GLUTATHIONE-S-TRANSFERASE ACTIVITY IN PLHC-1 CELLS DEPENDING ON THE EFFECT OF BENZISOTHIAZOLINONE

Abstract

Benzisothiazolinone (BIT) is an isothiazolinone biocide increasingly used in industrial and consumer products as a preservative against microbial growth. Due to restrictions on more water soluble isothiazolinones such as methylisothiazolinone (MI) and methylchloroisothiazolinone (MCI), the use of more lipophilic compounds including BIT has increased, raising concerns regarding their toxicological effects. The aim of the present study was to investigate the effects of BIT on the detoxification enzyme glutathione-S-transferase (GST) activity in PLHC-1 fish liver cells cultured in vitro, with additional assessment of CYP1A activity. Activity of GST enzymes was measured in situ after 24 h and 48 h exposure to BIT and compared with known modulators of detoxification pathways, including tert-butylhydroquinone (tBHQ), β-naphthoflavone (BNF), ethacrynic acid, and curcumin. The CYP1A activity and protein content were additionally evaluated fluorometrically. The GST activity was induced by BIT in a concentration-dependent manner similarly to the known GST inducer t-BHQ. In contrast, BIT produced little or no induction of CYP1A-associated EROD activity, suggesting that BIT primarily activates Phase 2 detoxification or oxidative stress related pathways rather than AhR-mediated phase 1 metabolism. Curcumin significantly reduced GST activity induced by BIT and t-BHQ, consistent with its inhibitory effects on GST enzymes. Protein content remained relatively stable across treatments, indicating that the observed effects were not primarily caused by cytotoxicity and tested ranges of chemicals and mixtures were not cytotoxic. The results suggest that BIT is capable of activating GST-dependent detoxification mechanisms in fish liver cells and may contribute to oxidative stress responses. The study further supports previous findings indicating that BIT interacts with multiple phases of the cellular detoxification system.