The Activity of Red Nigerian Propolis and Some of Its Components against Trypanosoma brucei and Trypanosoma congolense.

Propolis is a resin that is gathered by bees from exudates produced by various plants. Its exact chemical composition depends on the plants available near the hive. Bees use propolis to coat the surfaces of the hive, where it acts as an anti-infective. Regardless of the chemical composition of propolis, it is always anti-protozoal, probably because protozoan parasites, particularly Lotmarium passim, are widespread in bee populations. The protozoa Trypanosoma brucei and T. congolense cause disease in humans and/or animals. The existing drugs for treating these diseases are old and resistance is an increasingly severe problem. The many types of propolis present a rich source of anti-trypanosomal compounds-from a material gathered by bees in an environmentally friendly way. In the current work, red Nigerian propolis from Rivers State, Nigeria was tested against T. brucei and T. congolense and found to be highly active (EC50 1.66 and 4.00 µg/mL, respectively). Four isoflavonoids, vestitol, neovestitol, 7-methylvestitol and medicarpin, were isolated from the propolis. The isolated compounds were also tested against T. brucei and T. congolense, and vestitol displayed the highest activity at 3.86 and 4.36 µg/mL, respectively. Activities against drug-resistant forms of T. brucei and T. congolense were similar to those against wild type.

Evaluation of the antiprotozoan properties of 5'-norcarbocyclic pyrimidine nucleosides.

Carbocyclic nucleoside analogues have a distinguished history as anti-infectious agents, including key antiviral agents. Toxicity was initially a concern but this was reduced by the introduction of 5'-nor variants. Here, we report the result of our preliminary screening of a series of 5'-norcarbocyclic uridine analogues against protozoan parasites, specifically the major pathogens Leishmania mexicana and Trypanosoma brucei. The series displayed antiparasite activity in the low to mid-micromolar range and establishes a preliminary structure-activity relationship, with the 4',N3-di-(3,5-dimethylbenzoyl)-substituted analogues showing the most prominent activity. Utilizing an array of specially adapted cell lines, it was established that this series of analogues likely act through a common target. Moreover, the strong correlation between the trypanocidal and anti-leishmanial activities indicates that this mechanism is likely shared between the two species. EC50 values were unaffected by the disabling of pyrimidine biosynthesis in T. brucei, showing that these uridine analogues do not act directly on the enzymes of pyrimidine nucleotide metabolism. The lack of cross-resistance with 5-fluorouracil, also establishes that the carbocyclic analogues are not imported through the known uracil transporters, thus offering forth new insights for this class of nucleosides. The lack of cross-resistance with current trypanocides makes this compound class interesting for further exploration.

Synthetic ligustrazine based cyclohexanone and oxime analogs as Anti-Trypanosoma and Anti-Leishmanial agentes

In the present study a series of 34 synthetic ligustrazine-containing α, ß-Unsaturated carbonyl-based compounds and oximes, recognized as anticancer compounds were assessed against protozoa of the Trypanosoma and Leishmania species. Ligustrazine, chemically known as tetramethylpyrazine (TMP), was selected as the core moiety for the synthesis of α, ß-Unsaturated carbonyl-based compounds and these compounds were selected as precursors for the synthesis of new oximes. Some derivates, including 5f and 6i, showed multiple activities against all tested strains. In particular compounds 5f and 8o are the most potent and they are, therefore, potential candidates for trypanosomiasis and leishmaniasis