The determination of TBA-reactive substances and alkenals in the presence of antioxidants.

This study investigated the inhibitory efficiency of all-rac-alpha-tocopherol, 2,6-ditert-butyl-p-cresole (BHT), and 6-hydroxy-2,5,7,8-tetramethyl-chroman-2-carbonic acid (Trolox) on determination of thiobarbituric acid-reactive substances (TBARS) and short-chain alkenals in rat liver homogenates. The concentration of TBARS was measured fluorophotometrically. Aldehydes were determined after derivatization with methylhydrazine by gas chromatography (GLC). The concentrations of alkenals and TBARS in liver homogenates were diminished when antioxidants were present during the sample preparation. It is suggested that in the absence of antioxidants the samples are autoxidized further during the preparative procedures. For the aldehyde determination all-rac-alpha-tocopherol was the most effective antioxidant to reduce the bias due to autoxidation, whereas for TBARS it was Trolox.

Bioefficiency of different tocopherols in chicken as assessed by haemolysis test and microsomal pentane production.

Bioefficiencies of alpha-, gamma- and delta-tocopherol in comparison with all-rac-alpha-tocopherol were established in broiler chickens. For this, 1-d-old male broiler chickens received a diet deficient in vitamin E and supplemented with increasing doses of the corresponding tocopheryl acetates. After 2 and 3 weeks of feeding, the animals were killed to obtain blood and liver samples. The ex vivo tests used were detergent-induced haemolysis and pentane production by liver microsomes. Bioefficiencies were calculated by comparison of the dose-response curves. It is concluded that haemolysis and pentane production are appropriate indicators of the bioefficiency of tocopherols in broiler chickens. The values obtained by both tests hardly differed and agree well with the figures previously obtained from rats and other species.