Clement Oladapo Adewunmi

A triterpene glycoside from the fruits of Tetrapleura tetraptera

Abstract A new saponin has been isolated from the molluscicidal extract of the fruits of Tetrapleura tetraptera . Chemical, enzymatic and spectral methods (D/CIMS, 1 H, 13 C NMR) showed that it was a monodesmosidic diglycoside of the rare sapogenin 27-hydroxyolean-12(13)-en-28-oic acid.

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 (Fools 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.

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.

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.

Accumulation of copper, lead and cadmium in freshwater snails in southwestern Nigeria

Abstract The accumulation of copper, lead and cadmium in freshwater snails ( Biomphalaria pfeifferi, Bulinus globosus, Lanistes libicus, Lymnaea natalensis, Potadoma moerchi, Melanoides tuberculata, Gabiella africana, Pila ovum and Bellamya species) was analysed in man-made dams and rivers in southwest Nigeria using a flameless atomic absorption spectrophotometer. Metal concentrations varied widely among snail species and sites. Metal concentrations within the same snail species were strongly correlated with other metals within the same snail species. Seasonal changes in the metal concentrations occurred in some locations. The highest concentration of copper (2352 μg/g) was found in L. natalensis collected from Owena-Ondo daM in May, lead (52.1 μg/g) in B. globosus at Esa-Odo dam in July while cadmium (31.6 μg/g) was recorded in B. globosus sampled at Owena-Jesa dam in April, 1993. The results implicate the use of freshwater snails as a valuable tool for future monitoring programmes to evaluate the metal burden of man-made dams and rivers in the tropics.

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.

Lenticellarine, a molluscicidal alkaloid from Dysoxylum lenticellare

Abstract A new, homoerythrina-derived alkaloid with molluscicidal activity, lenticellarine, was isolated from the leaves of Dysoxylum lenticellare and its structure was determined by spectroscopic methods.

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.

Evaluation of aridanin, a glycoside, and Aridan, an aqueous extract of Tetrapleura tetraptera fruit, on Schistosoma mansoni and S. bovis.

Experiments were conducted on different stages of Schistosoma mansoni and S. bovis using various concentrations of aridanin and Aridan. Aridanin and Aridan were active against Schistosoma mansoni and S. bovis miracidia. A low concentration of aridanin (0.25 micrograms/ml) reduced the production of cercariae by snails already shedding cercariae. Aridanin and Aridan also produced profound reduction in the worm recovery of mice infected with pretreated cercariae of S. mansoni and S. bovis. Higher concentrations of the molluscicides were biocidal to the cercariae of these schistosomes. These results indicate that the molluscicides are capable of reducing the transmission of schistosomiasis at different stages of the schistosome development and suggest that a similar effect may occur under field conditions.