Toxicity assessment of Gentiana lutea L. root extract and its monoterpene compounds

Root of Gentiana lutea commercially available as gentian root, a natural antidote for different types of poisons, possess antioxidative, immunomodulatory, cytoprotective and anti-inflammatory, and adverse, genotoxic and mutagenic effects. It has monoterpenes loganic acid, swertiamarin, gentiopicroside and sweroside as most abundant constituents. In this study, we assessed the toxicity of monoterpenes' reactive molecular fragments using in silico prediction by VEGA-QSAR platform. Further, we compared the data obtained with in vitro geno- and cyto- toxicity testing of the above monoterpenes and the G. lutea root extract (GE), on human primary unstimulated and mitogen-stimulated peripheral blood mononuclear cells (PBMCs). Viability was assessed by TB and XTT tests after 48 h treatment. DNA damage was evaluated by alkaline comet assay on unstimulated cells, whereas cytokinesis-block micronucleus assay was employed on mitogen-stimulated PBMCs. Stability of compounds throughout treatment was monitored by UPLC. The observed in vitro results had highest compliance with in silico IRFMN/ISSCAN-CGX prediction model. Compounds showed high stability during experiment while treatment with single compounds reduced number of viable cells and increased DNA damage. GE treatment had toxic impact on unstimulated PBMCs but no significant genotoxic influence on mitogen-stimulated PBMCs. In summary, the mild GE effect suggests that the complexity of crude GE extract chemical composition may attenuate the toxicity of the tested monoterpenes loganic acid, swertiamarin, gentiopicroside and sweroside.