Validated RP-HPLC based characterization of synergistic antibacterial, antioxidant, and anticancer activities of combined mangosteen pericarp and turmeric extracts.

Background and Aim: Mangosteen (Garcinia mangostana) and turmeric (Curcuma longa) are medicinal plants with well-documented antimicrobial, antioxidant, and anticancer properties, attributed to α-mangostin and curcumin, respectively. While their individual bioactivities are recognized, their synergistic potential and standardization through analytical validation remain underexplored, particularly in veterinary and pharmacological applications. This study aimed to (1) evaluate the synergistic antibacterial, antioxidant, and anticancer effects of ethanolic extracts of mangosteen pericarp and turmeric rhizome and (2) develop and validate a high-performance liquid chromatography (HPLC) method for the simultaneous quantification of their major bioactive compounds. Materials and Methods: Ultrasound-assisted extraction was employed to prepare ethanolic extracts. Antibacterial activities were assessed using disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration assays against five bacterial strains, with synergy evaluated through checkerboard fractional inhibitory concentration index. Antioxidant activity was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and total phenolic content (TPC). Cytotoxicity was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays on human hepatocellular carcinoma cells (HepG2), human breast adenocarcinoma cells (MCF-7), and human normal fibroblast cells. A reversed-phase HPLC method was developed and validated to simultaneously quantify α-mangostin and curcumin in the combined extract. Results: Mangosteen and turmeric extracts showed MICs of 3.12 and 31.25μg/mL, respectively. Combined extracts demonstrated additive or synergistic effects against Gram-positive bacteria and enhanced the efficacy of gentamicin (up to 19-fold MIC reduction). The combined extract exhibited the strongest antioxidant activity (half-maximal inhibitory concentration = 5.78 μg/mL) and highest TPC (1227.38 mg gallic acid equivalent/g extract). Cytotoxic assays revealed selective inhibition of HepG2 and MCF-7 cells, with no toxicity toward normal fibroblasts. The validated HPLC method enabled accurate, simultaneous quantification of curcumin (73.23mg/g extract) and α-mangostin (146.80mg/g extract) with excellent linearity (R2 > 0.9995) and recovery (99.08%-104.72%). Conclusion: The combination of mangosteen and turmeric extracts exhibits potent, selective, and synergistic antibacterial and anticancer properties, along with enhanced antioxidant capacity. The validated HPLC method provides a reliable tool for quality control and standardization of such polyherbal formulations, supporting their potential for therapeutic and veterinary applications.