RESUMO
The purpose of this work was to study the cytotoxic effects of marine sponge Polymastia janeirensis, which has been observed in the field to release an orange substance that is toxic to fish. The result showed that aqueous extract (pH 7.0) was highly cytotoxic to glioma (U87) and neuroblastoma (SHSY5Y) cancer cell lines (IC50 < 1.0 µg/mL). In addition, this extract showed potent antioxidant and procoagulant (decreased the clotting time by 1.7-fold) activities. Interestingly, the cytotoxic effects were pH-dependent since the viability of the cancer cells was not affected with the extract (pH 5.5). The close similarity between the aqueous extract (pH 7.0) and the orange liquid that is released by the sponge indicates that this potential chemical defence of P. janeirensis deserves further investigation.
RESUMO
OBJECTIVES: Marine sponges are among the most promising sources of chemically diversified fatty acids (FAs). In addition, several studies have shown the effect of polyunsaturated FAs on cancer therapy. This research carried out a biological and chemical evaluation of the sponge Scopalina ruetzleri collected on the South Brazilian coastline. METHODS: Bioassay-guided fractionation of S. ruetzleri was performed in human glioma (U87) and neuroblastoma (SH-SY5Y) cell lines, and the in-vitro effects on free radicals were evaluated. KEY FINDINGS: The ethyl acetate fraction of S. ruetzleri showed promising cytotoxic effects in cancer cell lines, with IC50 < 20 µg/ml. Fingerprint (1) H Nuclear Magnetic Resonance (NMR) analysis showed that this fraction is mainly constituted of FAs. Through FA methyl ester analysis, it was possible to identify 32 FAs. In addition, some minor unusual FAs for the marine biosphere were identified. The results of conjugated dienes method showed that FAs fraction, at concentrations above 50 µg/ml, has a pro-oxidant effect, indicating that lipid peroxidation may be partially responsible for the mechanism of cytotoxicity on cancer cells. CONCLUSION: This work also contributes to studies that focus on the application of FAs on cancer therapy as a new adjuvant to radio or chemotherapy, or as a chemotherapeutic agent.