The structural characteristic of bamboo shoot shell polysaccharides extracted using ultrasound-assisted phosphotungstic acid hydrolysis and its protection against cell oxidative injury

Summary In this study, crude polysaccharide (BSSP) was extracted from bamboo ( Phyllostachys edulis ) shoot shell using the ultrasonic-assisted phosphotungstic acid hydrolysis method. Then, BSSP was further fractionated by DEAE Sepharose fast flow column and serial NaCl solution elutions to obtain two fractions, BSSP-A and BSSP-B. The results showed that the maximum yield of BSSP was 195.2 mg g −1 (19.52%) under optimised conditions. Structural analysis indicated that both BSSP-A and BSSP-B were heteropolysaccharides with α-pyranoside bond structure and mainly consisted of xylose by scanning electronic microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermal characterisation and nuclear magnetic resonance spectroscopy. BSSP-B showed a better protective effect than BSSP-A against H 2 O 2 -induced oxidative injury in WRL-68 cells by protecting the cell membrane structure, maintaining mitochondrial membrane potential and increasing intracellular antioxidant enzymes activities. Immunoblotting indicated that polysaccharides might up-regulate the expression of antioxidant enzymes through the Keap1/Nrf2 signalling pathway and thus alleviate H 2 O 2 -induced cell injury. The findings of this study suggested that polysaccharides from bamboo shoot shell may act as potent antioxidants in functional food industries.