Determination of three active principles in licorice extract by reversed-phase high-performance liquid chromatography

Quantitative Determination of 18-β-Glycyrrhetinic Acid in HepG2 Cell Line by High Performance Liquid Chromatography Method

A reverse phase high performance liquid chromatographic (RP-HPLC) method was developed for identification and estimation of 18-β-glycyrrhetinic acid (GA) in HepG2 cell line. The analysis was carried out using a JASCO HPLC system with a C-18 (3 μm) Supelco reversed phase column (150 x 4.7 mm) using a mobile phase of 80% CH₃OH and 20% of CH₃CN: tetrahydrofuran: water (10:80:10, v/v/v). The method was linear in the concentration range of 1.5–120 μg /mL (n = 5). The LOD and LOQ were determined based on standard deviation of the y-intercept and the slope of the calibration curve. The LOD and LOQ values were found to be 11.46 μg/mL and 34.72 μg/mL, respectively. The mean percentage recovery by standard addition experiments of GA is 92.4 % ± 5.2%. The intracellular GA concentration value, obtained as mean of five different determinations, was 45.8 ± 7.45 μg/mL. We have developed a HPLC-UV method for quantitative determination of GA inside cells, with advantages in the cost reduction and economy of the analytical process.

Disposition of asarone after intravenous administration to rabbits assessed using HPLC

A simple and sensitive high-performance liquid chromatography (HPLC) method for the determination of asarone in rabbit plasma has been developed. Up to 0·1 mL of plasma containing asarone was deproteinated by acetonitrile, which contained an internal standard (indomethacin). The supernatant was injected into a Nucleosil 7C18 column using acetonitrile-water-triethylamine (55:45:0·1 v/v, pH 5·4–5·5, adjusted with orthophosphoric acid) as the mobile phase and UV detection at 257 nm, followed by UV spectrum identification (between 200 and 380 nm) with a photodiode array detector. The method is rapid, easily reproduced, selective and sensitive. It was applied to pharmacokinetic studies of asarone in rabbit, after 5, 10, or 20 mg kg−1 intravenous administration. Rapid distribution followed by a slower elimination phase was observed from the plasma concentration–time curve. The plasma disposition at each dose fitted well to a two-compartment open model and the terminal disposition became much slower as the dose was increased, suggesting a nonlinear dose-dependent plasma asarone disposition.

Chemical analysis of the Chinese herbal medicine Gan-Cao (licorice)

Gan-Cao, or licorice, is a popular Chinese herbal medicine derived from the dried roots and rhizomes of Glycyrrhiza uralensis, G. glabra, and G. inflata. The main bioactive constituents of licorice are triterpene saponins and various types of flavonoids. The contents of these compounds may vary in different licorice batches and thus affect the therapeutic effects. In order to ensure its efficacy and safety, sensitive and accurate methods for the qualitative and quantitative analyses of saponins and flavonoids are of significance for the comprehensive quality control of licorice. This review describes the progress in chemical analysis of licorice and its preparations since 2000. Newly established methods are summarized, including spectroscopy, thin-layer chromatography, gas chromatography, high-performance liquid chromatography (HPLC), liquid chromatography/mass spectrometry (LC/MS), capillary electrophoresis, high-speed counter-current chromatography (HSCCC), electrochemistry, and immunoassay. The sensitivity, selectivity and powerful separation capability of HPLC and CE allows the simultaneous detection of multiple compounds in licorice. LC/MS provides characteristic fragmentations for the rapid structural identification of licorice saponins and flavonoids. The combination of HPLC and LC/MS is currently the most powerful technique for the quality control of licorice.

Simultaneous quantification of flavonoids and triterpenoids in licorice using HPLC

Numerous bioactive compounds are present in licorice (Glycyrrhizae Radix), including flavonoids and triterpenoids. In this study, a reversed-phase high-performance liquid chromatography (HPLC) method for simultaneous quantification of three flavonoids (liquiritin, liquiritigenin and isoliquiritigenin) and four triterpenoids (glycyrrhizin, 18alpha-glycyrrhetinic acid, 18beta-glycyrrhetinic acid and 18beta-glycyrrhetinic acid methyl ester) from licorice was developed, and further, to quantify these 7 compounds from 20 different licorice samples. Specifically, the reverse-phase HPLC was performed with a gradient mobile phase composed of 25 mM phosphate buffer (pH 2.5)-acetonitrile featuring gradient elution steps as follows: 0 min, 100:0; 10 min, 80:20; 50 min, 70:30; 73 min, 50:50; 110 min, 50:50; 125 min, 20:80; 140 min, 20:80, and peaks were detected at 254 nm. By using our technique, a rather good specificity was obtained regarding to the separation of these seven compounds. The regression coefficient for the linear equations for the seven compounds lay between 0.9978 and 0.9992. The limits of detection and quantification lay in the range of 0.044-0.084 and 0.13-0.25 microg/ml, respectively. The relative recovery rates for the seven compounds lay between 96.63+/-2.43 and 103.55+/-2.77%. Coefficient variation for intra-day and inter-day precisions lay in the range of 0.20-1.84 and 0.28-1.86%, respectively. Based upon our validation results, this analytical technique is a convenient method to simultaneous quantify numerous bioactive compounds derived from licorice, featuring good quantification parameters, accuracy and precision.

