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Introduction:The presence of microbes in our environment is always a permanent public health problem. In this context, research on natural treatment, less expensive and accessible to fight these microbial germs would be beneficial. Methods:During this work, molecules of thiosemicarbazones due to their numerous biological activities were hemi-synthesizedin situin the essential oil ofCymbopogon citratusin order to evaluate their antimicrobial activities. Results:Analysis of the essential oil extracted by hydrodistillation revealed the presence of 72.91% of citral. Citralthiosemicarbazone (CThio) and citral 4-phenyl-3-thiosemicarbazone (CPthio) were hemi-synthesized in this oil with interesting yields of 83% and 91%, respectively. After purification and confirmation of the structures of these molecules, the three substances were tested on eleven strains of microbes. Determination of the inhibition diameters showed that the activity of the essential oil is best in over 80% of strains. However, the largest diameter of inhibition (26 mm) was noted with CPthio againstSalmonella typhiR 30951401. The determination of the minimum inhibitory concentrations showed that the oil remains more active with the smallest value of 0.3125 mg / ml againstMicrococcus luteus. The lower value of minimum bactericidal concentrations was also obtained with the essential oil againstEnterococcus foecalisATCC 29212. Conclusion:The essential oil ofC. citratusremains more active in the majority cases. It could be a great alternative in the fight against bacteria, and the advantage is that it remains a natural substance.

Les shigelloses (dysenterie bacillaire) persistent actuellement sous forme endémique dans les pays tropicaux et sont accompagnées d’échecs thérapeutiques à cause des souches de Shigelles (agents pathogènes) résistantes aux antibiotiques, constituant ainsi une priorité de santé publique. En Côte d’Ivoire, dans lesrecherches d’alternatives thérapeutiques pour éradiquer ce fléau, les activités antishigella in vitro, d’extraits d’Euphorbia hirta, plante utilisée en médecine traditionnelle pour guérir les diarrhées sanglantes ont été comparées. Un extrait total aqueux (ETaq) a été obtenu par macération de la poudre végétale dans de l’eau distillée et un extrait hydroéthanolique (EETH70%) a aussi été obtenu par macération de la poudre végétale dans l’éthanol70%. Les tests bactériologiques ont été effectués sur les souches cliniques de Shigella sp (EEQ ; 1055) pour déterminer les Concentration Minimale Inhibitrice (CMI) et Concentration Minimale Bactéricide (CMB). Aussi, les rapports d’efficacité des différents extraits sur la base des CMB, ont été recherchés. Ces travaux ont montré que les valeurs des CMIs varient de 6,25 à 12,5 mg/mL tandis que celles des CMBs sont de 25 mg/mL pour l’E.ETH70% (respectivement contre les deux souches :1055 et EEQ de Shigella sp.). Les CMIs et CMBs prises dans ce même ordre sont respectivement de 50 mg/mL pour l’E.Taq. (contre les deux souches) et de 100 à 200 mg/mL respectivement contre les souches EEQ et 1055. Toutefois, l’E.ETH70% est quatre à huit fois plus actif que l’E.Taq. respectivement pour les inhibitions des souches cliniques EEQ et 1055 (par référence au rapport d’efficacité sur la base des CMBs, soit CMB E.Taq)/(CMB EETH70%, montrant ainsi que ces souches testées sont plus sensibles à l’E.ETH70%. Ces travaux constituent une assise scientifique à l’usage traditionnel de cette plante, dans le traitement des diarrhées sanglantes.

To ensure the safety of trypanocidal molecules of thiosemicarbazones hemi-synthesized in essential oil of Cymbopogon citratus, toxicology studies were conducted. These studies which were performed on rats “Wistar” had focused on our most active molecules: citral thiosemicarbazone, citral semicarbazone, citral 4-phenylthiosemicarbazone and the starting substrate which was the essential oil of Cymbopogon citratus. From these studies, it appears that citral semicarbazone, citral 4-phenylthiosemicarbazone and essential oil were no toxic as LD50 > 2000 mg/kg. Citral thiosemicarbazone was slightly more toxic with a LD50 = 315 mg/kg. The study of biochemical parameters revealed that the use of a high dose of the compounds may affect kidney function. A strong dose of essential oil of Cymbopogon citratus could affect liver function. It appears that the citral 4-phenylthiosemicarbazone is a very promising compound because it had an excellent antitrypanosomal activity and had very low toxicity (IC50 = 1.96 μM; LD50 > 2000 mg/kg).© 2019 International Formulae Group. All rights reserved.Keywords: Trypanocidal thiosemicarbazones, toxicology, essential oil, Cymbopogon citratus, biochemical parameters

This article reports data on four carbazones of piperitone: semicarbazone 1, thiosemicarbazone 2, 4-phenyl semicarbazone 3 and 4-phenyl thiosemicarbazone 4 prepared directly in situ from essential oil of Cymbopogon schoenantus, whose GC-FID and GC–MS analysis revealed piperitone as major component (68.20%). The structures of hemi-synthesized compounds were confirmed by high throughput IR, MS, 1H and 13C NMR based spectrometric analysis. Their antiparasitic activities were evaluated in vitro on Trypanosoma brucei brucei (Tbb). The compound 3 (IC50=8.63±0.81µM) and 4 (IC50=10.90±2.52µM) exhibited antitrypanosomal activity, 2 had a moderate activity (IC50=74.58±4.44µM) but 1 was void of significant activity (IC50=478.47µM). The in vitro tests showed that all compounds were less cytotoxic against the human non cancer fibroblast cell line (WI38) (IC50>80µM) while only 2 (IC50=21.16±1.37μM) and 4 (IC50=32.22±1.66µM) were cytotoxic against the Chinese Hamster Ovary (CHO) cells and toxic on Artemia salina (Leach) larvae. Piperitone 4-phenyl semicarbazone 3, the best antitrypanosomal compound, showed also a selectivity index (SI) higher than 7 on the larvae and the tested cells and therefore might be further studied as antitrypanosomal agent. Also, all compounds except 3 showed selectivity between the two tested cell lines (SI>2). This data reveals for the first time the antitrypinosomal properties of thiosemicarbazones, their cytotoxicity on mammalian cells as well as their activities against Tbb and A. salina Leach.