Effects of cadmium stress on the antioxidant system and chlorophyll fluorescence characteristics of two Taxodium clones.

KEY MESSAGE: The T.118 and T.406 seedlings showed strong adaptability under Cd concentrations ≤ 50 µM. The mechanisms of photoprotection in T.118 and T.406 differed in high-Cd concentrations. To explore the physiological response characteristics of Taxodium hybrids to cadmium (Cd) stress and provide basis for screening of Cd-tolerant species, the hydroponic cultivation of T.118 and T.406 seedlings was conducted to demonstrate the effects of Cd stress on seedling growth, antioxidant system, and chlorophyll fluorescence parameters. After 35 days of Cd stress at a concentration ≤ 50 µM, the dry weight biomass of the two clones did not significantly differ from that of the control. T.406 exhibited a significant increase in POD activity compared to T.118 and maintained high SOD activity after exposure to high concentrations of Cd, whereas MDA levels showed little changes. Under low-Cd stress, chlorophyll content and fluorescence parameters remained stable, especially for T.406. Under high-Cd concentration stress, the above parameters were lower than the control, with a more significant decrease in T.118 than in T.406. The non-photochemical quenching coefficient (NPQ) of both clones increased with increasing Cd concentration. T.118 showed a greater increase than T.406, particularly under high-Cd concentration stress. The T.118 and T.406 seedlings adapted to low-Cd concentration stress by enhancing their antioxidant enzyme activity to maintain the balance of reactive oxygen metabolism and reduce cellular damage. The photochemical activity of mesophyll cells remained high to maintain photosynthetic capacity and normal seedling growth. T.406 showed stronger resistance to Cd than T.118. T.406 prevented photodamage by promoting the photochemical utilization of the excitation energy and maintaining a strong antioxidant stress ability. Enhancement of heat dissipation capability may be the main photoprotection mechanism of T.118.

[Studies on pharmacokinetics of diosmin in rats].

OBJECTIVE: To establish a HPLC method for the determination of diosmin in Rats plasma and to study the pharmacokinetics of diosmin in Rats. METHOD: Rats were given diosmin with 3 doses as 225, 325, 425 mg x kg(-1). Blood samples were collected at different times after oral administration. The plasma concentration of diosmin was determined by HPLC, and the pharmacokinetics parameters were calculated by 3p97 program. RESULT: The typical equation of diosmin in rats plasma was Y = 3.05 x 10(-3) C + 1.55 x 10(-3), the calibration curves of diosmin was linear in the range from 0.5-100 microg x mL(-1) (R =0. 996 4). The lowest concentration of diosmin in plasma was 0. 2 g x mL(-1). Its recoveries was more than 85%, and the interday and intraday precision, which was expressed as RSD, were all less than 15%. After 3 doses oral administration of diosmin in rats, the mean plasma concentration-time curves were found to fit one compartment model, and the main pharmacokinetics parameters were obtained. CONCLUSION: It is first time to establish the HPLC method to determine the concentration of diosmin in rats plasma, and the method described in this report has high sensitivity and selectivity, and it was suitable for pharmacokinetics studies of diosmin. The internal process of diosmin in rats is fit to one compartment model.

Simultaneous determination of creatine phosphate, creatine and 12 nucleotides in rat heart by LC-MS/MS.

A simple, rapid and sensitive LC-MS/MS method was developed and validated for simultaneous determination of creatine phosphate (CP), creatine (Cr) and 12 nucleotides in rat heart. The analytes, ATP, ADP, AMP, GTP, GDP, GMP, CTP, CDP, CMP, UTP, UDP, UMP, CP, Cr, were extracted from heart tissue with pre-cooled (0°C) methanol/water (1:1, v/v) and separated on a Hypersil Gold AQ C18 column (150mm×4.6mm, 3µm) using an isocratic elution with a mobile phase consisting of 2mmol/L ammonium acetate in water (pH 10.0, adjusted with ammonia). The detection was performed by negative ion electrospray ionization in selective reaction monitoring mode (SRM). In the assay, all the analytes showed good linearity over the investigated concentration range (r>0.99). The accuracy was between 80.7% and 120.6% and the precision expressed in RSD was less than 15.6%. This method was successfully applied to measure the concentrations of the 12 nucleotides, creatine phosphate and creatine in rat heart for the first time.

Cardiac glycosides from erysimum cheiranthoides.

Two new cardiac glycosides were isolated from the seeds of Erysimum cheiranthoides. Their structures were characterized as strophanthidin glycosides of 3-O-alpha-L-rhamnopyranosyl-(1-->4)-3-O-acetyl-beta-D-digitoxopyranosyl and 3-O-beta-D-glucpyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->4)-3-O-acetyl-beta-D-digitoxopyranosyl.