Novel and simple nonaqueous capillary electrophoresis separation and determination bioactive triterpenes in Chinese herbs

Preparation of a novel MOF-POPM and its application in online purification and enrichment of oleanolic acid in medicinal plants

In present work, a method for enrichment, purification, and content determination of oleanolic acid (OA) in medicinal plants was established based on on-line solid phase extraction (SPE). A metal organic frameworks-porous organic polymer monolith (MOF-POPM) was prepared with functionalized UiO-66-(OH)2 as monomer and was used as SPE column for online enrichment and purification of OA. The ratio of adsorbent, enriching and eluting solvent, mobile phase pH, and flow rate had been systematically investigated. Under the optimum conditions, the linear range of OA was 0.59-2500 μg/mL with r = 0.9996. The limit of detection (LOD) was 0.18 μg/mL and the limit of quantification (LOQ) was 0.59 μg/mL. The intra-day relative standard deviations (RSDs) and inter-day RSDs of retention time and peak area were less than 0.3% and 1.3%, respectively. The average recoveries of OA in medicinal plants samples ranged from 87.7 to 104.6%. The results demonstrated that the online system was reliable and accurate for enrichment, purification, and content determination of OA in medicinal plants.

Potential and applications of capillary electrophoresis for analyzing traditional Chinese medicine: a critical review

Capillary electrophoresis (CE) presents a promising possibility for analyzing traditional Chinese medicine (TCM) due to its low reagent consumption, high analysis speed, and enhanced efficiency. Herein we review the employment of CE for analyzing the effective components in TCM and identifying TCM via a fingerprint. Furthermore, we discuss the application of state-of-the-art capillary electrophoresis modes for screening enzyme inhibitors and investigating the interactions between TCM and plasma proteins. The review concludes with recommendations for future studies and improvements in this field of research. The general development trend identified in this review indicates that the application of CE has significantly improved TCM assay performance.

Preparative separation of structural isomeric pentacyclic triterpene oleanolic acid and ursolic acid from natural products by pH-zone-refining countercurrent chromatography

In this work, pH-zone-refining countercurrent chromatography was investigated in the preparative separation of two bioactive components, oleanolic acid and ursolic acid, from three different natural products, Aralia chinensis, apple peels and Eriobotrya japonica Thunb. Oleanolic acid and ursolic acid are structurally isomeric pentacyclic triterpene acids that are widely distributed in many natural products. However, it was difficult to separate these components with high purity by conventional methods. A biphasic solvent system composed of n-hexane–dichloromethane–methanol–water (7 : 3 : 2 : 8, v/v) was selected, in which an optimized concentration of 10 mmol L⁻¹ trifluoroacetic acid was added in the upper phase as the retainer and 10 mmol L⁻¹ ammonia (with 25–28% NH₃) was added in the aqueous phase as the eluter. Consequently, 38.56 mg of oleanolic acid with 99.01% purity was separated from 100 mg of the crude extract of Aralia chinensis, while 65.6 mg of a mixture of ursolic acid (90.98%) and oleanolic acid (6.51%) and 46.6 mg of a mixture of ursolic acid (74.35%) and oleanolic acid (23.61%) were separated from 100 mg of the crude extract of apple peels and 100 mg of the crude extract of Eriobotrya japonica Thunb., respectively, by pH-zone-refining countercurrent chromatography using the above selected biphasic solvent system. The results showed that pH-zone-refining countercurrent chromatography is an efficient method for the preparative separation of pentacyclic triterpene acids from natural products.

pH-zone-refining countercurrent chromatography was investigated in preparative separation of oleanolic acid and ursolic acid from three different natural products, Aralia chinensis, apple peels and Eriobotrya japonica Thunb.

Study of isomeric pentacyclic triterpene acids in traditional Chinese medicine of Forsythiae Fructus and their binding constants with β-cyclodextrin by capillary electrophoresis

In this study, a capillary zone electrophoresis (CZE) method was first developed to identify three microconstituents of isomeric pentacyclic triterpene acids (PTAs including oleanolic acid (OA), ursolic acid (UA) and betulinic acid (BA)) in Forsythiae Fructus (FF). The baseline separation of PTAs by CZE were eventually achieved in a background electrolyte (BGE) containing 50.0 mmol/L borax and 0.5 mmol/L β-cyclodextrin (β-CD) at pH 9.5 within 13.0 min. Herein, it was not only the compositions of BGE were detail investigated for rapid and good separation, but also the binding ratio and the equilibrium constants (K) for OA, UA and BA with β-CD was estimated by double reciprocal equation to well understand the separation mechanism. The proposed method allowed the LODs of PTAs were averaged at 1.50 μg/mL with UV detection (at 200 nm). The interday RSD of migration time and peak area were around 2.0 and 4.7% (n = 5), respectively. Thus, the content of PTAs in 19 FF real samples distinguished from maturation stages and geographical areas in China was quantified with the proposed method. Depending on the amount of each PTA in FF, it was demonstrated these microconstituents might benefit to identify their harvested time even qualities.

