Fig. 2: Cyprocide-B is bioactivated to produce a reactive electrophile.

a Schematic of the proposed cyprocide-B sulfoxidation and LMW thiol conjugation pathway. P450s likely catalyze the S-oxidation of cyprocide-B, which produces an electrophilic sulfoxide metabolite. This sulfoxide metabolite reacts with glutathione (GSH) and is likely further processed to γ-glutamylcysteine (γ-Glu-Cys), cysteinylglycine (Cys-Gly) and cysteine (Cys) conjugates. The cyprocide-B sulfoxide metabolite can also react directly with γ-glutamylcysteine, cysteinylglycine and/or cysteine. b Extracted ion chromatograms (EICs) for indicated m/z values found in cyprocide-B treated C. elegans lysate (above) and paired DMSO solvent control (below). c–h Mass spectrometry (MS) data for the unmodified cyprocide-B parent (c), the sulfoxide metabolite (d), and the GSH-, γ-Glu-Cys-, Cys-Gly- and Cys- conjugates (e–h) from lysates of C. elegans treated with cyprocide-B and paired solvent-treated controls. The predicted structures of the thiol conjugates are supported by tandem mass spectrometry (MS/MS) (e–h). i C. elegans L1 larvae were preincubated with NACET or solvent control for 4 h before a 24-h exposure to 25 μM cyprocide-B, wact-11, or wact-55. The proportion of mobile worms in each condition is reported (n = 3 BRs). Error bars indicate SEM, p-values obtained from unpaired two-tailed Student’s t-tests, comparing means of the NACET and solvent preincubation conditions, ns is not significant (p = 0.6352 for wact-11 and p = 0.1496 for wact-55). Source data are provided as a Source data file.