Evaluation of antitrypanosomal and anti inflammatory activities of selected Nigerian medicinal plants in mice.

The extracts of nine selected Nigerian medicinal plants were investigated on Trypanosoma brucei brucei infected mice. The anti-inflammatory properties of hexane fraction of the most promising U. chamae extract was assessed by acute oedema of the mice paw model while the modulatory effect of the extract on Delayed-Type Hypersensitivity (DTH) response on in vivo leucocytes mobilization was evaluated. 'Dose-probing acute toxicity tests' established an oral and intraperitoneal LD50 for T. ivorensis stem bark as >1600 < 5000 mg/kg and 100 mg/kg respectively, while the oral LD50 of Uvaria. chamae was >5000 mg/kg. Extracts of Khaya senegalensis, Harungana madagascariensis, Terminalia ivorensis, Curcuma longa, Ocimum gratissimum and Alcornea cordifolia showed weak anti-trypanosomal effect and did not exhibit significant clearance in parasitemia at the test dose administered compared with the positive control (Diminal®). However, the leaf extract of U. chamae and its hexane fraction demonstrated a significant response (P < 0.01). The fraction at 1000 mg/kg inhibited oedema by 107%. Uvaria. chamae demonstrated both antitrypanosomal and anti-inflammatory properties by increasing the survival time of infected mice due to reduction in parasitemia caused by T. brucei brucei.

Distribution of iridiod glucosides and anti-oxidant compounds in Spathodea campanulata parts.

The antioxidant principles isolated from the various parts of the plant are verminoside (leaf, stem bark and flowers; EC(50) = 2.04 µg/ml), Specioside (flowers; EC(50) = 17.44 µg/ml), Kampeferol diglucoside (leaf; EC(50) = 8.87 µg/ml) and Caffeic acid (leaf and fruits). The non anti-oxidant components isolated in the study include ajugol (stem bark and fruits) and phytol (leaf).

Pharmacological properties of the extract and some isolated compounds of Clausena lansium stem bark: anti-trichomonal, antidiabetic, anti-inflammatory, hepatoprotective and antioxidant effects.

ETHNOPHARMACOLOGICAL RELEVANCE: Clausena lansium (Fool's Curry Leaf) is used for various ethnomedical conditions in some countries, including bronchitis, malaria, viral hepatitis, acute and chronic gastro-intestinal inflammation, and as a spicy substitute of the popular Curry leaf tree (Murraya koenigii). AIM OF THE STUDY: This study was to evaluate the ethnomedical uses of the stem bark in inflammatory conditions, hepatotoxicity and to determine the anti-diabetic and anti-trichomonal properties of the plant. MATERIALS AND METHOD: Anti-trichomonal, in vivo and in vitro antidiabetic and insulin stimulating, anti-inflammatory, hepatoprotective and anti-oxidant activities using Trichomonas gallinae, glucose loaded rats and in vitro insulin secreting cell line (INS-1 cell), carrageenin-induced rat paw oedema, CCl(4)-induced hepatotoxicity and DPPH scavenging ability methods respectively for the extracts and some isolates were determined. RESULTS: A dichloromethane extract was superior over methanolic extract with respect to an anti-trichomonal activity which was measured after 24 and 48 h. The isolated compounds imperatorin and 3-formylcarbazole had the main anti-trichomonal activity (LC(50)s of 6.0, 3.0 and 3.6, 9.7 microg/mL after 24 and 48 h, respectively). Methanolic extract (100 mg/kg) induced maximum and significant (p<0.05) anti-hyperglycaemic activity of 15.8% at 30 min and a 38.5% increase in plasma insulin at 60 min, compared to control. The increase in plasma insulin after 60 min, compared to 0 min, was 62.0% (p<0.05). The significant 174.6% increase of insulin release from INS-1 cells (in vitro) at 0.1 mg/ml indicates that it mediates its antidiabetic action mainly by stimulating insulin release. Imperatorin and chalepin were the major active constituents increasing in vitro insulin release to 170.3 and 137.9%, respectively. 100 mg/kg of the methanolic extract produced an anti-inflammatory activity after 4 h. A sedative effect was not observed. 100 and 200 mg/kg of methanolic extract administered i.p., reduced CCl4-induced hepatotoxicity firstly by 5.3 and 8.4% reduction in phenobarbitone-sleeping time respectively, secondly by reversing the reduction in serum liver proteins by 7.0-8.8%, serum AST, ALT and ALP activities by 27.7-107.9% and thirdly by diminishing increased values of plasma AST, ALT and ALP activities by 13.2-83.8%. The extract exhibited antioxidant activities. CONCLUSION: The hepatoprotective activity of C. lansium is partly due to its anti-oxidant and anti-inflammatory properties and confirms its folkloric use in the treatment of gastro-intestinal inflammation, bronchitis and hepatitis. In addition the use of C. lansium stem bark would be useful in diabetes and trichomoniasis.

