11-Deoxyfistularin-3, a New Cytotoxic Metabolite from the Caribbean Sponge Aplysina fistularis insularis Reinaldo S. Compagnone,* ,† Ramona Avila, †,1 Alı ´rica I. Sua ´ rez, ‡ Odette V. Abrams, † He ´ctor R. Rangel, § Francisco Arvelo, § Ivette C. Pin ˜ a, † and Elizabeth Merentes § Centro de Quı ´mica Orga ´ nica, Escuela de Quı ´mica Facultad de Ciencias, Universidad Central de Venezuela, Apartado 47102, Caracas, Venezuela, Facultad de Farmacia, Universidad Central de Venezuela, Apartado 40109, Caracas, Venezuela, and Laboratorio de Cultivo de Tejido Animal, Instituto de Biologı ´a Experimental, Facultad de Ciencias, Universidad Central de Venezuela, Apartado 47114, Caracas, Venezuela Received April 26, 1999 11-Deoxyfistularin-3 (1), a new bromotyrosine derivative, was isolated among other known compounds such as fistularin-3 (2), aerothionin (3), and 11-oxoaerothionin (4) from the Caribbean sponge Aplysina fistularis (Aplysinellidae). The structure of 1 was determined by spectroscopic analysis and showed in vitro activity against the human breast carcinoma cell line MCF-7. Sponge of the Verongida genera including Verongula, Pseudoceratina, Ianthella, and Psammaplysilla have been intensively studied due the presence of alkaloids with one, or more bromotyrosine residues. 2 Many of these metabolites show interesting antibiotic 3 and cytotoxic properties in cell lines. 4 Recently, particular interest has been given to the chemical analysis of these species because the presence of the bromotyrosine derivatives seems to be peculiar to the order and can be used as a chemical marker to support taxonomic work. 5 Previous reports on Aplysina fistularis insularis (Duchassaing & Michelotti) (family Aplisinidae) have documented the presence of a wide number of interesting metabolites, mainly of the bromotyrosine type. Examples of these brominated metabolites are the fistu- larins, 6 aerothionins, 7 ceratinamines, 8 aplysamines, 9 ana- monian, 10 and psammaplysin 3 . Continuing a program of searching for new metabolites with potential biomedical interest from marine species collected in the Caribbean, we report in this paper the isolation of a new metabolite: 11-deoxyfistularin-3 (1) from A. fistularis. This sponge was collected by hand using SCUBA in Chichiriviche de la Costa, located on the central coast of Venezuela, at 20 m depth. The MeOH/CH 2 Cl 2 extract of A. fistularis was chromato- graphed on silica gel using a mixture of hexane/EtOAc. After preparative TLC purification of selected, combined fractions, 11-deoxyfistularin-3 (1) was isolated as a solid and identified by analysis of spectral data. Other known metabolites such as fistularin-3 (2), 6 aerothionin (3), 7 and 11-oxoaerothionin (4) 11 were also isolated and identified. HRFABMS suggested the molecular formula C 31 H 30 N 4 O 10 - Br 6 for 1. The UV spectrum (λ max 209, 235, 283 nm; ǫ 42 400, 21 600, 11 200) was similar to fistularin 3 (2). The IR spectrum of 1 was closely related to fistularin-3 and showed bands at 3417 cm -1 characteristic of NH and OH groups and at 1656 cm -1 typical of an amide group. The 1 H NMR (Table 1) spectrum of 1 was very similar to that of 2, 6 except for the absence of the signal corre- sponding to 11-CHOH group. Instead of the 11-CHOH group the presence of a multiplet at 2.11 ppm with J ) 6.5 Hz due to methylene signals on 11-CH 2 was observed. The H-H COSY spectrum showed a correlation of 10-CH 2 and 12-CH 2 with 11-CH 2 indicating the presence of a 3 carbon chain between a tyrosine residue and the dibro- mophenoxy group. A similar H-H COSY correlation was found between 19-CHOH and 20-CH 2 . The 13 C NMR spectrum of 1 was also quite similar to that of 2 6 and differs only in the presence of a signal at 30.37 ppm as a triplet in the DEPT spectrum, corresponding to the 11-CH 2 instead of the 11-CHOH signal at 69.47 ppm. Additionally, chemical shifts were shifted from 76.13 and 43.95 ppm in 2, to 71.51 and 37.13 ppm in 1, corresponding to 12-CH 2 and 10-CH 2 , respectively. Further proof to assign the position of the OH group was carried out by reduction of an authentic sample of the known compound 11-ketofis- tularin-3 (5) 6 isolated by us from A. lacunosa. The reduction of 5 was carried out using tosylhydrazine and sodium borohydride to give compound 1. The spectral data of the reduction product of 5 matched our spectral data found for 1. Combination of all the data allowed us to establish the structure of 1 as 11-deoxyfistularin-3 (Table 1). 1 was tested against the following cell lines: X-17, Hela, Hep-2, RD, Lovo, and MCF-7. Among all these cell lines, compound 1 was most cytotoxic against MCF-7 (human * To whom correspondence should be addressed. Tel.: +58 2 6052236. Fax: 58 2 7534193. E-mail: rcompag@strix.ciens.ucv.ve. † Centro de Quı ´mica Orga ´ nica. ‡ Facultad de Farmacia. § Instituto de Biologı ´a Experimental. 1443 J. Nat. Prod. 1999, 62, 1443-1444 10.1021/np9901938 CCC: $18.00 © 1999 American Chemical Society and American Society of Pharmacognosy Published on Web 09/03/1999