Kwasi A. Ohemeng

Structure-activity relationships of analogs of pentamidine against Plasmodium falciparum and Leishmania mexicana amazonensis.

The antiprotozoal compound 1,5-di(4-amidinophenoxy)pentane (pentamidine) and 36 of its analogs were screened for in vitro activity against Leishmania mexicana amazonensis clone 669 C4S (MHOM/BR/73/M2269) and Plasmodium falciparum clones W2 (Indochina III/CDC) and D6 (Sierra Leone I/CDC). Pentamidine and each of the analogs tested exhibited activity in vitro against L. m. amazonensis and P. falciparum. The pentamidine analogs were more effective against the P. falciparum clones than against L. m. amazonensis. P. falciparum was extremely susceptible to these compounds, with 50% inhibitory concentrations as low as 0.03 microM. While none of the analogs exhibited marked improvement in antileishmanial activity compared with pentamidine, 12 of the pentamidine analogs showed activity approximately equal to or greater than that of the parent compound. From the promising activity exhibited by the pentamidine analogs in this in vitro study and their potential for reduced toxicity relative to the parent drug, pentamidine-related compounds hold promise as new agents for the treatment of protozoal infections.

Novel pentamidine analogs in the treatment of experimental Pneumocystis carinii pneumonia.

We have recently demonstrated that substitution of imidazoline moieties for the amidine groups of pentamidine produces a molecule that is effective against rat Pneumocystis carinii pneumonia and that is apparently less toxic than pentamidine. For this reason, 10 novel imidazoline substituted compounds were evaluated for their effect against rat P. carinii pneumonia. While several of the new compounds were observed to have advantages over pentamidine in the treatment of disease in the rat model, only one compound stood out as a potential new clinical agent. Treatment for 2 weeks with intravenous (i.v.) doses of 1,3-di(4-imidazolino-2-methoxyphenoxy)propane (DIMP) at 1 mg/kg per day produced an anti-P. carinii pneumonia effect equivalent to i.v. doses of pentamidine at 10 mg/kg per day. Although pentamidine and one of the test drugs, 1,3-di(4-imidazolinophenoxy)propane, showed no activity against P. carinii pneumonia when administered per os, DIMP exhibited potent anti-P. carinii pneumonia activity when given by daily gavage doses of 40 and 25 mg/kg. DIMP retained significant activity when given every other day by a gavage dose of 25 mg/kg. No toxicity was observed with the drug at any of the dose levels or by either of the routes of administration. However, the low solubility of the drug prevented testing at higher i.v. doses. Our conclusion is that DIMP has the potential of providing a safer and more effective alternative to pentamidine for the treatment of P. carinii pneumonia.

Anti-Pneumocystis carinii pneumonia activity of dicationic carbazoles

Summary A series of 2,7- and 3,6-bis cationic carbazoles was synthesized and evaluated for activity against a rat model of Pneumocystis carinii pneumonia (PCP). The compounds were also tested for inhibition of topoisomerase II and binding to DNA. Several of the compounds proved to be more potent and less toxic than a standard anti-PCP drug (pentamidine). While no quantitative correlation was seen between anti-PCP activity, topoisomerase inhibition and DNA binding, a minimal level of DNA binding was found to be necessary for antimicrobial activity.

Synthesis of the diaza analogue of ellagic acid

Abstract The novel diaza analogue 2 of DNA-gyrase inhibitor ellagic acid 1 was synthesized via the Ullmann coupling of methyl 2-bromo-3-nitroverauate 6 which, in turn, was prepared by a 7-step synthesis from 2-bromopiperonal 10 requiring a contrived, regiospecific 3-nitration as a crucial step. Analogue 2 was two-fold as potent a DNA-Gyrase inhibitor as 1