Assessment of the in vitro and in vivo genotoxic and antigenotoxic effects of pimaradienoic acid in mammalian cells.

The pimarane-type diterpene, pimaradienoic acid (PA), is known for its diverse biological properties such as antimicrobial, anti-inflammatory and trypanocidal. A preliminary study was undertaken to investigate in vitro the free radical-scavenging potential of PA. In addition, the genotoxic potential of PA and its ability to modulate genotoxicity induced by doxorubicin (DXR) and methyl methanesulfonate (MMS) were studied in Chinese hamster lung fibroblasts (V79 cells) and in male Swiss mice using the comet and micronucleus assays. The DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) assay showed that PA exerted no antioxidant activity when compared to quercetin. The colony-forming assay using V79 cells showed that PA was cytotoxic at concentrations >5.0μg/mL. Therefore, concentrations of 0.625, 1.25, 2.5, and 5.0μg/mL were used for evaluation of the genotoxic and antigenotoxic potential of PA in V79 cells. For genotoxic and antigenotoxic assessment in Swiss mice, three PA doses were tested (20, 40, and 80mg/kg body weight) based on the solubility limit of the diterpene in dimethylsulfoxide and water. The in vitro results demonstrated that PA induced DNA damage at concentrations of 2.5 and 5.0μg/mL in the comet assay. However, no genotoxic effect was observed in the micronucleus test using V79 cells. In the in vivo evaluation of genotoxicity, a significant increase in the frequency of DNA damage was observed in hepatocytes of animals treated with the highest PA dose (80mg/kg) when compared to the control group, but this difference was not seen in the micronucleus test. Furthermore, PA significantly reduced the frequency of DXR- and MMS-induced micronuclei and extent of DNA damage in in vitro and in vivo test systems.