Phytochemical profiling of Ocimum sanctum L. varieties and prediction of rosmarinic acid as a chemical marker for dermatological applications via in silico approaches

Ocimum sanctum L. (Sheng Luo Le) is utilized in Traditional Chinese Medicine (TCM) for clearing heat and treating skin infections. However, the chemical heterogeneity between the white and red varieties complicates quality standardization and the prediction of therapeutic efficacy. Ethanolic extracts of the white and red varieties were analyzed using HPLC. Antibacterial activity against Staphylococcus aureus was assessed (MIC/MBC), along with antioxidant (DPPH/ABTS) and enzyme inhibition activity (α-glucosidase/α-amylase). Molecular docking explored the binding affinity of chemical markers to relevant proteins. HPLC profiling distinguished the red variety as a caffeic acid-rich chemotype, while the white variety was rich in rosmarinic acid (51.47 mg/100g DW). The white leaf extract exhibited distinct antibacterial activity against S. aureus (MIC 125 mg/mL, MBC 250 mg/mL), moderate free radical scavenging activity (DPPH IC 50 172.76 µg/mL), and inhibitory effects on α-glucosidase and α-amylase. In contrast, the red variety showed no antibacterial activity despite its high caffeic acid content. Molecular docking analysis indicated that rosmarinic acid displayed a stronger binding affinity than caffeic acid toward sortase A (-7.4 kcal/mol) and other relevant targets, suggesting a potential multi-target mode of action. The white O. sanctum variety exhibits a chemical profile and biological activity more suitable for dermatological applications than the red variety. The integration of phytochemical, biological, and in silico analyses supports rosmarinic acid as a scientifically justified Quality Marker for the standardization of O. sanctum extracts intended for topical use.