Mohamed Moncef Chaabouni

Antibacterial Screening of Origanum majorana L. Oil from Tunisia

Abstract Two methods (agar diffusion and broth microdilution) were used to assess the antibacterial activity of Origanum majorana L. oil of Tunisian origin against 10 bacteria. The results showed that this oil was active against all of the tested strains. The most susceptible were Escherichia coli, Streptococcus A, Shigella dysenteria and Salmonella enteritidis. The least susceptible one was Pseudomonas aeruginosa.

Bromofluoration des alcools allyliques par NBS/Et3N, 3HF : une voie simple d'acces aux epifluorhydrines

Abstract Bromofluorination of allylic alcohols using a combination of N-bromosuccinimide and triethylamine tris-hydrofluoride gives the vicinal fluorobromohydrins. The treatment of the formed fluorobromohydrins with aqueous sodium hydroxide constitutes a convenient route to epifluorohydrins.

Dimercaptoethane oxirane ring opening reaction: β,β′-dihydroxy dithioether synthesis

Abstract The action of dimercaptoethane on alkyl oxiranes in the presence of benzyltrimethylammonium hydroxide (Triton B) allows, via regiospecific opening reaction, the preparation of the corresponding β,β′-dihydroxy dithioethers in excellent yields.

Chemical Composition of Laurus nobilis Oil from Tunisia

Abstract An oil obtained from the dried leaves of Laurus nobilis (origin Tunisia) in 1.5% yield was analyzed by capillary GC and GC/MS. 1,8-Cineole (42.3%) and the α-terpinyl acetate (11.2%) were the main components of the 24 constituents identified.

Betalain and Phenolic Compositions, Antioxidant Activity of Tunisian Red Beet (Beta vulgaris L. conditiva) Roots and Stems Extracts

In the present study, betalains content, phenolic composition, and antioxidant activity of different parts of red beet (Beta vulgaris L. conditiva) (i.e., roots and stems) were compared. Crude extract of root showed the highest betalain content with a maximum of 53 ± 4 mg betanin eq and 46 ± 3 mg vulgaxantin I eq g−1 of extract stems showed higher total phenolic concentration than roots, ranging between 2.0 ± 0.4 and 14.6 ± 0.5 mg gallic acid eq−1 of extract. Chemical composition was analyzed using LC-MS. Betalains (vulgaxanthin I, betanin, and isobetanin) and phenolics (gallic acid, ferulic acid, chlorogenic acid, caffeic acid, vanillic acid, syringic acid, ellagic acid myricetin, quercetin, rutin, kampferol) were identified in roots and stems. Betalain extract obtained from roots showed higher antioxidant activity than extract obtained from stems.

N-Bromosuccinimide-dimercaptoethane cobromination of alkenes: synthesis of β, β'-dibromodithioethers

Abstract Alkenes react in diethyl ether with N -bromosuccinimide (NBS) and dimercaptoethane to afford the corresponding β,β′-dibromodithioethers. Bromine and dimercaptoethane are added to the aliphatic terminal olefins in an anti-Markovnikov fashion.

Synthesis of F-alkyl α-hydroxy acids and esters from F-alkyl epoxides and F-alkyl α-bromo acids and esters from F-alkyl bromohydrins

Abstract F-alkyl α-hydroxy acids and F-alkyl α-bromo acids were prepared respectively by the nitric acid ring-opening oxidative reaction of F-alkyl oxiranes, and oxidation by chromic acid of F-alkyl bromohydrins. The synthesized acids were converted to the corresponding methyl esters which may prove to be useful in the synthesis of F-alkylated heterocycles.

Chemical Composition of Cyperus rotundus L. Tubers Essential Oil from the South of Tunisia, Antioxidant Potentiality and Antibacterial Activity against Foodborne Pathogens

Abstract The chemical composition of Cyperus rotundus L. tubers essential oil from the South of Tunisia was analyzed using GC-FID and GC-MS. Fifty compounds were identified representing 84.6% of the total oil. A new chemotype was found in Tunisia. This essential oil was characterized by sesquiterpenes abundance (78.3%) mainly represented by cyperene (15.2%) and cyperotundone (19.7%). The essential oil (EO) was further fractionated into three fractions (F1: n-pentane, F2: n-pentane/diethyl ether (95/5) and F3: diethyl ether). The antioxidant activity of the EO and its fractions was tested using the1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging test and β-carotene bleaching method. Results showed that the whole EO was more active than the fractions with an effective concentration (EC) of 0.85 ± 0.03 mg/mL and an antioxidant activity coefficient (AAC) of 396.0 ± 2.4. The antimicrobial activity of the EO and its fractions was evaluated using the disc diffusion method against six foodborne pathogens and results showed that Staphylococcus aureus was the most inhibited bacterium with an inhibition diameter of 15.2 ± 0.8 mm for the whole EO.

SYNTHESIS OF SUBSTITUTED DITHIA-9-CROWN-3-ETHERS

Abstract Diethylene glycol monochlorides were prepared from epoxides by action of the chloroethanol. Their conversion into substituted dithia-9-crown-3-ethers has been realized by treatment with p-toluenesulfonyl chloride, followed by the action of 1,2-dimercaptoethane.

Synthesis of 2-Fluoro- Acids, Esters, and Amides From Ã-Dicyanoepoxides

Abstract The opening of A-dicyanoepoxides by pyridine polyhdrofluoride yields polymerisable 2-fluorocyanoformyls which may be kept intact when diluated in dichloromethane or ether. These intermediates react with nuclecophiles such as water, methanol or amines to give respectivly 2-fluoroacids, esters or amides.