Calotroposides H–N, new cytotoxic oxypregnane oligoglycosides from the root bark of Calotropis procera

• Seven new oxypregnane oligoglycosides were isolated from the root bark of Calotropis procera.
• Their structures were established by different spectroscopic analyses.
• Their in vitro growth inhibitory activity was estimated.

As a part of our continuing interest in identifying anticancer drug leads from natural sources, we have investigated the n-BuOH fraction of the root bark of Calotropis procera (Ait) R. Br. Seven new oxypregnane oligoglycosides: calotroposides H–N (1–7) were isolated and identified. Their structures were established on the basis of 1D and 2D NMR studies, HRMS, and GCMS spectral data. The in vitro growth inhibitory activity of the n-BuOH fraction and compounds 1–7 was evaluated against A549 non-small cell lung cancer (NSCLC), U373 glioblastoma (GBM), and PC-3 prostate cancer cell lines. Compounds 4 and 6 showed subnanomolar growth inhibition activity with IC50 ranging from 0.5 to 0.7 μM against U373 glioblastoma (GBM) and PC-3 prostate cancer cell lines. These results provide further insight into the chemical diversity and biological activities of this class of compounds.

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