Characteristics, Biological Properties and Analytical Methods of Ursolic Acid: A Review

Ursolic acid (UA) is a naturally occurring triterpenoid which is a promising candidate for the development of new therapeutic approaches and for the prevention and treatment of several diseases owing to its pharmacological importance. However, its low solubility in aqueous medium affects its therapeutic application. Several strategies have been used to overcome this obstacle. In this study, the incorporation of UA in to different drug delivery systems was found to be highly efficient. In addition, important investigations were performed about methods for qualitative and quantitative analyses of UA in various raw materials, including plants, biological fluids, and drug delivery systems, were investigated. Most recently high performance liquid chromatography coupled with various detectors, gas chromatography-mass spectrometry and capillary electrophoresis were used for this purpose. Thus, this review was performed to evaluate the biological effects of UA demonstrated thus far as well as the currently used, delivery systems and analytical methods.

Factors affecting the content of the ursolic and oleanolic acid in apple peel: influence of cultivars, sun exposure, storage conditions, bruising and Penicillium expansum infection

BACKGROUND

For health promotion and as part of natural plant protection, it might be of interest to increase the content of oleanolic acid (OA) and ursolic acid (UA) by biofortification in breeding programs, although the extent of the influence of genetic and environmental factors needs to be clarified. The objective of this study was to determine the effect of cultivar, sun exposure, storage, bruising and fungal infection on the OA and UA content in apple peel.

RESULTS

Three apple cultivars with different ripening times--'Discovery' (early), 'Aroma' (middle) and 'Gloster' (late)--were investigated. The content of OA and UA was mainly influenced by cultivar and side subjected to sun exposure, and to a minor extent by storage and seasonal year. 'Gloster' had the highest OA and UA content of the investigated cultivars. OA and UA content on the shaded side was higher than that on the sun-exposed side in all three cultivars. Inoculation with Penicillium expansum did not have any consistent effect on OA or UA, except in a few cases where the levels decreased.

CONCLUSION

OA and UA content can be increased by choice of cultivar in the breeding process and to some extent by cultural practice.

Simultaneous HPTLC analysis of ursolic acid, betulinic acid, stigmasterol and lupeol for the identification of four medicinal plants commonly available in the Indian market as Shankhpushpi

In this study, we investigated a new, simple, sensitive, selective and precise high-performance thin-layer chromatography (HPTLC) fingerprint and quantitative estimation method for the analysis of ursolic acid, betulinic acid, stigmasterol and lupeol in Shankhpushpi botanicals. Linear ascending development was carried out in a twin trough glass chamber saturated with petroleum ether-ethyl acetate-toluene (7:2:1, v/v/v). The plate was dried, sprayed with anisaldehyde reagent and analyzed by CAMAG TLC scanner III at 580 nm. The system was found to give compact spots for ursolic acid (0.21), betulinic acid (0.29), stigmasterol (0.33) and lupeol (0.50). The relationship between the concentration of standard solutions and the peak response is linear within the concentration range of 100-600 ng/spot for ursolic acid, betulinic acid, stigmasterol and lupeol. The concentration of 134.2 and 146.1 mg of ursolic acid per gram of Clitorea ternatea (CT) and Canscora decussata (CD); 110.6 mg of betulinic acid per gram of EA; 92.75, 154.95, 31.947 and 39.21 mg of stigmasterol per gram of Evolvulus alsinoides (EA), Convolvulus pluricaulis (CP), CT and CD; 30.12 mg of lupeol per gram of CT were found. The proposed HPTLC method may use for routine quality testing and identification of Shankhpushpi botanicals.

A review on phytochemistry, pharmacology and toxicology studies of Aconitum

Objectives

A number of species belonging to herbal genus Aconitum are well-known and popular for their medicinal benefits in Indian, Vietnamese, Korean, Japanese, Tibetan and Chinese systems of medicine. It is a valuable drug as well as an unpredictable toxic material. It is therefore imperative to understand and control the toxic potential of herbs from this genus. In this review, the ethnomedicinal, phytochemistry, pharmacology, structure activity relationship and toxicology studies of Aconitum were presented to add to knowledge for their safe application.

