Lindane metabolism by human and rat liver microsomes

Area of Science:

• Environmental Toxicology
• Pharmacokinetics
• Biochemistry

Background:

• Lindane (gamma-hexachlorocyclohexane) is a pesticide used topically for scabies and lice.
• Understanding lindane's metabolism is crucial for assessing human health risks.

Purpose of the Study:

• To identify and characterize the primary and secondary metabolites of lindane in human liver microsomes.
• To compare the metabolic profile of lindane in human liver microsomes with that of rat liver microsomes.

Main Methods:

• Incubation of lindane with human and rat liver microsomes.
• Identification of metabolites using column chromatography and gas-liquid chromatography-mass spectrometry (g.l.c.-mass spectrometry).

Main Results:

• Human liver microsomes produced four primary metabolites (e.g., gamma-1,2,3,4,5,6-hexachlorocyclohex-1-ene) and two secondary metabolites (e.g., 2,3,4,6-tetrachlorophenol).
• Rat liver microsomes produced similar metabolites but at different rates, with some metabolites being significantly lower or undetected.
• The metabolite beta-1,3,4,5,6-pentachlorocyclohex-1-ene (3,4,6/5-PCCH) was identified in human liver microsomes for the first time.

Conclusions:

• Human liver microsomes exhibit significant metabolic activity towards lindane.
• Comparative analysis with rat liver microsomes highlights species-specific differences in lindane metabolism.
• The findings suggest potential for substantial hepatic metabolism of lindane in humans.