HALICHONADINS M-Q, SESQUITERPENES FROM AN OKINAWAN MARINE SPONGE HALICHONDRIA SP. (Dedicated to Professor Isao Kuwajima on the occasion of his 77th birthday)

Isolation and structure elucidation of four new dimeric sesquiterpenes, halichonadins M—P (I)—(IV) and new sesquiterpene, halichonadin Q (V), are described.