyan) from Bauhinia pulla (A). Structural alignment of 3,2’,4’-trihydroxy-4-methoxychalcone (Red) and 4-methyl ether isoliquiritigenin (Cyan) in the active site of glucosidase (Ivory) (B). 2D interaction diagram of 4-methyl ether isoliquiritigenin-glucosidase complex (C), 3,2’,4’-trihydroxy-4-methoxychalcone-glucosidase complex (D), quercetin-glucosidase complex (E), quercitrin-glucosidase complex (F), luteolin-glucosidase complex (I), and 5-deoxyluteolin-glucosidase complex (J). Catalytic residues in the active site indicated by red boxes and asterisks. A, B and C indicate the ring system in both flavonoids and chalcones.