Fabrication of Polysaccharides from a Fermented Tea and Their Antioxidant and Hypoglycemic Viability

The hypoglycemic effects of tea have been extensively studied, with fermented tea demonstrating notable efficacy owing to its distinct processing methods. This study involved the extraction of tea polysaccharides from Wuniuzao Black Tea (WTP) using a water extraction and ethanol precipitation method. WTP-1 and WTP-2 were obtained by separation and purification using DEAE-52 cellulose columns. Antioxidant activity was evaluated utilizing ABTS, DPPH, hydroxyl radical scavenging rates, and total reducing power assays. Hypoglycemic activity was assessed by evaluating the suppression of α-glucosidase and α-amylase integrated with experiments using Insulin resistance (IR) - HepG2 cell model. All the results proved that the WTP-1 and WTP-2 showed remarkable antioxidant activity and enzyme inhibitory effects. Following the intervention, the glucose consumption and glycogen content in IR-HepG2 cells was raised, while malondialdehyde (MDA) levels were decreased. Further, the viability of Superoxide Dismutase (SOD), Glutathione Peroxidase (GSH-Px), Hexokinase (HK), and Pyruvate Kinase (PK) were significantly enhanced. These polysaccharides also significantly altered the transcription levels of genes in the PI3K/Akt signaling pathway, causing an improvement in IR. This study provides scientific evidence that polysaccharides derived from Wuniuzao black tea alleviate IR by regulating the PI3K/Akt signaling pathway and mitigating oxidative stress, laying a groundwork for their utilization in diabetes intervention.