Inhibition of microsomal lipid peroxidation and monooxygenase activities by eugenol

Nagababu Enika, N. Lakshmaiah

Research output: Contribution to journalArticle

Abstract

Previously we reported that eugenol (4-allyl-2-methoxyphenol) inhibits non-enzymatic peroxidation in liver mitochondria (E. Nagababu and N. Lakshmaiah, 1992, Biochemical Pharmacology. 43,2393-2400). In the present study, we examined the effect of eugenol on microsomal mixed function oxidase mediated peroxidation using Fe+3-ADP-NADPH, carbon tetrachloride (CCL4)-NADPH and cumene hydroperoxide (CumOOH) systems. In the presence of eugenol the formation of thiobarbituric acid reactive substances (TBARS) was decreased in all the systems (IC50 values: 14 μM for Fe+3-ADP-NADPH, 4.0 μM for CCl4-NADPH and 15 μM for CumOOH). Oxygen uptake was also inhibited to a similar extent with Fe+3-ADP-NADPH and CumOOH systems. A comparative evaluation with other antioxidants showed that in Fe+3-ADP-NADPH and CumOOH systems, the antioxidant efficacy was in the order: butylated hydroxytoluene (BHT) > eugenol > αtocopherol, while in CCl4-NADPH system the order was αtocopherol > BHT > eugenol. Time course of inhibition by eugenol indicated interference in initiation as well as propagation of peroxidation. Eugenol did not inhibit cytochrome P-450 reductase activity but it inhibited P-450 - linked monooxygenase activites such as aminopyrine-N-demethylase, N-nitrosodimethylamine demethylase, benzo(a)pyrene hydroxylase and ethoxyresorufin-O-deethylase to different extents. However, CumOOH supported monooxygenases (aminopyrine-N-demethylase and benzo(a)pyrene hydroxylase) required much higher concentrations of eugenol for inhibition. The concentration of eugenol required to inhibit monooxygenase activities was more than that required to inhibit peroxidation in all the systems. Eugenol elicited type 1 changes in the spectrum of microsomal cytochrome P-450. These results suggest that the inhibitory effect of eugenol on lipid peroxidation is predominantly due to its free radical quenching ability. Eugenol significantly protected against the degradation of cytochrome P-450 during lipid peroxidation with all the systems tested. These findings suggest that eugenol has the potential to be used as a therapeutic antioxidant. Further evaluation may throw more light on this aspect.

Original languageEnglish (US)
Pages (from-to)253-266
Number of pages14
JournalFree Radical Research
Volume20
Issue number4
DOIs
StatePublished - 1994
Externally publishedYes

Fingerprint

Eugenol
Mixed Function Oxygenases
Lipid Peroxidation
Lipids
NADP
Benzopyrene Hydroxylase
Aminopyrine N-Demethylase
Butylated Hydroxytoluene
Tocopherols
Antioxidants
Cytochrome P-450 Enzyme System
Cytochrome P-450 CYP2E1
NADPH-Ferrihemoprotein Reductase
Cytochrome P-450 CYP1A1
Mitochondria
Thiobarbituric Acid Reactive Substances
Carbon Tetrachloride
Liver Mitochondrion
Liver
Inhibitory Concentration 50

Keywords

  • Antioxidants
  • Cytochrome P-450
  • Eugenol
  • Free radicals
  • Monooxygenases
  • Peroxidation

ASJC Scopus subject areas

  • Biochemistry

Cite this

Inhibition of microsomal lipid peroxidation and monooxygenase activities by eugenol. / Enika, Nagababu; Lakshmaiah, N.

In: Free Radical Research, Vol. 20, No. 4, 1994, p. 253-266.

Research output: Contribution to journalArticle

Enika, Nagababu ; Lakshmaiah, N. / Inhibition of microsomal lipid peroxidation and monooxygenase activities by eugenol. In: Free Radical Research. 1994 ; Vol. 20, No. 4. pp. 253-266.
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