Influence of curcumin, capsaicin, and piperine on the rat liver drug-metabolizing enzyme system in vivo and in vitro

The effect of dietary supplementation of spice-active principles, curcumin (0.2%), capsaicin (0.015%), and piperine (0.02%) on the activities of the liver drug-metabolizing enzyme system was examined. All the 3 dietary spice principles significantly stimulated the activity of aryl hydroxylase. A synergistic action of dietary curcumin and capsaicin with respect to stimulating the activity of aryl hydroxylase was also evidenced when fed in combination. The activity of N-demethylase essentially remained unaffected by dietary curcumin, capsaicin, or their combination, but was significantly lowered as a result of piperine feeding. Uridine dinucleotide phosphate (UDP)-glucuronyl transferase activity was decreased by dietary piperine and the combination of curcumin and capsaicin. NADPH-cytochrome c reductase activity was significantly decreased by dietary piperine. The levels of hepatic microsomal cytochrome P450 and cytochrome b5 were not influenced by any of the dietary spice-active principles. These spice-active principles were also examined for their possible in vitro influence on the components of the hepatic drug-metabolizing enzyme system in rat liver microsomal preparation. Piperine significantly decreased the activity of liver microsomal aryl hydroxylase activity when included in the assay medium at 1 × 10−6 mol/L, 1 × 10−5 mol/L, and 1 × 10−4 mol/L level. Lowered activity of N-demethylase was observed in presence of capsaicin or piperine at 1 × 10−6 mol/L in the assay medium. Hepatic microsomal glucuronyl transferase activity was significantly decreased in vitro by addition of capsaicin or piperine. Capsaicin and piperine brought about significant decrease in liver microsomal cytochrome P450 when included at 1 × 10−6 mol/L and 1 × 10−5 mol/L, the effect being much higher in the case of piperine. The results suggested that whereas the 3 spice principles have considerable similarity in structure, piperine is exceptional in its influence on the liver drug-metabolizing enzyme system. The study also indicated that a combination of curcumin and capsaicin does not produce any significant additive effect on the liver drug-metabolizing enzyme system.

The Petroleum-Inducible Mixed-Function Oxidase of Cunner (Tautogolabrus adspersus Walbaum 1792): Some Characteristics Relevant to Hydrocarbon Monitoring

The hepatic aryl hydrocarbon hydroxylase of the cunner (Tautogolabrus adspersus) is a sensitive indicator of petroleum contamination. This fish is a particularly favorable species because of its limited home range and ease of capture. Oil concentrations of 1–2 mg/L in water caused two- to sixfold induction of the enzyme above uninduced levels; induction decayed in < 7 d after exposure ceased. Feeding of crude oil or mussel tissue contaminated with oil at a concentration of 500 mg/kg caused up to fivefold induction. Males maintained a constant specific activity of aryl hydroxylase through the season, but females had a decreased activity before spawning. Starvation may also have reduced AHH activity. Correlations with liver and body weight were not observed. 2,5-Diphenyloxazole was found to be a safe substitute for benzo[a]pyrene in the assay. Key words: cunner, mixed function oxidase, aryl hydrocarbon hydroxylase, oil pollution, monitoring, biochemistry