Bridging in vitro bioactivities and in silico insights of Rubia cordifolia L. (Rubiaceae) leaf extracts for therapeutic applications.

Medicinal plants are important sources of bioactive compounds with significant therapeutic potential. This study evaluated the phenolic profile, biological activities, and molecular docking-based antiproliferative potential of the Rubia cordifolia leaf extracts in methanolic (RCLM), chloroform (RCLC), and distilled water (RCLD). Leaf extract was selected because of its richness in secondary metabolites and its roles in photosynthesis, defense mechanisms, and environmental interactions. Phytochemical screening was performed using High-Performance Liquid Chromatography (HPLC), while antioxidant activity was determined through DPPH scavenging, total antioxidant capacity (TAC), and total reducing power (TRP). Antibacterial activity was evaluated against Staphylococcus aureus, Listeria monocytogenes, and Bacillus subtilis. Cytotoxicity was investigated using the brine shrimp lethality assay and PC3 and 3T3 cell lines. Among the extracts, RCLM exhibited the strongest antioxidant activity with a DPPH IC50 of 54.41 ± 0.53 µg/mL, a TAC of 102.08 ± 0.89 µg/mL, and a TRP of 201.56 ± 0.61 µg/mL. The highest antibacterial activity was observed against Bacillus subtilis with an inhibition zone of 26 ± 0.7 mm. The methanolic extract also showed pronounced brine shrimp cytotoxic activity. Furthermore, RCLM showed > 50% inhibition against 3T3 cell lines and < 50% inhibition against PC3 cell lines. HPLC analysis revealed chlorogenic acid as the major phenolic compound (392.44 ppm), while salicylic acid was detected at the lowest concentration (3.408 ppm). Molecular docking demonstrated strong binding affinities for chlorogenic acid (- 7.7 kcal/mol) and HB acid (- 10.5 kcal/mol) to target proteins implicated in oxidative stress and cancer progression. These findings suggest that Rubia cordifolia leaf extract possesses promising pharmacological applications.