Identification of Crocin I as a positive modulator of GSTP1 with potential relevance to prostate cancer

Glutathione S-transferase Pi 1 (GSTP1) is frequently silenced in prostate adenocarcinoma (PRAD), yet whether its residual catalytic activity can be chemically enhanced is largely unexplored. Here, we identify Crocin I as a positive modulator of GSTP1 through structure-based screening, biophysical characterisation, and biochemical validation. Bio-layer interferometry (BLI) supported a concentration-dependent association between Crocin I and GSTP1, and enzymatic assays demonstrated enhanced catalytic activity. Michaelis-Menten kinetics showed that Crocin I increased V_max without markedly altering the apparent K_m, consistent with apparent non-competitive activation of 1-chloro-2,4-dinitrobenzene conjugation under the tested conditions. Differential scanning fluorimetry showed that Crocin I altered GSTP1 thermal behaviour, with a comparable shift in the presence of the H-site inhibitor NBDHEX. Exploratory systems-level analyses further connected Crocin I-GSTP1 modulation with redox- and PRAD-associated networks. Together, these findings establish Crocin I as a previously unrecognised positive modulator of GSTP1 and provide a biochemical foundation for GSTP1-directed modulation in PRAD.