Millettia Thonningii Research Articles

The plant molluscicide Millettia thonningii (Leguminosae) as a topical antischistosomal agent

The West African legume Millettia thonningii is used in Ghana as an anthelmintic and as a purgative agent. A chloroform extract of the seeds of Millettia thonningii which is known to be molluscicidal and cercaricidal was topically applied to mouse skin 2 and 24 h prior to exposure to Schistosoma mansoni cercariae. The presence of Millettia thonningii extract components on the surface of the skin appeared to be effective in preventing subsequent establishment of infection. The compound responsible for the activity is thought to be the isoflavonoid alpinumisoflavone.

Attenuation ofSchistosoma mansonicercariae with a molluscicide derived fromMillettia thonningii

A chloroform extract of molluscicidal plant secondary compounds from the seeds of a West African legume Millettia thonningii was used to attenuate cercariae of Schistosoma mansoni prior to infection of NMRI female mice. Exposure of cercariae to 0.3, 0.6, 1.3, 2.5, 10 or 20 mg/l concentrations of extract for 30 min, immediately before standardized infection, was associated with a concentration-dependent decline in worm establishment at 55 days post-infection. The mean numbers of adult worms established declined from about 17 worms/mouse with control cercariae and those exposed to 0.3 mg/l Millettia to 0.1 worms/mouse after 10 mg/l pre-treatment. Mice exposed to cercariae after 20 mg/l pre-treatment had no adult worms at 55 days post-infection. The activities of cercariae 30 min after exposure to Millettia extract at concentrations up to 2.5 mg/l were similar to those of control larvae: none was immobile. Exposure to higher concentrations of Millettia progressively reduced swimming activity and increased the proportion of immobile cercariae. After pretreatment with 20 mg/l Millettia the majority of larvae were immobile. Levels of anti-parasite antibodies (estimated by ELISA assay using an adult worm-based antigen preparation) rose between 21 and 55 days p.i. with control cercariae and those pre-treated with 2.5 mg/l Millettia. After 5 mg/l pre-treatment, cercariae induced a reduced antibody rise, while mice exposed to cercariae after 10 mg/l pre-treatment showed no rise in anti-parasite antibody levels. These results are discussed in the context of protocols which could possibly use Millettia-attenuated cercariae to induce useful levels of protection in mice towards further cercarial challenge.

Structure and dynamics of a tropical dry forest in Ghana

Forest under low rainfall (averaging 745 mm yr- 1) on the Shai Hills in S.E. Ghana has redeveloped following cessation of farming in the 1890s. Forest stature is low, with a canopy at about 11 m, principally of three species, Diospyros abyssinica, D. mespiliformis and Millettia thonningii. Drypetes parvifolia and Vepris heterophylla are common understorey trees. Twelve species of woody liane were recorded. Species of thicket vegetation in the area were also present at low density. Most species are evergreen. Tree mortality averaged 2.3~o yr ~ and exceeded recruitment (1.5~ yr-1). Differences between species in mortality and recruitment were pronounced: canopy species showed a small decline in density; understorey species increased markedly and the thicket species declined. Seed production was very variable, but seedling establishment was very poor for all species. Seedling mortality was high (11 ~o yr - 1 ) especially for small seedlings. These population trends probably represent the latter stages of succession of forest regrowth after farming about 100 years ago. Compared with tropical rain forest, Shai Hills forest has similar relative tree diameter growth (1-3.5 ~o yr- 1), mortality and recruitment rates, and small-litter fall (5.52 t ha-1 yr- 1). Shai Hills forest differs from rain forest by its short stature, relatively few (evergreen) tree species, poor regeneration from seed, high soil nutrient status and low rainfall. Similar forests have been reported in east Africa and in parts of New Guinea. Abbreviations: dbh = diameter at breast height (1.3 m), gbh = girth at breast height. Nomenclature: follows Hutchinson & D alziel (1954-72), except where authorities are given.

