Simultaneous determination of baicalin, oroxylin A-7-O-glucuronide and wogonoside in rat plasma by UPLC-DAD and its application in pharmacokinetics of pure baicalin, Radix Scutellariae and Yinhuang granule

Baicalin-Current Trends in Detection Methods and Health-Promoting Properties

Baicalin (7-D-glucuronic acid-5,6-dihydroxyflavone) belongs to natural flavonoids extracted from the roots of Scutellaria baicalensis, the plant used in traditional Chinese medicine. It has been proven that baicalin has various pharmacological activities, such as antioxidant, anti-inflammatory, anticancer, antibacterial, and anti-apoptotic ones. However, it is essential not only to determine the medical usefulness of baicalin, but also to find and develop the most effective methods for its extraction and detection. Therefore, the aim of this review was to summarize the current methods of detection and identification of baicalin and to present the medical applications of baicalin and the underlying mechanisms of its action. Based on the review of the latest literature, it can be concluded that liquid chromatography alone or together with mass spectrometry is the most commonly used method for the determination of baicalin. Recently, also new electrochemical methods have been established, e.g., biosensors with fluorescence, which have better detection limits, sensitivity, and selectivity.

HPLC-DAD-Q-TOF/MS-Based Screening and Analysis of the Multiple Absorbed Bioactive Components in Rat Serum after Oral Administration of Xiexin Tang

Background:

Xiexin Tang (XXT) is a classic Traditional Chinese Medicine (TCM) formula that has been used in herbal clinics for more than 1800 years. Recently, many studies have investigated the pharmacological effects and chemical composition of XXT. However, there is little information about systematic studies on the material basis of its efficacy. In the present study, the serum pharmacochemistry technique and HPLC-DAD-Q-TOF/MS were performed to screen and analyze the multiple absorbed bioactive components and metabolites of orally dosed XXT in rat serum.

Methods:

Bio-samples and herbal extracts were analyzed and detected by HPLC-DAD-Q-TOF/MS. Upon comparison of the chromatograms of the single-constituent decoctions with that of the XXT formulation, the peak quantity and peak intensity of the formulated decoction showed some variation from those of the single-constituent decoctions.

Results:

Twenty-one serum-adsorbed constituents were identified after intragastric administration of herbal extracts, of which 8 originated from Rhei Radix et Rhizoma (RRR), 5 from Coptidis Rhizoma (CR), and 8 from Scutellariae Radix (SR). The results showed that the main adsorbed constituents in the serum were anthraquinones, anthrones, chromones, and butyrophenones, alkaloids, and flavonoids.

Conclusion:

The results demonstrate that an effective and reliable analytical method is set up for screening the bioactive components of Chinese herbal medicine, which provided a meaningful basis for further pharmacology and active mechanism research of XXT.

Pharmacokinetics of B-Ring Unsubstituted Flavones

B-ring unsubstituted flavones (of which the most widely known are chrysin, baicalein, wogonin, and oroxylin A) are 2-phenylchromen-4-one molecules of which the B-ring is devoid of any hydroxy, methoxy, or other substituent. They may be found naturally in a number of herbal products used for therapeutic purposes, and several have been designed by researchers and obtained in the laboratory. They have generated interest in the scientific community for their potential use in a variety of pathologies, and understanding their pharmacokinetics is important for a grasp of their optimal use. Based on a comprehensive survey of the relevant literature, this paper examines their absorption (with deglycosylation as a preliminary step) and their fate in the body, from metabolism to excretion. Differences among species (inter-individual) and within the same species (intra-individual) variability have been examined based on the available data, and finally, knowledge gaps and directions of future research are discussed.

