Synergistic Antibacterial and Antioxidant Activities of Folium Aloe-Cortex Betulae Drug Combination: Optimization via Box-Behnken Design and In Vitro Validation.

This study aimed to screen for optimal Traditional Chinese medicine (TCM) combinations and subsequently optimize their extraction processes for developing antibacterial dressings by preparing aqueous and hydroethanolic extracts from Herba Centellae asiaticae, Flos Calendulae, Folium Aloe, Cortex Betulae and Rhizoma Curcumae longae and evaluating their inhibitory activity against E. coli, S. aureus, C. albicans, and T-Salmonella using an agar diffusion assay. Synergistic combinations were identified through a grid screening method, with extraction processes optimized via single-factor experiments and Box-Behnken response surface design. The results demonstrated that the Folium Aloe and Cortex Betulae formulation exhibited the strongest synergistic antibacterial activity, with the inhibition zone expanding from 11.1/12.8 mm for individual components to 17 mm after combination, representing an increase of 21-36%. Single-factor and response surface optimization identified optimal process parameters as a ratio of 1.53:1, a hydroethanolic concentration of 79.5%, and an extraction time of 2.6 h, with a model R2 value ranging from 0.9265 to 0.9783; the MIC values were reduced by 25-68.75%. The UPLC-QTOF-MS analysis of the optimized extract identified nine major constituents, including anthraquinones, chromones, and triterpenoids, providing the phytochemical basis for the observed bioactivities. Mechanistic studies via UV-Vis spectrophotometry and propidium iodide (PI) staining confirmed membrane disruption through nucleic acid and protein leakage. Cytocompatibility evaluation using L929 fibroblasts demonstrated >90% cell viability even at 1000 μg/mL. Additionally, the optimized extract exhibited concentration-dependent antibacterial activity, achieving a DPPH scavenging rate of 90% at 1.0 mg/mL, whereas its ABTS scavenging rate was comparable to that of ascorbic acid. The Folium Aloe and Cortex Betulae pair demonstrates dual antibacterial and antioxidant activities, providing an experimental basis for developing functional wound dressings and green antibacterial biomaterials.