Ferreira NH, Ribeiro AB, Morais MD, Peixoto AM, Bernardino MA, Moreira MR, Soares ACF, Heleno VCG, Veneziani RCS, Tavares DC. 2018. Cytotoxic and genotoxic effects of the ent-kaurenoic acid and ent-kaurenoic acid-enriched Mikania glomerata extract in V79. Biofarmasi J Nat Prod Biochem 17: xxxx. The ent-kaurenoic acid-rich extract from Mikania glomerata Sprengel was effective to inhibit the formation of Streptococcus mutans biofilm. In view of the biological potential of this extract and its major component, the present study was carried out to evaluate the safety of the ent-kaurenoic acid-rich extract from Mikania glomerata Sprengel and ent-kaurenoic acid alone in an in vitro test system. The results showed that the ent-kaurenoic acid-rich extract from Mikania glomerata Sprengel was cytotoxic at concentrations up to 40.0 μg/mL. Genotoxic effects were observed in cell cultures treated with the highest concentrations tested of ent-kaurenoic acid-rich extract from Mikania glomerata Sprengel (10.0 and 15.0 µg/mL) and ent-kaurenoic acid alone (2.5, 5.0 and 7.5 µg/mL) when compared to the control group. Therefore, the ent-kaurenoic acid-rich extract from Mikania glomerata Sprengel demonstrated cytotoxicity and genotoxicity effects at the highest concentrations tested, while ent-kaurenoic acid showed to be genotoxic at the same concentrations present in ent-kaurenoic acid-rich extract from Mikania glomerata Sprengel in V79 cells. These results demonstrate that the ent-kaurenoic acid should be responsible, at least in part, of the genotoxicity of ent-kaurenoic acid-rich extract from Mikania glomerata Sprengel.