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Poly[3-(3,4-Dihydroxyphenyl)glyceric acid] from Cynoglossum officinale L. (Boraginaceae)

Abstract:

According to UV, IR, 1H NMR data and to a 2D heteronuclear 1H/13C HSQC experiment the main chemical constituent of water-soluble high-molecular preparation of Cynoglossum officinale (Boraginaceae) (HMP-CO) by analogy with S. asperum, S. caucasicum, S. officinale, S. grandiflorum and Anchusa italica high-molecular fractions (HMFs), was found to be a caffeic acid-derived polymer, namely poly[oxy-1-carboxy-2-(3,4-dihydroxy-phenyl)ethylene] or poly[3-(3,4-dihydroxyphenyl)glyceric acid] (PDPGA). The IR spectrum of HMP-CO showed bands characteristic of phenols, carboxylic acids and ether groups. The 1H NMR spectrum of HMP-CO showed signals at 5.18 and 4.65 ppm, assigned to H-1 and H-2, respectively. A 1H signal at 7.15 ppm was assigned to the aromatic proton H-2'' and a signal at 7.04 ppm to the aromatic protons H-5'' and H-6''. These assignments were confirmed by a 2D heteronuclear 1H/13C HSQC experiment.