Efficacy of Catharanthus roseus leaf and flower extracts mediated Ag incorporated ZnO nanoparticles for enhanced antimicrobial and antioxidant abilities: a comparative analysis

In the present investigation, the bio-reduction of silver nitrate has been done using the extracts obtained from the leaves and flowers of Catharanthus roseus and the resultant silver nano particles were incorporated with ZnO through sonication. The ZnO was prepared via a simple soft chemical route. The characteristics of the resultant nanoparticles were analyzed using X-ray diffraction spectrometer, scanning electron microscope, Fourier Transform Infrared spectrophotometer, EDAX and elemental mapping techniques. The diffraction patterns of thus prepared ZnO nanomaterials revealed that they are crystallized with (101) plane which is the preferential orientation. The FTIR, report reveals that the phenolic compounds had played a vital role in the reduction of synthesized Ag nanoparticles. The SEM analysis revealed the coral rock like structure of the synthesized nanomaterials. The EDAX and mapping analysis confirms the presence of the elements Zn, Ag and O and C in the prepared samples. From the results, it can be concluded that the Catharanthus roseus leaves and flowers are good sources for the synthesis of silver nanoparticles. The plant mediated Ag incorporated ZnO showed better antibacterial property on Gram negative bacteria (Staphylococcus aureus and Escherichia coli) and Gram-positive bacteria (Klebsiella pneumonia).The antifungal action of Catharanthus roseus leaf and flower mediated Ag:ZnO nanoparticles were tested against three fungal strains namely Aspergillus Niger, Aspergillus flavus and Penicillium chrysogenum. Ag:ZnO:Leaf nanoparticles showed stronger antimicrobial activities when compared to the Ag:ZnO and Ag:ZnO:Flower nanoparticles. The radical scavenging activity named DPPH, was used to study antioxidant capability of the resultant nanoparticles and the related inhibition percentage of Ag:ZnO:Leaf and Ag:ZnO:Flower nanoparticles were found to be 65, 76 and 93%, respectively.