Li-Jia Liu

Characterization of the intestinal absorption of seven flavonoids from the flowers of Trollius chinensis using the Caco-2 cell monolayer model.

The human Caco-2 cell monolayer model was used to investigate the absorption property, mechanism, and structure-property relationship of seven representative flavonoids, namely, orientin, vitexin, 2”-O-β-L-galactopyranosylorientin, 2”-O-β-L-galactopyranosylvitexin, isoswertisin, isoswertiajaponin, and 2”-O-(2”‘-methylbutanoyl)isoswertisin from the flowers of Trollius chinensis. The results showed that these flavonoids were hardly transported through the Caco-2 cell monolayer. The compounds with 7-OCH3 including isoswertisin, isoswertiajaponin and 2”-O-(2”‘-methylbutanoyl)isoswertisin were absorbed in a passive diffusion manner, and their absorbability was increased in the same order as their polarity. The absorption of the remaining compounds with 7-OH including orientin, vitexin, 2”-O-β-L-galactopyranosylorientin, and 2”-O-β-L-galactopyranosylvitexin involved transporter mediated efflux in addition to passive diffusion. Among the four compounds with 7-OH, those with a free hydroxyl group at C-2” such as orientin and vitexin were the substrates of P-glycoprotein (P-gp) and that with a free hydroxyl group at C-2’ such as 2”-O-β-L-galactopyranosylorientin was the substrate of multidrug resistance protein 2 (MRP2). The results of this study also implied that the absorbability of the flavonoids should be taken into account when estimating the effective components of T. chinensis.

Absorption properties and mechanism of trolline and veratric acid and their implication to an evaluation of the effective components of the flowers of Trollius chinensis.

AIM To study the absorption properties and mechanism of two important components, trolline and veratric acid, from the flowers of Trollius chinensis, in order to better understand the contribution of these two compounds to the effectiveness of these flowers. METHOD The human Caco-2 cell monolayer model was employed to study the transport of trolline and veratric acid from apical side (AP) to basal side (BL), and from BL to AP by determining the transport rates as the function of time and concentration and calculating apparent permeability coefficients (Papp). RESULTS Trolline and veratric acid were transported across Caco-2 cell monolayer through different mechanisms in a concentration dependent manner. Trolline was transported at a Papp level of 10(-6) cm·s(-1) with a Papp AP→BL/Papp BL→AP ratio of more than 1.8 or less than 0.8, while veratric acid was transported at a Papp level of 10(-5)cm·s(-1) with a Papp AP→BL/Papp BL→AP ratio of close to 1.0. CONCLUSION Trolline is moderately absorbed through an associative mechanism involving active and passive transport, and veratric acid is well-absorbed mainly through passive diffusion. These factors should be taken into account when chemically assessing the pharmacodynamic material basis of the flowers of T. chinensis.

Contribution evaluation of the floral parts to orientin and vitexin concentrations in the flowers of Trollius chinensis.

AIM To provide a comprehensive procedure to evaluate the contribution of the floral parts to the yield of the major components from the flowers of Trollius chinensis, to underlay the selective breeding, cultivation, development, and utilization of the flowers. METHODS Five floral parts from eleven batches of the flowers of T. chinensis were examined by HPLC analysis for the content of orientin and vitexin, and by gravimetric analysis for their respective mass fraction. The contribution of each floral part was calculated using mathematical methods based on the results of the content and mass fraction. Variance analysis was carried out by Kruskal-Wallis H test and PCA method. RESULTS The calculated mean contributions of calyx, corolla, stamens and pistils, stalk, and ovary to the yield of both orientin and vitexin were 76.99% and 71.93%, 9.60% and 8.33%, 9.21% and 8.10%, 2.17% and 6.62%, and 2.03% and 5.02%, respectively. CONCLUSION The floral parts contribute unequally to the yield of orientin and vitexin, and the calyx contributes the highest and makes a significant difference compared with any other part.