Chromatographic determination of plant saponins

The methods used for saponin determination in plant materials are presented. It is emphasised that the biological and spectrophotomeric methods still being used for saponin determination provide, to some extent, valuable results on saponin concentrations in plant material. However, since they are sensitive to the structural variation of individual saponins they should be standardized with saponin mixtures isolated from the plant species in which the concentration is measured. However, one plant species may contain some saponins which can be determined with a biological test and others which cannot. That is why biological and colorimetric determinations do not provide accurate data and have to be recognized as approximate. Thin-layer chromatography on normal and reversed-phases (TLC, HPTLC, 2D-TLC) provides excellent qualitative information and in combination with on-line coupling of a computer with dual-wavelength flying-spot scanner and two-dimensional analytical software can be used for routine determination of saponins in plant material. The densitometry of saponins has been very sensitive, however, to plate quality, spraying technique and the heating time and therefore appropriate saponin standards have to be run in parallel with the sample. Gas-liquid chromatography has limited application for determination since saponins are quite big molecules and are not volatile compounds. Thus, there are only few applications of GC for determination of intact saponins. The method has been used for determination of TMS, acetyl or methyl derivatives of an aglycones released during saponin hydrolysis. However, structurally different saponins show different rates of hydrolysis and precise optimisation of hydrolysis conditions is essential. Besides, during hydrolysis a number of artefacts can be formed which can influence the final results. High performance liquid chromatography on reversed-phase columns remains the best technique for saponin determination and is the most-widely used method for this group of compounds. However, the lack of chromophores allowing detection in UV, limits the choice of gradient and detection method. The pre-column derivatisation with benzoyl chloride, coumarin or 4-bromophenacyl bromide has been used successfully in some cases allowing UV detection of separation. Standardisation and identification of the peaks in HPLC chromatograms has been based on comparison of the retention times with those observed for authentic standards. But new hyphenated techniques, combining HPLC with mass spectrometry and nuclear magnetic resonance are developing rapidly and allow on-line identification of separated saponins. Capillary electrophoresis has been applied for saponin determination only in a limited number of cases and this method is still being developed.

Efficient method for determining the glycyrrhizin content of fresh and dried roots, and root extracts, of Glycyrrhiza species

A reliable and efficient method suitable for the selective analysis of the glycyrrhizin content of fresh and dried roots of Glycyrrhiza species and of root extracts is described. The method was optimised for recovery and analysis of glycyrrhizin after conversion to its aglycone, 18 beta-glycyrrhetinic acid. The reversed-phase HPLC system was developed using a sterically protected C8 column that allowed UV detection of the aglycone at 254 mm without interference from co-occurring components. The average recovery through the method was determined at 83%, with a range of 65-99%. Analysis of 150 dried root samples gave levels of glycyrrhizin consistent with earlier reported values. A comparison of post-harvest treatment conditions. showed that the drying of root samples at up to 65 degrees C did not result in any measurable reduction in glycyrrhizin.

Application of capillary electrophoresis for organic acid analysis in herbal studies

A capillary electrophoresis (CE) procedure has been developed for the separation of 25 inorganic and organic acid anions using a buffer system consisting of 15 mM tris(hydroxymethyl)aminomethane, 3 mM 1,2,4-benzenetricarboxylic acid, 1.5 mM tetraethylenepentaamine (TEPA) and 20% methanol with pH adjusted to 8.4. A good separation of organic acids extracted from a mixture of Chinese traditional medicine (TCM) containing three herbs, Flos chrysthemi, Spica prunellae, and Folium mori was obtained using the procedure developed with satisfactory working range (0.20-77 mg/g), low detection limit (90-190 microg/g), and good repeatability (relative standard deviation 4.47-6.99%, n = 4). A satisfactory extraction of organic acids was achieved within 20 min using 0.1 M NaOH. The addition of TEPA to provide a reduced electroosmotic flow (EOF) environment was shown to remove interfering organic compounds extracted from TCM. The applicability of using organic acids as markers for determining the mixing ratio of constituent herbs for a TCM mixture was investigated using a three-component mixture with a 1:1:1 mixing ratio. A satisfactory mixing ratio of 1.04:1.09:0.98 was obtained using the methodology developed based on organic acids as markers. The application of our method for determining more complicated TCM mixtures has been discussed.

