Inhibition of rat liver microsomal lipid peroxidation elicited by simple 2,2-dimethylchromenes and chromans structurally related to precocenes
1992
Casas, J. | Gorchs, G. | Sanchez-Baeza, F. | Teixidor, P. | Messeguer, A.
The effects on rat liver microsomal lipid peroxidation elicited by 2,2-dimethylchromenes and chromans structurally related to precocenes was investigated in NADPH-dependent incubations by using the thiobarbituric acid reactive substances (TBARS) and oxygen uptake rate tests as evaluation methods. Precocene II (1) exhibited an unexpected inhibitory activity on lipid peroxidation (IC50 = 11.4 micromolar TBARS production test). Among the compounds tested, those which had a hydroxyl group on the aromatic ring, particularly at the C-6 position (i.e., 6-hydroxy-7-methoxy-2,2-dimethyl-1-2H-benzopyran (2) and its 3,4-dihydro derivative 5), appeared to be the best inhibitors. In this context, the inhibitory effect elicited by the hydroxychroman 5 (IC50 = 0.3,uM, TBARS production test) was higher than that shown by 2,6-di-tert-butyl-4-methylphenol (BHT, 11). These results suggested that the lipid peroxidation inhibitory effect exhibited by precocene II and related derivatives could be due to a vitamin E-like free radical scavenger based mechanism. The identification of phenolic metabolites in the incubations performed with precocene II or its benzopyranyl analogues lacking aromatic hydroxyl substituents supported the above postulated mechanism.
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