Contribuição ao Conhecimento Químico de Esponjas do Litoral Cearense: Monanchora arbuscula

Abstract

Monanchora arbuscula (DUCHASSAING & MICHELOTTI, 1864) (Crambeidae) is an incrustant sponge, massive or branched with 15 cm high. Its color ranges from salmon to bright red or light pink with white conspicuous channels. Previous studies of M. arbuscula led to the isolation of some polycyclic guanidine alkaloids; ptilocaulin, 8bhydroxyptilocaulin, dehydrobatzelladine C, crambescidin 800 and isoptilocaulin. In this work, the hydroethanol extract from M. arbuscula collected at “ Pedra da Risca do Meio” Marine State Park, in Fortaleza coast zone was partitioned with CH2Cl2/H2O (3:1) affording the crude extract which was submitted to liquid-liquid partition using petroleumether, dichloromethane, ethyl acetate and methanol as the solvents. Successive chromatograghy over silica gel, SEPHADEX LH-20 and/or HPLC of all solvent fractions led to the isolation of the guanidine alkaloids: mirabilin B, 8bβ-hydroxyptilocaulin, ptilocaulin, 1,8a;8b,3a-didehydro-8β–hydroxyptilocaulin, 1,8a;8b,3a-didehydro-8α-hydroxyptilocaulin, 3,3a;8b,8a-didehydro-8-hydroxyptilocaulin. Mirabilin B, 1,8a;8b,3adidehydro- 8β–hydroxyptilocaulin, 1,8a;8b,3a-didehydro-8α-hydroxyptilocaulin are reported for the first time for the species while 3,3a;8b,8a-didehydro-8-hydroxyptilocaulin has not being reported in the literature yet. Pharmacological assays revealed weak citotoxic activity against 4 cancer cell lines: HCT-8 (human colon carcinoma), MADMB-435 (melanoma), HL-60 (human leukemia) and SF-295 (glioblastoma). The assays indicated activity for the crude extract, several fractions and the isolated compounds ptilocaulin and 8bβ-hydroxyptilocaulin. The alkaloid 8b-hydroxyptilocaulin indicated antifungal activity against Microsporum canis and Trichophyton rubrum, while ptilocaulin against Microsporum canis, Mirabilin B antiprotozoal activity against Leishmania chagasi and amazonesis. Structure elucidation of the isolated substances was performed through spectroscopic methods, mainly NMR, including uni and bidimensional pulses sequences, and comparison with data from literature.