Cytotoxic and antitumor constituents in pericarps of Mallotus japonicus.

A variety of phloroglucinol derivatives isolated from the pericarps of Mallotus japonicus were assessed for growth inhibiting activity against human larynx (HEp-2) and lung (PC-13) carcinoma cells as well as mouse B16 melanoma, leukemia P388, and L5178Y cells. Most of these derivatives were proved to be significantly cytotoxic in culture. One of them, 3-(3,3-dimethylallyl)-5-(3-acetyl-2,4-dihydroxy-5-methyl-6-methoxybenzyl )- phloracetophenone showed an excellent cytotoxicity against all target tumor cells and a marked prolongation of life-span in mice bearing L5178Y leukemia.