Alkyl-N-phenyl carbamates (2-8) (see Figure 1), alkyl-N-phenyl thiocarbamates (9-15), 2,2'-biphenyl-2-ol-2'-N-substituted carbamates (16-23), and 2, 2'-biphenyl-2-N-octadecylcarbamate-2'-N-substituted carbamates (24-31) are prepared and evaluated for their inhibition effects on porcine pancreatic cholesterol esterase and Pseudomona species lipase. All inhibitors are characterized as transient or pseudo substrate inhibitors for both enzymes. Both enzymes are not protected from inhibition and further inactivated by carbamates 2-8 and thiocarbamates 9-15 in the presence of trifluoroacetophenone. Therefore, carbamates 2-8 and thiocarbamates 9-15 are exceptions for active site binding inhibitors and are probably the second alkyl-chain binding-site-directed inhibitors for both enzymes. The inhibition data for carbamates 2-8 and thiocarbamates 9-15 are correlated with the steric constant, E(s), and the hydrophobicity constant, pi; however, the inhibition data are not correlated with the Taft substituent constant, sigma. A comparison of the inhibition data for carbamates 2-8 and thiocarbamates 9-15 toward both enzymes indicates that thiocarbamates 9-15 are more potent inhibitors than carbamates 2-8. A comparison of the inhibition data for cholesterol esterase and Pseudomona species lipase by carbamates 2-8 or thiocarbamates 9-15 indicates that cholesterol esterase is more sensitive to the E(s) and pi values than Pseudomona species lipase. The negative slope values for the logarithms of inhibition data for Pseudomona species lipase by carbamates 2-8 and thiocarbamates 9-15 versus E(s) and pi indicate that the second alkyl-chain-binding site of Pseudomona species lipase is huge, hydrophilic, compared to that of cholesterol esterase, and prefers to interact with a bulky, hydrophilic inhibitor rather than a small, hydrophobic one. On the contrary, the second alkyl-chain-binding site of cholesterol esterase prefers to bind to a small, hydrophobic inhibitor. Both enzymes are protected from inhibition by carbamates 16-23 in the presence of trifluoroacetophenone. Therefore, carbamates 16-23 are characterized as the alkyl chain binding site, esteratic site oxyanion active site directed pseudo substrate inhibitors for both enzymes. Both enzyme inhibition data for carbamates 16-22 are well-correlated with sigma alone. The negative rho values for these correlations indicate that the serine residue of both enzymes and carbamates 16-22 forms the tetrahedral species with more positive charges than inhibitors and the enzymes and follow the formation of the carbamyl enzymes with more positive charges than the tetrahedral species. Carbamates 24-31 are also exceptions for active site binding inhibitors and probably the second alkyl chain binding site-directed inhibitors for both enzymes. However, the enzyme inhibition constants for carbamates 24-31 are correlated with values of sigma, E(s), and pi. The negative rho values for these correlations indicate that both enzymes and carbamates 24-31 form the tetrahedral species with more positive ...

The chain gang: The α(2→9) dodecasialic acid has been stereoselectively synthesized in 12 steps by using a convergent block synthesis (see scheme). The use of chloroacetyl protecting groups and a phosphate group as a leaving group led to the improvement of the α selectivity of the glycosylation reactions, thus allowing synthesis of oligomers.

