We have found that 2-methoxy-1,4-naphthoquinones easily react with primary alcohols to produce the corresponding 2-alkoxyderivatives. Using this reaction, we synthesized methyl-6-O-(naphthalene-1,4-dione-2-yl)-α-D-glucopyranosides, a new type of water soluble quinone-carbohydrate nonglucoside conjugates. The resulting conjugates induced apoptosis in human cancer HeLa and normal mouse JB6 P(+) Cl41 cells with simultaneous inhibition of p53-dependant transcriptional activity, suggesting that the observed cell death was p53-independent. Furthermore, we analyzed structure-activity relationship and bioactivity of 2-hydroxy- and 2-methoxy-1,4-naphthoquinones as well as carbohydrate nonglucoside conjugates. All compounds containing a quinone moiety were able to inhibit p53-dependant transcriptional activity and exerted moderate inhibitory effects on HeLa cell colony formation. Investigations of structure-activity relationships revealed that cytotoxicity depended on the type of substituent at C-2 of the quinone moiety, decreasing in the following order: methoxyderivatives > carbohydrate nonglucoside conjugates > hydroxyderivatives. Furthermore, cytotoxicity depended on the position of the hydroxy substituent in the quinone moiety in all derivatives and decreased in the following order: 8- > 5- > 5,8-derivatives. In conclusion, this is the first report on synthesis and biological structure-activity relationships of the new class of quinone-carbohydrate nonglucoside conjugates.
