Structural elucidation a complex galactosyl and glucosyl-rich pectin from the pericarp of immature fruits of Juglans mandshurica Maxim.

Abstract

A glucosyl-rich pectin, JMMP-3 (M_w, 2.572 × 10⁴ g/mol, O-methyl % = 3.62%), was isolated and purified from the pericarp of the immature fruit of Juglans mandshurica Maxim. (QingLongYi). The structure of JMMP-3 was studied systematically by infrared spectroscopy, monosaccharide compositions, methylation analysis, partial acid hydrolysis, and 1/2D-NMR. The backbone of JMMP-3 possessed a smooth region (→ ⁴GalA¹ →) and a hairy region (→ ⁴GalA¹ → ²Rha¹ →) with a molar ratio of 2: 5. The substitution of four characteristic side chains (R₁-R₄) occurs at C-4 of → 2,4)-α-Rhap-(1→, where R₁ is composed of → 5)-α-Araf-(1→, R₂ is composed of → 4)-β-Galp-(1 → and β-Galp-(1→, R₃ is composed of α-Glcp-(1→, →4)-α-Glcp-(1 → and → 4,6)-α-Glcp-(1→, and R₄ is composed of → 5)-α-Araf-(1→, β-Galp-(1→, → 4)-β-Galp-(1→, → 3,4)-β-Galp-(1→, → 4,6)-β-Galp-(1 → and → 2,4)-β-Galp-(1 → . In addition, the antitumor activity of JMMP-3 on HepG2 cells was preliminarily investigated.