The effect of daily administration of 12 mmol/kg 2,2,4-trimethylpentane for 10 d on hepatic and renal microsomal mono-oxygenase activity, peroxisomal beta-oxidation and the concentration of alpha 2u-globulin has been examined in male and female rats. 2,2,4-Trimethylpentane produces liver and, to a lesser extent, kidney enlargement. This is associated with the selective induction of cytochrome P-450-mediated omega-oxidation and peroxisomal beta-oxidation of fatty acids and proliferation of peroxisomes. Male rats show a more marked response than female rats. 2,2,4-Trimethylpentane produces an increase in alpha 2u-globulin in the kidney of male rats. The relevance of selective induction of omega- and beta-oxidation of fatty acids and accumulation of alpha 2u-globulin to renal tubular necrosis in male rats requires further study.
Carotenes, especially beta-carotene, occurs abundantly in the natural plant world. It is estimated that nearly more than 500 different carotenoids such as ß-carotene, α -carotene, lutein, cryptoxanthins, zeaxanthins, etc distributed throughout the plant and algae kingdoms. Although many of these have proven independent functions, around 50 or more can be metabolized to vitamin-A inside the human body. ß-carotene is the most prevalent carotenoid in the plant sources of the food chain and, for the same reason, is also known as pro-vitamin A .