Comparison on chemical features and antioxidant activity of polysaccharides from Auricularia auricula by three different enzymes

To investigate and compare the chemical features and antioxidant activities of Auricularia auricula polysaccharides (AAPs), three different AAPs (AAP-M, AAP-D, and AAP-C) were prepared by mannanase, β-dextranase, and cellulase. Their chemical features were determined using high-performance liquid chromatography and infrared spectroscopy. The antioxidant properties were performed both in vitro and in vivo. Results showed that the surface morphology of the A. auricula cell wall treated with three enzymes was slightly different under scanning electron microscopy. The extraction yields of AAP-M, AAP-D, and AAP-C were 18.33% ± 1.93%, 26.42% ± 0.87%, and 17.17% ± 0.08% under optimal conditions, respectively. The monosaccharide composition, molecular weight (AAP-M, AAP-D, and AAP-C were 1.03E+03 kDa, 1.76E+03 kDa, and 1.15E+03 kDa, respectively), and antioxidant activities of the three AAPs were different. AAP-C composed of mannose, glucuronic acid, glucose, and galactose, exhibiting the remarkable ability of scavenging ABTS⁺ , DPPH, and H₂ O₂ (IC₅₀ was 0.065, 0.081, and 0.293 mg/ml, respectively). Moreover, AAP-C could significantly prolonged the lifespan of Caenorhabditis elegans under oxidative stress (p < .05). The results showed that cellulase could be served as an efficient enzyme to prepare AAPs with higher antioxidant capacity. PRACTICAL APPLICATIONS: According to the statistics of China Edible Fungi Association in 2019, the output of Auricularia auricula was accounting for 17.54% of the total output of edible fungi. AAPs account for more than 60% of the fruiting bodies and have various biological activities. Cell wall breaking is an important process of extracting AAPs which has always been the bottleneck restricting the production of AAPs. The traditional chemical acid-base method will pollute the environment, and the yield of hot water extraction is low. In contrast, the bioenzyme method widely used because of its mild conditions and environmental friendly. In this paper, three common bioenzymes which have been widely used in food industry were used to extract AAPs, and Box-Behnken design to improve the yield of AAPs. The results show that AAP-C had high yield and strong antioxidant activity. This study could provide a reference for the industrial production of AAPs.