abstract |
The present invention relates to the use of compounds of formula (I) (I) In this formula, R 0 is C 1 -C 4 alkyl; R 1 is H, C 1 -C 4 alkyl, a sulfo group, -CO-NH- (C 1 -C 4 alkyl), CN or (C 1 -C 4 alkylene) sulfo; R 2 is H or C 1 -C 4 alkyl; R 3 is H, a sulfo group, C 1 -C 4 alkyl or C 1 -C 4 alkoxy; R 4 is H, C 1 -C 4 alkyl or C 1 -C 4 alkoxy. |