As part of an ongoing investigation on the discovery of
natural anticancer agents from tropical plants, compounds1−6
were evaluated for their cytotoxic activity against HT-29 human
colon cancer cells. Compound 1was found to be the most
active in inhibiting the proliferation of HT-29 cancer cells, with
an IC
50value of 6.8μM. Screening of1against CCD-112CoN
normal colon cells resulted in an IC50 value of 30.4 μM.
Therefore, the selectivity ratio of compound1for cancerous
colon cells versus normal colon cells was found to be
approximately 4. Microgrewiapine 3-acetate (1a) and com-pounds2, 3, 5, and 6showed IC
50 values greater than 10μM
when evaluated against the HT-29 cancer cell line and were
therefore deemed inactive