No abstract

A simple, optimized and sensitive high-performance liquid chromatograph method with ultraviolet (UV) detection (HPLC/UV) was developed and validated for determination of isochlorogenic acid A in rat plasma. The analytes were successfully separated on a Shodex C18 column (5 μm particle size, 250 mm × 4.6 mm, i.d.), the mobile phase contained 0.1% phosphoric acid aqueous solution (solvent A) and methanol (solvent B) (50:50, v/v) at a flow rate of 1.0 mL/min. The wavelength for UV detection was set at 300 nm and the column temperature was maintained in 30°C. Calibration curve for isochlorogenic acid A was found to be good linear over the range of 0.04-40 μg/mL (r = 0.9998). The intra- and inter-day precisions (relative standard deviation) were within 7.63% and the assay accuracy (RE) ranged from -1.41 to 3.25%. The limit of detection and the lower limit of quantification were 0.012 and 0.04 μg/mL, respectively. The validated method was successfully applied to pharmacokinetic study of isochlorogenic acid A in rats for the first time. The pharmacokinetic parameters were evaluated after the rats were administered intravenously and intragastrically isochlorogenic acid A at the single dose of 18 mg/kg, respectively. The absolute bioavailability was calculated to be 22.6%.

Context Oxymatrine (OMT) is beneficial to human health by exerting various biological effects. Objective To investigate the absorption mechanism of OMT and discover absorption enhancers using Madin-Darby canine kidney (MDCK) cell monolayers. Materials and methods Concentration effects on the transport of OMT were measured in the range of 1.0 Â 10 À5 -1.0 Â 10 À3 M in 2 h. Then, the effect of time, direction, temperature and pH on the transport of OMT at 10 À4 M was studied. Moreover, P app of OMT was determined in the absence/presence of cyclosporine and surfactants at 100 mM to further confirm the relative transport mechanism. Results The P app APBL ranged from (3.040 ± 0.23) Â 10 À6 to (3.697 ± 0.19) Â 10 À6 cm/s as the concentration varied from 10 À5 to 10 À3 M. OMT showed similar P app at 4 and 37 C (p40.05). Increasing the apical pH 7.4 and 8.0 resulted in P app versus pH 5.0 (p50.01). Furthermore, in the presence of cyclosporine and surfactants including sodium citrate, sodium dodecyl sulphate (SDS) and deoxysodium cholate, P app was (0.318 ± 0.033) Â 10 À5 , (0.464 ± 0.048) Â 10 À5 , (0.897 ± 0.115) Â 10 À5 and (1.341 ± 0.122) Â 10 À5 cm/s, respectively. In the presence of surfactants, P app significantly increased up to 1.5-4.3-fold (p50.05). Discussion and conclusion OMT transport across MDCK cell monolayers was by passive diffusion. Sodium citrate, SDS and deoxysodium cholate serve as excellent absorption enhancers which are useful for the related research improving the oral bioavailability of OMT. ARTICLE HISTORY