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1.  In vivo antimalarial activity of the crude leaf extract and solvent fractions of Croton macrostachyus Hocsht. (Euphorbiaceae) against Plasmodium berghei in mice 
The issue of resistance in malarial infection makes development of novel drugs a necessity. An alternative source for discovering such drugs is natural products. Croton macrostachyus H. (Euphorbiaceae) is used in Ethiopian folklore medicine for the treatment of malaria and found to possess antimalarial activity in vitro. However, no further scientific investigations have been carried out to substantiate the claim. This study therefore aimed at investigating the in vivo antiplasmodial activity of 80% methanol extract and solvent fractions of the leaves of Croton macrostachyus H. in rodent model of malaria.
A rodent malaria parasite, Plasmodium berghei, was used to inoculate healthy male Swiss Albino mice of age 6–8 weeks and weight 23–27 g. A hydro-alcoholic crude extract and the solvent fractions (chloroform, methanol and aqueous) were administered at different doses 200, 400 and 600 mg/kg. Parameters, including parasitemia, survival time, body weight, temperature, and packed cell volume were then determined using standard tests such as Peter’s and Rane’s test.
Chemoprotective effect exerted by the crude extract and fractions ranged between 44-91% and 12-76%, respectvely. The chemotherapeutic effect of the crude extract and chloroform fraction was in the range of 39-83% and 66-82%, respectively. Maximum effect in both tests was observed with the larger dose of the crude extract and chloroform fraction. The crude extract prevented loss of weight and reduction in temperature but did not affect packed cell volume. However, the chloroform fraction did also reverse reduction in packed cell volume due to the absence of saponins in the fraction.
The results collectively indicate that the plant has a promising antiplasmodial activity against Plasmodium berghei, which upholds the earlier in vitro findings as well as its folkloric use. Thus, it could be considred as a potential source to develop new antimalarial agents.
PMCID: PMC3943266  PMID: 24580778
Antimalarial activity; Plasmodium berghei; Croton macrostachyus; Chloroform fraction; In vivo study
2.  Subacute administration of crude khat (Catha edulis F.) extract induces mild to moderate nephrotoxicity in rats 
Although various studies have been conducted to shed light on the pharmacological actions of khat, little or no data are available regarding khat’s effect on the renal redox system. The aim of this study was therefore to investigate the potential of nephrotoxicity associated with khat exposure in rats.
Sprague Dawely rats were randomly assigned into eight experimental groups. Animals were treated with Tween80, gentamicin 100 mg/kg and khat at various doses (100, 200 and 400 mg/kg) alone or in combination with gentamicin for ten days. The animals were then sacrificed to obtain blood and renal tissues for subsequent analysis. Renal markers, including creatinine, blood urea nitrogen, antioxidant enzymes as well as markers for lipid peroxidation were determined using established protocols. In addition, histopathological changes were evaluated with hematoxilin and-eosin staining technique.
Lower and moderate doses of khat did not alter the measured parameters compared to controls. By contrast, higher dose (400 mg/kg) of khat not only increased levels of serum creatinine and blood urea nitrogen (p < 0.001) but also levels of malondialdehyde (p < 0.01). Moreover, 400 mg/kg of khat significantly decreased enzymatic activities of superoxide dismutase (p < 0.01) and catalase (p < 0.001). When khat was administered with gentamicin, it was again the higher dose that significantly accentuated gentamicin-induced alterations in the renal system.
Khat treatment at high dose is demonstrated to induce mild to moderate renal damage. Moreover, it creates synergy when combined with nephrotoxic drugs such as gentamicin.
PMCID: PMC3933508  PMID: 24555719
Nephrotoxicity; Superoxide dismutase; Catalase; Malondialdehyde; Khat; Rat
3.  Evaluation of the effects of 80% methanolic leaf extract of Caylusea abyssinica (fresen.) fisch. & Mey. on glucose handling in normal, glucose loaded and diabetic rodents 
The leaves of Caylusea abyssinica (fresen.) Fisch. & Mey. (Resedaceae), a plant widely distributed in East African countries, have been used for management of diabetes mellitus in Ethiopian folklore medicine. However, its use has not been scientifically validated. The present study was undertaken to investigate antidiabetic effects of the hydroalcoholic leaf extract of C. abyssinica extract in rodents.
