Antioxidant and α-Glucosidase Inhibitory Activities of Procyanidins from Sea Buckthorn

This study investigated the free radical scavenging capacity of sea buckthorn procyanidins (SBPC) and evaluated their antioxidant activity at the cellular level, and it also assessed the α-glucosidase inhibitory effect and mechanism of SBPC. The results indicated that SBPC exhibited stronger scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2’-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) cation radical, and Fe3+ reducing power than did VC within the concentration range of 0–40 μg/mL. At concentrations of 10 and 40 μg/mL, SBPC scavenged 98.18% and 87.08% of DPPH radical and ABTS cation radical, respectively. At the cellular level, 20 μg/mL of SBPC significantly reversed the decline in HepG2 cell viability caused by palmitic acid (P < 0.001), and various concentrations of SBPC significantly reduced cellular ROS levels (P < 0.001). Additionally, SBPC exerted antioxidant effects by inhibiting the production of lipid oxidation products such as malondialdehyde (MDA) and by regulating the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Furthermore, SBPC demonstrated a significant inhibitory effect on α-glucosidase in a reversible competitive manner, with a 50% inhibition concentration of 8.646 μg/mL. It was found that SBPC interacted with amino acid residues at one or more active sites in α-glucosidase, forming hydrogen bonds and hydrophobic interactions, thereby inhibiting α-glucosidase. This study confirmed that SBPC possessed significant antioxidant and α-glucosidase inhibitory activities, providing a theoretical basis for its potential development as a hypoglycemic ingredient of functional foods.