Computer-aided synthesis of dapsone-phytochemical conjugates against dapsone-resistant Mycobacterium leprae.

Leprosy continues to be the belligerent public health hazard for the causation of high disability and eventual morbidity cases with stable prevalence rates, even with treatment by the on-going multidrug therapy (MDT). Today, dapsone (DDS) resistance has led to fear of leprosy in more unfortunate people of certain developing countries. Herein, DDS was chemically conjugated with five phytochemicals independently as dapsone-phytochemical conjugates (DPCs) based on azo-coupling reaction. Possible biological activities were verified with computational chemistry and quantum mechanics by molecular dynamics simulation program before chemical synthesis and spectral characterizations viz., proton-HNMR, FTIR, UV and LC-MS. The in vivo antileprosy activity was monitored using the 'mouse-foot-pad propagation method', with WHO recommended concentration 0.01% mg/kg each DPC for 12 weeks, and the host-toxicity testing of the active DPC4 was seen in cultured-human-lymphocytes in vitro. One-log bacilli cells in DDS-resistant infected mice footpads decreased by the DPC4, and no bacilli were found in the DDS-sensitive mice hind pads. Additionally, the in vitro host toxicity study also confirmed that the DCP4 up to 5,000 mg/L level was safety for oral administration, since a minor number of dead cells were found in red color under a fluorescent microscope. Several advanced bioinformatics tools could help locate the potential chemical entity, thereby reducing the time and resources required for in vitro and in vitro tests. DPC4 could be used in place of DDS in MDT, evidenced from in vivo antileprosy activity and in vitro host toxicity study.

Synthesis and antileprosy activity of some dialkyldithiocarbamates.

OBJECTIVES: To investigate the antileprosy potential of a set of original compounds with antimycobacterial activity. METHODS: We developed a facile synthesis of 2-chloro-3-cyano-5-nitropyridine and synthesized a series of 3-cyano-2-dialkyldithiocarbamoyl-5-nitropyridine derivatives. In vivo therapeutic efficacy against Mycobacterium leprae was assessed in the infected mouse footpad model. RESULTS: The compounds were active in vitro against Mycobacterium smegmatis, Mycobacterium aurum, Mycobacterium vaccae and Mycobacterium fortuitum, with MICs generally in the range of 0.4-6.25 mg/L. Reduction of the bacterial load in vivo in the mouse footpad and toxic side effects were dependent on the individual structure of the compounds and on the doses applied. Compounds 2a, 3a and 3b reduced the number of M. leprae by two orders of magnitude, comparable to the effect of dapsone. Co-administration of compounds 2a and 3a with dapsone synergistically enhanced the activity. In addition, these compounds were well tolerated over the treatment period of 7.5 months. CONCLUSIONS: Individual synthetic dithiocarbamate derivatives have promising antileprosy activity.

[Synthesis of promin in Japan and global elimination of Hansen's disease].

Prof. Morizo Ishidate synthesized "Promin" for the treatment of leprosy/Hansen's disease which had been considered "incurable" until the discovery of antileprosy effect of that drug by Dr. Faget of U.S.A. in 1941. Prof. Ishidate was the first to synthesize the drug in Japan in 1946 based on a brief news item on a Swiss journal smuggled in during the War. For this achievement, he is known as "father of chemotherapy for leprosy in Japan." Prof. Ishidate also contributed to the global fight against leprosy as the Chairman of the Board of Directors of Sasakawa Memorial Health Foundation, which he helped to establish in May 1974, with a full financial backing of Mr. Ryoichi Sasakawa, President of Japan Shipbuilding Industry Foundation. Prof. Ishidate, with his scientific knowledge as well as christianity based humanitarian concern, advised Mr. Sasakawa how to spend JSIF money wisely for eliminating leprosy and nearly US$200 million was channeled through WHO and SMHF. The successful outcome of global multidrug therapy (MDT) programme in the '80s resulted in the adoptation of resolution by the World Health Assembly, "Elimination of Leprosy, as a public health problem" by the Year 2000. The synthesis of "Promin" in Japan and promoting the global implementation of MDT, both achievement can be attributed to Prof. Ishidate.