Cell-suspension cultures of rose (Rosa sp.) accumulated approximately micromolar concentrations of a novel, extracellular, non-reducing trisaccharide, characterised here as α-D-mannopyranosyl-(1→4)-α-D-glucuronopyranosyl-(1→2)-myo-inositol (MGI). Acid hydrolysis of [glucuronic acid-14C]MGI, isolated after incubation of the cells with D-[6- 14C]glucuronic acid, readily yielded [14C]glucuronic acid-inositol, which was relatively resistant to further hydrolysis, as revealed by chromatography and electrophoresis. The complete structure and stereochemistry of MGI was elucidated using one and two dimensional NMR spectroscopic techniques. The structure of MGI suggests a biosynthetic origin from a membrane-bound glycophosphosphingolipid (GPS). We propose that GPSs represent a hitherto unrecognised source of oligosaccharin signalling molecules in plants.

oligosaccharide, trisaccharide, NMR spectroscopy, glucuronic acid, Mannose, HMQC, HMBC, myo-inositol, oligosaccharin, Rosa sp, glycophosphosphingolipid, 1D TOCSY, DQFCOSY

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
2,4	aDManp	100.4	70.1	70.0	66.2	72.7	60.4
2	aDGlcpA	100.3	71.6	73.5	76.2	71.6	174.9
	xXmyoIno	70.1	81.3	71.7	72.8	74.3	72.4


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
2,4	aDManp	5.345	4.019	3.782	3.689	3.630	3.765-3.802
2	aDGlcpA	5.188	3.664	3.887	3.770	4.445	-
	xXmyoIno	3.570	4.095	3.607	3.719	3.284	3.652


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
2,4	aDManp	100.4/5.345	70.1/4.019	70.0/3.782	66.2/3.689	72.7/3.630	60.4/3.765-3.802
2	aDGlcpA	100.3/5.188	71.6/3.664	73.5/3.887	76.2/3.770	71.6/4.445	
	xXmyoIno	70.1/3.570	81.3/4.095	71.7/3.607	72.8/3.719	74.3/3.284	72.4/3.652

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

O=C(O)[C@H]1O[C@H](O[C@H]2[C@@H](O)[C@H](O)[C@@H](O)[C@H](O)[C@H]2O)[C@H](O)[C@@H](O)[C@@H]1O[C@H]1O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]1O

518.421 g/mol (C₁₈H₃₀O₁₇)