Andrew J. Nok

In vitro trypanocidal effect of methanolic extract of some Nigerian savannah plants

Methanol extracts from twenty three plants harvested from the Savannah vegetation belt of Nigeria were analyzed in vitro for trypanocidal activity against Trypanosoma brucei brucei and Trypanosoma congolense at concentrations of 4 mg/ml, 0.4 mg/ml and 0.04 mg/ml. Extracts of Khaya senegalensis, Piliostigma reticulatum, Securidaca longepedunculata and Terminalia avicennoides were strongly trypanocidal to both organisms while extracts of Anchomanes difformis, Cassytha spp, Lannea kerstingii, Parkia clappertioniana, Striga spp, Adansonia digitata and Prosopis africana were trypanocidal to either T. brucei brucei or T. congolense. These findings provide evidence of the effects of some plants in the traditional management of trypanosomiasis.

Arsenicals (melarsoprol), pentamidine and suramin in the treatment of human African trypanosomiasis

Human African trypanosomiasis (HAT), otherwise known as sleeping sickness, has remained a disease with no effective treatment. Recent progress in HAT research suggests that a vaccine against the disease is far from being successful. Also the emergence of drug-resistant trypanosomes makes further work in this area imperative. So far the treatment for the early stage of HAT involves the drugs pentamidine and suramin which have been very successful. In the second stage of the disease, during which the trypanosomes reside in the cerebrospinal fluid (CSF), treatment is dependent exclusively on the arsenical compound melarsoprol. This is largely due to the inability to find compounds that can cross the blood brain barrier and kill the CSF-residing trypanosomes. This review summarises our current understanding on the treatment of HAT.

Allium sativum-induced death of African trypanosomes

Abstract The effect of Allium sativum (Liliacea) on trypanosome-infected mice was examined. At a dose of 5.0 mg/ml, the oily extract from the pulp completely suppressed the ability of the parasites to be infective in the host. Column chromatography of the extract gave four fractions: ethylacetate/methanol, ethylacetate/ethanol, benzene/methanol, and acetic acid/methanol. Among these fractions, the acetic acid/methanol fraction retained the trypanocidal features of the crude extract. It cured experimentally infected mice of trypanosomiasis in 4 days when given at a dose of 120 mg/kg per day. The extract also manifested inhibition of procyclic forms of Trypanosoma brucei brucei and phospholipases from T. congolense, T. b. brucei, T. vivax. The extract appears to be diallyl-disulfide (DAD) and may interfere with the parasites’ synthesis of membrane lipids.

Production and regulation of lignin degrading enzymes from Lentinus squarrosulus (mont.) Singer and Psathyrella atroumbonata Pegler

The influence of metal ions on the production and regulation of ligninase and mycelia extension of two type Basidiomycetes (Lentinus squarrosulus and Psathyrella atroumbonata) cultivated on lignocellulose waste was investigated. Mn2+ and Ca2+ ions stimulated growth of both fungi and mycelia extension significantly. Ligninase production increased two to twelve fold under the influence of Mn2+ and Ca2+ ions at concentrations of 20 to 80 mM. Mg2+ and K+ ions did not stimulate growth and extension of fungal mycelia, rather fungal cultures became deactivated after six days. The importance of mycelia extension and enhanced enzyme production has biotechnological applications in wood and pulp, textile and tanning, as well as in oil industries. Key words : Basidiomycetes, Lentinus squarrosulus, Psathyrella atroumbonata, ligninase, cofactors. African Journal of Biotechnology Vol.2(11) 2003: 444-447

Pathogenesis and pathology of blackleg in ruminants: The role of toxins and neuraminidase. A short review

Summary There is no consensus on the pathogenesis of blackleg infection that occurs in ruminants, but toxins and neuraminidase produced by Clostridium chauvoei are believed to play a significant role in the pathogenesis of the disease. This paper provides an update on the role of toxins and neuraminidase in the pathogenesis and pathology of the disease. The use of neuraminidase inhibitors to manage clinical blackleg infections is therefore an alternative therapeutic protocol that should be thoroughly investigated. It is suggested that in vivo clinical trials should be carried out to determine the mechanism of action and clinical efficacy of neuraminidase inhibitors.

In vitro anti trypanosomal activity of some medicinal plants used in the treatment of trypanosomosis in Northern Nigeria

The in vitro trypanocidal activity of 13 medicinal plants used by local herdsmen in Northern Nigeria for the treatment of trypanosomosis was investigated. Forty-four different extracts prepared from the 13 plants were screened for in vitro activity against Trypanosoma brucei brucei . Four of the extracts showed activity against the parasite at minimum concentration of 8.3 mg/ml of blood. Key Words: Medicinal plants, Trypanosomosis, Trypanosoma brucei brucei African Journal of Biotechnology Vol.3(9) 2004: 481-483

Enhancing comparative rabies DNA vaccine effectiveness through glycoprotein gene modifications.