Anti-protozoan activities of Harungana madagascariensis stem bark extract on trichomonads and malaria.

AIM OF THE STUDY: The ethanolic stem bark extract of Harungana madagascariensis (Hypericaceae), (Choisy) Poir were evaluated for their activities on Trichomonas gallinae (Rivolta) Stabler isolated from the pigeon (Columba livia). It was also tested for their anti-malarial activity on N67 Plasmodium yoelii nigeriensis (in vivo) in mice and on Plasmodium falciparum isolates in vitro. MATERIALS AND METHODS: The anti-trichomonal screening was performed in vitro using Trichomonas gallinae culture. The minimum lethal concentration (MLC) is the lowest concentration of the test extract in which no motile organisms were observed. The anti-malarial effects were determined in-vivo for suppressive, curative and prophylactic activities in mice receiving a standard inoculum size of 1 x 10(7) (0.2 ml) infected erythrocytes of Plasmodium yoelii nigeriensis intraperitoneally, and the in vitro was performed against 3 isolates of Plasmodium falciparum in a candle jar procedures. RESULTS: The IC(50) of the extract and metronidazole (MDZ) (Flagyl) on Trichomonas gallinae at 48 h are 187 and 1.56 microg/ml. The IC(50) of the extract, chloroquine (CQ) and artemether (ART) on Plasmodium falciparum are between 0.052 and 0.517 microg/ml for the extract and 0.021 and 0.0412 microg/ml for ART and CQ, respectively. The actions of the extract in in vivo study on Plasmodium yoelii nigeriensis showed that in both suppressive and prophylactic tests the percentages chemo-suppressive were between 28.6-44.8% and 30.2-78.2% respectively, while only 80 mg/kg of the extract reduced the parasitaemia level when compared to the control and the standard drugs in curative test. CONCLUSIONS: Harungana madagascariensis stem bark extract therefore exhibited significant anti-protozoan effects against Trichomonas and Plasmodium both in vivo and in vitro.

Anti-trichomonal, biochemical and toxicological activities of methanolic extract and some carbazole alkaloids isolated from the leaves of Murraya koenigii growing in Nigeria.

The methanolic extract of Murraya koenigii leaf was screened for toxicological and biochemical effects on rats because of the folkloric uses as an anti-dysentery and anti-diabetes. The extract was moderately toxic (LD(50)=316.23 mg/kg body weight) to rats and had appreciable effect on the liver and kidney at higher doses leading to liver inflammation. It had little or no effect on haematology and relative organ weight of lungs, heart and spleen. Acute doses (500 mg/kg) reduced significantly serum globulin, albumin, urea, glucose, total protein, aspartate transaminase (AST), and increased cholesterol and alanine transaminase (ALT) indicating hepatic injury. However, chronic administration for 14 days gave a significant (p<0.05) reduction in the serum cholesterol, glucose, urea, bilirubin, ALT and AST showing that the plant has hypoglycaemic and hepatoprotective effects after prolonged use. The activity demonstrated by some of the isolated carbazole alkaloids and their derivatives against Trichomonas gallinae confirmed that the anti-trichomonal activity of the leaf may be due to its carbazole alkaloids. The order of activity was C(18)>C(23)>C(13). Girinimbine and girinimbilol with IC(50) values of 1.08 and 1.20 microg/ml were the most active. Acetylation of girinimbilol and mahanimbilol improved their activities to 0.60 and 1.08 microg/ml.

Pro- and antioxidant effects and cytoprotective potentials of nine edible vegetables in southwest Nigeria.

