Cytotoxic Effects of the Monomer and Dimer of 3, 4-seco-ent-kaurene from Croton Micans and their Interaction with Antitumoral Drugs on Cellular Line of Human Prostate Cancer

The cytotoxic activity of two bioactive molecules obtained from Croton species, caracasine acid (monomer) and micansinoic acid (dimer) belonging to the group of the seco-ent-kaurenes was evaluated against the prostate cancer cell line PC3 and human dermis fibroblasts (control cells). In addition, the combination of the monomer and dimer was realized with the antitumoral drugs taxol and adriamycin. The PC3 and normal cells were growth-inhibited in a dosedependent manner after exposure to both natural products. These two seco-ent-kaurenes exhibited practically the similar cytotoxic activity against human tumor cells but not to normal cells. The monomer and the dimer in combination with adriamycin and taxol respectively showed a synergistic effect on tumor cells, resulting that the combination of adriamycin with the monomer or dimer was more effective than with the taxol. Moreover, the combination of monomer and dimers showed a strong antagonistic effect.