Khat-induced conditioned place preference, extinction, and reinstatement in female mice.

Khat ( Forsk), the natural source of cathinone and other psychoactive agents, is chewed by millions of persons in eastern Africa and the Arabian Peninsula for its psychostimulant effect. Using the conditioned place preference paradigm, this study tested fresh khat extract for place preference induction, extinction, and reinstatement. Female mice treated with 100 and 250 mg/kg of khat extract showed conditioned place preference, which was extinguished following a 16-day khat-free period.

Forsk (khat) reduces spontaneous and rewarded alternation in female mice.

Around 10 million people chew the fresh leaves and twigs of Forsk (khat), which synthesize cathinone, for its psychostimulatory effect. Several studies have reported that regular khat users show executive and cognitive dysfunction, such as impaired inhibitory control and poor performance on memory tests. In this study, the effect of fresh khat extract (100 and 250 mg/kg) on spatial working memory and short-term memory in mice was assessed using spontaneous and rewarded alternation T-maze tests.

Biology of the coconut bug, Pseudotheraptus wayi, on French beans.

The coconut bug, Pseudotheraptus wayi Brown (Heteroptera: Coreidae), is a major pest of a wide range of economically important crops in Eastern and Southern Africa. The suitability of French beans, Phaseolus vulgaris L. (Fabales: Fabaceae) as an alternative food for mass rearing of P.

Cashew volatiles mediate short-range location responses in Pseudotheraptus wayi (Heteroptera: Coreidae).

Pseudotheraptus wayi Brown (Heteroptera: Coreidae) is a major pest of cashew in East Africa, but little is known about its chemical ecology. Here, we show by using behavioral assays and chemical analysis that some components of cashew leaf volatiles are attractants for male P. wayi.

Structure, Composition, and Properties of Silk from the African Wild Silkmoth, (Boisduval) (Lepidoptera: Thaumetopoeidae).

Silk cocoon nests, as well as the fiber structure, compositions, and properties of the African wild silkmoth, , collected from Kakamega tropical rainforest (western Kenya) were studied using scanning electron microscopy, high-pressureliquid chromatography, tensile tests, and thermogravmetric analysis, and they were compared with the industrial standard, Cocoon nests are complex structures made up of inner, middle, and outer layers. The inner hard parchment was found to protect a mass of (20-200) individual soft flossy cocoons that enclose the pupae. The outer surface of the cocoon nests was covered with a mass of hair-like bristles.

Description of pre-adult stages of the coconut bug, Pseudotheraptus wayi.

The coconut bug, Pseudotheraptus wayi Brown (Hemiptera: Heteroptera: Coreidae), is a serious pest of a number of crops in Eastern and Southern Africa. Both adults and nymphal stages are destructive because they suck sap from their hosts. The identity of the pest is currently based exclusively on the description of adults.

Study on the microstructure of African wild silk cocoon shells and fibers.

Silk fibers and cocoon shells from four African wild silkmoths Gonometa postica, Anaphe panda, Argema mimosae and Epiphora bauhiniae-were studied to gain insight into the structure-property-function relations and potential commercial application. The surface and cross-section of cocoon shells and fibers revealed the presence of prominent structural variations. Cocoon shells were multilayered and porous structures constructed from highly cross-linked fibers that are densely packed within the sericin/gum.

Two unusual rotenoid derivatives, 7a-O-methyl-12a-hydroxydeguelol and spiro-13-homo-13-oxaelliptone, from the seeds of Derris trifoliata.

The crude methanol extract of the seeds of Derris trifoliata showed potent and dose dependent larvicidal activity against the 2nd instar larvae of Aedes aegypti. From this extract two unusual rotenoid derivatives, a rotenoloid (named 7a-O-methyl-12a-hydroxydeguelol) and a spirohomooxarotenoid (named spiro-13-homo-13-oxaelliptone), were isolated and characterised. In addition a rare natural chromanone (6,7-dimethoxy-4-chromanone) and the known rotenoids rotenone, tephrosin and dehydrodeguelin were identified.

7a-O-methyldeguelol, a modified rotenoid with an open ring-C, from the roots of Derris trifoliata.

From the acetone extract of the roots of Derris trifoliata an isoflavonoid derivative, named 7a-O-methyldeguelol, a modified rotenoid with an open ring-C, representing a new sub-class of isoflavonoids (the sub-class is here named as rotenoloid), was isolated and characterised. In addition, the known rotenoids, rotenone, deguelin and alpha-toxicarol, were identified. The structures were determined on the basis of spectroscopic evidence.