Enhancing DNA vaccine effectiveness remains a challenge, especially if the desired goal is immunization efficacy after a single dose. The glycoprotein gene from the rabies virus Evelyn-Rokitnicki-Abelseth (ERA) strain was modified by mutation at amino acid residue 333 from arginine to glutamine. The modified and original unmodified glycoprotein genes were cloned separately and developed as DNA vaccines for immunization in mice. The intramuscular (IM) route using a single dose (100 microg) of a modified DNA vaccine showed virus neutralizing antibody induction by d30, and 80% of the mice survived a challenge in which 100% of unvaccinated controls succumbed. Similar results were obtained using a single dose (10 microg) by the intradermal (ID) route with one-tenth amount of the DNA administered. Administration of single dose of DNA vaccine with unmodified G did not result in the production of detectable levels of virus neutralizing antibody by d30. The results of the IM and the ID routes of administration were statistically significant (P<0.01). Based on these preliminary results, a modified glycoprotein gene from the ERA rabies virus strain may be an ideal candidate for DNA vaccine efficacy enhancement.

The Inhibition of Clostridium chauvoei (Jakari strain) Neuraminidase Activity by Methanolic Extracts of the Stem Barks of Tamarindus indicus and Combretum fragrans

The inhibition of neuraminidase from Clostridium chauvoei (jakari strain) with partially purified methanolic extracts of some plants used in Ethnopharmacological practice was evaluated. Extracts of two medicinal plants, Tamarindus indicus and Combretum fragrans at 100–1000 μg/ml, both significantly reduced the activity of the enzyme in a dose-dependent fashion (P < 0.001). The estimated IC50 values for Tamarindus indicus and Combretum fragrans were 100 and 150 μ/ml respectively. Initial velocity studies conducted, using fetuin as substrate revealed a non-competitive inhibition with the Vmax significantly altered from 500 μmole min−1 mg−1 to 240μmole min−1 mg−1 and 340 μmole min−1 mg−1 in the presence of Tamarindus indicus and Combretum fragrans respectively. The KM remained unchanged at 0.42 mM. The computed Index of physiological efficiency was reduced from 1.19 min−1 to 0.57 min−1 and 0.75 min−1 with Tamarindus indicus and Combretum fragrans as inhibitors respectively.

Ethnomedical Treatment of Poisonous Snakebites: Plant Extract Neutralized Naja nigricollis Venom

Abstract The neutralizing effects of methanol extracts of Indigofera pulchra. Willd (Papilionaceae), Aristolochia albida. Duch (Aristolochiaceae), Guiera senegalense. J.F.Gmel (Combretaceae), and Sterculia setigera. K. Schum (Sterculiaceae) were investigated to validate traditional claims of usefulness of the plants in management of poisonous snakebites. Extracts of Indigofera pulchra. and Aristolochia albida. gave 33.3% and 44.4% protection to mice treated with minimum lethal dose of venom; some gross pathologic symptoms of envenomation were alleviated. However, minimal activities were shown by Guiera senegalense. and Sterculia setigera.. Both Indigofera pulchra. and Aristolochia albida. were found to neutralize the anticoagulant, hemolytic, and phospholipase activity of crude venom. This study showed that Indigofera pulchra. and Aristolochia albida. are useful in some pathologic effects of Naja nigricollis. Broadley (Elapidae) venom, and this provides some scientific basis for the use of the plants in management of poisonous snakebites.

Relationship between outbreaks of blackleg in cattle and annual rainfall in Zaria, Nigeria

and wasfirst reported in 1870 (Armstrong and MacNamee 1950).Reports suggest that pigs and mink (Langford 1970), freshwater fish (Prevot and others 1950), whales and frogs (Scott1928) are susceptible to the disease, while human beings,birds, cats, dogs and rabbits are resistant to it (Cato and oth-ers 1986); however, the bacterium has been isolated fromwounds in dogs and cats (Berg and Fales 1977) and hens witha disease of complex aetiology (Pruckner-Radovcic and oth-ers 1995).The organism has also been isolated from ostricheswith a paralytic-like disease (Lublin and others 1993).Vaccination is the most reliable preventive approach againstthe disease worldwide (Kijima-Tanaka and others 1997,1998,Useh 2002,Useh and others 2003).In Nigeria,the disease wasfirst reported in 1929 (Osiyemi 1975) and it has remained amajor problem for cattle in the country. Although vaccina-tion has been carried out since 1930, sporadic outbreaks arerecorded annually. The disease is classified as a ‘list A disease’in Nigeria, which means that it is associated with a highannual mortality of cattle in the country (Abdulkadir 1989).The economic losses due to blackleg in Nigeria have been esti-mated at four million naira annually (Agba and Princewill1986).Cattle ingest the spores of