Sialidase (EC: 3.2.1.18) from Trypanosoma vivax (Agari Strain) was isolated from bloodstream forms of the parasite and purified to apparent electrophoretic homogeneity. The enzyme was purified 77-fold with a yield of 32% and co-eluted as a 66-kDa protein from a Sephadex G 110 column. The T. vivax sialidase was optimally active at 37 degrees C with an activation energy (E(a)) of 26.2 kJ mole(-1). The pH activity profile was broad with optimal activity at 6.5. The enzyme was activated by dithiothreitol and strongly inhibited by para-hydroxy mercuricbenzoate thus implicating a sulfhydryl group as a possible active site residue of the enzyme. Theenzyme hydrolysed Neu5Ac2,3lac and fetuin. It was inactive towards Neu5Ac2,6lac, colomic acid and the gangliosides GM1, and GDI. Initial velocity studies, for the determination of kinetic constants with fetuin as substrate gave a V(max) of 142.86 micromol h(-1) mg(-1) and a K(M) of 0.45 mM. The K(M) and V(max) with Neu5Ac-2,3lac were 0.17 mM and 840 micromole h(-1) mg(-1) respectively. The T. vivax sialidase was inhibited competitively by both 2,3 dideoxy neuraminic acid (Neu5Ac2,3en) and para-hydroxy oxamic acid. When ghost RBCs were used as substrates, the enzyme desialylated the RBCs from camel, goat, and zebu bull. The RBCs from dog, mouse and ndama bull were resistant to hydrolysis.

SummaryThe effect of vitamin C supplementation on the development of organ pathology in experimental Trypanosoma brucei infection in rats was investigated. Infection caused significant (p<0.05) increases in serum alanine and aspartate aminotransferases as well as in blood urea nitrogen and serum creatinine. Infection also caused significant (p<0.05) hypoproteinemia and hypoalbuminemia as well as decreases in liver and kidney total homogenate proteins. Supplementation of infected rats with vitamin C prevented the disease-induced elevation of serum creatinine and alanine aminotransferase (ALAT) and also significantly ameliorated the decreases in total protein levels in serum, liver, and kidney, as well as the elevated serum aspartate aminotransferase (ASAT). The trypanosome infection caused depletion of the levels of reduced glutathione (GSH) in the blood, liver, and kidney, as well as reduced the plasma level of ascorbic acid. Vitamin supplementation prevented the depletion of these endogenous antioxidants.We concluded that vitamin C supplementation ameliorates oxidative stress, thereby sparing endogenous antioxidant reserves and protecting tissues and organs against T. brucei-induced damage.

The crude aqueous extract of Guiera senegalensis stem bark was evaluated for its phytochemistry, acute toxicity and in vitro antitrypanosomal efficacy in this study. Tests for alkaloids, flavonoids, tannins, phlabotannins, saponins, steroids, cardenolides, terpenoids, cardiac glycosides, and anthraquinones were conducted. A total of 15 albino rats of both sexes were used and grouped into 5 (A to E) of 3 rats each. Groups A-D were intraperitoneally treated with graded doses of 100, 200, 400, 800mg/kg body weight of the crude aqueous extract of G. senegalensis stem bark. Group E was treated with Physiological Saline Solution serving as the control. All groups were observed for 24 hours for clinical signs and death to determine the median lethal dose (LD50). An in vitro experiment was carried out with 2 drops of blood from a donor rat added to 5 ml of phosphate buffer glucose solution out of which 0.2ml was finally used at 40, 20, 10, 5, 2.5, 0.625, 0.313, 0.156 and 0.078 concentrations of the extract. The phytochemical screening for bioactive substances had tannins, terpenoids, alkaloids, flavonoids, saponins, anthraquinones and cardiac glycosides. Phlabotannins and cardenolides were not detected. The clinical signs observed were sluggishness, awkward posture, loss of appetite, starry hair coat and terminal death within 24 hours with LD50 value of 600mg/kg. The in vitro antitrypanosomal efficacy of the extract showed 100% inhibition of motility against Trypanosoma brucei at 20mg/ml. In conclusion, the crude aqueous extract of G. senegalensis stem bark contains phytochemical components that exhibit inhibitory trypanosomal activity.

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The aqueous extract of Carica papaya leaf was evaluated for its phytochemistry, acute toxicity and in vitro antitrypanosomal efficacy in this study. A total of 15 albino rats grouped into 5(A-E) of 3 rats each were intraperitoneally treated with graded doses of 100, 200, 400, 800mg/kg body weight of the aqueous extract and observed for 24 hours for clinical signs and death. The calculated median lethal dose (LD50) was 600mg/kg body weight, with clinical signs of sluggishness, awkward pasture, loss of appetite, starry hair coat and terminal death within 24 hours. Severity of clinical signs varied with increasing doses. The in vitro antitrypanosomal efficacy of the aqueous extract showed 100% inhibition of Trypanosoma brucei at concentrations of 40mg/ml, 20mg/ml, 10mg/ml, 5mg/ml and 2.5mg/ml respectively. In conclusion the aqueous extract of C. papaya leaf has bioactive components that are moderately toxic and has trypanosomal inhibitory activity.