Preliminary investigation on chiral recognition of rare monosaccharide lyxose enantiomers by spectroscopic methods

Both D-lyxose and L-lyxose, as chiral enantiomers of the four kinds of aldopentoses C 5 H 10 O 5 , possess a biomolecular structure similar to that of the common aldopentose monosaccharides D-xylose, L-arabinose and D-ribose in nature. However, they are rare sugars that can only be prepared via artificial synthesis. As the inevitable bioactivity difference between them needs a simple chiral recognition of both samples by an effective method, we endeavour to do this by the normal vibration spectroscopy, i.e., mid-infrared (MIR) and Raman spectroscopy, other than other complex methods. By comparing the high-precision MIR (4000–400 cm –1 ) and Raman (4000–50 cm –1 ) spectra of D-lyxose and L-lyxose, small but distinctive spectral bands are found. Our study demonstrates that almost all vibrational bands observed in the MIR spectral region of D- and L-lyxoses are characteristically analogical, so normal MIR spectroscopic methods cannot be applied as a chirality recognition method. For the Raman spectral bands in the middle-frequency and low-frequency regions, the far-IR / terahertz and Raman spectral technologies can be used as suitable chirality recognising tools for enantiomers.