Transformation of trollioside and isoquercetin by human intestinal flora in vitro.

The present study was designed to determine the intestinal bacterial metabolites of trollioside and isoquercetin and their antibacterial activities. A systematic in vitro biotransformation investigation on trollioside and isoquercetin, including metabolite identification, metabolic pathway deduction, and time course, was accomplished using a human intestinal bacterial model. The metabolites were analyzed and identified by HPLC and HPLC-MS. The antibacterial activities of trollioside, isoquercetin, and their metabolites were evaluated using the broth microdilution method with berberine as a positive control, and their potency was measured as minimal inhibitory concentration (MIC). Our results indicated that trollioside and isoquercetin were metabolized by human intestinal flora through O-deglycosylation, yielding aglycones proglobeflowery acid and quercetin, respectively The antibacterial activities of both metabolites were more potent than that of their parent compounds. In conclusion, trollioside and isoquercetin are totally and rapidly transformed by human intestinal bacteria in vitro and the transformation favors the improvement of the antibacterial activities of the parent compounds.

Pharmacokinetics of tecomin in rats after intragastric and intravenous administration

The pharmacokinetics of tecomin, which is a potential bioactive compound from the flowers of Trollius chinensis, was studied. The results showed that this compound was easily absorbed and rapidly metabolized into veratric acid in vivo, and then the latter was eliminated slowly. In addition, the simulant in vitro gastrointestinal transformation experiments demonstrated that the basic enteral environment and intestinal bacterial flora also contributed to the metabolism of tecomin to veratric acid.

Chromatographic fingerprint analysis of the floral parts of Trollius chinensis.

This study provided a practical procedure, for the first time, to compare the component difference of the floral parts of Trollius chinensis and identify the characteristic peaks of each floral part using the high-performance liquid chromatographic fingerprint technique followed by similarity analysis. The results showed that the constituents of different floral parts exhibited lower similarity than those of the same part. It can be concluded that the procedure established herein is useful for analysis of variability in constituent distribution of herbal drugs, and the components are unevenly distributed in the floral parts of T. chinensis.

Pharmacokinetics and tissue distributions of veratric acid after intravenous administration in rats

The present study was designed to investigate the pharmacokinetics and tissue distributions of veratric acid following intravenous administration in rats. The concentrations of veratric acid in rat plasma at various times after administrated at doses of 2.5, 5, and 10 mg·kg(-1) were quantified by HPLC. The tissue distributions of veratric acid at various times after a single intravenous dose of 2.5 mg·kg(-1) were also analyzed. The plasma pharmacokinetic parameters at the three doses were as follows: t(1/2), (86.23 ± 6.83), (72.66 ± 4.10) and (71.20 ± 2.90) min; C0, (11.10 ± 1.47), (23.67 ± 1.24) and (39.17 ± 3.90) μg·mL(-1); and AUC(0→∞), (1 240.90 ± 129.14), (2 273.84 ± 132.47) and (3 516.4 ± 403.37) min·μg·mL(-1), respectively. The compound was distributed into tissues rapidly and extensively after intravenous administration and was mainly distributed into the liver, heart and kidneys.

Absorbability, Mechanism and Structure-Property Relationship of Three Phenolic Acids from the Flowers of Trollius chinensis

The absorption properties, mechanism of action, and structure-property relationship of three phenolic acids isolated from the flowers of Trollius chinensis Bunge, namely, proglobeflowery acid (PA), globeflowery acid (GA) and trolloside (TS), were investigated using the human Caco-2 cell monolayer model. The results showed that these three phenolic acids were transported across the Caco-2 cell monolayer in a time and concentration dependent manner at the Papp level of 10−5 cm/s, and their extent of absorption correlated with their polarity and molecular weight. In conclusion, all three of these compounds were easily absorbed through passive diffusion, which implied their high bioavailability and significant contribution to the effectiveness of T. chinensis.