A simple steady-state kinetic high-throughput assay was developed for the salicylate synthase MbtI from Mycobacterium tuberculosis, which catalyzes the first committed step of mycobactin biosynthesis. The mycobactins are small-molecule iron chelators produced by M. tuberculosis, and their biosynthesis has been identified as a promising target for the development of new antitubercular agents. The assay was miniaturized to a 384-well plate format and high-throughput screening was performed at the National Screening Laboratory for the Regional Centers of Excellence in Biodefense and Emerging Infectious Diseases (NSRB). Three classes of compounds were identified comprising the benzisothiazolones (class I), diarylsulfones (class II), and benzimidazole-2-thiones (class III). Each of these compound series was further pursued to investigate their biochemical mechanism and structure-activity relationships. Benzimidazole-2-thione 4 emerged as the most promising inhibitor owing to its potent reversible inhibition.

A series of 2-aminothiazoles was synthesized based on a HTS scaffold from a whole-cell screen against Mycobacterium tuberculosis (Mtb). The SAR shows the central thiazole moiety and the 2-pyridyl moiety at C-4 of the thiazole are intolerant to modification. However, the N-2 position of the aminothiazole exhibits high flexibility and we successfully improved the antitubercular activity of the initial hit by more than 128-fold through introduction of substituted benzoyl groups at this position. N-(3-Chlorobenzoyl)-4-(2-pyridinyl)-1,3-thiazol-2-amine (55) emerged as one of the most promising analogues with a MIC of 0.024 μM or 0.008 μg/mL in 7H9 media and therapeutic index of nearly ~300. However, 55 is rapidly metabolized by human liver microsomes (t1/2 = 28 min) with metabolism occurring at the invariant aminothiazole moiety and Mtb develops spontaneous resistance with a high frequency of ~10−5.

Combining triflic acid promoted glycosylations of trichloroacetimidates with reductive opening of benzylidene acetals with triflic acid and triethylsilane as one-pot procedures provides easy access to a wide range of di-and branched trisaccharides.Protein-and lipid-bound saccharides are ubiquitous in biological systems involved in many important molecular processes such as fertilization, embryogenesis, neuronal development, hormone activities, and the proliferation of cells and their organization into specific tissues. 1, 2 These interactions are also important in health science and are involved in the invasion and attachment of pathogens, inflammation, metastasis, blood group immunology, and xenotransplantation. [3][4][5] A major obstacle to advances in glycobiology is the lack of pure and structurally well-defined carbohydrates and glycoconjugates. These compounds are often found in low concentrations and in micro-heterogeneous forms, greatly complicating their isolation and characterization. In many cases, well-defined oligosaccharides can only be obtained by organic synthesis. [6][7][8][9] Although the methods for oligosaccharide synthesis have improved considerably during the past decade, the construction of complex carbohydrates remains a significant challenge due to the combined demands of elaborate procedures for glycosyl donor and acceptor preparation and the requirements of regio-and stereoselectivity in glycoside bond formation. To streamline the preparation of complex oligosaccharides, one-pot multi-step approaches for selective monosaccharide protection and oligosaccharide assembly are being pursued, which do not require intermediate work-up and purification step and hence speed-up the process of chemical synthesis considerably.10 ,11 For example, the observation that acetal formation, regioselective reductive opening of arylidene acetals, reductive etherification and acetylation can be catalyzed by triflic acid (TfOH) or trimethylsilyl triflate (TMSOTf) made it possible to program these gjboons@ccrc.uga.edu. Supporting Information Available Experimental procedures and 1 H and 13 C NMR spectra. This information is available free of charge via the Internet at http://pubs.acs.org. To further streamline the process of oligosaccharide assembly, we report here a strategy whereby a regioselective opening of a benzylidene acetal and glycosylations are combined in a one-pot multi-step synthetic procedure. The attraction of the approach is that it makes it possible to assemble branched oligosaccharides by a one-pot procedure; a task that cannot readily be accomplished by chemoselective, orthogonal and iterative glycosylations. In this respect, differential reactivities of hydroxyls have been exploited for the synthesis of branched oligosaccharides by one-pot procedures 18-24 but the scope of this approach is limited because of the need of exceptional high regioselectivities. Trichloroacetimidates were selected as glycosyl donors because their activation requires only catalytic TfOH or TMSOTf. 25 Furt...

Bacillus anthracis vaccine candidate: Sera of rabbits exposed to live and irradiated-killed spores of B. anthracis Sterne 34F2 or immunized with B. anthracis polysaccharide conjugated to KLH elicited antibodies that recognize isolated polysaccharide and two synthetic trisaccharides providing a proof-of-concept step in the development of vegetative and spore-specific reagents for detection and targeting of non-protein structures of B. anthracis.

LPS from Rhizobium sin-1 (R. sin-1) can antagonize the production of tumor necrosis factor alpha (TNF-α) by E. coli LPS in human monocytic cells. Therefore these compounds provide interesting leads for the development of therapeutics for the prevention or treatment of septic shock. Detailed structure activity relationship studies have, however, been hampered by the propensity of these compounds to undergo β-elimination to give biological inactive enone derivatives. To address this problem, we have chemically synthesized in a convergent manner a R. sin-1 lipid A derivative in which the β-hydroxy ester at C-3 of the proximal sugar unit has been replaced by an ether linked moiety. As expected, this derivative exhibited a much-improved chemical stability. Furthermore, its ability to antagonize TNF-α production induced by enteric LPS was only slightly smaller than that of the parent ester modified derivative demonstrating that the ether-linked lipids affect biological activities only marginally. Furthermore, it has been shown for the first time that R. sin-1 LPS and the ether modified lipid A are also able to antagonize the production of the cytokine interferoninducible protein 10, which arises from the TRIF-dependent pathway. The latter pathway was somewhat more potently inhibited than the MyD88-dependent pathway. Furthermore, it was observed that the natural LPS possesses much greater activity than the synthetic and isolated lipid As, which indicates that di-KDO moiety is important for optimal biological activity. It has also been found that isolated R. sin-1 LPS and lipid A agonize a mouse macrophage cell line to induce the production of TNF-α and interferon beta in a Toll-like receptor 4-dependent manner demonstrating species specific properties.