Linking phytochemistry to bioactivity: in vitro, in vivo, and in silico insights into Rubia tinctorum.

INTRODUCTION

This study investigated the phytochemical composition and biological activities of the aqueous root extract of Rubia tinctorum L. using in vitro, in vivo, and in silico approaches.

METHODS

Phenolic compounds were extracted by decoction and quantified as total polyphenols, flavonoids, and condensed tannins. The chemical profile of the extract was characterized using HPLC/UV-ESI-MS. Antioxidant activity was evaluated using total antioxidant capacity (TAC), DPPH radical scavenging, and ferric reducing antioxidant power (FRAP) assays, while antimicrobial activity was assessed against selected bacterial and fungal strains. Acute toxicity and antihyperglycemic effects were investigated in vivo, and molecular docking explored interactions between the extract's major compounds and selected biological targets.

RESULTS

The extract contained 40.58 ± 1.01 mg GAE/g DE, 9.43 ± 0.81 mg QE/g DE, and 11.96 ± 0.45 mg CE/g DE of total polyphenols, flavonoids, and condensed tannins, respectively. HPLC/UV-ESI-MS revealed the presence of ruberythric acid, galiosin, rubiadin, salvianolic acid C, and pseudopurpurin glucoside as major compounds. The extract exhibited antioxidant activity (IC50 = 265.17 ± 0.68 μg/mL for DPPH; EC50 = 147.04 ± 0.71 μg/mL for FRAP) and a TAC of 165.26 ± 0.46 mg AAE/g DE. Significant antimicrobial activity was observed against Escherichia coli, Proteus mirabilis, Saccharomyces cerevisiae, Aspergillus niger, and several Candida strains. In addition, the extract exhibited notable antihyperglycemic activity without inducing acute toxicity. Molecular docking revealed strong binding affinities of ruberythric acid and salvianolic acid C toward key protein targets.

DISCUSSION: These findings highlight the significant antioxidant, antimicrobial, and antihyperglycemic potential of the extract.