Ethnopharmacological relevance: Croton lechleri Mull. Arg. (Euphorbiaceae) is a traditional medicinal plant which produces a red sap, traditionally known as "Sangre de Drago"; it is used in folk medicine externally for wounds, fractures, and haemorrhoids, internally for intestinal and stomach ulcers and also for the empirical cure of cancers.
Materials and methods: We investigated the effects of Croton lechleri sap and taspine in comparison with taxol and vinblastine on the growth of human cancer cell lines of SK23 (melanoma), LoVo and HT29 (colorectal cancer) using MTT and Trypan blue assays. Further, we studied cell cycle by flow cytometry and detected acetylated-α-tubulin by confocal microscope.
Results: Croton lechleri inhibited cell proliferation starting from 1 μg/mL in SK23 cells, whereas 10 times higher concentrations were required for growth inhibition of HT-29 and LoVo cell lines. Also taspine (0.1 μg/mL) inhibited the SK23 and HT29 cell proliferation. Further, assay was assessed on SK23 and HT29 cell lines with 24-48 h treatment with sap and taspine. Both sap and taspine inhibited cancer cell proliferation; taspine showed higher activity on SK23 cells, which was significantly increased after 48 h of SK23 treatment. Using confocal microscopy we observed that Croton lechleri (1 μg/mL) caused a loss of microtubule structure, whereas taspine (0.5 μg/mL) caused an increase in acetylated α-tubulin and a modification of cellular morphology, mainly in SK23 cells. Croton lechleri sap 10 and 50 μg/mL influence cell cycle; 50 μg/mL sap caused a dramatic reduction of cells in G(1)/G(0) and S phases with a great increase of subG(0) cells.
Conclusions: The data showed that Croton lechleri and taspine could inhibit cell proliferation with higher potency against melanoma SK23 cells, supporting the empirical use of the sap as anticancer in ethnomedicine and taspine as a possible anticancer agent.
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