Determination of 14 chemical constituents in the traditional Chinese medicinal preparation Huangqin-Tang by high performance liquid chromatography

The high performance liquid chromatographic (HPLC) method for the identification and determination of baicalin (BG), wogonoside (WG), oroxylin-A-glucoside (OG), baicalein (B), wogonin (W), orxylin-A (O), paeoniflorin (PF), glycyrrhizic acid (GL), glycyrrhetinic acid (GA), liquiritin (LG), isoliquirition (ILG), liquiritigenin (L), isoliquiritigenin (IL) and ononin (ON) in Huangqin-Tang [Chinese characters: see text] was established. The samples were separated with a Wakosil C18 column (4.6 x 150 mm) by linear gradient elution using A (MeOH-HAC 100:1, v/v)-B (Water-HAC 100:1, v/v) (0 min, 30:70; 15 min, 40:60; 30 min, 60:40; 45 min, 80:20; 60 min, 100:0) as the mobile phase at a flow-rate of 1.0 ml/min. The detection was by diode-array UV/Vis detector (DAD), and the wavelength was set at the range of 200-400 nm. Satisfactory results were obtained within 60 min for the simultaneous determination of the 14 constituents. The repeatability (RSD) of the method was generally less than 2% (n=5, interday and intraday). The recovery of BG was 96.9+/-1.71, WG was 98.9+/-2.99, PF was 99.7+/-0.52, LG was 95.3+/-2.67, GL was 96.7+/-3.44, and GA was 94.8+/-4.16, respectively.

HPLC analysis of liquorice triterpenoids--applications to the quality control of pharmaceuticals

A reversed-phase HPLC method is proposed for the separation of five liquorice triterpenoids, 18 beta glycyrrhetic acid (beta GA), 18 alpha glycyrrhetic acid (alpha GA), 24-hydroxy-18 beta-glycyrrhetic acid (24-OH-beta GA), alpha and beta liquiritic acid (alpha and beta LA), with potentially different biological activities. The method has been developed by studying the influence of the type of stationary phase, pH, amine modifier and organic modifier on the resolution of the five compounds. The optimized chromatographic conditions were then successfully applied to the analysis of alpha- and beta-GA in pharmaceutical preparations (toothpaste and creams) on a reversed-phase Phenomenex Ultracarb 5 ODS (30) column (150 x 4.6 mm i.d.), using as the mobile phase acetonitrile-THF-0.010 M dioctylammonium phosphate buffer (pH 6.5) (25:20:55, v/v/v) at a flow-rate of 0.8 ml min-1. SPE methods with diolic and C18 sorbents were developed to isolate and concentrate the analytes and to enhance the sensitivity for the determination of alpha-GA as an impurity in the beta-GA preparations. The method was found to be reliable and suitable for the quality control of beta-GA preparations.

High-performance liquid chromatographic determination of rutaecarpine in rat plasma: application to a pharmacokinetic study

A simple and sensitive high-performance liquid chromatographic method for determination and identification of rutaecarpine in rat plasma has been developed. Up to 0.1 ml of plasma containing rutaecarpine was deproteinized by acetonitrile, which contained an internal standard (paeonol). The supernatant was injected onto a reversed-phase column using a acetonitrile-water-orthophosphoric acid (85%) (60:40:0.1, v/v/v, pH 2.5-2.8) as the mobile phase and ultraviolet detection at 344 nm. It was applied to the pharmacokinetic study of rutaecarpine in rat after a 2 mg/kg intravenous administration. A biphasic process with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve. Compartmental analysis yielded a two-compartment model.

Determination of glycyrrhizin in rabbit plasma by high-performance liquid chromatography with photodiode-array ultraviolet detection and its pharmacokinetics application

A simple and sensitive high-performance liquid chromatographic method for the determination of glycyrrhizin in rabbit plasma has been developed. Up to 0.1 ml of plasma containing glycyrrhizin was deproteinized by acetonitrile, which contained an internal standard (indomethacin). The supernatant was injected onto a LiChrospher RP-18 column using a methanol-water-ammonia solution (80:20:0.1, v/v, pH 3.0-3.2, adjusted with perchloric acid) as the mobile phase and ultraviolet detection at 254 nm, followed by ultraviolet spectrum identification (between 200 and 380 nm) with a photodiode-array detector. The method is rapid, easily reproduced, selective and sensitive. It was applied to pharmacokinetic studies of glycyrrhizin in rabbit, after a 2 mg/kg intravenous administration. A biphasic phenomenon with a rapid distribution followed by a slower elimination phase was observed from the plasma concentration-time curve. Compartmental analysis yielded a two-compartment model.