| The genus Pleurotus is one of the higher basidimycetes, which widely distributed in many countries. By now, more than fifty Pleurotus sp. have been discovered all over the word. P. eryngii SI-01, P. nebrodensis SJ-02 and P. cornucopiae SS-01 are common mushrooms. Pleurotus contains many biological active materials, such as carbohydrate, protein, trace elements, dietary fiber and vitamins, etc. The polysaccharides from Pleurotus had the functions of antitumour, fatigue resistance, antivirus and immunoregulation.In this paper, the extraction conditions of intracellular polysaccharide (IPS) from Pleurotus sp. mycelium in submerged culture were investigated, and single-factor tests and orthogonal experiments were used to dertermine the optimal conditions of intracellular polysaccharide. The extraction conditions of EPS and IPS by P. eryngii SI-01 in submerged culture were optimized on the basis of Plackett-Burman (PB) design and response surface methodology (RSM). The in vitro and in vivo antioxidant activities of polysaccharide were evaluated.The results of orthogonal experiments for IPS extraction of P. eryngii SI-01 were ultrasonic treatment time 20min (P<0.01), extraction temperature 80℃(P<0.01), extraction time 2.5h (P<0.01) and ethanol concentration 90% (P<0.01), while the extraction rate of IPS was 7.5±0.3%. When the conditions were ultrasonic treatment time 25min (P<0.01), extraction temperature 85℃(P<0.01), extraction time 2h (P<0.01) and ethanol concentration 90% (P<0.01), the peak values of IPS extraction of P. nebrodensis SJ-02 and P. corncopiae SS-01 reached 7.1±0.4% and 8.2±0.5%, respectively. The result of response surface methodology of IPS and EPS of P. eryngii SI-01 were ultrasonic treatment time 14.22min (P<0.01), extraction temperature 80℃and ethanol concentration 91.28% and pH 7.59, and the peak values of IPS extraction was estimated at 6.58% and when precipitation time was 20.24h, ethanol concentration was 89.62% and pH 8.17, and EPS production was estimated at 7.27g/L.Hydroxyl radical scavenging activities of IPS of P. nebrodensis SJ-02, P. eryngii SI-01 and P. corncopiae SS-01 were concentration-dependent at the dosage range of 12-60μg/mL. The inhibition percentage of IPS of P. corncopiae SS-01 at 60μg/mL was 38.7±3.1% (P<0.01), which was 20.5±1.7% and 140.8±12.8% higher than that of P. nebrodensis SJ-02 (32.2±2.8%, P<0.05) and P. eryngii SI-01 (16.1±1.5%, P<0.01), respectively. The inhibition percentages of IPS of P. corncopiae SS-01, P. nebrodensis SJ-02 and P. eryngii SI-01 at 60μg/mL were 20.3±1.8% (P<0.01), 19.1±1.5% (P<0.01), and 16.3±1.3% (P<0.05), respectively, and the DPPH scavenging rate of IPS of P. corncopiae (SS-01) at 60μg/mL was 20.5±1.7% (P<0.01), which was 14.5±1.2% and 21.4±1.7% higher than that of P. nebrodensis SJ-02 (17.9±1.6%, P<0.05) and P. eryngii SI-01 (16.8±1.4%, P<0.05), respectively. EPS of P. eryngii SI-01 also had significantly scavenging effects on superoxide anion, hydroxyl and DPPH radicals and reducing power. The scavenging rate of superoxide anion, hydroxyl radicals and DPPH of EPS of P. eryngii SI-01 reached (38.69±2.59%, P<0.01), (59.63±3.72%, P<0.01) and (66.36±4.42%, P<0.05) at a dosage of 400mg/L, respectively.The in vivo antioxidant effects of IPS and EPS on superoxide dismutase (SOD) and glutathione peroxidsade (GSH-Px) activity and malondialdehyde (MDA) content in the blood, heart, liver, kidney, spleen of mice were investigate. Results showed that IPS and EPS could remarkably increase the activity of SOD and GSH-Px, decrease the MDA content.The results suggest that the IPS and EPS of Pleurotus sp. had significantly antioxidant activity in vivo and in vitro, which could be used as natural and potential antioxidants.
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