Bacterial polysaccharides are known to induce the immune response in macrophages. Here we isolated a novel extracellular polysaccharide from the biofilm of Thermus aquaticus YT-1 and evaluated its structure and immunomodulatory effects. The size of this polysaccharide, TA-1, was deduced by size-exclusion chromatography as 500 kDa. GC-MS, high performance anionexchange chromatography with pulsed amperometric detection, electrospray ionization-MS/MS, and NMR revealed the novel structure of TA-1. The polysaccharide is composed of tetrasaccharide-repeating units of galactofuranose, galactopyranose, and N-acetylgalactosamine (1:1:2) and lacked acidic sugars. TA-1 stimulated macrophage cells to produce the cytokines TNF-␣ and IL-6. Screening of Toll-like receptors and antibodyblocking experiments indicated that the natural receptor of TA-1 in its immunoactivity is TLR2. Recognition of TA-1 by TLR2 was confirmed by TA-1 induction of IL-6 production in peritoneal macrophages from wild-type mice but not from TLR2 ؊/؊ mice. TA-1, as a TLR2 agonist, could possibly be used as an adjuvant and could enhance cytokine release, which increases the immune response. Furthermore, TA-1 induced cytokine release is dependent on MyD88/TIRAP.The excessive use of antibiotics poses tremendous selection pressure on microorganisms to develop drug resistance, which eventually leads to incurable diseases. Recent alternatives to antibiotics are immunomodulators. Instead of combating pathological microbes directly, the immunomodulators act to enhance the host defense responses without the development of drug resistance.Natural products extracted from microorganisms, mushrooms, algae, lichens, and higher plants were known to induce positive immunological effects and have been frequently used in the ancient practice of Chinese medicine (1). The mechanisms of action of these substances are often unknown, but polysaccharides in these extracts have been found to be the primary factor for macrophage stimulation through induction of the immune system of Toll-like receptors (2, 3). These biopolymers often show advantages over the polysaccharides that are currently in use, especially in combating microbial infections (4). Consequently, modulation of the innate immune system significantly improves the host ability to respond to different pathogens and diseases.The innate immune system is the first line of host defense. It protects the host from a variety of pathogens based on a limited repertoire of germ line-encoded receptors called pattern recognition receptors (PRRs). 4 PRRs include members of the Toll-like receptor (TLR) family and nucleotide binding oligomerization domain-like receptors and retinoic acidinducible gene-I-like receptors, which recognize pathogenassociated molecules, such as microbial components, and then trigger the release of inflammatory cytokine and type I interferons for host defense (5-8). These PRRs are localized in distinct cellular compartments. TLR1, TLR2, TLR4, TLR5, and TLR6 are expressed on the cell surface, whereas TLR3, ...

For substituted phenyl-N-butyl carbamates (1) and 4-nitrophenyl-N-substituted carbamates (2), linear relationships between values ofNH proton chemical shift (&JH), pKa, and 10gk [oH] and Hammett substituent constant (0) or Taft substituent constant (a*) are observed. Carbamates 1 and 2 are pseudo-substrate inhibitors of porcine pancreatic cholesterol esterase. Thus, the mechanism of the reaction necessitates that the inhibitor molecule and the enzyme form the enzyme-inhibitor tetrahedral species at the K; step of the reaction and then form the carbamyl enzyme at the k, step of the reaction. Linear relationships between the logarithms of K; and k; for cholesterol esterase by carbamates 1 and o are observed, and the reaction constants (ps) are -3.4 and -0.13, respectively. Therefore, the above reaction forms the negative-charge tetrahedral species and follows the formation of the relatively neutral carbamyl enzymes. For the inhibition of cholesterol esterase by carbamates 2 except 4-nitrophenyl-N-phenyl carbamate and 4-nitrophenyl-N-t-butyl carbamate, linear relationships of -logK; and loge, with a* are observed and the p* values are -0.50 and 1.03, respectively. Since the above reaction also forms the negative-charge tetrahedral intermediate, it is possible that the K; step of this reaction is further divided into two steps. The first K; step is the development of the positive-charge at the carbamate nitrogen from the protonation of the carbamate nitrogen. The second Z, step is the formation of the tetrahedral intermediate with the negative-charge at the carbonyl oxygen. From Arrhenius plots of a series of inhibition reactions by carbamates 1 and 2, the isokinetic and isoequilibrium temperatures are different from the reaction temperature (25°C). Therefore, the observed p and p* values only depend upon the electronic effects of the substituents. Taken together, the cholesterol esterase inhibition mechanism by carbamates 1 and 2 is proposed. 489

Trichloroethylene (TCE) and tetrachloroethylene (PCE) are commonly found contaminants in soil and groundwater. However, the persulfate anion (S 2 O 8 2-) is an oxidant; when activated with ferrous cation (Fe 2+ ), it generates a stronger oxidant (known as a sulfate free radical, SO 4 -• ), which may be used for the destruction of contaminants. Hydroxypropyl-β-cyclodextrins (HP-β-CDs) are environmentally benign glucose-based molecules that have the ability to increase the solubility of contaminants such as TCE and PCE and make them more amenable to degradation by chemical oxidation. The ultraviolet (UV) and hydrogen nuclear magnetic resonance ( 1 H NMR) spectra of various inclusion complexes of HP-β-CD, Fe 2+ cations, and TCE showed that HP-β-CD forms inclusion complexes with organics, Fe 2+ cations, and combinations thereof. The apparent solubilities of TCE and PCE in aqueous solutions that contain HP-β-CD were observed to increase linearly with concentration. When persulfate was activated by the continuous addition of Fe 2+ cations in a system where TCE and PCE were present as dense nonaqueous phase liquids (DNAPLs), the presence of HP-β-CD increased the dissolved contaminant concentrations and the contaminants were attacked preferentially, most likely because of a controlled and slower rate of generation of the SO 4 -• species.