Two C-24 epimers
, (20R,24R)-3,6-diacetyl-epoxydammar-3[beta],6[alpha],12[beta],25-t etraol (3) and (20R,24S)-3,6-diacetyl-epoxydammar-3[beta],6[alpha],12[beta],25-t etraol (4), were synthesized and their structures were identified by HR-MS, 1H NMR, 13C NMR and X-ray single-crystal diffraction.
It was found that 3[alpha]-[[sup.18]F]FCA shows slightly faster hepatobiliary transport than its epimer
Caption: Figure 2: Comparison of the separation of budesonide epimers
with four different columns during method development.
The authors obtained good signal resolutions (Rs > 1) and average recoveries (79-95%) even when epimers
are included and demonstrated that other antibiotics and conventional feed ingredients do not interfere with the analysis conveying high specificity.
In the present study, a rapid, sensitive, and specific LCMS was developed and validated for stereoselective determination and pharmacokinetic studies of 20(R)- and 20(S)ginsenoside Rh1 and 20(R)- and 20(S)-ginsenoside Rg3 epimers
in rat plasma after oral administration of Radix Ginseng Rubra or SMS extracts.
The isolated compounds were identified in each chromatogram whenever possible, whereas compounds 1a/b and 2 gave one sharp peak at 22.4 min, compound 3, a peak at 26.7 min, and the two epimers
4 and 5 appeared as one sharp peak at 28.5 min (Fig.
Misleading measures in vitamin D analysis: a novel LCMS/ MS assay to account for epimers
Meanwhile, lectins have unique ability to distinguish subtle structural differences among saccharides, e.g., epimers
, anomers, and linkage isomers, etc.
No attempt was made to distinguish between sterol epimers
baumannii may also have equal specificity for glucose as well as mannose, because mannose and glucose are epimers
Pheophorbide a and two related epimers
were drawn in ChemSketch  based on reported structure by Lai et al.