The present study evaluates the photochemical behavior of a nitroimidazole derivative drug metronidazole in presence of N,N dimethylaniline and ZnO nanoparticles. The photochemical behavior was examined in a photochemical reactor by irradiating with a light of 254 and 310 nm. After completion of reaction one photoproduct was obtained. The photoproduct was isolated by using column chromatography and the structure of the isolated photoproduct was established by different spectroscopic techniques. This study provides the probable mechanism of the photochemical transformation of metronidazole in presence of an electron donor and in presence of ZnO NPs. During the photochemical transformation the nitro group of metronidazole was reduced in the amine group by a series of electron transfer processes. The ZnO nanoparticles are very efficient catalysts, and they degrade almost 90% metronidazole in the 60 min of UV irradiation. The photocatalytic mechanism of the ZnO nanoparticles is also discussed.

Several Plant products have been found to be a part of phytomedicines since time immemorial. These plant products can be derived from barks, leaves, flowers, roots, fruits, and seeds. It has been found that the light radiation affects the antimicrobial activity of herbal products. The present study was aimed to investigate the phytochemical screening and antimicrobial activities of Calotropis gigantea leaf extracts. In addition to these studies we also check the effect of UV light radiation on the anti microbial activity of leaf extract. Phytochemical screening revealed the presence of various active phytochemicals in the extracts of aerial part of Calotropis gigantea. Ethanol, chloroform and hexane extract of leaves were tested against Clostridium botulinum, Proteus vulgaris, Escherichia coli and Arthrographis cuboid, Aspergillus fumigatus, Aspergillus niger by the agar disc diffusion method. The antimicrobial activity of the extracts generally reduces significantly after exposure to the UV radiations.