分类： 生物学 >> 植物学 提交时间： 2017-10-27
摘要： Polygala tenuifolia root is usually used for functional food due to attractive health benefits. In this work, ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) were utilised to characterise the bioactive compounds in P. tenuifolia root. The UPLC-MS/MS information revealed 36 bioactive compounds, including oligosaccharide esters, polygalasaponins and polygalaxanthones. GC-MS identified 34 volatile compounds with fatty acids as the main chemicals. The leading compound judged by UPLC-MS/MS was tenuifoliside A, and oleic acid was the leading volatile from GC-MS profiles. All the samples showed similar bioactive compounds compositions, but the level of each compound varied. The results of principal component analysis revealed the principal bioactive compounds with significant level variations between samples. These principal chemicals could be used for quality judgement of P. tenuifolia root, instead of measuring the levels of all compositional compounds.
分类： 生物学 >> 植物学 提交时间： 2017-07-10
摘要： Due to their impressive pharmaceutical activities and safety, prenylated flavonoids have a high potent to be applied as medicines and nutraceuticals. Biocatalysis is an effective technique to synthesize prenylated flavonoids. The major concern of this technique is that the microbe-derived prenyltransferases usually have poor regiospecificity and generate multiple prenylated products. In this work, a highly regiospecific prenyltransferase (FoPT1) was found from Fusarium oxysporum. It could recognize apigenin, naringenin, genistein, dihydrogenistein, kampferol, luteolin and hesperetin as substrates, and only 6-C-prenylated flavonoids were detected as the products. The catalytic effeciency of FoPT1 on flavonoids was in a decreasing order with hesperetin > naringenin > apigenin > genistein > luteolin > dihydrogenistein > kaempferol. Chalcones, flavanols and stilbenes were not active when acting as the substrates. 5,7-Dihydroxy and 4-carbonyl in flavonoid skeleton were required for the catalysis. 2,3-alkenyl was beneficial to the catalysis whereas 3-hydroxy impaired the prenylation reaction. Docking studies simulated the prenyl transfer reaction of FoPT1. E186 was involved in the formation of prenyl carbonium ion. E98, F89, F182, Y197 and E246 positioned apigenin for catalysis.
分类： 生物学 >> 植物学 提交时间： 2017-06-15
摘要： Banana is a tropical fruit widely accepted by people over the world. Its chemical composition is critical for the organoleptic property and nutritional value. In this work, the metabolites change during postharvest senescence was investigated by using NMR spectroscopy. The 1D and 2D NMR spectroscopic information revealed the primary and secondary metabolites in banana fruit, including organic acids, amino acids, carbohydrates and phenolics. Bananas at five senescence stages showed similar chemical profiles, but the levels of the individual compounds varied to a large extent. The principal metabolites responsible for postharvest senescence of banana were valine, alanine, aspartic acid, choline, acetate, glucose, malic acid, gallic acid and dopamine. At stage V, ethanol was present due to the conversion of glucose. Salsolinol was generated due to the conversion of dopamine. This was a characteristic marker for the postharvest senescence of banana fruit.
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