Architectural features and antioxidative biofunctionality of a novel pectin from <i>Angelica keiskei</i> Koidz

In this study, a novel RG-I polysaccharide (AKJP-1B, 3.78 kDa) featuring an AG-I-type pectin structural domain within its side chain region was isolated from the aerial parts of medicinal-edible plant <i>Angelica keiskei</i> Koidz. Monosaccharide compositional analysis revealed that AKJP-1B is a heteropolysaccharide primarily composed of rhamnose, galacturonic acid, galactose, and arabinose in a molar ratio of 1.00: 0.85: 1.54: 0.59. Structural characterisation through methylation analysis confirmed that all galacturonic acid residues in the homogeneous polysaccharide AKJP-1B exist as →4)-Gal<i>p</i>A-(1→. Notably, AKJP-1B alleviated oxidative stress in HepG2 cells through dual mechanisms: scavenging intracellular ROS and enhancing the activities of SOD alongside GSH synthesis. The low molecular weight and unique AG-I domain position AKJP-1B a promising phytochemical antioxidant.