Unlike many researchers of natural product chemistry, I was fortunate to have the opportunity to study phytochemical metabolites and isolates of microbial origin. I began my career isolating the active compound(s) from the medicinal plants. After obtaining a Ph.D. degree from Tohoku University, I flew to Chicago, College of Pharmacy, University of Illinois, where I carried out research on the chemistry of acronycine and discovered several interesting chemical reactions regarding this alkaloid. After returning to Japan, I began to work at the Kitasato Institute, to search for novel antitumor antibiotics. During this period, 27 new antibiotics were isolated, and the new chemical structures were elucidated. After rejoining the Pharmaceutical Institute at Tohoku University, I again began to work on the phytochemical substances, mainly alkaloids. These studies continued after I moved to Aomori University and finally to Nihon Pharmaceutical University. I was interested in the biosynthesis of the alkaloids and found that all alkaloids could be classified into 16 classes based on their method of biosynthesis. I wrote a book about this in Japanese, and subsequently the book was translated into English as "ALKALOIDS-A Treasury of Poisons and Medicines." After completing the publication of this book, I had many chances to write books, mainly concerning poisons and medicines. Totally, I have been able to publish 26 books regarding on these fascinating topics until now. I am feeling very satisfied with my natural product chemistry contributions, especially those of alkaloids and poisons.
Keywords: Shosoin; Taketori-Monogatari; alkaloid; antibiotic; hypotensive principle; poison.