Antioxidant and cytoprotective activities of boiled, cold, and methanolic extracts of nine edible vegetables in Southwest Nigeria were evaluated in the 1,1-diphenyl-2-picrylhydrazyl free radical assay and hemagglutination assay in bovine erythrocytes, respectively. Crassocephalum rubens showed the highest antioxidant activity (56.5%), Solanum americanum and Vernonia amygdalina exhibited moderate antioxidant activity (26.0-37.5% and 14.8-36.2%, respectively), Solanum macrocarpon, Telfaria occidentalis, Amaranthus hybridus, and Jatropha tanjorensis produced weak activity (1.6-15.8%, 1.6-7.7%, 2.8-6.62%, and 10.7-12.1%, respectively), while Celosia argentea and Talinum triangulare were pro-oxidants. It was also shown that extracts from all the vegetables are pro-oxidants at high concentrations of either 1 or 5 mg/mL or both. On the other hand, the studies on the cytoprotective effect showed that all the plant extracts demonstrated a very low hemagglutination titer value between 0.32 and 5.56 except S. americanum methanolic extract, which had a titer of 50.0. These results indicated correlation between the antioxidant properties and the hemagglutination values of these plant extracts; however, the membrane stabilizing capacity of the extracts supports the plants' antioxidant activity.

Antitrichomonal and antioxidant activities of Dorstenia barteri and Dorstenia convexa.

Dorstenia barteri and D. convexa extracts and some isolated components of the former were investigated for effectiveness against Trichomonas gallinarum and compared with quercetin and quercitrin. The antioxidant activity of the extracts/compounds was also determined. The minimum lethal concentrations (MLCs) for the extract of D. barteri leaves and twigs at 24 h were found to be 15.625 and 15.625 microg/ml, respectively. However, the MLCs of the leaf and twig extract of D. convexa were 125 and 437.5 microg/ml, respectively. The prenylated and geranylated chalcones were as active as the prenylated flavones, 6-prenylapigenin and the diprenylated derivative 6,8-diprenyleridictyol. The order of the antitrichomonal activity of the compounds at 24 h was: quercetin (0.121 microg/ml) > quercitrin (0.244 microg/ml) > or = bartericin B (0.244 microg/ml) > bartericin A (0.73 microg/ml) > stigmasterol (0.98 microg/ml) > 6,8-diprenyleridictyol = isobavachalcone = dorsmanin F (31.25 microg/ml). D. barteri extracts, quercitrin, and bartericin A, and the prenylated flavonoids had potent antioxidant properties. The twig extract of D. barteri was more potent than the leaf extract. Moderate (EC50 >50 microg/ml) and high (EC50 <50 microg/ml) antioxidant activities were detected in the leaf and twig extracts of D. barteri and the prenylated flavonoids. Prenylated flavonoids and the isolated compounds with antioxidant properties described here may account for the anti-inflammatory action of these extracts. The antitrichomonal and antioxidant activities shown by the extracts and compounds in this study are consistent with the ethnomedicinal and local use of the Dorstenia species studied.

Antitrichomonal and antioxidant activities of Dorstenia barteri and Dorstenia convexa

Dorstenia barteri and D. convexa extracts and some isolated components of the former were investigated for effectiveness against Trichomonas gallinarum and compared with quercetin and quercitrin. The antioxidant activity of the extracts/compounds was also determined. The minimum lethal concentrations (MLCs) for the extract of D. barteri leaves and twigs at 24 h were found to be 15.625 and 15.625 æg/ml, respectively. However, the MLCs of the leaf and twig extract of D. convexa were 125 and 437.5 æg/ml, respectively. The prenylated and geranylated chalcones were as active as the prenylated flavones, 6-prenylapigenin and the diprenylated derivative 6,8-diprenyleridictyol. The order of the antitrichomonal activity of the compounds at 24 h was: quercetin (0.121 æg/ml) > quercitrin (0.244 æg/ml) > or = bartericin B (0.244 æg/ml) > bartericin A (0.73 æg/ml) > stigmasterol (0.98 æg/ml) > 6,8-diprenyleridictyol = isobavachalcone = dorsmanin F (31.25 æg/ml). D. barteri extracts, quercitrin, and bartericin A, and the prenylated flavonoids had potent antioxidant properties. The twig extract of D. barteri was more potent than the leaf extract. Moderate (EC50 >50 æg/ml) and high (EC50 <50 æg/ml) antioxidant activities were detected in the leaf and twig extracts of D. barteri and the prenylated flavonoids. Prenylated flavonoids and the isolated compounds with antioxidant properties described here may account for the anti-inflammatory action of these extracts. The antitrichomonal and antioxidant activities shown by the extracts and compounds in this study are consistent with the ethnomedicinal and local use of the Dorstenia species studied.

