| At present,the research on Dendrobium at home and abroad mainly focuses on several well-known medicinal Dendrobium germplasm such as Dendrobium group and Dendrobium parietalis group,while the research on other types of Dendrobium resources is relatively weak.Dendrobium henanense is a herbaceous plant of the genus Dendrobium of the family Orchidaceae,and belongs to the compound group of Dendrobium with fine stems.At present,there are few reports on the research on the medicinal components and pharmacological activities of Dendrobium henanense herbs.Because of this,the food value and clinical medicinal value of Dendrobium henanense have not been exploited.Therefore,in this experiment,the contents of polysaccharides,total flavonoids,total alkaloids,total saponins and proteins of Dendrobium henanense in different growth years were determined by UV spectrophotometric method using annual,biennial,triennial and quadrennial growths of Dendrobium henanense.Based on gas chromatography-mass spectrometry(GC-MS)and high performance liquid chromatography(HPLC),the contents of polyphenols,free monosaccharides and free amino acids in Dendrobium henanense of different growth years were qualitatively and quantitatively analyzed.In addition,the aqueous extracts and alcoholic extracts of Dendrobium henanense of different growth years were assayed for DPPH radical scavenging rate,total antioxidant,reducing power,superoxide anion radical scavenging rate and in vitro α-glucosidase inhibitory activity,and the differences of antioxidant and hypoglycemic activities of Dendrobium henanense of different growth years were initially explored.The main research contents and conclusions are as follows:1.There are differences in the chemical composition content of Dendrobium henanense with different growth years.The highest polysaccharide content was found in two-year old Dendrobium henanense,reaching 37.815%,while the polysaccharide content in four-year old Dendrobium henanense was 16.424%.The total polyphenol content,total alkaloid content,and total saponin content of four year old Dendrobium henanense reached 0.937%,0.0204%,and 0.2852%,respectively.The total polyphenol,total alkaloid,and total saponin content of four year old Dendrobium henanense were the highest among different growth years,followed by three year old Dendrobium henanense,with the contents of 0.735%,0.158%,and 0.2207%,respectively.The annual Dendrobium henanense had the lowest,with the contents of 0.313%,0.067%,and 0.1464%,respectively.The protein content extracted from Dendrobium henanense in different growth years was detected using the BCA reagent kit.The highest protein content was 8.48% for four-year old Dendrobium henanense,while the lowest was 3.53% for two-year old Dendrobium henanense.2.35 compounds have been preliminarily identified,and their content varies in Dendrobium henanense with different growth years.The growth years have a significant impact on the composition of free monosaccharides in Dendrobium henanense.The free monosaccharides of Dendrobium henanense are mainly composed of glucose,mannose,galactose,xylose,arabinose and rhamnose,among which mannose,glucose and galactose account for a large proportion.With the increase of years,the content of glucose increased,while the content of galactose and mannose decreased.This study established 13 methods for determining the content of free amino acids using PITC pre column derivatization method.After determination,proline had the highest content in Dendrobium henanense in various years.3.The alcohol extract of Dendrobium henanense has higher antioxidant activity,among which the four year old Dendrobium henanense has the best antioxidant activity. |
