The quantum chemical (INDO) calculations have been undertaken for 10 STX derivatives, various informations of electronic structure were obtained. The feature of electronic structure and active site in these compounds were investigated on the basis of calculated results. It was found that there are remarkable correlation relationships between some indices of electronic structure and the toxicity by the studies of structure-activity relationship. These results provides useful informations for discussion on acting mechanism, interaction with receptor and further molecular design.

Key words: ELECTRONIC STRUCTURE, STRUCTURE ACTIVITY RELATIONSHIP, SAXITOXIN, QUANTUM CHEMISTRY, CORRELATION COEFFICIENT