Calystegin N1, a novel nortropane alkaloid with a bridgehead amino group from Hyoscyamus niger: structure determination and glycosidase inhibitory activities

✍ Scribed by Naoki Asano; Atsushi Kato; Yoshie Yokoyama; Miwa Miyauchi; Masaru Yamamoto; Haruhisa Kizu; Katsuhiko Matsui

• Book ID: 102995277
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 459 KB
• Volume: 284
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(96)00017-1

✦ Synopsis

Seven calystegins were isolated from the whole plant of Hyoscyamus niger. They are calystegins A 3, A 5, A 6, B t , B 2, B 3, and N 1. The structure of new calystegin A 6 was determined as la,2~,7a-trihydroxy-nor-tropane, and another new calystegin N 1 was elucidated to be a trihydroxy-nor-tropane alkaloid with a bridgehead NH 2 group in the place of a bridgehead OH group in calystegin B 2. Very interestingly, on storage for a half year in a refrigerator, approximately 40% of calystegin N I was nonenzymically converted into calystegin B 2. Calystegin N~ was a weaker inhibitor of glycosidases compared to calystegin B 2 but with the same inhibitory spectrum. However, calystegin N~ inhibited porcine kidney trehalase in a noncompetitive manner, whereas calystegin B 2 inhibited this enzyme in a competitive manner.