Effect Of RS4-type Sweet Potato Resistant Starch On Blood Lipid And Intestine Of C57BL/6J Mice Fed With High-fat Diet

In the experiment,3kinds of RS4-type sweet potato resistant starch (RS), cross-linked octenyl succinic anhydride modified sweet potato starch (CLOSA-SPS), hydroxypropyl cross-linked modified sweet potato starch (HPCL-SPS) and citric acid acetylation modified sweet potato starch (CAAC-SPS) were prepared by chemical modification, and the content of RS of the modified starch and native starch was determined. Then the effect of RS4-type sweet potato RS on blood lipid and intestine of C57BL/6J mice fed with high-fat diet was studied through animal experiment.72male C57BL/6J mice whose body weight was (21±2)g were randomly divided into six groups: The normal control group (CL, given basal diet), the high-fat group (HF, given high-fat diet), the high-fat diet containing SPS, CLOSA-SPS, HPCL-SPS and CAAC-SPS groups(respectively150g/kg). The mice were killed after12weeks to determine part of their growth performance indices, serum biochemical parameters and intestine health indicators. The main findings were as follows:(1) The content of RS of SPS, CLOSA-SPS, HPCL-SPS and CAAC-SPS was determined by Englyst method:4.10%,11.38%,33.17%and41.91%. Compared with SPS, the RS content of the RS4-type sweet potato RS was increased in varying degrees.(2) At the end of the experiment, the body weight of C57BL/6J mice of the HF group was significantly greater than the CL group (P<0.05), and the difference between the HF group and HF-SPS group was not significant (P>0.05). The HF-HPCL-SPS group, HF-CAAC-SPS group and CL group did not exist significant difference (P>0.05). The liver weight of C57BL/6J mice of the HF group was significantly greater than the CL group (P<0.05). The difference between the HF-CAAC-SPS group and CL group was not significant (P>0.05), and there is no significant difference among the HF-HPCL-SPS group, HF-CLOSA-SPS group and HF-SPS group (P>0.05). It showed that the3kinds of RS4-type sweet potato RS had a certain role in decreasing body and liver weight of C57BL/6J mice fed with high-fat diet, and the effect of CAAC-SPS was most obvious. The mice cecal wall weight of the CL group was significantly greater than the HF group (P<0.05). The difference among the RS4-type RS groups and CL group did not exist (P>0.05), but the cecal wall of the CL group was heaviest, the HF-CAAC-SPS group followed. The RS4-type sweet potato RS could maintain the cecal wall weight of C57BL/6J mice fed with high-fed diet.(3) The serum TC, TG and VLDL-C conents of C57BL/6J mice of the HF group were significantly higher than the CL group (P<0.05), it showed that the mice fed with high-fat diet got hyperlipidemia. The serum TG andVLDL-C conents of the RS4-type RS groups were significantly lower than the HF group (P<0.05), the RS4-type sweet potato RS played a certain role in the regulation of blood lipid. Compared with the HF group, the serum HDL-C content of the CL group and RS4-type RS groups did not exist significant difference (P>0.05). Furthermore, the serum LDL-C content among the groups was not significantly different (P>0.05). The RS4-type sweet potato RS did not have an impact on the serum HDL-C and LDL-C contents of the mice fed with high-fat diet.(4) Compared with the CL group, intestinal villus height of the HF group and HF-SPS group reduced, crypt depth increased, the ratio of villus height and crypt depth reduced, muscular layer thickness decreased and the differences were significant (P<0.05). And compared with the HF group, intestinal villus height of the RS4-type RS groups increased, crypt depth decreased, the ratio of villus height and crypt depth and muscular layer thickness increased. The HF-CAAC-SPS group amd HF-HPCL-SPS group, compared with the HF group, had significant difference (P<0.05), and CAAC-SPS, HPCL-SPS significantly improved the small intestine, but the small intestine of C57BL/6J mice of the CL group was still relatively healthier.(5) The fecal water content and pH value of C57BL/6J mice of each group were determined every3weeks. The RS4-type sweet potato RS could make the mice fecal water content gradually increase, and it was positively correlated with RS content.The mice fecal pH value of the CL group was basically stable and the HF group had a upward trend.The mice fecal pH value of the HF-CLOSA-SPS group declined first and then rose, but the upward trend was slower than the HF group. The measurement result between the HF-HPCL-SPS group and CL group was not significantly different (P>0.05). The pH value of the HF-CAAC-SPS group from the3th weekend was beginning less than the CL group and showed significant difference from the9th weekend (P<0.05). The RS4-type sweet potato RS could increase the fecal water content and decrease fecal pH value of the mice fed with high-fat diet, and the effect was more obvious in CAAC-SPS and HPCL-SPS.(6) Cluster analysis showed that the intestinal flora of C57BL/6J mice of the CL group was very different from the HF group, and the diversity index of the former was significantly greater than the latter (P<0.05). Compared with the HF group, the intestinal flora of the RS4-type RS groups was more similar to the CL group, and the diversity indices were significantly greater than the HF group and HF-SPS group (P<0.05). The3kinds of RS4-type sweet potato RS, to some extent, avoided the intestinal flora of C57BL/6J mice fed with high-fat diet be disordered and diversity indices decrease, maintained the flora balance, and the effect of CAAC-SPS and HPCL-SPS was more significant.