Effects of Gut Microbiota on the Bioavailability of Bioactive Compounds from Ginkgo Leaf Extracts

Ginkgo leaf extract (GLE) is a popular herbal medicine and dietary supplement for the treatment of various diseases, including cardiovascular disease. GLE contains a variety of secondary plant metabolites, such as flavonoids and terpenoids, as active components. Some of these phytochemicals have been known to be metabolized by gut microbial enzymes. The aim of this study was to investigate the effects of the gut microbiota on the pharmacokinetics of the main constituents of GLE using antibacterial-treated mice. The bilobalide, ginkgolide A, ginkgolide B, ginkgolide C, isorhamnetin, kaempferol, and quercetin pharmacokinetic profiles of orally administered GLE (600 mg/kg), with or without ciprofloxacin pretreatment (150 mg/kg/day for 3 days), were determined. In the antibacterial-treated mice, the maximum plasma concentration (C_max) and area under the curve (AUC) of isorhamnetin were significantly (p < 0.05) increased when compared with the control group. The C_max and AUC of kaempferol and quercetin (other flavonol glycosides) were slightly higher than those of the control group, but the difference was not statistically significant, while both parameters for terpenoids of GLE showed no significant difference between the antibacterial-treated and control groups. These results showed that antibacterial consumption may increase the bioavailability of isorhamnetin by suppressing gut microbial metabolic activities.

Polyphenols of Chinese skullcap roots: from chemical profiles to anticancer effects

Great efforts have been made to identify the principle bioactive constituents of Chinese herbs and to unravel the molecular mechanisms behind their anticancer effects.

The pharmacokinetics of Tiangou antihypertensive capsule in rat in vivo

The aim of the study was to examine the effect of complex prescription on the pharmacokinetics of baicalin, rhynochophylline and gastrodin in Tiangou antihypertensive capsule. After administration, rat plasma was collected at different time-points. High-performance liquid chromatography was used to determine the content of baicalin, rhynochophylline and gastrodin in plasma. Two peaks occurred in the baicalin concentration-time curve. No significant difference was found for the peak concentration time (t_max) and area under concentration-time curve (AUC) of baicalin between the complex prescription and baicalin groups. The peak concentration (C_max) of baicalin in the complex prescription group was significantly decreased, while no significant difference was found for the absorption factor (K_a) and AUC of baicalin between the complex prescription and gastrodin groups. The elimination factor (K_e) of gastrodin in the complex prescription group was significantly decreased, while the apparent volume of distribution (Vd) of gastrodin was significantly increased. No significant difference was found for AUC of baicalin between the complex prescription and rhynochophylline groups. Levels of K_a and K_e of rhynochophylline were lower in the complex prescription group while Vd was higher. Thus, complex prescription made plasma concentration-time curve more smooth. By contrast, the Tiangou antihypertensive capsule improved the distribution of baicalin, rhynochophylline and gastrodin in vivo.

LC-UV Determination of Baicalin in Rabbit Plasma and Tissues for Application in Pharmacokinetics and Tissue Distribution Studies of Baicalin after Intravenous Administration of Liposomal and Injectable Formulations

A simple and sensitive LC-UV method to investigate the pharmacokinetics and biodistribution pattern of baicalin in rabbits was established and validated. Baicalin and the internal standard, rutin, were extracted from biosamples using acetonitrile as protein precipitation after pretreated with ammonium acetate buffer (pH 3.5; 1 M) to obtain a pure chromatographic peak and high extraction recovery. Chromatographic separation was achieved on a reverse-phase C18 column with a gradient elution at flow rate of 1.0 mL/min. UV absorption was set at 278 nm. Chromatographic response was linear over the ranges of 0.05–10.00 μg/mL in plasma and 0.05–300.00 μg/g in tissues with the limits of quantification of 50.0 ng/mL in plasma and tissues, and the limit of detection of baicalin in bio-samples of 15 ng/mL. The RSD of intra-and inter-day for the biosamples were from 4.19% to 10.84% and from 4.37% to 10.93%, respectively. The accuracy of plasma and tissue samples ranged from 81.6% to 95.2% and 80.8% to 98.4%, respectively. The extraction recoveries ranged from 81.5% to 88.3% for plasma, from 73.1% to 93.2% for tissues, respectively. Baicalin was stable in rabbit biosamples. The validated method was successfully applied to the study of the pharmacokinetics and tissue distribution of baicalin after intravenous administration of liposomal and injectable formulations to rabbits. Compared to baicalin injection, the pharmacokinetics and biodistribution behavior of baicalin was altered significantly in rabbits treated with its liposomes and drug concentration in the lungs was greatly increased.