Integrative Pharmacological and Computational Analysis of Abelmoschus esculentus Phytochemicals: Enzyme Inhibition, Molecular Docking, and Dynamics Simulation Against Key Antidiabetic Targets

TL;DR

This study explores how compounds from okra may help manage diabetes by inhibiting key enzymes, using both experiments and computer simulations.

Contribution

The study integrates experimental enzyme inhibition with computational methods to identify promising antidiabetic phytochemicals in okra.

Findings

Okra extract showed moderate enzyme inhibition against alpha-glucosidase, alpha-amylase, DPP-4, and pancreatic lipase.

Alpha-Carotene, Vitamin E, and Spiraeoside were top compounds with strong binding affinity, especially alpha-Carotene against pancreatic lipase.

Molecular dynamics simulations confirmed the stability of alpha-Carotene's binding to pancreatic lipase.

Abstract

The present work set out to examine the antidiabetic capacity of Abelmoschus esculentus (okra) fruit extract through a combined experimental and computational framework. Enzyme inhibition assays were carried out against four metabolic targets, and IC50 values stood at 7.66 ± 0.31 mg/mL for alpha-glucosidase, 5.21 ± 0.18 mg/mL for alpha-amylase, 2.11 ± 0.15 microg/mL for DPP-4, and 9.17 ± 0.54 mg/mL for pancreatic lipase. The extract showed moderate-to-weak activity relative to standard inhibitors acarbose, sitagliptin, and orlistat. Sixteen drug-like phytochemicals obtained from the IMPPAT 2.0 database were docked against the crystal structures of all four tested enzymes (PDB: 8CB1, 5E0F, 2ONC, 1LPB). Alpha-Carotene, Vitamin E, and Spiraeoside emerged as the top-ranked compounds across all targets, with alpha-Carotene recording the strongest binding affinity of −11.1 kcal/mol against pancreatic lipase, which was 4.2 kcal/mol more negative than the positive control orlistat (−6.9 kcal/mol). PLIP-based interaction profiling mapped out hydrogen bonds, hydrophobic contacts, pi-stacking, and salt bridges at the atomic level. Absorption, distribution, metabolism, and excretion (ADME) and toxicity screening of alpha-Carotene returned a favourable pharmacokinetic profile with predicted LD50 of 1510 mg/kg (Class 4) and inactivity across most toxicity endpoints. A 100 ns molecular dynamics simulation of the pancreatic lipase-alpha–Carotene complex, alongside the orlistat control, showed stable root mean square deviation (RMSD) (0.15–0.22 nm), a consistent Rg (~1.97 nm), and sustained hydrogen bonding throughout the trajectory. Free-energy landscape analysis revealed a well-defined single energy basin for alpha-Carotene, suggesting a thermodynamically stable binding conformation. These findings lay the molecular basis for using okra phytochemicals as adjunctive agents in diabetes management, though in vivo validation remains necessary.

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