Pseudomonas caryophylli is the causal agent of the bacterial wilt of carnation (Dianthus caryophyllus L.) [1]. We are interested in the structural determination of the O-chain of the cell wall lipopolysaccharide of this bacterium. This paper describes a preliminary result concerning the isolation of a novel branched sugar carrying a C6-chain at position 4.
The lipopolysaccharide (LPS), obtained from the cell wall by phenol-water extraction, was purified by gel filtration on Bio-Gel A-15m and acid-hydrolyzed. The 1H NMR spectrum (Fig. 1 and Table 1) of the main product isolated from the hydrolysate showed signals at 6 5.15 (d, 3.5 Hz) and 4.56 (d, 8.2 Hz) assignable to a-and /3-anomeric protons, in addition to signals assignable to methylene and methyl protons, suggesting a dideoxy sugar structure. The assignments indicated in Table 1 were inferred from a COSY experiment that also revealed the interruption of the scalar connectivities at position 4. The 13C on-resonance and DEPT NMR spectra showed two anomeric carbons at 6 98.5 (1Jc, H 160 Hz, /3 anomer) [2] and 91.6 (1Jc, H 174 Hz, ol anomer) [2], * Corresponding author.