Materials and method
Male Animals were randomly divided into five groups for each diabetic, normoglycemic and oral glucose tolerance test (OGTT) studies. Group 1 served as controls and administered 2% Tween-80 in distilled water, (TW80); Group 2 received 5 mg/kg glibenclamide (GL5); Groups 3, 4 and 5 were given 100 (CA100), 200 (CA200) and 300 (CA300) mg/kg, respectively, of the hydroalcoholic extract of C. abyssinica. Blood samples were then collected at different time points to determine blood glucose levels (BGL). Data were analyzed using one way ANOVA followed by Dunnet’s post hoc test and p < 0.05was considered as statistically significant.
In normal mice, CA200 and GL5 induced hypoglycemia starting from the 2nd h but the hypoglycemic effect of CA300 was delayed and appeared at the 4th h (p < 0.05 in all cases). In diabetic mice, BGL was significantly reduced by CA100 (p < 0.05) and CA300 (p < 0.01) starting from the 3rd h, whereas CA200 (p < 0.001) and GL5 (p < 0.05) attained this effect as early as the 2nd h. In OGTT, TW80 (p < 0.01) and CA100 (p < 0.01) brought down BGL significantly at 120 min, while CA200 (p < 0.001) and GL5 (p < 0.001) achieved this effect at 60 min indicating the oral glucose load improving activity of the extract. By contrast, CA300 was observed to have no effect on OGTT. Acute toxicity study revealed the safety of the extract even at a dose of 2000 mg/kg. Preliminary phytochemical study demonstrated the presence of various secondary metabolites, including, among others, saponins, flavonoids and alkaloids.
The results indicate that C. abyssinica is endowed with antidiabetic and oral glucose tolerance improving actions, particularly at the dose of 200 mg/kg in experimental animals. These activities of the plant extract may be related to the presence of secondary metabolites implicated in antidiabetic activities of plant extracts via different hepatic and extra-hepatic mechanisms. These results thus support the traditional use of the leaf extract for the management of diabetes mellitus.
PMCID: PMC3495218  PMID: 22967092
Caylusea abyssinica; Diabetes; Hypoglycemic effect
4.  Lead exposure study among workers in lead acid battery repair units of transport service enterprises, Addis Ababa, Ethiopia: a cross-sectional study 
Lead exposure is common in automobile battery manufacture and repair, radiator repair, secondary smelters and welding units. Urinary Aminolevulinic acid has validity as a surrogate measure of blood lead level among workers occupationally exposed to lead. This study had therefore assessed the magnitude of lead exposure in battery repair workers of three transport service enterprises.
To this effect, a cross-sectional study was carried out on lead exposure among storage battery repair workers between November 2004 and May 2005 from Anbasa, Comet and Walia transport service enterprises, Addis Ababa, Ethiopia. Subjective information from the workers was obtained by making use of structured questionnaire. Other information was obtained from walkthrough evaluation of the repair units. Aminolevulinic acid levels in urine were used as an index of the exposure. This was coupled to measurements of other relevant parameters in blood and urine collected from adult subjects working in the repair units as well as age matched control subjects that were not occupationally exposed to lead. Aminolevulinic acid was determined by spectrophotometry, while creatinine clearance, serum creatinine, urea and uric acid levels were determined using AMS Autolab analyzer.
Urinary aminolevulinic acid levels were found to be significantly higher in exposed group (16 μg/ml ± 2.0) compared to the non-exposed ones (7 μg/ml ± 1.0) (p < 0.001). Alcohol taking exposed subjects exhibited a significant increase in urinary aminolevulinic acid levels than non-alcohol taking ones (p < 0.05). Moreover, urinary aminolevulinic acid levels of exposed subjects increased with age (p < 0.001) as well as duration of employment (p < 0.001). Whereas serum uric acid levels of exposed subjects was significantly higher than non-exposed ones (p < 0.05), no statistically significant difference had been found in renal indices and other measured parameters between exposed and non-exposed subjects. From the questionnaire responses and walkthrough observations, it was also known that all the repair units did not implement effective preventive and control measures for workplace lead exposure.
Taken together, these findings indicated that workers in lead acid battery repair units of the transport service enterprises are not protected from possibly high lead exposure. Thus, strict enforcement of appropriate and cost effective preventive and control measures is required by all the enterprises.
PMCID: PMC2612669  PMID: 19040746

Results 1-4 (4)