In natural product chemistry, it is often crucial to determine sugar composition as well as the absolute configuration of each monosaccharide in glycosides. An ultra-performance liquid chromatography method using both photodiode array (PDA) and mass spectrometry detectors (UPLC-UV/MS) was developed for qualitative analysis of the absolute configuration of monosaccharide enantiomers. Within a single injection, 16 monosaccharide derivatives including 6 pairs of aldose enantiomers (D/L-glucose, D/L-galactose, D/L-allose, D/L-arabinose, D/L-xylose, and D/L-fucose) and 4 other monosaccharides (L-rhamnose, 2-deoxy-D-glucose, 6-deoxy-D-glucose, and 2-deoxy-D-glalactose) were identified in less than 25 minutes. It was found that the structures of derivatives of sugar enantiomers correlated with retention time. Among derivatives of sugar enantiomers in the current study, the stereoisomer of R-configuration at C-3' retained longer than the corresponding S-configuration isomer. The UPLC-MS method can increase sensitivity of detection of the saccharides by more than 10 times compared to previously reported methods. The one-pot reaction of monosaccharide with L-cysteine methyl ester and phenyl isothiocyanate is easily reproduced, clean, and relatively simple in a screw-capped reaction vial. The developed method was successfully applied for the analysis of different types of glycosides, viz., glycosides of triterpenes, steroids, and flavonoids, that commonly exist in nature. The absolute configurations of composed monosaccharides are clearly characterized from tested samples.
Four new cycloartane glycosides, sutherlandiosides A–D (1–4), were isolated from the South African folk medicine Sutherlandia frutescens and their structures established by spectroscopic methods and X-ray crystallography as 1S,3R,24S,25-tetrahydroxy-7S,10S-epoxy-9,10-seco-9,19-cyclolanost-9(11)-ene 25-O-β-d-glucopyranoside (1), 3R,7S,24S,25-tetrahydroxycycloartan-1-one 25-O-β-d-glucopyranoside (2), 3R,24S,25-trihydroxycycloartane-1,11-dione 25-O-β-d-glucopyranoside (3), and 7S,24S,25-trihydroxycycloart-2-en-1-one 25-O-β-d-glucoyranoside (4). Compound 1 represents the first secocycloartane skeleton possessing a 7,10-oxygen bridge. Compounds 2–4 are also the first examples of naturally occurring cycloartanes with a C-1 ketone functionality. Biosynthetic considerations and chemical evidence suggest that the presence of the C-1 ketone in 2 may facilitate the ring opening of the strained cyclopropane system.
Bioremediation is the use of microorganisms for the degradation or removal of contaminants. Most bioremediation research has focused on processes performed by the domain Bacteria; however, Archaea are known to play important roles in many situations. In extreme conditions, such as halophilic or acidophilic environments, Archaea are well suited for bioremediation. In other conditions, Archaea collaboratively work alongside Bacteria during biodegradation. In this review, the various roles that Archaea have in bioremediation is covered, including halophilic hydrocarbon degradation, acidophilic hydrocarbon degradation, hydrocarbon degradation in nonextreme environments such as soils and oceans, metal remediation, acid mine drainage, and dehalogenation. Research needs are addressed in these areas. Beyond bioremediation, these processes are important for wastewater treatment (particularly industrial wastewater treatment) and help in the understanding of the natural microbial ecology of several Archaea genera.
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