Investigation of the cytocidal potential of Rhinella jimi skin methanol extracts.

CONTEXT: Amphibian skins have wide variety of biologically active compounds associated with the natural defenses of these animals.

OBJECTIVES: To study the in vitro anticancer activity of methanol extracts of the skin of Rhinella jimi Stevaux (Anura: Bufonidae).

MATERIAL AND METHODS: The extract was obtained by cold methanol extraction for 96 h using dried skins (295 mg). The methanol skin extract was dried under reduced pressure, giving a 5.5% yield. In order to test for growth-inhibitory activity, in vitro tests were performed with the following cancer cell lines using concentrations ranging between 0.25-250 µg/mL of the extract by 48 h: K562 (leukemia), MCF-7 (breast), NCI-ADR (breast with MDR phenotype), UACC-62 (melanoma), NCI460 (lung), PCO3 (prostate), HT-29 (colon), OVCAR (ovary), and 786-0 (kidney).

RESULTS: The methanol extract of R. jimi produced a growth inhibition in a dose-dependent manner against the most of the assayed cell lines. In addition to the growth inhibition, the extract induced the cell death in the ovary and colon lines (EC₅₀ 0.125 and 0.2 µg/mL, respectively), demonstrating 100% of inhibition with 2.5 µg/mL. However, prostate and leukemia cell lines demonstrated less sensitivity, with EC₅₀ of 24 and 235 µg/mL, respectively. This is the first report about the anticancer activity by natural products from the skin of R. jimi.

CONCLUSIONS: The methanol extracts of R. jimi significantly affected the growth of several cell lines, demonstrating that these compounds are a potential source of substances that could be utilized in cancer treatments.