Tsuyoshi Uchibori

Enzymatic synthesis of carbohydrate esters of fatty acid (I) esterification of sucrose, glucose, fructose and sorbitol

The authors attempted to synthesize carbohydrate esters of fatty acids enzymatically in order to overcome the problems associated with the chemical processes for the synthesis of commercial sucrose esters. The enzymes used were lipases from microorganisms belonging toRhyzopus, Enterbacterium, Aspergillus, Pseudomonas, Chromobacterium, Candida, Mucor andPenicillium. Fatty acids (stearic, oleic and linoleic) and carbohydrates (sucrose, glucose, fructose and sorbitol) used for the reaction were obtained from commercial sources. The enzyme reaction was performed by mixing the enzyme and the substrates in the buffer solution and incubating at 40 C; after freeze-drying the mixture, the products were extracted and subjected to thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). It was observed by TLC and HPLC that carbohydrate esters of fatty acid were produced by the enzyme reaction, and their structures were confirmed by infra red (IR) and nuclear magnetic resonance (NMR) spectrometries. The lipase fromCandida cylindracea was the most enzyme active on the synthesis of carbohydrate esters. The optimum conditions for its activity were as follows: molar ratio of carbohydrate to fatty acid: 0.05mol/l : 0.2mol/l; amount of lipase: 4g/l; pH of the reaction mixture: 5.4 in phosphate buffer; reaction period: 72 hr.

Surface activities, biodegradability and antimicrobial properties of glucosamine derivatives containing alkyl chains

Three series of D-glucosamine derivatives containing an alkyl chain with 8 to 14 atoms, methyl 2-acylamino-2-deoxy-D-glucopyranosides,n-alkyl 2-acetylamino-2-deoxy-D-glucopyranosides andn-alkyl 2-amino-2-deoxy-D-glucopyranoside hydrochlorides, were synthesized, and their surface properties (such as surface tension, critical micelle concentration (CMC), dynamic surface tension and foaming properties), biodegradability and antimicrobial activities were evaluated.n-Alkyl 2-amino-2-deoxy-D-glucopyranoside hydrochlorides containing C8 to C12 carbon chains showed surface activities, a CMC and excellent foaming properties. The α-anomers showed a slightly lower CMC than the β-anomers, indicating less hydrophilicity of the α-anomers. On the other hand, glucosamine derivatives containing amide groups showed poor surface activities in water due to their lower solubilities in water. All glucosamine derivatives containing alkyl chains were biodegraded as well as conventional ethoxylated nonionics by activated sludge from the municipal sewage treatment plant. Methyl 2-acylamino-2-deoxy-D-glucopyranosides andn-alkyl 2-amino-2-deoxy-D-glucopyranoside hydrochlorides showed a broader spectrum of antimicrobial activity than the correspondingn-alkyl glucopyranosides. Among them the C12 derivatives showed the best results.

Antioxidant effect and antimicrobial activity of phenolic sulfides

Some phenolic compounds containing both phenolic hydroxyl groups and sulfide groups in the molecules were prepared by Michael addition and radical addition reactions of ethanethiol and ethanedithiol witho-, m- andp-vinylphenol. The antioxidant effect of these products on the autoxidation of lard was examined by an oven test at 60°C. The antimicrobial activities of these products were evaluated by an agar dilution method. Three kinds of gram-positive and three kinds of gram-negative bacterial strains, as well as six kinds of fungal strains were used for the test. It was found that the Michael addition products showed considerably better antioxidant effects than BHT, whereas the radical addition products did not show any antioxidant effect. The antioxidant effects of these compounds were influenced by the positions of the sulfide groups in their molecules. The phenolic sulfides tested in this report showed good antimicrobial activities against bacteria and fungi.