Novel sesquiterpenes from Schisandra grandiflora: isolation, cytotoxic activity and synthesis of their triazole derivatives using 'click' reaction.
Poornima B, Siva B, Shankaraiah G, Venkanna A, Nayak VL, Ramakrishna S, Venkat Rao C, Babu KS.
Phytochemical investigation of hexane extract from the fruits of Schisandra grandiflora afforded three novel sesquiterpenes (1-3) along with the three known compounds (4-6). The structures of these isolates were determined by extensive analysis of spectroscopic data (1D, 2D NMR). Further, a series of triazole analogues of 3 and 4 were prepared using 'Click' reaction protocol. The reaction scheme involving one-carbon homologation of 3 and 4 using the Bestmann-Ohira reagent followed by regioselective Huisgen 1,3-dipolar cycloaddition reaction of various azides leading to the formation of triazole analogues (20a-20k &21a-21c) which is being reported for the first time. All the triazole products were characterized using spectral data analysis. The anti-proliferative activity of the isolates and the synthetic analogues were studied against Hela (Cervical cancer), A549 (Lung cancer), DU-145 (Prostate cancer), MCF-7 (Breast cancer) and B-16 (Mouse melanoma) cancer cell lines.