Études phytochimiques de plantes médicinales djiboutiennes à effets antimicrobiens et anticancéreux

Abstract : This research focused on the bio-analysis of Djiboutian medicinal plants. These latter were selected on ethnobotanical criteria applied to the plants traditionally used against microbial infections. This selection retained six plants which were then subjected to a biological screening including antibacterial and anti-oxidant activities. Three plants were finally study: Acacia seyal, Indigofera caerulea and Cymbopogon commutatus. The search of compound in Acacia seyal was carried out by means of bio-guidance. Two extracts, aqueous and methanolic, of the bark of this plant were evaluated for their antibacterial activity. Four compounds were isolated, characterized (epicatechin, catechin, digallic catechin and β-sitosterol) and tested for their activity. Also four extracts (hexanic, acetonic, methanolic and aqueous) of the fruit of Indigofera caerulea were tested for their antibacterial and antioxidant activities. The Hexanic and methanolic extracts were the most active. Six compounds were isolated from these extracts (methyl gallate, gallic acid, rutin, isoquercetin, kaempferol-3-rutinoside and β-sitosterol). Methyl gallate inhibited Staphylococcus aureus with a MIC of 64 μg / mL. Finally, the activity of the essential oil of Cymbopogon commutatus was evaluated on seven bacterial strains, two fungal strains and eleven types of cancer cells. On the latter, it exhibits a high cytotoxicity with IC50s ranging from 0.05 μg / mL on PC3 and HCT116 (prostate and colorectal cancer cells) to 0.67 μg/mL on NCI-N87 (gastric cancer cell). Surprisingly, an antibacterial activity not so high was observed. GCMS analysis of the solubilized part in the culture medium showed that only the hydrophilic compounds were present. The formulation of a microemulsion was performed and the IC50 decreased to a hundred times. We have found that this essential oil contained more than 73.9 % piperitone (monoterpene). In conclusion, these three plants showed antimicrobial activities and the work confirms their traditional uses. In addition, we have shown that they have other biological activities (anti-oxidant and anti-cancer). These results should contribute to the establishment of a traditional pharmacopoeia and formulations of 'improved traditional medicines' (MTAs)
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http://docnum.univ-lorraine.fr/ulprive/DDOC_T_2018_0160_ELMI_FOURREH.pdf
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https://hal.univ-lorraine.fr/tel-01948696
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Submitted on : Saturday, December 8, 2018 - 10:06:37 AM
Last modification on : Thursday, January 24, 2019 - 1:40:13 PM

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Abdirahman Elmi Fourreh. Études phytochimiques de plantes médicinales djiboutiennes à effets antimicrobiens et anticancéreux. Chimie analytique. Université de Lorraine; Centre d’études et de recherche de Djibouti (CERD), 2018. Français. ⟨NNT : 2018LORR0160⟩. ⟨tel-01948696⟩

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