Green synthesis of zinc oxide nanoparticles by Zataria multiflora extract and evaluation of its antimicrobial, cytotoxic and apoptotic effects on HT-29 cell line.

Introduction: Metal oxide nanoparticles have long been challenged as a candidate for cancer treatment. In the present study, for the first time, biosynthesis of zinc oxide nanoparticles was performed by Zataria multiflora extract and then their antimicrobial, cytotoxic and apoptotic effects on colon cancer cell lines were investigated. Materials and Methods: The zinc oxide (ZnO) nanoparticles were biosynthesized using an aqueous extract of Z. multiflora shoots. The shape, size and structure of the synthesized nanoparticles were evaluated by EDS, XRD, FE-SEM and FTIR analysis. The antimicrobial effect of ZnO nanoparticles was investigated by the MIC method and their cytotoxic effects against two colorectal cancer cell lines HT-29 and normal HEK-293 were evaluated by the MTT method within 24 hours. The expression of p53 and Casp3 gene in cells treated with IC50 dose was then evaluated by Real-time PCR. Also, the type of cell death was determined by flow cytometry. Results: Findings showed that ZnO nanoparticles were star-shaped and were synthesized with a size of 35-95 nm. MIC of ZnO nanoparticles was reported for the studied bacteria between 100-200 µg/ml. The results of MTT showed that the IC50 of nanoparticles was 282.4 µg/ml and in this concentration, the expression of p53 and Casp3 genes increased by 1.22 and 3.81 fold, respectively, which in terms of it was statistically significant. In addition, flow cytometry results showed an apoptosis rate of 76%. Conclusion: ZnO nanoparticles synthesized through Z. multiflora plant extract showed antimicrobial effect and can be used as part of antitumor drug formulation. [ABSTRACT FROM AUTHOR]