| Objective:This study was aiming at optimizing the best semi-bionic extraction process of Astragalus polysaccharide and analysing the differences in the Astragalus polysaccharide homogeneity,molecular weight and the gastroprotective effects between the semi-bionic extraction alcohol precipitation process and water extraction alcohol precipitation process.Furthermore,the mechanism of gastric mucosal protection of Astragalus polysaccharide was discussed preliminaryly.MethodsTaking the extraction yield and extraction rate of polysaccharide and saponins of Astragalus as indicators,orthogonal design experiments were projected to optimize the semi-bionic extraction process which would be compared with traditional extraction process further.The crude Astragalus polysaccharide obtained from the traditional extraction process and the semi-bionic extraction process were purified by Sevag deproteination method and DEAE-52 cellulose column chromatography.The differences in the Astragalus polysaccharide homogeneity,molecular weight between the two different extraction processes were detected by high performance gel permeation chromatography(HPGPC).Additionally,the gastroprotective effects of Astragalus polysaccharides extracted by two different extraction processes were compared using indomethacin-induced or enthanol-induced gastric mucosal injury model in rats respectively..What's more,the expression of Bcl-2,Bax and Caspase-3 in gastric mucosa tissues were investigated to explore the underlying gastroprotective mechanism of semi-bionic extracted Astragalus polysaccharides.wasResults1.Results of orthogonal experiments taking the total polysaccharide extraction rate(p/%),total saponin extraction rate(p/%)and extraction yield(p/%)as indicators showed that under simulated gastric juice conditions,the weighted contribution to the semi-bionic extraction process from large to small was the extraction temperature(28.9)>material-liquid ratio(12.8)>extraction time(1.5),of which,the material-liquid ratio(P<0.05)and extraction temperature(P<0.01)played a major role and had statistical differences(P<0.05),however,the extraction time was not so obvious.(P>0.05).Under intestinal juice situation,The weighted contribution from large to small was the material-liquid ratio(49.6)>extraction temperature(12.8)>extraction time(4.0).Among these 3 factors,the material-liquid ratio(P<0.01)and extraction temperature(P<0.05)were the major factors and had statistical differences(P(0.05),the extraction time was secondly with no statistical difference(P>0.05).From the perspective of economic benefits,the optimized process condition for the semi-bionic extraction is 1:30 of solid-liquid ratio,100? of extraction temperature and 1 h of extraction time no matter under the simulated gastric juice condition or the intestinal juice condition.2.Compare two kinds of extraction processes of Astragalus polysaccharides in terms of the homogeneity and the molecular weight,we found that the Astragalus polysaccharides obtained from two kinds of extraction processes are heterogeneous polysaccharide and the molecular weight of them are more different.The molecular weight distribution of the semi-bionic extracted Astragalus polysaccharides was about 30 thousand to 6.7 million,and the content of polysaccharides in low molecular weight segment was slightly higher than that in high molecular weight segment.Nevertheless,the molecular weight distribution of the Astragalus polysaccharides extracted by traditional water extraction method was about 50 thousand to 16.7 million,and the content of polysaccharides in high molecular weight segment was far higher than that in other molecular weight segment.Results illustrated above indicated that Astragalus polysaccharide obtained from semi-bionic extraction was significantly different from that obtained from the traditional extraction in term of molecular weight.3.The results of protective effects of Astragalus polysaccharide obtained from two different extraction processes on two kinds of gastric mucosal injury models in rats are depicted below:? Results of protective effects on ethanol-induced gastric mucosal lesion showed that the gastric mucosal injury scores of rats administrated with semi-bionic extracted Astragalus polysaccharide markedly decreased when compared with the model group(P<0.05)and the goup(P<0.05)which treated with water extraction alcohol precipitated Astragalus polysaccharide.?Results of protective effects on indomethacin-induced gastric mucosal lesion showed that there was no significant difference between the group treated with semi-bionic extracted Astragalus polysaccharide and the group treated with water extraction alcohol precipitated Astragalus polysaccharide in the term of the gastric mucosal injury scores(P>0.05),but scores of both groups were notably lower(P<0.05)than that in the model group.These results unequivocally indicated that semi-bionic extracted Astragalus polysaccharide could effectively prevent the gastric mucosal lesion no matter the lesion induced by ethanol or indomethacin,and the efficacy was better than that of the water extraction alcohol precipitated Astragalus polysaccharide.4.The influence of semi-bionic extracted Astragalus polysaccharide to the ethanol-induced gastric mucosal lesion and the indomethacin-induced gastric mucosal lesion revealed that treatment with low dose or high dose of semi-bionic extracted Astragalus polysaccharide could also significantly reduce the ethanol-induced gastric mucosal injury scores(P<0.05),especially for the high dose group.In addition,in the indomethacin-induced gastric mucosal injury model,scores were reduced obviously in the high dose group(P<0.05),but were not significantly different between the low dose group and the model group(P>0.05).The experimental results proved that the semi-bionic extracted Astragalus polysaccharide had obvious protective effects on gastric mucosal injury no matter induced by ethanol or indomethacin,and presented dosage dependence relations.5.The underlying mechanism of the gastroprotective effect of semi-bionic extracted Astragalus polysaccharide on ethanol-induced gastric mucosal lesion was researched by detecting the expression of anti-apoptotic protein(Bcl-2)and pro-apoptotic protein(Bax,Caspase-3)using immunohistochemical detection technique.In comparison with the normal control group,the expression of Bcl-2 of the gastric mucosa was significantly decreased(P<0.05),and the expression of Bax and Caspase-3 was significantly increased in the model group(P<0.01).Nevertheless,the decrease of Bcl-2 and the increase of Bax and Caspase-3 were markedly reversed by the application of low dose and high dose semi-bionic extracted Astragalus polysaccharide when compared with that in the model group.(P<0.05 or P<0.01),.Taken together,theseresults suggested that the semi-bionic extracted Astragalus polysaccharide was able to protect the gastric mucosal lesion induced by ethanol through the adjustion of apoptotic signaling pathway such as up-regulate anti-apoptotic protein Bcl-2 expression and down-regulate pro-apoptotic protein Bax and Csspase-3 expression.ConclusionBased on the results of the orthogonal tests and the pharmacodynamics experiments,we found that the optimized process condition for the semi-bionic extraction is 1:30 of solid-liquid ratio,100? of extraction temperature and 1 h of extraction time no matter under the simulated gastric juice condition or the intestinal juice condition,and this semi-bionic extraction process is superior to the traditional water extraction process in terms of yield and extraction rate of total Astragalus polysaccharide,the gastroprotective efficacy on ethanol or indomethacin-induced gastric mucosal lesion.The Astragalus polysaccharides obtained from two kinds of extraction processes are heterogeneous polysaccharide with different relative molecular weight.Moreover,the semi-bionic extracted Astragalus polysaccharide can effectively prevent the gastric mucosal lesion induced by ethanol or indomethacin,and present dosage dependence relations.Additionally,the underlying mechanism of rats'gastroprotective effect of semi-bionic extracted Astragalus polysaccharides on ethanol-induced gastric mucosal lesion is through the adjustion of apoptotic signaling pathway such as up-regulate anti-apoptotic protein Bcl-2 expression and down-regulate pro-apoptotic protein Bax and Csspase-3 expression.. |
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