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. 2022 Oct 31;23(21):13293. doi: 10.3390/ijms232113293

Figure 2.

Figure 2

Naphthoquinones oxidize H2S to polysulfides (SSP4 fluorescence). (A) Effect of increasing concentrations of 1,4-naphthoquinone (1,4-NQ) with constant 300 μM H2S, or (B) effect of 10 and 30 μM 1,4-NQ with increasing concentrations of H2S. (C,D) Effect of increasing concentrations of juglone (Jug) or plumbagin (Pbn) on SSP4 fluorescence from 300 μM H2S. All naphthoquinones initially increased, then decreased SSP4 fluorescence, whereas H2S concentration-dependently increased fluorescence at both concentrations of 1,4-NQ. (E) LC-ESI-HRMS identification of IAM-derivatized polysulfides produced from 1 mM H2S and 1 mM 1,4-NQ. Samples were derivatized after 10 min with 5 mM IAM and three aliquots (1, 2, 3) were analyzed serially at approximately 1 h intervals. (A–D) Mean + SE, n = 4 wells per treatment. *, p < 0.05; **, p < 0.01; ***, p < 0.001 compared to buffer; ##, p < 0.01; ###, p < 0.001 compared to maximum response.