Beneficial effects of thyme oil on age-related changes in the phospholipidC-20 and C-22 polyunsaturated fatty acid composition of various rat tissues

The aim of this study was to determine any age-related changes in phospholi pid polyunsaturated fatty acid composition, in particular C-20 and C-22 fat ty acids in rat liver, brain, kidney and heart, and to assess and compare t he effects of dietary supplementation (42.5 mg/kg body weight/day) of the n atural antioxidant thyme oil and its major component thymol throughout the rat life span. The fatty acid composition in the various tissues from young (7 months) and aged (28 months) rats was determined and compared. Livers f rom aged control, thyme oil and thymol treated rats exhibited an increase i n 22:6(n-3). In contrast, 22:6(n-3) content of brain, kidney and heart decl ined in aged rats in all three dietary groups. However, aged rats treated w ith thyme oil and thymol displayed significantly higher levels of 22:6(n-3) than the respective age-matched controls. Tissue compositions of 20:4(n-6) were found to be significantly lower in the liver and kidney from aged con trol rats but not those fed either thyme oil or thymol. In aged rats, the c omposition of 20:4(n-6) in all tissues was highest in rats fed either thyme oil or thymol. These results show that dietary supplementation with thyme oil tended to maintain higher PUFA levels in all tissues studied. The major ity of protection provided by thyme oil was by virtue of its thymol compone nt, which comprises 49% of the whole oil. Thymol administered alone did not provide significantly higher protection than the whole oil, suggesting tha t other components within thyme oil are also contributing antioxidant activ ity. (C) 1999 Elsevier Science B.V. All rights reserved.