Effects Of Two Extraction Techniques On Polysaccharides From Tricholoma Lobayense And Morchella Esculenta

Mushroom polysaccharides have many important pharmacological effects.They are the main bioactive components that play a crucial role in therapeutics.However,despite massive health benefits,the methods for extraction of polysaccharides from edible mushrooms influence their molecular structure and recovery which affects their bioactivities.There is always a need for novel extraction techniques for polysaccharides extraction which should be quick and efficient.In the present dissertation,we studied the effects of two extraction techniques other than conventional methodologies.Moreover,the bioactivities and yield of extracted polysaccharides were confirmed.The two edible mushrooms utilized in the study were Tricholoma lobayense and Morchella esculenta which have beneficial health effects due to their medicinal importance.We elucidated the effects of flash and hydrothermal extraction on the structures and bioactivities of these mushroom polysaccharides.Hence,our main research contents are as follows:1.Structural elucidation and antioxidant activity of a novel heteroglycan from Tricholoma lobayense by flash extractionThe Flash extraction of polysaccharides from Tricholoma lobayense mushroom with water as solvent was carried out and structural analysis and antioxidant study of the obtained polysaccharide TLH-G were studied.The study found that TLH-G is a heteropolysaccharide with a molecular weight of 4.1×10³ Da.The total sugar,protein,and uronic acid contents were 99.10%,0.72%,and 13.85%,respectively.The monosaccharide composition is mannose,rhamnose,glucuronic acid,glucose and galactose,and the molar ratio is 1.00:0.33:0.56:14.13:2.92.Its main chain consists of?1)-?-D-Glcp-?6?and?1?-?-D-Galp-(3?composition.Antioxidant studies show that the IC₅₀ values of TLH-G for DPPH and ABTS radical scavenging are 0.43 mg/mL and>0.5 mg/mL,respectively.The relationship analysis showed that compared with molecular weight and uronic acid content,the monosaccharide composition,glycosidic bond type and degree of branching had greater influence on antioxidant activity.2.Extraction of polysaccharides from Tricholoma lobayense by hydrothermal methodologyThis study successfully optimized and elucidated the key extraction parameters for hydrothermal extraction of Tricholoma lobayense mushroom polysaccharides.The factors like temperature,time and solid to liquid ratio?S/L?were optimized and our results confirmed that 3.5 g/40 mL?S/L?ratio,120?extraction temperature and 2.5 h extraction time were the ideal extraction parameters for hydrothermal extraction methodology.The average percentage extraction yield at these ideal extraction conditions was 2.33%and the scavenging rate against different radicals was assessed and was found maximum against hydroxyl radicals?87.86%?.Therefore,the trend of scavenging rate was hydroxyl radicals>superoxide radicals>DPPH radicals>ABTS radicals.Similarly,the reducing power of the polysaccharides was related with its concentration.The reducing power was 0.082,using ascorbic acid?Vc?as a standard,at the same concentration of 500?g/mL.Hence,with an absorbance value of 0.082 of our sample,our results showed that with a small amount of water?40 mL?as a solvent and a small amount of substance?3.5 g?,better antioxidant activity and percentage yield could be obtained.This study provided a profound insight into the use of subcritical water technology to improve the recovery rate of bioactive raw materials.3.Effects of hydrothermal extraction on polysaccharides from Morchella esculentaThe effect of subcritical water extraction on Morchella esculenta mushroom was studied at the same optimized conditions as used for Tricholoma lobayense.The percentage yield of the polysaccharides and their protein content was not consistent with that of T.lobayense.The scavenging rate was higher for hydroxyl>DPPH>ABTS radicals,while the absorbance power was 0.06 for ABTS radicals,hence,lower than T.lobayense polysaccharides.The scavenging rate against hydroxyl radicals was also lower than that of T.lobayanse polysaccharides?87.86%?,extracted at same hydrothermal conditions.Furthermore,following ethanol gradient precipitation method,ME20-I polysaccharide was obtained with the molecular weight of about 4×10⁵ Da.However,due to higher uronic acid content?8.51%?,cetyltrimethylammonium bromide?CTAB?protocol was utilized to further purification of polysaccharides.Hence,the molecular weight of the sugar after CTAB treatment turned out to be about 5.3×10³ Da.However,we expect to elucidate structural characterization of the purified sugar in the near future.We conclude that our study provides advantages of being safe and less time consuming.