Analysis of endogenous H2S and H2Sn in mouse brain by high-performance liquid chromatography with fluorescence and tandem mass spectrometric detection.

Previous studies indicated that bound sulfur species (BSS), including hydrogen polysulfide (H 2 S n ), have various physiological functions in mammalian cells. Although H 2 S n molecules have been considered as secondary metabolites derived from hydrogen sulfide (H 2 S) based on in vitro studies or predetermined reaction formula, the physiological form of BSS and their endogenous concentration remain unclear. In the present study, we aimed to improve the usual method using monobromobimane (mBB) followed by high performance liquid chromatographic (HPLC) analysis for HS － for simultaneous determination of H 2 S, H 2 S 2 , H 2 S 3 and cysteine persulfide in biological samples. We demonstrated that mBB derivatization of H 2 S and H 2 S n standards under alkaline conditions (pH 9.5) induced significant decreases in H 2 S 2 and H 2 S 3 levels and a significant increase in the H 2 S level in an incubation time-dependent manner. Conversely, the derivatization of mBB adducts of H 2 S 2 and H 2 S 3 were stable under neutral conditions (pH 7.0), which is physiologically relevant. Therefore, we re-examined the method using mBB and applied an improved method for the evaluation of H 2 S, H 2 S 2 , and H 2 S 3 in mouse brain under physiological pH conditions. The concentrations of H 2 S and H 2 S 2 were 0.030 ± 0.004 μmol/g protein and 0.026 ± 0.002 μmol/g protein, respectively. Although the level of H 2 S 3 was below the quantification limit of this method, H 2 S 3 was detected in mouse brain. Using the method established here, we reveal for the first time the existence of endogenous H 2 S 2 and H 2 S 3 in mammalian brain tissues. H 2 S 2 and H 2 S 3 exert anti-oxidant activity and anti-carbonyl stress effects through the regulation of redox balance in neuronal cells. Thus, our observations provide novel insights into the physiological functions of BSS in the brain and into neuronal diseases involved in redox imbalance. [ABSTRACT FROM AUTHOR]