Antibacterial and Antiproliferative Effect of ZnO Nanoparticles Prepared Using Origanum marjorana Plant and Garcinia indica Fruit extracts

In the present study, the aqueous seed extract of an Origanum marjorana plant and the fruit rind extract of a Garcinia indica plant were used to prepare ZnO nanoparticles. The antimicrobial effects of the prepared nanoparticles on bacterial pathogens and their antiproliferative effects on the HCT 116 cancer cell line were evaluated, with a specific focus on colon cancer. The prepared ZnO nanoparticles were characterized via XRD, SEM, FTIR, and UV‒Vis spectroscopy. The antibacterial activities of the synthesized nanoparticles were studied against both the gram-positive and gram-negative microorganisms B. cereus and S. typhi. These compounds presented moderate activity compared with the standard ciprofloxacin. The MICs for OM-ZnO were 2 µg/mL for S. typhi and 2 µg/mL for B. cereus. For GI-ZnO, 4 µg/mL for S. typhi and 4 µg/mL for B. cereus were observed. These results confirmed that the antibacterial efficacy of the nanoparticles depends on their concentration. The antiproliferative effects of the ZnO nanoparticles were evaluated using the MTT assay and cell cycle analysis. ZnO nanoparticles showed good antiproliferative effects on the tested cell lines. Studies on the cell cycle have suggested that ZnO nanoparticles effectively induce cell cycle arrest at the G2/M phase and trigger apoptosis. Compared with untreated HCT 116 cells (9.31%), those treated with 80 and 160 µg/mL ZnO nanoparticles arrested 25.92% and 33.57%, respectively, at the G2/M phase of the cell cycle. This study effectively demonstrates the synthesis of ZnO nanoparticles using plant extracts, highlighting their antimicrobial and antiproliferative properties. The detailed characterization underscores their potential for applications in antimicrobial therapies and cancer treatment.