Ultrastructure changes induced by the phloroglucinol derivative agrimol G isolated from Leucosidea sericea in Haemonchus contortus.

Plant extracts used for the treatment of helminth infections in sheep are an alternative to chemical anthelmintic drugs. Previous studies have reported the anthelmintic activity of acetone leaf extracts of Leucosidea sericea. For this study, we evaluate the ultrastructure changes induced by the acetone leaf extract of L. sericea and the component agrimol G (AG) that was isolated for the first time on adult haemonchus parasites. Adult haemonchus parasites harvested from sheep were incubated with the plant extract and AG for 3 h and evaluated by both scanning and transmission electron microscopy in comparison and in combination with albendazole or ivermectin. In all cases the method of evaluation shows ultrastructural changes, with albendazole inducing mitochondrial damage and ivermectin inducing muscle degeneration, both as previously described. Incubation with the plant extract and AG resulted in the formation of numerous non-membrane bound multi-vesicular like bodies and evenly spread disruptions/erosion in the epicuticle. Combining AG with ivermectin or albendazole resulted in an absence of effect of AG. Based on the structural changes induced by AG, together with the absence of an effect in combination with ivermectin and albendazole would suggest a disrupted microtubular network. The latter does however require biochemical confirmation.

The use of Clausena anisata in insect pest control in Africa: A review.

ETHNOPHARMACOLOGICAL RELEVANCE: Clausena anisata is used traditionally by various communities across Africa against pests such as mosquitoes, flies and weevils among others. Pests are a major cause of disease and production losses in various crop and livestock production systems in Africa. This review discusses the available information on the occurrence, chemistry, biological activity and possible commercialization of Clausena anisata with a view to see the plant species being integrated in pest management. MATERIALS AND METHODS: Information on the ethnomedical use, chemistry and biological activity of C. anisata published between 1980 and 2016 was accessed from various databases namely Science Direct, Springer Link and Wiley Online Library. In addition various relevant books were also consulted. RESULTS: The crude extracts as well as different fractions of C. anisata have been evaluated for activity against various insect pests and have been shown to be active. Furthermore, close to 50 compounds have been isolated and identified from C. anisata, which include coumarins, carbazole alkaloids, limonoids and essential oils (monoterpenes). Some of these compounds have been proven to exhibit pesticidal properties in both laboratory and field studies against various pests including mosquitoes, flies and weevils. The possible mechanisms of action of these compounds have been explored in this review. CONCLUSION: The results of pesticidal and phytochemical screening of C. anisata strongly indicate that the species is endowed with pesticidal properties that can be harnessed into commercial products. However, one glaring challenge in the evaluation of this plant species for pesticidal activity has been the non-availability of standard testing systems. Researchers have used various methods which they developed based on their own circumstances and resources. Formulation, standard appropriate testing systems and agronomic research are key in unlocking the potential of this important African species.

Isolation of seselin from Clausena anisata (Rutaceae) leaves and its effects on the feeding and development of Lucilia cuprina larvae may explain its use in ethnoveterinary medicine.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves of Clausena anisata are used traditionally to expel maggots from wounds of animals in Zimbabwe. We have previously proved in the laboratory that the plant certainly affects the behaviour and growth of blowfly larvae. The objective of this study was to isolate and identify the active compounds responsible for this activity. MATERIALS AND METHODS: The acetone extract of Clausena anisata leaf powder was separated by solvent-solvent partition into five fractions. The n-hexane fraction was the most active in the larvicidal assay and therefore subjected to open column chromatography on silica gel. RESULTS: The isolated compound was identified by nuclear magnetic resonance (NMR) and mass spectroscopy (MS) as the pyranocoumarin, seselin, chemically known as 2',2'-dimethylpyranocoumarin. It inhibited feed intake in the first and second instars of blowfly larvae at the minimum concentration tested of 1 ppm resulting in significant lower mass pupae (13.5±0.5 mg and 22.4±0.4 mg for the first and second instar larvae respectively) compared to the solvent control group (26.19±0.8 mg) (p<0.05). CONCLUSIONS: This is the first report of the isolation of seselin from the leaves of Clausena anisata and the first report of the compound having an effect against blowfly larvae.

Evaluation of plant species used traditionally to treat myiasis for activity on the survival and development of Lucilia cuprina and Chrysomya marginalis (Diptera: Calliphoridae).

Myiasis is a common parasitic problem of livestock responsible for severe economic losses in developing and developed countries. There are a number of challenges with the current control strategy, which depends largely on the use of pharmaceutical chemicals. These include inaccessibility, the increasing concern about pesticide accumulation in the environment and potential development of insecticide resistance in the devastating myiasis-causing flies. Consequently the search for alternatives is important. The use of plants in the treatment of wound myiasis in livestock as an alternative to commercial insecticides has been reported in resource poor areas worldwide. We therefore, undertook a study to establish the biological activity of seven plant species used against blowflies in southern Africa. A larvicidal assay was carried out in which third instar larvae of blowfly were fed meat treated with acetone leaf extracts of selected plant species. Four of the species, Aloe zebrina, Clausena anisata, Erythrina lysistemon and Spirostachys africana, induced developmental anomalies in the blowfly such as paralysis, prolongation of the prepuparium stage, reduced pupation rates, pupal malformations and reduced adult emergence. These results suggest that the plants may contain compounds that interfere with the neuroendocrine control mechanisms in the blowfly.