Synthesis of N-substituted 1,2,3,4-tetrahydrobenz[g]isoquinoline-5,10-diones

Synthesis and anti-tubercular activity of N(2)-arylbenzo[g]isoquinoline-5,10-dione-3-iminium bromides

Tuberculosis has remained a challenge for medicinal chemists worldwide. In the framework of a collaborative program to identify and evaluate novel antitubercular candidate compounds, the biological properties of benzo[g]isoquinoline-5,10-diones have been found to be very promising. In this paper we have further expanded the library by incorporation of an amidinium moiety into the benzo[g]isoquinoline-5,10-dione scaffold. The presence of this functional group also increased the solubility of the quinones in polar solvents. To this purpose N(2)-arylbenzo[g]isoquinoline-5,10-dione-3-iminium bromides were synthesized in a straightforward way by means of a reaction of anilines with 2-(bromomethyl)-3-(cyanomethyl)-1,4-dimethoxynaphthalene. Following the biological evaluation, N(2)-(4-chlorophenyl)-5,10-dioxobenzo[g]isoquinoline-3(2H)-iminium bromide (MIC = 1.16 μM, CC50 = 28.51 μM, SI = 24.58) was selected as the most promising representative. Apart from the nano-molar anti-mycobacterial activity, the compound was able to target intracellular residing Mycobacterium tuberculosis and the susceptibility of a multi-drug-resistant strain towards the compound was confirmed.

Novel synthesis and reactions of pyrazolyl-substituted tetrahydrothieno[2,3-c]isoquinoline derivatives

Treatment of isoquinolinecarboxamide 4a with triethyl orthoformate, chloroacetyl chloride or carbon disulfide afforded the pyrimidinone 7, oxopyrimidinethione 12 and chloromethylpyrimidinone 18, respectively. These products were used as versatile starting materials for synthesis of other heterocyclic compounds. The heterocyclic hydrazide 6 was also obtained.

Straightforward palladium-mediated synthesis and biological evaluation of benzo[j]phenanthridine-7,12-diones as anti-tuberculosis agents

In 1991, WHO recognized the resurgence of tuberculosis as a global health problem. Although modern chemotherapy is effective against the causative pathogen Mycobacterium tuberculosis, the current drug regimens have failed to eradicate the disease. The success of the pathogen, partially attributed to drug resistance, necessitates the development of novel anti-tuberculosis drugs. Benzo[j]phenanthridine-7,12-diones, tetracyclic derivatives of the natural product benz[g]isoquinoline-5,10-dione, were conveniently synthesized via palladium-catalyzed intramolecular cyclization of N-methanesulfonyl-3-bromo-2-(arylamino)methyl-1,4-naphthoquinones. Here we report on the bioactivity of eight benzo[j]phenanthridine-7,12-dione derivatives as candidate drug molecules against M. tuberculosis and on their cytotoxicity on C3A human hepatocytes. The strongest antimicrobial activity (as detected by growth inhibition of bacteria, using luminometry and BACTEC 460-TB) and lowest cytotoxicity was found for 3-methylbenzo[j]phenanthridine-7,12-dione 5e, which was also effective in targeting intracellular M. tuberculosis (in murine J774 macrophages) and was not genotoxic for C3A hepatocytes.