Optimization of Potent Hepatitis C Virus NS3 Helicase Inhibitors Isolated from the Yellow Dyes Thioflavine S and Primuline

Abstract

A screen for hepatitis C virus (HCV) NS3 helicase inhibitors revealed that the commercial dye thioflavine S was the most potent inhibitor of NS3-catalyzed DNA and RNA unwinding in the 827-compound National Cancer Institute Mechanistic Set. Thioflavine S and the related dye primuline were separated here into their pure components, all of which were oligomers of substituted benzothiazoles. The most potent compound (P4), a benzothiazole tetramer, inhibited unwinding >50% at 2±1 μM, inhibited the subgenomic HCV replicon at 10 μM, and was not toxic at 100 μM. Because P4 also interacted with DNA, more specific analogs were synthesized from the abundant dimeric component of primuline. Some of the 29 analogs prepared retained ability to inhibit HCV helicase but did not appear to interact with DNA. The most potent of these specific helicase inhibitors (compound 17) was active against the replicon and inhibited the helicase more than 50% at 2.6±1 μM.

Primuline Derivatives That Mimic RNA to Stimulate Hepatitis C Virus NS3 Helicase-catalyzed ATP Hydrolysis

“…Primuline derivatives were prepared as described previously (1 In Fig. 2, concentration of ATP cleaved in 15 min (v) and total enzyme concentration (E t ) were used to calculate specific activities (v/E t ).…”

“…Primuline is a fluorescent dye composed of a mixture of benzothiazole oligomers terminating with p-aminobenzene groups, and it prevents proteins from binding ssDNA or RNA (1,10). Li et al synthesized a series of chemical derivatives from a benzothiazole dimer purified from primuline, and they showed that some of these compounds potently and specifically inhibit HCV helicase (1).…”

“…Li et al synthesized a series of chemical derivatives from a benzothiazole dimer purified from primuline, and they showed that some of these compounds potently and specifically inhibit HCV helicase (1). Later, Mukherjee et al (10) showed that these primuline derivatives inhibit NS3h by displacing the protein after it is bound to its nucleic acid substrate.…”

“…Here, we have analyzed the rest of the primuline derivatives in the Li et al (1) collection with regard to their effect on NS3 helicase-catalyzed ATP hydrolysis. We report the surprising discovery that two primuline derivatives stimulate helicase-catalyzed ATP hydrolysis.…”

Synthesis of 6-(arylthio)phenanthridines by cyclization reaction of 2-isocyanobiphenyls with thiols

“…[6][7][8][9][10][11] In addition, they have excellent optical and electronic properties in the fields of functional materials. 12,13 In recent years, the synthesis of phenanthridine derivatives via the radical addition and cyclization of 2-isocyanobiphenyls has received much attention.…”