ABSTRACT
Objective: Kalanchoe hybrida (Crassulaceae) is naturalized throughout all the island of Taiwan in China. The preliminary bioassay-guided fractionation of the crude extract of K. hybrida exhibited that the chloroform and n-butanol fractions possessed potent cytotoxicity against MCF-7, NCI-H460, and SF-268 tumor cell lines at 50 µg/mL concentration. Therefore, K. hybrida was selected as a target and the chemical constituents from the chloroform and n-butanol fractions of the crude extracts of K. hybrida were identified. The potential constituents were examined for their cytotoxicity against the tumor cell lines. Methods: A combination of conventional chromatographic techniques was performed on the crude extract of K. hybrida. The chemical structures of the purified constituents were identified on the basis of spectroscopic and spectrometric analysis. Results: The purification results had led to the characterization of totally 37 compounds. The isolated compounds 1, 2, and 4–12 were examined for their cytotoxicity in vitro, and bufadienolides 4–8 and flavonol glycoside 11 displayed significant cytotoxicity towards all the tested tumor cell lines among these tested compounds. Conclusion: The results indicated that these principles should be responsible for the bioactivity of corresponding partial fractions. The potential constituents could be further investigated to explore the new natural lead drugs.