Nanoparticles Using Lavender and Rosemary Extracts as Reducing Agent: Physicochemical Characterization and Antiproliferative Activity Against Human Cancer Cells

Silver nanoparticles (AgNPs) synthesized using plant extracts represent a promising approach combining environmentally friendly nanoparticle synthesis with potential biomedical applications. In this study, AgNPs were synthesized using aqueous extracts of dried Lavandula angustifolia (LEx) and Salvia rosmarinus (REx) leaves, physicochemically characterized, and evaluated for their antiproliferative activity against six human cancer cell lines and one non-tumorigenic human cell line. HPLC analysis revealed distinct phytochemical profiles of the two extracts, while UV–Vis, FTIR, TEM, SAED, and SEM–EDX analyses were used to characterize the resulting lavender-mediated (LAg) and rosemary-mediated (RAg) AgNPs. TEM analysis showed a greater proportion of smaller nanoparticles in RAg than in LAg. Antiproliferative activity was evaluated using the MTT assay after 48 h of exposure, with LEx, REx, and AgNO3 included as controls. Both AgNP formulations exhibited cell-line-dependent activity. LAg reached IC50 values of 19.4–20.8 µmol Ag/L in five cancer cell lines, whereas RAg reached IC50 values of 14.4–25.2 µmol Ag/L. The lowest IC50 was observed for RAg in PaTu 8902 pancreatic adenocarcinoma cells (14.4 ± 0.6 µmol Ag/L). In contrast, the IC50 was not reached in A549 or non-tumorigenic CCD-18Co cells at concentrations up to 50 µmol Ag/L (IC50 > 50 µmol Ag/L). Neither LEx nor REx produced 50% inhibition of cell viability at concentrations up to 1.7% (v/v). Similarly, AgNO3 did not achieve 50% inhibition at concentrations up to 50 µmol/L in any of the cell lines tested. These findings demonstrate formulation- and cell-line-dependent antiproliferative activity of green-synthesized AgNPs and support further investigation of their biological effects and underlying mechanisms.