Antinociceptive and anti-inflammatory effects of Dorstenia barteri (Moraceae) leaf and twig extracts in mice.

The present study was undertaken to investigate the antinociceptive and anti-inflammatory activities of the leaf and twig extracts of Dorstenia barteri (Moraceae) in mice. Both the leaf and twig extracts of Dorstenia barteri at 50, 100 and 200 mg/kg showed significant (P < 0.05-0.01) antinociceptive activities in chemical-, mechanical- and thermal-induced pain test models. Intraperitoneal administration of the plant extracts at 50, 100 and 200 mg/kg significantly (P < 0.05-0.01) inhibited carrageenin-induced acute inflammation in oedema paw weight, pulmonary oedema and number of pleural leucocytes in a dose-dependent way. The twig extract was found to be more active than the leaf extract in all the experimental models used. The inhibitory effects of the plant extracts were comparable to those of the reference drugs acetylsalicyclic acid (ASA) and phenylbutazone (PBZ) at 100 mg/kg i.p. The significant reduction in acetic acid-induced abdominal contractions, the decrease in oedema paw weight as well as in the number of leucocytes in the pleural cavity exudates, and the significant increase in the reaction time and pain threshold of mice observed in this study suggest that Dorstenia barteri extracts possess both anti-inflammatory and antinociceptive activities. The present study, therefore, lend pharmacological support to the folkloric uses of Dorstenia barteri extracts in the treatment, control and/or management of arthritis, rheumatism, gout, headache and other forms of body pains in some parts of Africa.

Preliminary studies on the prevalence and distribution of urinary schistosomiasis in Ondo State, Nigeria.

The prevalence of S. haematobium infection in 18 Local Government Area (LGA) in Ondo state was determined by examining pupils from randomly selected schools in the state. A total of 4266 urine samples were examined and 1303 (30.5%) were infected with the parasite. The infection was recorded in both rural and urban communities in each LGA. The overall prevalence was significantly higher in males (33.7%) than in females (26.0%) (P = -0.001). The LGA exhibiting the highest overall prevalence of infection was Akure north (86.2%; Cl, 0.82-0.9). The infection was most common in subjects between the ages of 11 and 15 years. Seven species of aquatic snails were encountered and B. (P). globosus was the most abundant and widespread species. The Owena river/dam in Idanre LGA was richest in molluscan fauna. B. (P). globosus and Biomphalaria pfeifferi shedding cercariae were recovered from Owena river and dam. The study shows that there were spatial heterogeneities in the prevalence of infections in both human population and the snail intermediate hosts. The implications of the clustering nature of the disease, for a successful control program in the state, were discussed.

Hypoglycemic effect of methanolic extract of Musa paradisiaca (Musaceae) green fruits in normal and diabetic mice.

Diabetes mellitus is a debilitating hormonal disorder in which strict glycemic control and prevention of associated complications are of crucial importance. This study was designed to evaluate the hypoglycemic effect of methanolic extract of mature, green fruits of Musa paradisiaca (MEMP) in normal (normoglycemic) and streptozotocin (STZ)-treated, diabetic (hyperglycemic) mice, using chlorpropamide as the reference antidiabetic agent. MEMP (100-800 mg/kg p.o.) induced significant, dose-related (p < 0.05-0.001) reductions in the blood glucose concentrations of both normal and diabetic mice. Chlorpropamide (250 mg/kg p.o.) also produced significant (p < 0.01-0.001) reductions in the blood glucose concentrations of normal and diabetic mice. The results of this experimental study indicate that, in the mammalian model used, MEMP possesses hypoglycemic activity. Although the precise mechanism of the hypoglycemic action of MEMP is still unclear and will have to await further studies, it could be due, at least in part, to stimulation of insulin production and subsequent glucose utilization. Nevertheless, the findings of this experimental animal study indicate that MEMP possesses hypoglycemic activity, and thus lends credence to the suggested folkloric use of the plant in the management and/or control of adult-onset, type-2 diabetic mellitus among the Yoruba-speaking people of South-Western Nigeria.

Ethno-veterinary medicine: screening of Nigerian medicinal plants for trypanocidal properties.

