Insecticidal activity and physiopathological effects of Cotula cinerea crude extract against Culex pipiens

@#The development of new alternatives strategies to synthetic insecticides aimed at reducing pest populations by developing pesticides based on plant extracts without negative effects in non target organisms and environment. The present study was undertaken in order to assess the insecticidal activity of the crude methanolic extract of the Algerian Asteraceae Cotula cinerea, against the larval and the pupal stage of Culex pipiens (Diptera: Culicidae). It is also to determine the chemical composition of the used extract, and to understand the mechanism of toxic action of the tested extract. Based on the preliminary tests, five concentrations of the crude methanolic extract of C. cinerea (0.62, 1.25, 2.50, 3.75, and 5 mg/mL) were tested for their insecticidal activity according to the protocol recommended by the World Health Organization. The chemical profile of the extract was also obtained by high performance liquid chromatography (HPLC). Histopathological effects and inhibition of acetylcholinesterase activity in treated mosquitoes with LC90 were examined to elucidate the mechanism of the toxic effect of the tested extract (48 h post treatment). Eight compounds have been identified by HPLC. That includes four flavonoids (rutin, quercetin, myrcetin and cathechin), three phenolic acids (benzoic acid, vanillic acid, p-coumaric acid) and one alkaloid (berberine). C. cinerea methanolic extract showed good larvicidal and pupicidal activities with LC50 and LC90 values of 1.10 and 4.37 mg/mL respectively against pupae, 24h post treatment and 1.26, 2.35 mg/mL respectively against the fourth instar larvae. Data of enzymatic assay performed on LC50 and LC90 pupae and larvae revealed prominent neurotoxic effects. C. cinerea extract reduced the activity of acetylcholinesterase (AChE) enzyme in a concentration dependent manner. Obtained inhibition percentages, 48 h after treatment, were 35.11 ± 7.44 and 51.83 ± 4.04% for pupal stage and 30.98 ± 2.97 % and 48.77 ± 4.72% for the fourth instar larvae for LC50 and LC90 values respectively. Treated larvae and pupae showed also histopathological damages in the pupal cuticle and larval midgut. The results of this study showed that C. cinerea crude methanolic extract could be considered as an eco-friendly alternative for mosquito control.

Chemical composition and antimicrobial activity of essential oils in Xerophytic plant Cotula cinerea Del (Asteraceae) during two stages of development: flowering and fruiting.

The essential oil (EO) of Cotula cinerea Del collected in the region of Oued Souf (South-eastern Algeria) during two stages (flowering and fruiting), gave a performance that are 0.0801% ± 0.0117% at the flowering stage; and 0.391% ± 0.0664% at the fruiting stage. The chemical study of the (EO) of C. cinerea Del, analyzed by GCMS, showed the presence of 22 chemical compounds in the flowering period with the dominance of: 3-Carène (30.99%), Thujone (21.73%), Santolina triene (18.58%) and Camphor (6.21%). While 21 chemical compounds were obtained during the fruiting period with the dominance: Thujone (28.78%), 3-Carène (15.90%), Eucalyptol (15.13%), Santolina triene (13.38%) and Camphor (7.49%).Viewpoint chemical kinetics and composition, it was noticed that during the flowering stage the plant has produced eight compounds that are absent during the fruiting period. While seven other compounds appeared only during fruiting. It appears the antibacterial of (EO) has C. cinerea Del The sensitivity of the bacterial strains tested ; And E. faecium, E.coli, M. morganii, P. vulgaris, S. aureus and A. baumannii has shown great sensitivity; the strain P. aeruginosa have shown stiff resistance with every concentrations of (EO). As we did not notice any differences significant in the diameters of inhibition with all strains in two stages of growth.

Chemical constituents in the essential oil of the endemic plant Cotula cinerea (Del.) from the southwest of Algeria

Objective: To extract and identify the main constituents of the essential oil of Cotula cinerea (Del.) (Asteraceae family) from southwest of Algeria. Methods: The essential oils obtained by hydrodistillation, from the aerial parts of the endemic plant Cotula cinerea which was collected in the region of Sahara from southwest of Algeria, were analyzed by gas chromatography-mass spectrometry. Results: A total of 33 compounds were identified representing 98.66% of the oil. The main compounds were (E)-citral (24.01%), limonene epoxide cis- (18.26%), thymol methyl ether (15.04%), carvacrol (15.03%), trans-carveol (13.79%), carvone (3.06%) and trans-piperitol (2.54%). Conclusions: The main constituents in essential oil of the aerial part of the plant from southwest of Algeria were different from that collected from southeast of Algeria or in Morocco.

Chemical constituents in the essential oil of the endemic plantCotula cinerea (Del.) from the southwest of Algeria

Objective:To extract and identify the main constituents of the essential oil ofCotula cinerea (Del.) (Asteraceae family) from southwest of Algeria. Methods: The essential oils obtained by hydrodistillation, from the aerial parts of the endemic plantCotula cinerea which was collected in the region of Sahara fromsouthwest of Algeria, were analyzed by gas chromatography-mass spectrometry. Results: A total of 33 compounds were identified representing 98.66% of the oil. The main compounds were (E)-citral (24.01%), limonene epoxide cis- (18.26%), thymol methyl ether (15.04%), carvacrol (15.03%), trans-carveol (13.79%), carvone (3.06%) and trans-piperitol (2.54%). Conclusions: The main constituents in essential oil of the aerial part of the plant from southwest of Algeria were different from that collected from southeast of Algeria or in Morocco.