ABSTRACT
The study is aimed to fully analyze antioxidant activty and stability of color-related components from Dendrobium officinale flower. The contents of anthocyanins,carotenoids and flavonoids of 10 varieties including whole flower and labellum of D.officinale flower were detected using UV visible spectroscopy technique and evaluated for their 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·), superoxide anion radical (·O⁻₂) and hydroxy radical (·OH) scavenging activty. And the effects of 4 kinds of metal ions (Cu²⁺, Mg²⁺, Al³⁺,K⁺) and 2 kinds of food additives were investigated on the stability of anthocyanins pigment from D.officinale flower. The results indicated that the flower of D.officinale contained anthocyanins,carotenoids and flavonoids,and their contents in different parts of different families varied. The content of anthocyanins (1 330.9 μg·g⁻¹) in labellum was significantly higher than that in the whole flower (696.3 μg·g⁻¹). The content of carotenoids was positively correlated with the content of anthocyanins,and there was significant positive correlation between the scavenging capacities of the three free radicals and the contents of anthocyanin,respectively (0.415,0.384,0.455). The Cu²⁺, Mg²⁺, Al³⁺, K⁺ and glucose showed significant color-enhancing effect and could increase the stability of anthocyanin in D.officinale flower,while ascorbic acids showed remarkably degradation effect of anthocyanin in D.officinale flower.
ABSTRACT
In order to provide new information on polysaccharide in Dendrobium officinale flowers,the monosaccharide composition and relative molecular mass distribution of 11 families of flowers were investigated and analyzed by high performance gel filtration chromatography (HPGFC) and pre-column derivatization ultra performance liquid chromatography (UPLC) in this study. Then cluster analysis was carried out for the monosaccharide peak areas by utilizing SPSS 19.0 software. The results showed that the polysaccharides of all the above 11 hybrid families of D. officinale flower were separated into three fractions (DOP-1, DOP-2 and DOP-3) with the average relative molecular mass of 5.53×105, 3.49×105 and 2.12×105. The polysaccharides in 11 different families were mainly composed of glucose, mannose, galactose, galacturonic acid and arabinose; mannose had the highest proportion among them, with mannose/glucose ratio of 0.302-3.335. Additionally, the relative contents of various monosaccharides in different families varied. 11 families of D. officinale flower could be classified into four categories according to their monosaccharide components and relative contents. In this study, the relative molecular mass distribution and monosaccharide composition of polysaccharides in D. officinale flowers were defined, which can provide foundations for its resource utilization．.