Fish toxicity of the molluscicidal seeds ofMillettia thonningii(leguminosae: papilionoideae): impact onTilapia nilotica/auraeahybrids andCtenopharyngodon idella

Ground seed suspensions of the West African legume, Millettia thonningii are known to be molluscicidal and have potential for use in schistosomiasis control programmes. The toxic effect of these suspensions on two species of fish found in Egypt was examined. Tilapia nilotica/auraea hybrids were less tolerant to the toxic effect than were Ctenopharyngodon idella. For both species, filtering the suspension reduced is toxity. A range of suspension concentrations were tested in order to determine which ones could be tolerated. It was demonstrated that at concentrations causing little or no harm to these fish species, i.e. 90 ppm unfiltered and 150 ppm filtered, effective snail kill could be achieved.

Millettia thonningii molluscicide: A rapid knockdown cercaricide for schistosome cercariae

AbstractSuspensions of ground seed material from the West African legume, Millettia thonningii, have previously been shown to be molluscicidal to schistosome‐transmitting snails and thus potentially useful as a control agent for schistosomiasis. It is demonstrated here that Millettia seed suspensions, in addition to their molluscicidal action, show considerable toxicity towards the infective cercarial stage of Schistosoma mansoni, a causative agent of human intestinal schistosomiasis. This toxicity consists of a rapid knockdown effect on the cercariae, producing unresponsive immobility in times from 11 to 42 min in a concentration range from 500 to 100 parts per million. Filtering reduced the speed of this effect. Cercaricidal activity of the suspensions is also demonstrated in a range of unfiltered suspension concentrations, with 100% mortality occurring from 120 to 310 min after exposure. This potent action will add to the potential effectiveness of a Millettia molluscicide preparation when used as a control agent for schistosomiasis.

Thonningine-A and thonningine-B: two 3-phenylcoumarins from the seeds of Millettia thonningii

The seeds of Millettia thonningii have yielded four isoflavones and three 4-hydroxy-3-phenylcoumarins, of which two are novel. On the basis of spectral analyses the novel compounds have been identified as 4-hydroxy-5,8-dimethoxy-3-(3′,4′-methylenedioxy)phenyl-2″-isopropenylfurano (4″,5″:6,7)coumarin (thonningine-A) and 4-hydroxy-5,8-dimethoxy-3-(4′-methoxy)phenyl-2″-isopropenylfurano(4″, 5″: 6,7)coumarin (thonningine-B).

A Structural and Floristic Analysis of Woody Fallow Vegetation Near Ibadan, Nigeria

SUMMARY (1) The structure and floristics of 8-year-old secondary forest regrowth covering an area of 40 ha of abandoned farmland near Ibadan in Nigeria were studied, with the aim of improving the basis for the use of such vegetation as an index of site conditions. (2) All vascular species occurring in each of fifty randomly-located 25 x 25 m plots were recorded. In addition, woody stems 10 cm girth at breast height (1.3 m) were enumerated in each plot. Vertical structure was examined by constructing a profile diagram for a 10 x 100 m transect. (3) The general features of the vegetation were dominance by phanerophytes, a rich flora (c. 150 species on 0.25 ha), and a high stem diversity. (4) The families represented by the greatest number of species were Papilionaceae, Euphorbiaceae, Rubiaceae and Gramineae. The Apocynaceae, Euphorbiaceae, Mimosaceae, Moraceae and Sapindaceae were each represented by at least three species with frequencies exceeding 60%4. The abundance of Holarrhenafloribunda and Newbouldia laevis was the most distinctivefloristicfeature of the vegetation as a whole. (5) The vegetation profile showed a patchy upper canopy-layer at 20 m and a more continuous one at 5 m. (6) Ordination by principal components analysis showed that there were detectable gradients in both structure and floristic composition of the vegetation, reflecting variations in stem density and the abundance of certain species. The gradients were interpretable in terms of soil type, topography and previous land-use. (7) The absence or rarity of species (e.g. Acioa barteri) typical of fallows on soils derived from sedimentary rocks, and of Musanga cecropioides (abundant in wetter areas), was noteworthy in the drier Ibadan site, located on metamorphic Basement Complex rocks. Intensive land-use in the Ibadan area was indicated by the abundance of Allophylus africanus, Millettia thonningii and Phyllanthus discoideus. (8) Attention is drawn to the implications of these findings for the assessment of site conditions in the Ibadan area.