Biocher&al Systemath and Ecology. Vd. 24, Na 2, pp 115-118.1996 Pergamon Copyright 0 1998 Elsetier Science Ltd Printed in Great Britain. All rights reserved 0305-1976/96 $15.00+0.00 PII: 80305-lS78(S6)OOOtIl-4 Main Sterols from the Echinoid Encope emarginata MARINA G. PEREZ,’ ALEJANDRO J. ROCCATAGLIATA,’ MARTA S. MAIER,*t ALICIA M. SELDES” and JUAN M. DiAZ DE ASTARLOAS ?? Departamento de Quimica OrgBnica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellbn 2, Ciudad Univanitaria, 1428 Buenos Aires, Argentina; SDepartamento de Ciencias Marinas, Facultad de Ciencias Exactas y Naturales, Universidad de Mar del Plata, Funes 3350,760O Mar del Plata, Buenos Aires, Argentina Key Word Index: Encope emarginafa; Clypeasteroida; Echinoidea; sand dollar; marine sterols; cholestan- 3p-01; cholest-4-en-3-one. Abstract-The hitherto undescribed sterol composition of the masticatory apparatus and the body of the echinoid Encope emarginata was studied, revealing the presence of common BP-hydroxy sterols. A com- parison between the sterol composition of both mixtures shows the presence of very small amounts of cholestan-3B-ol and cholest-4-en-3-one in the masticatory apparatus only. These had not previously been detected in sand dollars. Copyright 0 1996 Elsevier Science Ltd Introduction In continuation of our studies on the metabolites of echinoderms (Maier et al., 1993; Roccatagliata et al, 1994) we had occasion to examine the echinoid Encope emar- ginata, a very common sand dollar of the Atlantic South American coast. Previous work on this organism involved the isolation of echinochrome A, a red naphtho- quinone pigment widely distributed in the Echinoidea (Stonik and Eliakov, 1988), but no study on its steroidal content has been reported. Several important papers and a general review of sterols from the phyllum Echi- nodermata have been published (Goad, 1978; Kerr and Baker, 1991) and it is known that from the five classes in the phyllum, sea cucumbers (class Holothuroidea) and starfishes (class Asteroidea) contain a predominance of A’ sterols, whereas sea lilies (class Crinoidea), sea urchins and sand dollars (class Echinoidea) as well as brittle stars (class Ophiuroidea) predominantly produce conventional A5 sterols. Sand dollars live in or on soft sediments. Most of them are detritus and particulate feeders and their feeding depends in large part of the action of a highly modified masticatory apparatus (commonly called Aristotle’s lantern) with nonprotractable teeth. In order to analyze the sterol composition of Encope emarginata and to establish the possible contributing sources to this content, i.e. de nova biosynthesis and assimilation or modification of dietary sterols, we have undertaken a careful study of the sterol composition of the masticatory apparatus and the body of this organism. Materials and Methods Fresh specimens of Encope emarginata (Leske 1778) (4.0 kg) were collected in 1993 off the coast near Mar del Plata, Buenos Aires, Argentina and were identified by Dr Alejandro Tablado of the Museo de Ciencias Naturales “Bernardino Rivadavia” where a voucher specimen (No. 31238) is preserved. The masticatory apparatus (0.1 kg) was separated from the body (3.8 kg) and each part analyzed separately. SAuthor to whom correspondence should be addressed. (Received 13 January 1995; accepted 9 June 1995) 115