In-Vitro Inhibition of Camel Hepatic Glutathione Transferase by Quercetin

Abstract: Glutathione S-transferases (GST) are a group of multifunctional ubiquitous enzymes widely present in animals and plants, which catalysis the conjugation of glutathione to different exogenous and endogenous electrophilic compounds. This study was carried out to characterize the purified GST enzyme from camel liver tissues and to investigate the in-vitro inhibitory effect of the flavonoid quercetin by measuring S-2,4-dinitrophenyl glutathione (DNP-GSH) formation from 1-chloro-2,4-dinitrobenzene (CDNB) and reduced glutathione(GSH) as substrates. The Km values for reduced GSH and CDNB were found to be 0.08438 and 0.6827 mM while Vmax values were 6.935 and 15.599 mM/min respectively. The IC 50 was determined to be 1.8 mM. The inhibition constant (Ki) was estimated to be 1.91 mM at 0.5 mM and 1.76 mM at 2 mM. The mean inhibition constant (Ki) was estimated to be 1.835±0.075mM which revealed an uncompetitive profile and indicated quercetin as a weak inhibitor with the varied concentration of CDNB and fixed concentration of reduced GSH as a substrate