Figure 4. TP219 depletes intracellular GSH levels via a covalent bond.

(A) Effect of TP219 (black squares) and BSO (white circles) versus control (black squares) on intracellular reduced (GSH) levels in BGM cells, quantified at various time points post incubation. (B) LC/MS/MS followed by collision induced dissociation analysis identified the ion [M-H]⁻ at m/z 570.71 and several fragment ions. Proposed structure of TP219-GEE adduct corresponding to [M-H]⁻ is provided as well. (C) The inhibition of infectious particle formation by TP219 can be reversed by a dose dependent exogenous addition of reduced GSH (GEE) to TP219-treated cell cultures. Control or TP219-treated (50 µM) cell cultures were co-incubated with varying concentrations of GEE, infected with CVB3 at an MOI of 5 and harvested 7 h pi. Virus titers were calculated by endpoint titration and expressed as the tissue culture 50% infectious dose per ml (Log₁₀ TCID₅₀). Data are average values ± SD.