44 海綿由来のキノリチジンアルカロイド大環状二量体の化学構造と光学活性(口頭発表の部)  [in Japanese] 44 Chemical Structures and Optical Properties of Dimeric Quinolizidine-Alkaloid Macrocycles Isolated from An Marine Sponge  [in Japanese]

In search of new bioactive substances from marine organisms, we have investigated the chemical constituent of an Okinawan marine sponge Xestosponqia sp. and isolated eight new alkaloids named araguspongines B (8), C (9), D (1), E (7), F (3), G (2), H (5), and J (4) which were characterized by having two 1-oxaquinolizidine moieties. By HPLC analysis using a chiral column, these alkaloids were divided into two classes: the one obtained as a single enantiomer [F (3), G (2), H (5), J (4)] and the other as an enantiomeric mixture [B (8), D (1), E (7)]. In the further study, we isolated a new alkaloid named aragupetrosine A (18) (single enantiomer) together with two knowns, petrosin (11)(an enantiomeric mixt.) and petrosin A (15)(mesomeric), which were characterized by having two 2-oxoquinolizidine moieties. Aragupetrosine A (18) is a hybrid of petrosin (11) and araguspongine F (3). The fact, that araguspongines F (3), G (2), H (5), J (4), and aragupetrosine A (18) were respectively obtained as a single enantiomer while others as enantiomeric mixtures or as a mesomeric compound, may be explained by presuming enantio-selective methylation to occur at C-3 prior to (or after) formation of the racemic 1-oxaquinolizidine moieties. These alkaloids showed stronger vasodilative activities than papaverine in the perfusion model experiment using an isolated mesenteric artery of SD-rat.