4--7-8-trihydroxyisoflavone and 3--4--7-trihydroxyisoflavone

One new ortho-dihydroxyisoflavone, 7,3',4'-trihydroxyisoflavone (2), and two known ortho-dihydroxyisoflavone derivatives were isolated from 5-year-old Doenjang (Korean fermented soypaste), and evaluated as potent antioxidant by comparing with other known isoflavones. 7,8,4'-Trihydroxyisoflavone (1), 7,3',4'-trihydroxyisoflavone (2), and 6,7,4'-trihydroxyisoflavone (3) inhibited DPPH (Diphenyl-1-picryl hydrazyl) formation by 50% at a concentration of 21.5+/-0.2, 28.7+/-0.4 and 32.6+/-0.6 (IC(50)), respectively, whereas three isoflavones showed weak DPPH radical scavenging activity. In xanthine oxidase (XO) system, in which both inhibition of xanthine oxidase and superoxide scavenging effect were measured in one assay. Compound 1 (IC(50)= 6.6+/-0.4 microM) and 2 (IC(50)=16.8+/-1.2 microM) show significant inhibitory activity and greater effect than allopurinol. But, compound 3 and other isoflavones showed lower inhibition activity. This study shows that the position of hydroxyl substituent at the aromatic ring of isoflavone plays an important role in radical scavenging effect.

Topics: Free Radical Scavengers; Humans; Isoflavones; Molecular Structure; Soy Foods; Structure-Activity Relationship

Three antioxidant isoflavonoids characterized as 4',7,8-trihydroxyisoflavone (1), 3',4',7-trihydroxyisoflavone (2) and 8-chloro-3',4',5,7-tetrahydroxyisoflavone (3) were isolated from the cultured broth of Streptomyces sp. OH-1049. Among them, 3 is a novel isoflavonoid possessing a chlorine atom in the molecule. In in vitro studies, these antibiotics were found to possess antioxidant activity whereas showed almost no cytocidal activities against HeLa S3 cells.

Topics: Animals; Anti-Bacterial Agents; Antioxidants; Fermentation; Flavonoids; HeLa Cells; Isoflavones; Male; Microbial Sensitivity Tests; Rats; Rats, Inbred Strains; Streptomyces; Structure-Activity Relationship

Structures of three antioxidant isoflavonoids isolated from the cultured broth of Streptomyces sp. OH-1049 were shown to be 4',7,8-trihydroxyisoflavone (1), 3',4',7-trihydroxyisoflavone (2) and 8-chloro-3',4',5,7-tetrahydroxyisoflavone (3), respectively. Among them, 3 is a novel isoflavonoid possessing a chlorine atom in the molecule. Compound 1 was synthesized and its antitumor activities were tested against IMC carcinoma, S180, P388 leukemia and P388/ADM leukemia in vivo. As a result, 1 showed 139% increase in life span (ILS) against S180 bearing mice whereas it showed slight or no ILS against IMC carcinoma, P388 leukemia and P388/ADM leukemia bearing mice.

Topics: Animals; Antibiotics, Antineoplastic; Antioxidants; Chemical Phenomena; Chemistry; Drug Evaluation, Preclinical; Female; Fermentation; Flavonoids; Isoflavones; Leukemia, Experimental; Mice; Streptomyces; Structure-Activity Relationship