Calosides A–F, Cardenolides from <i>Calotropis gigantea</i> and Their Cytotoxic Activity
Mai Thanh Thi Nguyen, Khang Duy Nguyen, Phu Hoang Dang, Hai Xuan Nguyen, Suresh Awale, Nhan Trung Nguyen
Abstract
Phytochemical analysis of the roots of Calotropis gigantea led to the isolation of six new cardenolide glycosides, calosides A–F (1–6), and five known cardenolides (7–11). The structures of 1–6 were elucidated based on NMR and ECD spectroscopic data interpretation. Caloside D (4) is the first naturally occurring example of a cardenolide containing a C-8/C-19 oxygen bridge. In turn, calosides E (5) and F (6) represent the first naturally occurring 3-epi-cannogenol diglycosides having potent cytotoxicity against the PANC-1 cell line (IC50, 0.081 and 0.070 μM, respectively) and HeLa (IC50, both 0.17 μM) cells, under normoglycemic conditions.