Inhibitory evaluation of Curculigo latifolia on α-glucosidase, DPP (IV) and in vitro studies in antidiabetic with molecular docking relevance to type 2 diabetes mellitus

Abstract

The inhibition of α-glucosidase and DPP enzymes capable of effectively reducing blood glucose level in the management of type 2 diabetes. The purpose of the present study is to evaluate the inhibitory potential of α-glucosidase and DPP (IV) activity including with the 2-NBDG uptake assay and insulin secretion activities through in vitro studies. The selected of active compounds obtained from the screening of compounds by LC-MS were docked with the targeted enzyme that involved in the mechanism of T2DM. From the results, root extracts displayed a better promising outcome in α-glucosidase (IC₅₀ 2.72 ± 0.32) as compared with the fruit extracts (IC₅₀ 3.87 ± 0.32). Besides, root extracts also displayed a better activity in the inhibition of DPP (IV), enhance insulin secretion and glucose uptake activity. Molecular docking results revealing that phlorizin binds strongly with α-glucosidase, DPP (IV) and Insulin receptor (IR) enzymes with achieving the lowest binding energy value. The present work suggests several of the compounds have the potential that contribute towards inhibiting α-glucosidase and DPP (IV) and thus effective in lowering post-prandial hyperglycaemia.

Keywords: Curculigo latifolia; DPP (IV); molecular docking; type 2 diabetes; α-glucosidase.

Figure 1.

α-Glucosidase inhibitory effects of the extracts and the acarbose reference as a positive control. Values are expressed as the mean ± SD (n = 3). Different letters indicate significant differences (p < 0.05) within the same sample/control as increasing the concentration.

Figure 2.

DPP (IV) inhibitory effects of the extracts and sitagliptin reference as a positive control. Values are expressed as the mean ± SD (n = 3). The different letter indicates there is a significant difference by comparing in each sample/drug under different concentrations (p < 0.05) according to ANOVA and Tukey’s tests.

Figure 3.

LC-MS chromatogram screening of C. Latifolia. (A) root extract and (B) fruit Extract. Peaks: 1, phlorizin; 2, scandenin; 3, mundulone; 4, hydroquinone; 5,dimethylcaffeic acid; 6, hordatine A; 7, berberine; 8, pomiferin; 9, hordatine A; 10, monobenzone; 11, frangulin B; 12, robustine.

Figure 4.

Percentage of glucose uptake after treatment with various concentration (A) 3T3-L1 adipocyte cell; (B) differentiated L6 muscle cell. Values are expressed as the mean ± SD (n = 6). *p < 0.05, **p < 0.01, ***p < 0.001 and ****p < 0.0001 compared to the control.

Figure 5.

Insulin secretion assay for root and fruit of C. latifolia extracts. Values are expressed as the mean ± SD (n = 5). *p < 0.05, **p < 0.01, ***p < 0.001 and ****p < 0.0001 compared to the control.

Figure 6.

Compounds from SWE of C. latifolia with potential antidiabetic activity selected for in silico studies with selected anti-diabetic drugs.

Figure 7.

Active site in each targeted protein(A) Structure of α-glucosidase enzyme surface (green) with an active pocket site (red) and active site of the protein. (B) Structure of DPP (IV) enzyme surface (blue) with the active pocket site (pink) and active site of the protein.(C) Structure of Insulin receptor (green) with the active pocket site (pink) and active site of the protein.

Figure 8.

Binding energy between targeted protein and ligand. DPP (IV): Dipeptidyl Peptidase IV; IR: insulin receptor.

Figure 9.

Best docked of complex molecule. (A) α-glucosidase (B) DPP (IV) and (C) IR. Blue structures indicate the enzyme/protein, the blue line indicates the hydrogen bonds formed between the residues, and the orange structures indicate the ligands involved respectively for both diagrams. The green line indicates the π-staking interactions and yellow lines indicate the formed salt bridge.