INFLUENCE OF CYCLOPROPENE FATTY-ACIDS (BAOBAB SEED OIL) FEEDING ON THE INVITRO DELTA-9 DESATURATION OF STEARIC-ACID IN RAT-LIVER MICROSOMES

DELTA9 desaturation of [1-C-14] stearic acid to oleic acid was studied in liver microsomes of rats fed either fresh Baobab seed oil, containing cyclopropene fatty acids (malvalic acid and sterculic acids), or heated Baobab oil, containing only minor amounts of these acids. This was compared with rats fed a control oil mixture or a fat-free diet. Up to 50 nmol of substrate, DELTA9 desaturation rate was the same in rats fed the three fat diets. From 50 to 150 nmol, the desaturation rates were practically constant in rats fed fresh Baobab seed oil. It increased in heated oil-fed rats at the same rate as in the control group, but more slowly than in the fat-free diet group. Fatty acid composition of liver microsomal lipids did not reflect the in vitro observed desaturation rate because monounsaturated fatty acids were in the same percentages in fresh and heated Baobab seed oil-fed rats. Moreover, the proportion of arachidonic acid was lower, and that of linoleic acid higher for both diets, in comparison with controls, suggesting a decreased DELTA6 and/or DELTA5 desaturation rate.