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.

Simultaneous determination of seven hydrophilic bioactive compounds in water extract of Polygonum multiflorum using pressurized liquid extraction and short-end injection micellar electrokinetic chromatography.

BACKGROUND: Polygoni Multiflori Radix, He-Shou-Wu in Chinese, is a widely used traditional Chinese medicine. Clinically, water decoction is the major application form of He-Shou-Wu. Therefore, simultaneous determination of bioactive compounds in water extract is very important for its quality control. RESULTS: A pressurized liquid extraction and short-end injection micellar electrokinetic chromatography (MEKC) were first developed for simultaneous determination of seven hydrophilic bioactive compounds in water extract of He-Shou-Wu. The influence of parameters, such as pH, concentration of phosphate, SDS and HP-ß-CD, capillary temperature and applied voltage, on the analysis were carefully investigated. Optimum separation was obtained within 14 min by using 50 mM phosphate buffer containing 90 mM SDS and 2% (m/v) HP-ß-CD (pH 2.5) at 15 kV and 20°C. All calibration curves showed good linearity (R2>0.9978) within test ranges. The overall LOD and LOQ were lower than 2.0 µg/mL and 5.5 µg/mL, respectively. The RSDs for intra- and inter-day of seven analytes were less than 3.2% and 4.6%, and the recoveries were 97.0%-104.2%. CONCLUSION: The validated method was successfully applied to the analysis of He-Shou-Wu samples, which is helpful for its quality control.