Chemical Modifications Of Polysaccharides Extracted From Peony Seed Dreg,and Their Antioxidant And Antibacterial Activities In Vitro

Peony seed dreg is a by-product of the processing of peony seed oil.With the great heat of peony seed oil,the development and utilization of peony seed dreg has been widely studied.In this paper,the peony seed dreg polysaccharides were modified by sulfation,phosphorylation and carboxymethylation,and their physicochemical properties were determined.The in vitro antioxidant activity and bacteriostatic properties of peony seed dreg polysaccharides and its modified products were analyzed and compared.The results showed that different modified products of peony seed dreg polysaccharides have potential significance as new antioxidants and bacteriostatic agents in the food industry.The peony seed dreg polysaccharides(PSDPs)were modified by sulfation,phosphorylation and carboxymethylation to obtain the corresponding modified products S-PSDPs,P-PSDPs and C-PSDPs.Ultraviolet absorption peak detection showed that the modified polysaccharides had similar maximum absorption peaks(215 nm,206 nm,216 nm,204 nm)compared with the natural polysaccharides.Fourier transform infrared spectroscopy(FT-IR)analysis showed that S-PSDPs had an absorption peak caused by asymmetric stretching vibration of S=O bond at 1250 cm-1,and O-S-O and C-S-O stretching vibration existed near 588 cm-1 and 830 cm-1;P-PSDPs have an absorption peak caused by P-OH near 1033 cm-1 and an absorption peak caused by asymmetric stretching vibration of P=O bond at around 1245 cm-1.And there is an absorption peak caused by P-O-C in the vicinity at 898 cm-1.C-PSDPs exhibited absorption peaks caused by-COO,C-H,C=O at 1596,1422 and 1328 cm-1.The above results indicated that the sulfation,phosphorylation and carboxymethylation were successfully modified.The antioxidant activities of unmodified polysaccharides,sulfated modified polysaccharides,phosphorylated modified polysaccharides and carboxymethylated modified polysaccharides were explored and compared by reducing ability determination,DPPH free radical scavenging capacity determination,ABTS free radical scavenging activity determination,hydroxyl radicals scavenging activity assay and determination of ferrous ion chelation ability.The results showed that the sulfated polysaccharides had the highest reducing ability,DPPH free radical scavenging ability and ABTS free radical scavenging activity;phosphorylated polysaccharides showed the largest hydroxyl radical scavenging activity and ferrous ion chelation ability;carboxymethylated polysaccharides in vitro antioxidant activity were not significantly enhanced.The results suggest that the introduction of chemical groups may alter the antioxidant activity of the polysaccharide,but the effects of different chemical groups are different.Based on the inhibition zone size,minimum inhibitory concentration and bacterial growth curve,the PSDPs and their chemically modified products S-PSDPs,P-PSDPs and C-PSDPs were evaluated against Bacillus subtilis,Staphylococcus aureus,Escherichia coli and Salmonella typhimurium.The results showed that PSDPs and their derivatives showed significant inhibition to all four bacteria.Among the four polysaccharide components,HBSS has the greatest antibacterial activity;for the modified derivative,the sulfated modified fraction(S-HBSS)showed the greatest antibacterial activity against all tested organisms,followed by carboxymethyl and phosphorylated derivatives;Salmonella typhimurium was most effectively inhibited by all polysaccharide fractions in the four tested bacterial strains.The above results indicate that S-HBSS has potential bacteriostatic activity and may play a role in natural antibacterial functional foods in the future.The anticoagulant index of thrombin activity time(APTT),prothrombin time(PT)and thrombin time(TT)in vitro of polysaccharides were determined by kit method using semi-automatic coagulation instrument.The results showed that the natural peony seed dreg polysaccharides and their modified products all had certain anticoagulant effects,but the anticoagulant ability was different.Among the four polysaccharide components,CHSS and its polysaccharide modifications have the best anticoagulant effect.For the three modification methods,the anticoagulant activity of the sulfated modified polysaccharide is more prominent,and the anticoagulant effect is enhanced with the increase of the polysaccharide concentration,which has obvious concentration dependence.Second,all coagulation is not an exogenous pathway,but rather inhibition of the endogenous coagulation pathway and thrombin-mediated fibrin formation to complete anticoagulant effects.