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A fluorometric imaging plate reader (FLIPR) assay utilizing Chinese hamster ovary (CHO) cells stably transfected with GABAA receptors of α 1 β 2 γ 2 subunit composition was evaluated and validated for rapid screening of plant extract libraries and efficient localization of active compounds in extracts. Validation was performed with pure compounds and extracts known to contain allosteric GABAA receptor modulators. Plants extracts that had been previously reported as active in an assay using Xenopus laevis oocytes transiently expressing GABAA receptors of α 1 β 2 γ 2 subunit composition were also active in the FLIPR assay. A protocol for HPLC-based activity profiling was developed, whereby separations of 0.4 – 1.2 mg of extracts on an analytical HPLC column were found to be sufficient for the sensitivity of the bioassay. The protocol successfully localized the activity of known GABAergic natural products, such as magnolol in Magnolia officinalis , valerenic acid in Valeriana officinalis , and piperine in Piper nigrum extract. EC50 values of compounds (magnolol: 4.81 ± 1.0 µM, valerenic acid: 12.56 ± 1.2 µM, and piperine: 5.76 ± 0.7 µM) were found to be comparable or lower than those reported using Xenopus oocyte assays. [ABSTRACT FROM AUTHOR]

Valerian extract is used in complementary and alternative medicine for its anxiolytic and sedative properties. Our previous research demonstrated valerian interactions with glutamate receptors. The purpose of this study was to determine if valerian anxiolytic properties are mediated by metabotropic glutamate receptors (mGluR) such as mGluR (1/5) (mGluR I) and mGluR (2/3) (mGluR II). Adult wild-type zebrafish (Danio rerio) prefer the black compartment and avoid the white compartment in the dark/light preference task. Zebrafish exposed to 1mg/mL of valerian extract or 0.00117 mg/mL valerenic acid increased their residence time in the white side by 84.61 ± 6.55% and 58.30 ± 8.97%, respectively. LAP3 (mGluR I antagonist) and EGLU (mGluR II antagonist) significantly inhibited the effects of valerian and valerenic acid. These results demonstrated that valerian and valerenic acid have anxiolytic properties in the zebrafish. Moreover, the selective interaction of valerianwith mGluR I and II represent an alternative explanation for the anxiolytic properties of this plant and support the role of mGluR in anxiety. [ABSTRACT FROM AUTHOR]

Valerenic acid (VA), a sesquiterpenoid, is one of the major secondary bioactive metabolites of Valeriana officinalis L. Until now in vivo studies on the absorption, bioavailability, disposition, and metabolism of VA are limited. We established and validated an LC-MS/MS assay for the determination of VA in rat plasma and successfully used this method for pharmacokinetic studies in rats after intravenous (i.v.) and oral administrations. The plasma concentration-time data was analyzed by both non-compartmental and compartmental approaches using Win Nonlin software. Following i.v. administration, the disposition of VA in rat plasma was biphasic, subdivided into a fast distribution and a slow elimination phase. The half-life of the distribution phase was 6-12min, and that of the terminal elimination phase 6-46 h, indicating a possible large tissue binding. Disposition PK of valerenic acid after oral treatment was also described by a two-compartment model with a clearance (CL/F) of 2-5L ⋅ h ⋅ kg-1 and volume of distribution of (Vd) 17-20 L ⋅ kg-1. The extent of absorption (F) after oral administration was estimated to be 33.70% with a half-life of 2.7-5 h. Dose proportionality was observed in terms of dose and AUCs, suggesting linear pharmacokinetics at the dose levels studied in rats. [ABSTRACT FROM AUTHOR]