Screening for anticancer compounds from herbal extracts.

Natural medicines are used for the treatment of infections, inflammatory symptom, and endocrine and metabolic diseases in all over the world. In Japan, these medications are typically combined with Western medicines to induce additive and synergistic effects. From natural medicines, numerous prototype compounds utilized as anticancer drugs in Western medicine were discovered, including camptothecin, podophyllotoxin, taxanes, and vinca alkaloids, and from bacteria, such as mitomycin and anthracyclines. Although these agents act against cancer using a variety of mechanisms, they can be classified into two major groups, namely, DNA replication inhibitors and mitosis inhibitors. Identifying novel compounds from traditional medicines and understanding the mechanism of their action would contribute the advance in chemical and biological studies as well as in cancer cures. Therefore, we screen for anticancer compounds from herbal extracts. To date, we have discovered several compounds that can be a potential anticancer substance. From natural compounds, numbers of topoisomerase inhibitors were identified. Now we have manipulated potential topoisomerase inhibitors that can act against camptothecin- and etoposide-resistant cancers and we investigate their pharmacological actions (Fig.1).

We have also discovered novel type of mitotic poisons (Fig.2).

Through these studies, we would like to develop a new type of anticancer compounds and would like to apply to clinical use.