| Mulberry leaves were originally recorded in the"Shennong Herbal Classic",which originated from the dried leaves of the mulberry plant Morus alba L.,distributed in most parts of the country.In the current market of medicinal materials,M The leaves of austalis Poi.and M.cathayana Hemsl.of Huasang are also used as mulberry leaves in Chongqing and other places,with the same effect and common medicinal materials.Mulberry leaf is one of the typical medicinal and food homologous resources.It is rich in protein,alkaloids,free amino acids,flavonoids and other nutrients with special physiological activities.It is a natural raw material for developing drugs or functional foods.This study combined the main marker functional components of mulberry leaves,flavonoids and freeγ-The determination of free amino acids such as aminobutyric acid and inorganic elements,the analysis of the activity and nutritional components of mulberry leaves such as mulberry,chicken mulberry and Chinese mulberry in different production areas of the Three Gorges and the reservoir area,and the evaluation of their safety risks combined with the detection of heavy metal and other indicators,provide theoretical basis for the rational use of mulberry leaves and Chinese mulberry in the reservoir area and lay a foundation for their use as hypoglycemic active drugs and foods.The contents of free amino acids in the protein and water extracts of mulberry leaves from different areas in Chongqing were determined by Kjeldahl nitrogen determination method and HPLC fluorescence method;The effects of different extraction methods,extraction solvents,extraction time and sample weight on the content of five flavonoids in mulberry leaves were investigated by HPLC ultraviolet method;The contents of 22inorganic elements and 6 heavy metal elements in mulberry leaves from different areas in Chongqing were determined by ICP-MS.1.The average protein content of mulberry leaves measured was 24.798%.The protein content of different habitats was significantly different,with obvious regional characteristics.There was no significant difference in species.There is no obvious difference in the types of free amino acids in mulberry leaves from different varieties and different places of origin,but the difference in their amino acid content is relatively obvious.The highest total amino acid content can be measured is 1927.33 mg·100g-1,the essential amino acid content is 322.6 mg·100g-1,the semi-essential amino acid content is46.17 mg·100g-1,and the non-essential amino acid content is 1558.56 mg·100g-1;Compared with its nutrition and flavor characteristics,its flavor characteristics are as follows:fresh amino acid>sweet amino acid>bitter amino acid;The 17 samples were divided into 3 categories by cluster analysis,and the free amino acid quality of the three producing areas was high:Zhuyuan Town,Fengjie County,Chongqing（S5）,Huangjueya Town,Nan’an District,Chongqing（S9）,and Linjiang Town,Kaizhou District,Chongqing（S14）.2.The best pretreatment method was ultrasonic extraction,extraction solvent was70%methanol,extraction time was 30 min,sample weight was 0.5g,extraction solvent was 10ml,and extraction was once.This method has strong specificity and good precision,and can be used for the determination of five chemical components in mulberry leaves.The total content of five flavonoids in 17 batches of mulberry leaves was in the order of mulberry glycoside<rutin<astragaloside<Isoquercetin<chlorogenic acid;In addition,the contents of various components in different species vary greatly,with mulberry leaves being the highest,15.685mg/g,followed by chicken mulberry,8.01mg/g,and Chinese mulberry,6.98 mg/g.3.The content of K in 17 kinds of mulberry leaf samples is relatively high,rich in Ca,Mg,P and other major elements,and also rich in trace elements,which has high development and utilization value.The results of correlation analysis showed that it was speculated that high concentration of K in mulberry leaves of different varieties might inhibit the absorption of Ca and Mg.The results of principal component analysis showed that Jisang,Zhuyuan Town,Fengjie County,Chongqing,Huasang,Zhuyuan Town,Fengjie County,Chongqing,and Huasang,Huangjueya Town,Nan’an District,Chongqing were the most abundant in major and trace elements,with high quality.Through methodological investigation,4.The content of heavy metals in 17 kinds of mulberry leaf samples ranked in the order of Cu>Pb>Cr>As>Cd>Hg,and Hg,Cd and As did not exceed the standard（Hg≤0.2μg/g、Cd≤0.3μg/g、As≤2.0μg/g）,the total amount of Cu,Pb and heavy metals exceeded the standard（Cu≤20.0μg/g,Pb≤5.0μg/g,total≤20.0μg/g）,there are certain security risks.The results of principal component analysis and cluster analysis showed that different varieties of mulberry leaves from the same production area had similar rankings and could be well classified into one category,indicating that there were obvious regional differences in the enrichment results of heavy metals in the samples.The results of correlation analysis showed that there was an extremely significant synergy between the six heavy metals. |
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