Bioassay-guided chromatographic separation of the cytotoxic MeOH extract of Phaius mishmensis led to the isolation of two known and six new indoloquinazolinones, phaitanthrins A-E (1-5) and methylisatoid (6). The structures of the new compounds were elucidated by spectroscopic analysis. Phaitanthrin A (1) and tryptanthrin (7) showed moderate cytotoxicity against MCF-7, NCI-H460, and SF-268 cell lines. A series of ketone adducts of tryptanthrin were prepared and tested initially for anticancer activity in vitro against MCF-7, NCI-H460, and SF-268 human cancer cell lines. The 3-pentanone adduct 13 showed activity similar to tryptanthrin.
In addition to six known phenanthroindolizidine alkaloids, eight new alkaloids, namely, ficuseptines B-D (1-3), 10R,13aR-tylophorine N-oxide (4), 10R,13aR-tylocrebrine N-oxide (5), 10S,13aR-tylocrebrine N-oxide (6), 10S,13aR-isotylocrebrine N-oxide (7), and 10S,13aS-isotylocrebrine N-oxide (8), were isolated from a methanol extract of the stems of Ficus septica. The structures of the new compounds were elucidated by means of spectroscopic data interpretation. Cytotoxicity of some of these alkaloids was assessed in vitro using the HONE-1 and NUGC cell lines.
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