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Summary: The poor water solubility of flavonoids has always been a bottleneck restricting industrial production and application. The key problem of water‐solubility of flavonoids was solved by establishing an alkali substrate‐feeding engineering conversion platform using recombinant rhamnosidase. The results showed that the recombinant enzyme had α‐L‐rhamnosidase activity. Using this enzyme, four kinds of flavonoids such as hesperidin (HSD) were successfully hydrolyzed to products such as hesperetin 7‐O‐glucoside (HMG). Four key enzyme reaction conditions such as temperature, pH, feed rate and substrate specificity were investigated, and the optimum process parameters of the conversion platform were obtained. That was, under the conditions of temperature 50 °C, pH 6 and feeding speed 0.5 mL min−1, HSD conversion efficiency can reach 8.65 mg min−1. In addition, the changes in enzyme protein structure during basic feeding were elucidated by circular binary chromatography (CD) and fluorescence spectrum. The platform has the advantages of low cost, simple process, green environmental protection, high conversion rate and product purity. This method laid a solid foundation for the resource utilisation of flavonoid glycosides and industrial production. [ABSTRACT FROM AUTHOR]

An analysis method was developed for the separation and quantification of hesperidin, neohesperidin, neohesperidin dihydrochalcone and hesperetin by using HPLC-UV. Single factor experiments and Box-Behnken Designs were used to optimize separation of four flavonoids, in which a gradient elution method was adopted with 99% acetonitrile and 0.1% formic acid as mobile phases at a flow rate of 0.9 mL/min. A C18 column was used with a column temperature of 35 °C. LODs and LOQs were below 0.84 µg/mL and 2.84 µg/mL, respectively. Linearity with good correlation coefficients (r > 0.99, n = 5) was attained, recovery rate of four flavonoids ranged from 88% to 130%, the RSD indicating results precision for analyzing hesperidin, neohesperidin, neohesperidin dihydrochalcone and hesperetin ranged from 1.2% to 4.6%. Finally, the present method could be successfully applied to identify and quantify hesperidin, neohesperidin and hesperetin in Fructus Aurantii Immaturus and Pericarpium Citri Reticulatae. [ABSTRACT FROM AUTHOR]

Summary: A solvent method was used to prepare the inclusion compound of neohesperidin (NH) and hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) to improve the water solubility and thermal stability of NH. The physical and chemical properties and supramolecular structure of the inclusion complex were investigated by UV–vis spectroscopy, FTIR, SEM, TG‐DTG, PXRD, NMR and molecular docking techniques. The results showed that the C‐ring of NH was embedded in the cavity of HP‐β‐CD to form an inclusion complex. The phase has changed significantly, NH is completely dispersed in HP‐β‐CD in an amorphous state, and the two are combined in the form of non‐covalent bonds such as hydrogen bonds or van der Waals forces. Through inclusion of HP‐β‐CD, the solubility of NH in water at 37 °C increased from 161.81 μg ml−1 to 1927.12 μg ml−1, and its stability was also significantly improved. [ABSTRACT FROM AUTHOR]