Abstract
Thirteen cycloartane-type tritepenes (1—13) and four prenylated flavanones (14—17) isolated from propolis collected in Myanmar, were evaluated for their cytotoxic activity against a panel of six different cancer cell lines; three murine cancer cell lines (colon 26-L5 carcinoma, B16-BL6 melanoma, and Lewis lung carcinoma) and three human cancer cell lines (lung A549 adenocarcinoma, cervix HeLa adenocarcinoma and HT-1080 fibrosarcoma). Among them, a cycloartane-type triterpene, 3α,27-dihydroxycycloart-24E-en-26-oic acid (3), showed the most potent cytotoxicity against B16-BL6 cells with an IC50 value of 5.91 μM, comparable to those of positive controls, doxorubicin (IC50, 5.66 μM) and 5-fluorouracil (IC50, 4.88 μM). In addition, (2S)-5,7-dihydroxy-4′-methoxy-8,3′-diprenylflavanone (14) exhibited strong cytotoxicity against all the tested cancer cell lines with the IC50 values ranging from 14.0 to 26.4 μM. Based on the observed results, the structure–activity relationships are discussed.
