Isolation and Structure of Cancer Cell Growth Inhibitory Tetracyclic Triterpenoids from the Zimbabwean Monadenium lugardae

The Zimbabwean medicinal plant Monadenium lugardae was evaluated as a potential source of new anticancer constituents. Four new tetracyclic triterpene (1-4) were isolated, accompanied by four previously known triterpenes (5-8). Against a panel of human tumor cell lines, lugardstatins 1 (1) and 2 (2) had good cancer cell growth inhibitory activity. All of the triterpene structures (1-8) were established by 1D and 2D NMR spectrometric and HR mass spectrometric analysis.