Pteridines, Sterols, and Indole Derivatives from the Lithistid Sponge Corallistes undulatus of the Coral Sea

Abstract

The lithistid sponge Corallistes uizdulatus, which inhabits the base (- 5 10 m) of the New Caledonian coral reef, is shown here to contain the pteridines 1-methylpteridine-2,4- dione}, alreadyknownfromanotherCwalliJtB, and thenew(lrR,2'S)-6-(1',2'-dihydroxypropyl)- l-met$lpteridine-2,4-dione together with the steroids 3s-hydroxy-24- methylenecholest-5-en-7-one fl5)~7/23-hydroxysitosterol f161,7 s-hydroxysitosterol 1171, and 3s-hydroxystigmast-5-en-7-one {lS}, typical of higher terrestrial plants, and the indole derivatives methyl(2E)-3-(indol-3-yl-2-propenoate <g1, methyl(2E)-3-(6-bromoindol-3-yl)- ' 2-propenoate mf, and serotonin &l. The presence of the same compounds in taxonomically, phyletically, and ecologically unrelated organisms is viewed here as resulting from evolutionary convergence toward adaptive products. Pteridines have long been known as yellow pigments frominsects (l), with biopterin {(-)-1} acting also as growth factor in some cases (2). As far as sea life is concerned, biopterin has been found as a constituent of diatoms (3), while other pteridines known from terrestrial sources were detected in ascidians (4,5) and copepods (6). The lithistid sponge Corallistes~~luodesztodesnzzls of the Coral Sea has recently been shown to contain l-methyI-pteridine-2,4-dione (a} (7), previously known as a synthetic product (8). Pteridines unknown in terrestrial life have also been found in marine organisms: for example, 3-methylbiopterin {( -)-3} in the Mediterranean dendrophylliid coral Astroides cuZycdaris (9), leucettidine I( -)-4 in the Bermudian calcareous sponge Leucetta microraphis (10,l l), and the 1'-ketoanalogue 5 ofleucettidine, togetherwith congeners 6 and 7(12) and analogues with 1',3'-dioxygenated side chain (1 3), in the freepolychaete Odontosyllis andecimonta of Toyama Bay in Japan.