Antiradical Activity of Naphthazarin

The ABTS·+ scavenging activity of known (4, 6-8) and new (5, 9-12) naphthazarin-carbohydrate nonglycoside conjugates, and methoxynaphthazarins 1-3 was evaluated. The study of structure-activity relationships showed that the presence of carbohydrate fragments in the structure of naphthazarin-carbohydrate conjugates increased their antiradical activity compared with starting methoxynaphthazarins. Antiradical activity depends on the structure of carbohydrate fragments, their number, and position. Depending on the carbohydrate fragment the activity increased in the following order: methyl-α-d-glucopyranoside < d-glucofuranose < 1,2-O-isopropylidene-α-d-glucofuranose. The 2 sugar residues and their 3,7-position enhanced the activity of the conjugates