From Gardneria multiflora Makino (Loganiaceae) we have further isolated several new alkaloids. Structure elucidation of the six of them are presented. Alkaloid J (IX) and L (X) are trimethoxy oxindole alkaloids having gardneramine skeleton. The characteristic feature of these alkaloids is their C-16-R configuration, which was proved by formation of the ether ring between C-16 and C-20 on heating of IX or X in dilute hydrochloric acid. IX and X were derived from known bases gardneramine I and 18-demethylgard-neramine III respectively as shown in charts 1 and 3. Alkaloid N (XII) is also trimethoxy oxindole alkaloid which has glycol function at C-16 and C-17. This functionality was proved by formation of acetonide f. The configurations of C-7 and C-16 of XII were determined by generation of iminoether compound h via mesylate g. Gardneramine-N-oxide (XIII), alkaloid M (XI), exomethylene compound (XIV) were also isolated. Alkaloidal constitution of Gardneria liukiuensis was also studied, which was proved to be quite similar to that of Gardneria multiflora.
