HPLC analysis, molecular docking of phenolic compounds and screening of antioxidant and cytotoxic potential of Diospyros malabarica bark extract

Background

Diospyros malabarica, a flowering tree native to the Indian Subcontinent and Southeast Asia, is widely utilized in ayurvedic medicine. This plant is known to contain numerous bioactive compounds. As a result of its traditional uses and medicinal properties, we aim to evaluate the pharmacological properties of its bark both experimentally and in silico.

Methods

Polyphenolic compounds in the extracts were identified using High-Performance Liquid Chromatography (HPLC). The antioxidant potential of the extracts was assessed through various methods, including DPPH radical scavenging, reducing power assay, total antioxidant capacity, and protection against oxidative DNA damage. Cytotoxic activity was evaluated using A549 cell growth inhibition and the brine shrimp lethality bioassay. To predict the binding modes of the active compounds within the target protein, molecular docking analysis was conducted.

Results

HPLC analysis on EAF confirmed the presence of six polyphenolic compounds including Catechin hydrate, Catechol, (-) Epicatechin, Syringic acid, Rutin hydrate and Kampherol. Antioxidant assay revealed that etylacetate fraction (EAF) showed stronger antioxidant activity as well as better protective effect on oxidative damage to DNA than other fractions. According to docking studies, compounds found in EAF by HPLC showed an impressive propensity for binding to Topoisomerase II. In the brine shrimp assay, different fractions showed moderate cytotoxicity, with LC₅₀ values of 20.63 (CHF), 32.3 (EAF), and 58.17 (NHF) μg/ml, compared to 1.27 μg/ml for vincristine sulfate. Cytotoxicity against A549 human lung cancer cell line, the percentage of cell viability of CHF and EAF (300 μg/ml) were 34.5 and 41.5, respectively. In silico analysis, rutin hydrate exhibited the strongest binding affinity (-9.0 kcal/mol) with Topoisomerase II.

Conclusion

The in-vitro study and docking result demonstrates the possession of significant antioxidant and cytotoxic potential of D. malabarica bark extract which could be helpful for anticancer drug development program.