Isodiospyrin

Isodiospyrin, a natural dimeric naphthoquinone, is a human DNA topoisomerase I (Topoisomerase) inhibitor. Isodiospyrin can prevent both DNA relaxation and kinase activities of human topoisomerase I. Isodiospyrin shows anticancer, antibacterial and antifungal activities^[1][2][3]. In Vitro:Isodiospyrin (10-40 μM) does not induce human topoisomerase I (htopo I)-DNA covalent complexes. However, Isodiospyrin antagonizes Camptothecin-induced, htopo I-mediated DNA cleavage. Isodiospyrin binds htopo I but not DNA. Isodiospyrin exhibits strong inhibitory effect on the kinase activity of htopo I toward splicing factor 2/alternate splicing factor in the absence of DNA^[1].
Isodiospyrin against Gram-positive bacteria with MICs ranged from 0.78 to 50 μg/mL. While Isodiospyrin against Pseudomonas aeruginosa ATCC 15443 and S. typhi ranged from 50 to 100 μg/mL. The MIC for M. chelonae is between 6.25 and 25 μg/mL^[2].
Isodiospyrin (30 μM; 120-144 hours) shows 81.4 % growth inhibition of P. obscurans. The antifungal activity of Isodiospyrin at 30 μM against P. viticola is 57.7 %^[3].