Trypanosoma congolense and T. brucei bloodstream form parasites were propagated axenically in suitable standard media at 34 degrees C. The effects of 33 plant extracts, fractions and pure compounds were evaluated on two clones of T. brucei and drug-sensitive and multi-drug-resistant clones of T. congolense. The cytotoxic activity of the trypanocidal extracts was also evaluated on calf aorta endothelial cells in vitro. Of the extracts tested, 22% killed T. congolense IL 1180 at a concentration of 100 microg/ml while 18% killed 90-100% of T. brucei ILTat 1.4 at the same concentration. However, 6% of the active extracts killed 93% of a dyskinetoplastid form of T. brucei IL Tat 1.1, indicating that the intact kinetoplast is a target of some of the compounds tested. Of the 12 extracts that displayed activity against drug sensitive trypanosomes, 66.7% had trypanocidal activity on a multi-drug-resistant clone, T. congolense IL 3338. The extracts of Eugenia uniflora, Acacia artaxacantha, Terminalia ivorensis, T. superba and Alchornea cordifolia had median lethal concentrations of between 13 and 69 microg/ml on both the drug-sensitive, IL 1180 and multi-drug-resistant clone, IL 3338. The median lethal doses of the active plant extracts on the calf aorta endothelial cells varied between 112 and 13750 microg/ml while the calculated selective indices ranged between 0.71 and 246.8 indicating bright prospects for the development of some of these extracts as potential trypanocidal agents.

The effects of extracts from Tetrapleura tetraptera (Taub.) and Bayluscide on cells and tissue structures of Biomphalaria glabrata (Say).

Subchronic experiments were conducted with low concentrations of saponins from Tetrapleura tetraptera and Bayluscide to study the ultrastructural effects of these molluscicides on Biomphalaria glabrata. The ratio of the digestive cells to the crypt cells was inverted in molluscicide treated snails which showed an increase in the number of secretory cells and a decrease in the number of digestive cells. In the snail foot connective tissues, dose-dependent autolytic areas were observed. The major ultrastructural effects were seen in the digestive gland with dose-dependent autolysis of the membranous structures such as the golgi apparatus, mitochondria and endoplasmic reticulum. The results show that the molluscicides produced non-specific effects on the membranous structures.

Hirudinicidal activities of some natural molluscicides used in schistosomiasis control.

Experiments were conducted with (molluscicides) aridanin isolated from Tetrapleura tetraptera, aridan, an extract from T. tetraptera, endod, an extract from Phytolacca dodecandra and niclosamide on non-target aquatic organisms such as leech, hydra, tadpoles, anopheline mosquito larvae and brine shrimps and compared with their toxicity to the target snail. Biomphalaria glabrata. Aridanin, aridan, endod, and niclosamide produced rapid knockdown effects on B. glabrata at 0.04, 1.00, 30.00, and 40.00 ppm, respectively. All the molluscicides killed the leech, a pest of animals and man at molluscicidal concentrations. The hydra and tadpoles tested were sensitive to the molluscicides except aridanin but the shrimps and anopheline mosquito larvae were resistant to all the molluscicides.

Schistosomiasis and intestinal parasites in rural villages in southwest Nigeria: an indication for expanded programme on drug distribution and integrated control programme in Nigeria.

A cross sectional survey of schistosomiasis, intestinal parasite infections and pattern of schistosomiasis transmission was undertaken in four rural villages around the Erinle dam, Nigeria. The prevalence of Schistosoma haematobium ranged from 10% to 60%. 30% of infected school children excreted over 50 eggs/10 ml urine and high rates of haematuria, proteinuria, leucocyturia and nitrites in urine were observed in infected children and the villagers. Prevalence of infection with S. mansoni ranged from 11.4% to 36.8%. Intensity of infection based on geometric mean eggs/gram of faeces ranged between 100 and 545.7 eggs/g. Malacological surveys showed that Biomphalaria pfeifferi was the predominant potential snail hosts recovered at all the contact sites. Higher infections with schistosome parasites were also recorded for B. pfeifferi than Bulinus globosus. The pattern of transmission of schistosomiasis by the snails is consistent and makes incorporation of community-based focal application of a molluscicide such as Tetrapleura tetraptera in integrated control of schistosomiasis feasible in the area. Prevalence and intensity with Ascaris lumbricoides was high. The highest prevalence was 68.9% while the highest intensity of infection was 2,440.9 eggs/gram of faeces. Multiple infections occured with various combinations of Ascaris lumbricoides, hookworm, S. haematobium, Fasciola gigantica, S. mansoni, and Entamoeba histolytica (as double, triple or quadruple infections). The results suggest an integrated approach to the control of schistosomiasis and intestinal parasites in this part of the country.

