Green Synthesis of Zinc Oxide Nanoparticles (ZnO NPs) using Aqueous Extract of Tagetes Erecta flower and Evaluation of its Antioxidant, Antimicrobial, and Cytotoxic activities on HeLa cell line.

The Zinc oxide Nanoparticles (ZnO NPs) were synthesized successfully by using Tagetes erecta flower aqueous extract and evaluated for their antioxidant potential, antimicrobial and cytotoxic potential. Phytochemical screening of aqueous crude extract and synthesized ZnO NPs of Tagetes erecta flower revealed the presence of alkaloids, flavonoids, carbohydrates, amino acids, tannins, proteins, etc. The characterization was done by various spectral analyses. In vitro antioxidant activities of synthesized ZnO NPs were found to possess concentration-dependent free radical scavenging activity was carried on different free radicals i.e. DPPH and ABTS. Antimicrobial activity of synthesized ZnO NPs was performed by agar well diffusion method and compared with control ampicillin, while cytotoxic effects were determined by MTT assay against human cervical cancer cell line. UV-Visible spectra were conducted to confirm the synthesis of ZnO NPs and peak obtained at 364.15nm. X-ray analysis confirmed the crystalline nature of the nanoparticles and the average size of the nanoparticles was 30-50nm and was spherical shape analyzed by SEM. The synthesized ZnO NPs showed antimicrobial activity against all tested microorganisms and a maximum inhibition zone was found against E. coli in gram-negative and S. aureus in gram-positive bacteria. Synthesized ZnO NPs were showed 50% cell viability at 26.53μg/ml against the HeLa cancer cell line. The conclusion of this study suggests both the aqueous crude extract of Tagetes erecta flower and synthesized ZnO NPs showed an excellent alternative source of antimicrobial agent also an attractive selective cytotoxic activity against HeLa tested cancer lines, offering satisfying ‘safe and cheaper’ alternatives to conventional therapy protocols.