Bioassay-guided fractionation of the crude extract derived from the marine sponge Monanchora arbuscula collected at Pedra da Risca do Meio Marine State Park, Ceará, Brazil

This study performed a cytotoxicity-guided fractionation of the extract derived from the marine sponge Monanchora arbuscula (Duchassaing & Michelotti, 1864) collected at the Pedra da Risca do Meio Marine State Park, Ceará State, off the northeastern Brazilian coast. The material was homogenized in EtOH and concentrated to a crude extract. The extract was partitioned with different solvents and chromatographed in silica gel and HPLC. Compounds ptilocaulin (PT), 8β-hydroxyptilocaulin (8HPT), mirabilin B and the epimeric mixture of 1,8a;8b,3a-didehydro-8α-hydroxyptilocaulin and 1,8a;8b,3a-didehydro-8β-hydroxyptilocaulin were obtained from the active fractions dichloromethane and ethyl acetate. For cytotoxicity evaluation, the MTT method was used, along with four tumor cell lines – HL-60 (leukemia), HCT- 8 (colon), MDA-MB-435 (melanoma) and SF-295 (glioblastoma) – during a 72h incubation period. The active samples were evaluated for lytic effects on Mus musculus mouse erythrocytes. PT and 8HPT were cytotoxic against all cell lines tested, with IC₅₀ ranging from 1.10 to 11.26µg/mL and 1.82 to 18.85µg/mL, respectively. These compounds also showed hemolytic activity (EC₅₀ of 87.17 and 152.50µg/mL, respectively for PT and 8HPT), but in much higher concentrations than those for antiproliferative activity.

Acknowledgement: Supported by FINEP, CNPq and InCB