Comprehensive Metabolite Profile and Cytotoxic Constituents of Cryptolepis decidua.

Root extracts of Cryptolepis decidua are used in the traditional medicine of South-West Africa to treat various conditions. Here, we report the potent cytotoxic activity of a methanol root extract against a human adenocarcinomic cell line, which prompted us to establish a comprehensive metabolite profile. Overall, six previously undescribed compounds were isolated from this extract by a combination of open-column chromatography (CC), centrifugal partition chromatography (CPC), and preparative HPLC. They include two sarmentogenin-type cardenolides (2 and 3), an androstane lactone (5), two dinormonoterpenoid diglucosides, dinosides A and B (9 and 10), and a quinic acid derivative (12). In addition, six previously reported constituents were identified (1, 4, 6-8, 11). The structures of the isolates were elucidated using HPLC-MS2/3, HRESIMS, and NMR spectroscopy. Feature-based molecular networking was used to map a comprehensive metabolite profile. The cytotoxic activity of the methanol extract was evaluated by WST-1 cell-viability assays, apoptosis/necrosis tests, and cell-cycle analyses. Cardenolides 1-3 were identified as the primary cytotoxic agents, exhibiting IC50 values of 0.25 μM (1), 2.20 μM (2), and 0.28 μM (3) in A549 human lung epithelial cancer cells, and 0.41 μM (1), 2.31 μM (2), and 0.39 μM (3) against peripheral blood mononuclear cells (PBMCs).