Cytochrome P-450 Enzyme Inhibitors

Publication Title: 
Phytotherapy research: PTR

The hydroalcoholic extract of fruit pulp of Terminalia chebula Retz. was standardized and evaluated for its safety through cytochrome P450 (CYP 450) inhibition assay. Standardization was performed through high performance thin layer chromatography (HPTLC) using gallic acid (GA) standard. Cytochrome P450-CO complex microplate assay was performed using rat liver microsomes. The effect of standardized extract, its fraction and bioactive marker compound were comparatively evaluated for its effect on CYP P450 enzymes.

Author(s): 
Ponnusankar, S.
Pandit, S.
Venkatesh, M.
Bandyopadhyay, A.
Mukherjee, Pulok K.
Publication Title: 
The Journal of Nutritional Biochemistry

The present studies characterized the influence of dietary selenium (Na2SeO3) on the duration of pentobarbital (PB) induced hypnosis (sleep) in the rat. Rats were fed semipurified diets varying from 0.01 to 2.0 mg Se/kg for up to 4 weeks. Consumption of diets containing 1.0 and 2.0 mg Se/kg significantly prolonged PB induced hypnosis. Hepatic selenium, but not hepatic glutathione peroxidase activity, correlated with the length of PB induced hypnosis. The prolongation of hypnosis caused by diets containing 1.0 mg Se/kg was substantially reduced or eliminated by repeated exposure to PB.

Author(s): 
Debski, Bogdan
Milner, John A.
Publication Title: 
Drug Metabolism and Disposition: The Biological Fate of Chemicals

In this study we have evaluated the application and reliability of using fluorescence (FLUO)-based high throughput screening assays with recombinant CYPs (rCYP). This was accomplished by screening 29 clinically important antiparasitic drugs for inhibition of the five major drug-metabolizing CYPs (-1A2, -2C9, -2C19, -2D6, and -3A4). Data from FLUO/rCYP assays were compared with that obtained by conventional HPLC assays using human liver microsomes (HLM) and rCYPs.

Author(s): 
Bapiro, T. E.
Egnell, A. C.
Hasler, J. A.
Masimirembwa, C. M.
Publication Title: 
The American Journal of Tropical Medicine and Hygiene

The antimalarial peroxide, dispiro-1,2,4,5-tetraoxane WR 148999, was synergistic with chloroquine, quinine, mefloquine, and artemisinin against both D6 and W2 clones of Plasmodium falciparum. In consideration of the contrasting antagonism between artemisinin and chloroquine, these drug combination data imply that WR 148999 and artemisinin may not share a common mechanism of action.

Author(s): 
Vennerstrom, J. L.
Ager, A. L.
Andersen, S. L.
Grace, J. M.
Wongpanich, V.
Angerhofer, C. K.
Hu, J. K.
Wesche, D. L.
Publication Title: 
Drug Metabolism and Disposition: The Biological Fate of Chemicals

Artemisinin drugs have become the first-line antimalarials in areas of multidrug resistance. However, monotherapy with artemisinin drugs results in comparatively high recrudescence rates. Autoinduction of cytochrome P450 (P450)-mediated metabolism, resulting in reduced exposure, has been supposed to be the underlying mechanism.

Author(s): 
Xing, Jie
Kirby, Brian J.
Whittington, Dale
Wan, Yakun
Goodlett, David R.
Publication Title: 
Presse Médicale (Paris, France: 1983)

GRAPEFRUIT: Essentially consumed in the form of juices with its bitterness helping to quench thirst, grapefruit contains not only vitamin C but also many complex antioxidizers, licopene, lemonoids and naringine. It also contains large quantities of pectin. Grapefruit juice is a metabolic inhibitor of medicinal substances that constitute an exclusive target for the CYP 3A4 isozyme and glycoprotein P in the enterocytes. Above all, it affects the drugs with strong intestinal metabolic first pass effect, phenomenon provoking the reduction of their oral bioavailability.

Author(s): 
Neuman, Maur
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