Endemicity, seasonality and focality of transmission of human schistosomiasis in 3 communities in southwestern Nigeria.

The pattern of transmission of human schistosomiasis was studied in 3 communities in southwestern Nigeria. The prevalence of Schistosoma haematobium in school children aged 5-16 years in the 3 communities was 76.2, 70.3 and 66.4%, respectively. The percentage of infected children harbouring heavy infections (greater than 50 eggs/10 ml urine) in the 3 communities was 75.5, 69.2 and 48.1% with a prevalence of visible haematuria among the heavily infected children of 29.5, 19.4 and 24.3%, respectively. Bulinus globosus, the snail host for S. haematobium, was found in all 7 sites sampled. The population density and the seasonal fluctuations in density and in prevalence of infection with S. haematobium differed markedly among the different sites. B. pfeifferi, the snail host of S. mansoni, was encountered in 2 of the 7 sites. The pattern of occurrence of infection with S. mansoni differed markedly between the 2 sites. The lack of consistency in the transmission pattern as regards both the seasonality and focality makes a thorough knowledge on the transmission pattern essential for the incorporation of community-based focal mollusciciding into the integrated approach to control of schistosomiasis morbidity in this ecological complex and highly endemic area.

Subchronic exposure of Biomphalaria glabrata eggs to aridanin and niclosamide.

Treatment of 3-day-old Biomphalaria glabrata eggs with aridanin caused a knock-down effect on the prehatch snails, making this group the most susceptible. The development and hatching of 0- to 1-day-old eggs could not be prevented but was prolonged by continuous exposure to aridanin (0.5-10 mg/l). Prehatch snails were less susceptible than juvenile and adult snails. Niclosamide (0.625-0.35 mg/l) arrested the development of B. glabrata. The results predict a poor action of aridanin as an ovicidal agent in the control of snail intermediate hosts of schistosomiasis.

Plant molluscicides: potential of Aridan, Tetrapleura tetraptera, for schistosomiasis control in Nigeria.

Molluscicides are crucial for the control of schistosomiasis. The need to use plant molluscicides has received increased interest as an inexpensive technology because of the high cost of synthetic compounds for snail control in the endemic areas of poor nations of the world. Laboratory screening of Nigerian medicinal plants has shown that some of these contain chemicals which are among the most potent natural molluscicides available today. Field trials have been carried out on Tetrapleura tetraptera, locally known as Aridan, which is widely distributed in West Africa and can be collected and processed locally for the control of schistosomiasis. Research efforts in identifying botanical molluscicides, such as Aridan, should be encouraged by strong support, both from the Government and the private sector, in a current period of economic depression.

Endemicity and seasonality of transmission of human schistosomiasis in Ile-Ife, south western Nigeria.

Endemicity and seasonality of transmission of Schistosoma mansoni and S. haematobium were studied in Ile-Ife, south western Nigeria. Transmission of S. mansoni was demonstrated throughout the year in a man-made dam, whereas transmission of S. haematobium in a stream only occurred in the dry season. This difference in the transmission patterns should be considered when incorporating community-based focal plant molluscicide application in the integrated strategy for the control of schistosomiasis morbidity.

Molluscicidal trials and correlation between the presence of Tetrapleura tetraptera in an area and the absence of the intermediate hosts of schistosomiasis and fascioliasis in southwest Nigeria.

A schistosomiasis research project, carried out in Southwest Nigeria, yielded data by which it was possible to relate snail recovery from potential transmission sites to the presence or absence of Tetrapleura tetraptera. A significant negative correlation with snail numbers was found for distance of T. tetraptera from transmission sites and fruiting of the trees when these variables were tested individually. There were no significant differences between individual variables such as pH, Ca2+ concentrations and temperatures for these snail habitats but these variables produced significant positive correlation with the number of snails recovered. Thus, the presence of T. tetraptera appeared to be the most important limiting factor for the presence of snails. Aqueous extracts of T. tetraptera were effective as a molluscicide against Bulinus globosus and Lymnaea natalensis. However, pollution of the environment by oils reduced or abolished the molluscicidal activity of T. tetraptera. The results indicate that the planting of T. tetraptera has potential for the local control of schistosomiasis.