Cause and control of Radix Ophiopogonis browning during storage.

In the storage of Radix Ophiopogonis, browning often happens to cause potential risk with regard to safety. Previously few reports investigate the browning of Radix Ophiopogonis. In this research, the causes and mechanisms of the browning of Radix Ophiopogonis were preliminarily elucidated. Content determination by high-performance liquid chromatography (HPLC) and spectrophotometry, enzyme activity determination by colorimetry, and morphological observation by electron microscopy were performed in the present study. Uniform design and three-dimensional response surfaces were applied to investigate the relationship between browning and storage factors. The cortex cell wall of browned Radix Ophiopogonis was ruptured. Compared with the normal Radix Ophiopogonis, cellulase and polyphenol oxidase enzymes were activated, the levels of 5-hydroxymethylfurfural (5-HMF), total sugars, and reducing sugars were increased, while the levels of polysaccharides and methylophiopogonanone A were decreased in browned Radix Ophiopogonis. The relationship between the storage factors and degree of browning (Y) could be described by following correlation equation: Y = - 0.625 4 + 0.020 84 × X3 + 0.001 514 × X1 × X2 - 0.000 964 4 × X2 × X3. Accompanied with browning under storage conditions, the chemical composition of Radix Ophiopogonis was altered. Following the activation of cellulase, the rupture of the cortex cell wall and the outflow of cell substances flowed out, which caused the Radix Ophiopogonis tissue to become soft and sticky. The main causes of the browning were the production of 5-HMF, the activation of polyphenol oxidase, Maillard reactions and enzymatic browning. Browning could be effectively prevented when the air relative humidity (HR), temperature, and moisture content were under 25% RH, 12 °C and 18%, respectively.

Structural characterization and identification of major constituents in radix scrophulariae by HPLC coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry.

AIM: To analyze the major constituents in Radix Scrophulariae (Scrophularia ningpoensis). METHOD: Radix Scrophulariae was analyzed by HPLC coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF MS/MS). Compounds were separated by HPLC using a C18 column and gradient elution of acetonitrile and 0.1 % (V/V) acetic acid-water. Negative ion mode was employed. RESULTS: A total of thirty-six compounds, including fourteen iridoid glycosides, nineteen phenylpropanoid glycosides, and three organic acids, were identified from Radix Scrophulariae based on the accurate mass measurement of precursor and product ions. Twenty-one of the constituents were identified by comparing their retention times (tR) and ESI-MS/MS data with those of reference standards and/or previous publications, while another fifteen compounds were tentatively identified or deduced according to their Q-TOF MS/MS data which afforded sufficient structural information. CONCLUSION: It is believed that this study is useful for the identification of constituents in Radix Scrophulariae, as well as related plants and complex prescriptions.