Time-dependent stimulations of 1-alkyl-3-methylimidazolium chloride on redox reactants and antioxidases in Vibrio qinghaiensis sp.-Q67.

Previously, 1-alkyl-3-methylimidazolium chloride ([Cnmim]Cl) showed time-dependent hormesis on Vibrio qinghaiensis sp.-Q67 (Q67). Yet, the underlying mechanism remained unexplored. Currently, the biochemical effects of [Cnmim]Cl in Q67 were studied by ELISA kits. [C2mim]Cl firstly inhibited (0.25h) and then stimulated flavin mononucleotide (FMN), nicotinamide adenine dinucleotide (NADH), superoxide dismutase (SOD) and catalase (CAT). The stimulations of [C2mim]Cl firstly increased (from 2 to 8h) and then decreased (from 8 to 12h). Positive correlations among FMN, NADH and luminescence indicated the essential role of NADH:FMN reaction in the light production system, and those among SOD, CAT and luminescence indicated a time-dependent generation of reactive oxygen species (ROS). Notably, the maximum stimulations of [C2mim]Cl on FMN and NADH were at 4h, and the stimulations were 184% and 186% higher than the control, respectively, earlier and stronger than those on luminescence. The FMN/NADH ratios were 3.7 at 0.25h and decreased to 1.15 at 12h, without a concentration-dependence. The maximum stimulations of [C4mim]Cl were at 8h and the stimulations were 48.8% and 47.9% higher than the control for FMN and NADH, respectively. Meanwhile, the inductions of [C4mim]Cl on SOD and CAT continuously increased from 2 to 12h. Thus, [C4mim]Cl showed lower stimulation levels and different time-dependences. [Cnmim]Cl (n=6, 8, 12) did not show significant biochemical effects. Therefore, the biochemical effects of [Cnmim]Cl depended on both time and side chain. Our findings demonstrated a common pattern, FMN/NADH stimulations and antioxidant inductions, in the hormesis of ILs, and also called for future mechanisms studies.