[Enzymatic characteristics of peroxidase from Chrysanthemum morifolium cv. Bo-ju].

The enzymatic browning is one of the main reasons for affecting the quality of medicinal flowers. In the process of chrysanthemum harvesting and processing, improper treatment will lead to the browning and severely impact the appearance and quality of chrysanthemum. Peroxidase enzyme is one of the oxidoreductases that cause enzymatic browning of fresh chrysanthemum. The enzymatic characteristics of peroxidase (POD) in chrysanthemum were studied in this paper. In this experiment, the effects of different reaction substrates and their concentrations, PH value of buffer and reaction temperatures on the activity of POD enzyme were investigated. The results showed that the optimal substrate of POD was guaiacol, and the optimal concentration of POD was 50 mmol·L⁻¹. The optimal pH value and reaction temperature were 4.4 and 30-35 °C, respectively. Michaelis-Menten equation was obtained to express the kinetics of enzyme-catalyzed reaction of POD, Km=0.193 mol·L⁻¹, Vmax=0.329 D·min⁻¹. In addition, the results of POD enzyme thermal stability test showed that the POD enzyme activity was inhibited when being treated at 80 °C for 4 min or at 100 °C for 2 min. The above results were of practical significance to reveal the enzymatic browning mechanism, control the enzymatic browning and improve the quality of chrysanthemum, and can also provide the basis for the harvesting and processing of medicinal materials containing polyphenols.

Inhibitory effects of Schisandra chinensis on acetaminophen-induced hepatotoxicity.

Schisandra chinensis is a well-known traditional medicinal herb. Acetaminophen is a commonly used over-the-counter analgesic and overdose of acetaminophen was the most frequent cause of acute liver failure. However, no studies have demonstrated the role of Schisandra chinensis in acetaminophen-induced acute liver failure to the best of our knowledge. In this study, an acute liver injury model was established in mice using acetaminophen. The protective role of Schisandra chinensis was detected by histopathological analysis, and measurement of the serum transaminase levels and hepatic Cyp activity levels in the mouse model. Subsequently, hepatocytes were isolated from the livers of the mouse model. The cell cycle, apoptosis, mitochondrial membrane potential and reactive oxygen species were determined using flow cytometry. Cell proliferation and 26S proteasome activity were determined using spectrophotometry. Schisandra chinensis was found to resist acetaminophen-induced hepatotoxicity by protecting mitochondria and lysosomes and inhibiting the phosphor-c-Jun N-terminal kinase signaling pathway. These findings provide a novel application of Schisandra chinensis against acetaminophen-induced acute liver failure.

Determination of tryptophan in bee pollen and royal jelly by high-performance liquid chromatography with fluorescence detection.

A method for tryptophan analysis in bee pollen and royal jelly was developed using HPLC with fluorescence detection. To determine the free tryptophan in bee pollen and royal jelly, ultrasonic extraction was performed using water (pH 6.3)-acetonitrile (10:1, v/v) as extraction solvent. While determining the total tryptophan in these bee products, the method involves alkaline hydrolysis of the proteins with 4 mol/L sodium hydroxide at 110 degrees C for 20 h under anaerobic conditions. The operating conditions for the HPLC analysis were: Symmetry C(18) column (4.6 x 250 mm, 5 microm), 0.1% trifluoroacetic acid-methanol (75:25, v/v) as the mobile phase at a flow rate of 1.0 mL/min at 30 degrees C. The fluorescence detector was operated at an excitation wavelength of 280 nm and an emission wavelength of 340 nm. A linear response (r(2 )> 0.9998) was obtained in the range 0.0625-5.0 microg/mL. The method was successfully applied to the determination of the free and total tryptophan contents in bee pollens, which were 0.069 +/- 0.003 and 2.693 +/- 0.476 mg/g, respectively, while only the total tryptophan was detected in royal jelly, with a content of 1.743 +/- 0.066 mg/g.