抄録
In order to study the relation between the chemical structure and the antioxidant property, 12 hydroxycoumarin derivatives were synthesized and their activities for stabilizing vitamin A in cod-liver oil were examined using the same method described in the previous paper. The results, were as follows
1) 3, 4-Dimethyl-esculetin (mp. 260°), 3-iso-propyl-4-methyl-esculetin (mp. 280°), 3, 4-dimethyl-daphnetin (mp. 278°) and 4-methyl-3, 4-dihydro-esculetin (mp. 155°) were new compounds.
2) 6-Hydroxy-4-methyl-, 7-hydroxy-, 7-hydroxy-4-methyl-, 5, 7-dihydroxy-4-methyl-coumarins were found to be inactive.
3) The derivatives of esculetin were found to be more active than those of daphentin in general.
4) The alkyl substitution into the 4-position of esculetin caused no enhancement in activity but the substitution into the 3-position increased activity.
5) Among all hydroxycoumarins which were tested, 3, 4-dimethylesculetin was the most effective but its activity was inferior to that of methyl caffeate.
6) 4-Methyl-3, 4-dihydro-esculetin prepared by the hydrogenation of 4-methyl-esculetin showed marked effectiveness and its activity was almost the same as that of ethyl gallate.
