Inhibition of P-glycoprotein ATPase and its transport function of Helicoverpa armigera by morin, quercetin and phloroglucinol |
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Authors: | Ravindra M. Aurade S.MD. Akbar Hanumanth GoudSenigala K. Jayalakshmi Kuruba Sreeramulu |
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Affiliation: | a Department of Biochemistry, Gulbarga University, Gulbarga 585106, Karnataka, India b Agricultural Research Station, University of Agricultural Sciences, Gulbarga 585103, India |
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Abstract: | Flavonoids (morin, quercetin and phloroglucinol) were tested for their ability to modulate the function of P-glycoprotein ATPase of the insecticide resistant pest Helicoverpa armigera (Ha-Pgp). Flavonoids in the presence of ethylparaoxon or cypermethrin significantly reduced both larval weight as well as survival rate 40-50%. Morin and quercetin inhibited the activity of Ha-Pgp ATPase by 80-90%, whereas phloroglucinol inhibited ATPase activity by 40% at 100 μM concentration. These flavonoids inhibited the verapamil, ethylparaoxon and cypermethrin-stimulated Ha-Pgp ATPase activity. Morin, quercetin and phloroglucinol binding were quantitated by quenching of the intrinsic Trp fluorescence of purified Ha-Pgp ATPase. Drug transport was monitored in proteoliposomes containing Ha-Pgp ATPase using the high affinity fluorescent substrate tetramethylrosamine (TMR) in real time. Addition of the morin and quercetin mediated the collapse of the TMR concentration gradient generated by Ha-Pgp ATPase. The inhibition studies on Ha-Pgp ATPase activity may contribute towards understanding new strategies of the pest to overcome insecticide resistance. |
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Keywords: | Helicoverpa armigera P-gp ATPase Flavonoids Tryptophan quenching Proteoliposome Drug transport |
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