Flavonoid-mediated inhibition of ovarian glutathione S-transferase in Schistocerca gregaria: Biochemical characterization and in vitro evaluation.

Authors

Ghada S A Abdel Karim, Ragaa R Hamed, Tahany M Maharem, Manal A Emam, Rasha A Guneidy

Published in

Pesticide biochemistry and physiology. Volume 223. Pages 107309. Epub Aug 22, 2026.

Abstract

The desert locust, Schistocerca gregaria, remains one of the most destructive agricultural pests, posing a serious threat to crop production and food security. Current control strategies rely heavily on synthetic insecticides, raising concerns about environmental contamination and the development of insecticide resistance. Glutathione S-transferases (GSTs) are major phase II detoxification enzymes involved in xenobiotic metabolism and insecticide tolerance; however, their physiological role in reproductive tissues remains poorly understood. This study aimed to purify and characterize ovarian GST from S. gregaria and evaluate the inhibitory effects of selected plant-derived flavonoids as potential GST-targeting compounds. Ovarian GST activity was purified by GSH-affinity chromatography, yielding a predominant protein band with an apparent molecular mass of approximately 24 kDa. The purified enzyme exhibited maximum activity at pH 8.5 and showed the highest catalytic activity toward 1-chloro-2,4-dinitrobenzene (CDNB), followed by 1,2-dichloro-4-nitrobenzene (DCNB) and ethacrynic acid. Among the inhibitors tested, Cibacron Blue showed the greatest inhibitory potency, followed by bromosulfophthalein and ethacrynic acid, with IC₅₀ values of 0.48, 1.17, and 3.0 nM, respectively. The Michaelis-Menten constants (Kₘ) for glutathione (GSH) and CDNB were 0.10 and 0.086 mM, respectively. Kinetic analyses revealed that quercetin and delphinidin chloride competitively inhibited GST activity with respect to CDNB. In contrast, quercetin exhibited non-competitive inhibition toward GSH, whereas delphinidin chloride acted as a competitive inhibitor. These results demonstrate that ovarian GST possesses distinct kinetic characteristics and can be effectively inhibited by naturally occurring flavonoids. Although these findings are based on in vitro biochemical analyses, they suggest that inhibition of ovarian GST may reduce the detoxification capacity of S. gregaria and provide a biochemical basis for future in vivo investigations. Collectively, this study identifies ovarian GST as a potential biochemical target and highlights the potential of flavonoid-based GST inhibitors for further evaluation as synergists in integrated desert locust management.

PMID:
42697678
Bibliographic data and abstract were imported from PubMed on 05 Sep 2026.

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