Phytochemistry-Guided Green Synthesis of Antimicrobial Silver Nanoparticles from Cannabis sativa Chemovars

Abstract

The phytochemical variability in Cannabis sativa L. chemovars represents an underexplored factor in environmentally sustainable nanomaterial production. In this study, three distinct chemovars, (i) High-Δ9-Tetrahydrocannabinol (THC) (89% THC), (ii) Balanced (60% Cannabidiol (CBD)), and (iii) High-CBD (89% CBD), were comparatively evaluated to determine their suitability for the green synthesis of silver nanoparticles (AgNPs). Ethanolic inflorescence extracts were used to recover bioactive secondary metabolites; among them, the High-CBD extract exhibited the highest total phenolic (3.34 mg gallic acid equivalent/g) and flavonoid (29.49 mg quercetine equivalent/g) contents, together with superior antioxidant capacity (53.16% 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) inhibition), indicating enhanced redox potential for nanoparticle formation. The terpene profile of High-CBD showed a dominance of myrcene (21.4%), contributing to the stabilization of the system. Using the High-CBD extract, predominantly spherical nanoparticles of 5 ± 0.9 nm were synthesized and confirmed by UV–vis, EDS, and TEM. The biogenic AgNPs demonstrated significant dose-dependent antibacterial activity, with minimum bactericidal concentration (MBC) of 1.0 mg/mL against Staphylococcus aureus and 4.5 mg/mL against Escherichia coli. These findings highlight the critical role of chemovar-dependent phytochemical composition and support a phytochemistry-guided approach for developing silver nanoparticles with potential biomedical applications.