Suwanna Niamsanit

Novel anti-bacterials against MRSA: synthesis of focussed combinatorial libraries of tri-substituted 2(5H)-furanones.

Mucobromic and mucochloric acid were used as building blocks for the construction of a chemical combinatorial library of 3,4,5-trisubstituted 2(5H)-furanones. With these 2 butenolide building blocks, and eight alcohols a sublibrary of 16 dihalogenated 5-alkoxy-2(5H)-furanones was prepared. This sublibrary of 5-alkoxylated furanones was reacted with 16 amines generating a full size focussed combinatorial library of 256 individual compounds. This three dimensional combinatorial library of 3-halogen-4-amino-5-alkoxy-2(5H)-furanones was prepared around the benzimida-zolyl furanone lead structure by applying a solution phase combinatorial chemistry concept. Typical representatives of the library were purified and fully characterized and one x-ray structures was recorded, additionally. The 3-bromo-4-benzimizazolyl-5-methoxy-2(5H)furanone, Br-A-l, showed an MIC of 8 microg/ml against the multiresistant Staphylococcus aureus (MRSA).

Dextran producing microorganisms from Mitr Phuveing sugar factory, Thailand.

Dextran is a polysaccharide consisting of glucose monomers linked mainly by α(1–6) bonds, produced by numerous microorganisms. It is well known that dextran in cane detrimentally affects processing in the sugar industry. Many microorganisms have been isolated from sugarcane juice during the milling process at Mitr Phuveing Sugar Factory. These organisms were screened for their dextran producing property by selecting mucoid colonies on plate count agar (PCA), MRS agar and malt extract (ME) agar medium containing 10% sucrose. The secondary and tertiary screening was accomplished by growing them in sugarcane juice and complete liquid medium (CM) adding 10% sucrose, aerobically at the appropriate temperature for each isolate. The rapidly growing strains were selected. The bacterial strains were Klebsiella pneumoniae, Enterobacter cloacae, and Lactobacillus fermentum. Among these K. pneumoniae P100 produced the maximum concentration of dextran (6,800 ppm) at stationary phase within 12 h of incubation in CM. Biocide, Dimethyl Benzyl Ammonium Chloride (DBAC) (2 ppm) commonly used to inhibit some microorganisms in the modern cane milling process at Mitr Phuveing Sugar Factory, could not inhibit K. pneumoniae P100 within 30 minutes. From these experiments, the factory has changed the sanitization during the milling process, which has saved on biocide costs.

Efficacy of dimethyl benzyl ammonium chloride and microbial contamination studies in a modern sugarcane milling unit in Thailand

The modern milling process at Mitr Phuveing Sugar factory takes less than 10 min from cane stalk to mixed juice stage before the liming process. However, the microorganisms still affect sugar yield in the factory. The efficacy of dimethyl benzyl ammonium chloride (DBAC) and microbial contamination in the sugar cane juice from milling process were studied. The inhibitory effect of DBAC on the total microorganism, yeast and mold, and lactic acid bacteria in sugar cane juice was assessed aerobically by shaking at 45°C for 10 minutes. The concentration of sucrose and dextran were determined by High Performance Liquid Chromatography and Haze method of ICUMSA, respectively. The results showed that 2 and 6 ppm of DBAC cannot inhibit all kinds of microorganism within 10 minutes. The microbial population and dextran did not increase in sugar cane juice within 10 minutes. However, sucrose losses were noticed because of microbial utilization. Microbial population in the first, third and mixed juice in the milling process were monitored before and after sanitation by hot water and biocide application. The results showed that all kinds of microbial population varied with raw material. The microbial contaminations in some samples of sugar juice from the milling process were selected from plate count agar, malt extract agar and MRS agar medium containing 10% sucrose and identified by physiological and biochemical tests. The microbial contaminations found were mainly yeast: Saccharomyces cerevisiae, Candida guilliermondii and Candida tropicalis, and bacteria: Klebsiella pneumoniae, Lactobacillus fermentum, Enterobacter agglomerans and E. cloacae.

Antibacterial activity of 3-substituted pyrrole-2,5-diones against Pseudomonas aeruginosa

3-Substituted pyrrole-2,5-diones were synthesised from mucohalogen acids and the antibacterial activity was subsequently determined in biological assays. The minimum inhibitory concentration and the minimum bactericidal concentration of 2a were determined for a wide range of microorganisms in the low micromolar range. Protein identification using SDS-PAGE and LC/MS/MS demonstrated a partly degradation of OprF-related proteins giving an insight into the underlying mechanism of these novel antibacterial agents.

Characterization and Rheological Behavior of Dextran from Weissella confusa R003

Dextran from Weissella confusa R003 isolated from sugar cane juice was purified and characterized. Dextran synthesis was performed by fermenting W. confusa R003 in MRS medium containing 10% (w/v) sucrose with continuous shaking at 125 rpm and at 30°C. For 24 hours, the 50% efficiency yield was obtained. Dextran in the culture medium was purified by ethanol precipitation. Structural analysis of dextran using 1H NMR, 13C NMR, and 2D NMR techniques showed the existence of glucoses with 97.4%  α (1→6) linkage in the main chains and 2.6%  α (1→3) in branches. The estimation of molecular weight by dynamic light scattering exhibited average molecular weight of 1.0 × 104 kDa. At low concentration (2.5% w/v), dextran behaved like liquid structure, while, increasing the concentration (5.0 and 10.0% w/v), it was revealed as viscoelastic behavior. The highest gelling phenomenon was found in the concentration of 10% w/v and at 37°C. Due to its production and properties, it may be suitable for commercial production and application in the field of foods as well as hydrogel.