Structural characterization of a nonionic rhamnolipid from Burkholderia lata.

We present the isolation and structural characterization of a novel nonionic dirhamnolipid methyl ester produced by the bacterium Burkholderia lata. The structure and the absolute configuration of the isolated dirhamnolipid bearing a symmetrical C-C methyl ester chain were thoroughly investigated through chemical degradation and spectroscopic methods including 1D and 2D NMR analysis, HR-ESI-TOF-MS, chiral GC-MS, and polarimetry. Our work represents the first mention in the literature of a rhamnolipid methyl ester from Burkholderia species.

C7 Epimerization of Benzylidene-Protected β-d-Idopyranosides Brings Structural Insights into Idose Conformational Flexibility.

Idose is unique among other aldohexoses because of its high conformational flexibility in solution. We herein show that benzylidene acetal-protected 3--acyl-β-d-idopyranosides undergo Lewis acid-catalyzed C7 epimerization with concomitant to ring inversion. The reaction conditions and structural parameters for this transformation to occur have been thoroughly investigated through an extensive glycosylation study combined with NMR analyses, X-ray diffraction, and quantum molecular modeling.

Total Synthesis of a Chimeric Glycolipid Bearing the Partially Acetylated Backbone of Sponge-Derived Agminoside E.

We describe the total synthesis of a chimeric glycolipid bearing both the partially acetylated backbone of sponge-derived agminoside E and the ()-3-hydroxydecanoic acid chain of bacterial rhamnolipids. The branched pentaglucolipid skeleton was achieved using a [3 + 2] disconnection approach. The β-(1 → 2) and β-(1 → 4)-glycosidic bonds were synthesized through a combination of NIS/Yb(OTf)- and TMSOTf-mediated stereoselective glycosylations of thiotolyl, -phenyltrifluoroacetimidate, and trichloroacetimidate donors.

Bacterial rhamnolipids and their 3-hydroxyalkanoate precursors activate innate immunity through two independent mechanisms.

Plant innate immunity is activated upon perception of invasion pattern molecules by plant cell-surface immune receptors. Several bacteria of the genera and produce rhamnolipids (RLs) from l-rhamnose and ()-3-hydroxyalkanoate precursors (HAAs). RL and HAA secretion is required to modulate bacterial surface motility, biofilm development, and thus successful colonization of hosts.

Total synthesis, isolation, surfactant properties, and biological evaluation of ananatosides and related macrodilactone-containing rhamnolipids.

Rhamnolipids are a specific class of microbial surfactants, which hold great biotechnological and therapeutic potential. However, their exploitation at the industrial level is hampered because they are mainly produced by the opportunistic pathogen . The non-human pathogenic bacterium is an alternative producer of rhamnolipid-like metabolites containing glucose instead of rhamnose residues.

Progress toward the Development of Glycan-Based Vaccines against Campylobacteriosis.

As one of the main causes of bacterial diarrhea and a major risk factor for triggering Guillain-Barré autoimmune syndrome, campylobacteriosis, that is, spp. infections, represents a major health issue worldwide. There is thus a pressing need for developing an effective and broad-coverage campylobacteriosis vaccine.

Melioidosis patient serum-reactive synthetic tetrasaccharides bearing the predominant epitopes of Burkholderia pseudomallei and Burkholderia mallei O-antigens.

Melioidosis and glanders, respectively caused by the Gram-negative bacteria Burkholderia pseudomallei (Bp) and Burkholderia mallei (Bm), are considered as urgent public health issues in developing countries and potential bioterrorism agents. Bp and Bm lipopolysaccharides (LPS) have been identified as attractive vaccine candidates for the development of prophylactic measures against melioidosis and glanders. Bp and Bm express structurally similar LPSs wherein the O-antigen (OAg) portion consists of a heteropolymer whose repeating unit is a disaccharide composed of d-glucose and 6-deoxy-l-talose residues, the latter being diversely acetylated and methylated.

Polysaccharides from Burkholderia species as targets for vaccine development, immunomodulation and chemical synthesis.

Covering: up to 2018 Burkholderia species are a vast group of human pathogenic, phytopathogenic, and plant- or environment-associated bacteria. B. pseudomallei, B.