Key findings

A total of about 76 of all aconite species growing in China and surrounding far-east and Asian countries are used for various medical purposes. The main ingredients of aconite species are alkaloids, flavonoids, free fatty acids and polysaccharides. The tuberous roots of genus Aconitum are commonly applied for various diseases such as rheumatic fever, painful joints and some endocrinal disorders. It stimulates the tip of sensory nerve fibres. These tubers of Aconitum are used in the herbal medicines only after processing. There remain high toxicological risks of the improper medicinal applications of Aconitum. The cardio and neurotoxicities of this herb are potentially lethal. Many analytical methods have been reported for quantitatively and qualitatively characterization of Aconitum.

Summary

Aconitum is a plant of great importance both in traditional medicine in general and in TCM in particular. Much attention should be put on Aconitum because of its narrow therapeutic range. However, Aconitum's toxicity can be reduced using different techniques and then benefit from its pharmacological activities. New methods, approaches and techniques should be developed for chemical and toxicological analysis to improve its quality and safety.

The application of capillary electrophoresis techniques in toxicological analysis

Capillary electrophoresis (CE) comprises a group of techniques used to separate chemical mixtures. Analytical separation is based on different electrophoretic mobilities, thereby allowing qualitative and quantitative evaluations to be made. The application of CE in medical science, especially in toxicological studies, is developing rapidly because of the short time required for analysis and its high sensitivity, selectivity and ability to determine substances of an acidic, alkaline and neutral character. This review focuses on the possibility of applying CE in toxicological analysis. Advances in different CE analyses and detection techniques connected with this method are described.

Oleanolic acid

Oleanolic acid (3β-hydroxyolean-12-en-28-oic acid) is a pentacyclic triterpenoid compound with a widespread occurrence throughout the plant kingdom. In nature, the compound exists either as a free acid or as an aglycone precursor for triterpenoid saponins, in which it can be linked to one or more sugar chains. Oleanolic acid and its derivatives possess several promising pharmacological activities, such as hepatoprotective effects, and anti-inflammatory, antioxidant, or anticancer activities. With the recent elucidation of its biosynthesis and the imminent commercialization of the first oleanolic acid-derived drug, the compound promises to remain important for various studies. In this review, the recent progress in understanding the oleanolic acid biosynthesis and its pharmacology are discussed. Furthermore, the importance and potential application of synthetic oleanolic acid derivatives are highlighted, and research perspectives on oleanolic acid are given.

The use of ethylene glycol solution as the running buffer for highly efficient microchip-based electrophoresis in unmodified cyclic olefin copolymer microchips

An ethylene glycol solution was used as the electrophoretic running buffer in unmodified cyclic olefin copolymer (COC) microchips to minimize the interactions between the analytes and the hydrophobic walls of the plastic microchannels, enhance the resolution of the analytes and eliminate the uncontrollable dispersion caused by uneven liquid levels and non-uniform surfaces of the separation channels. Five amino acids that were labeled with fluorescein isothiocyanate (FITC) were used as model analytes to examine the separation efficiency. The effects of ethylene glycol concentration, pH and sodium tetraborate concentration were systematically investigated. The five FITC-labeled amino acids were effectively resolved using a COC microchip with an effective length of 2.5 cm under optimum conditions, which included using a running buffer of 20 mmol/L sodium tetraborate in ethylene glycol:water (80:20, v/v), pH 6.7. A theoretical plate number of 4.8 × 10(5)/m was obtained for aspartic acid. The system exhibited good repeatability, and the relative standard deviations (n=5) of the peak areas and migration times were no more than 3.4% and 0.7%, respectively. Furthermore, the system was successfully applied to elucidate these five amino acids in human saliva.

Determination of oleanolic and ursolic acid in Chinese herbs using HPLC and γ-CD as mobile phase modifier

To separate and determine oleanolic acid and ursolic acid, a rapid and accurate HPLC using γ-CD as the mobile phase additive was developed. The effect of CD nature and concentration, and the acidity of the mobile phase on the chromatographic behavior of two bioactive triterpenes were systematically studied. Two bioactive triterpenes were completely separated (R = 3.11) on a Kromasil(®) C(18) column (150×4.6 mm id, 5 μm) with the mobile phase consisting of acetonitrile/0.1% phosphoric acid with 2 mM γ-CD as the mobile phase modifier (60:40, v/v). The flow rate was set at 1.0 mL/min and the eluent was detected at 210 nm for two bioactive triterpenes. The linearity of the method was excellent (r=0.9999) over the studied range of 6-300 μg/mL for oleanolic acid, and 12-600 μg/mL for ursolic acid. The LOD and LOQ were 1.5 and 5.0, 1.0 and 3.0 μg/mL for oleanolic acid and ursolic acid, respectively. The optimized method was successfully applied to separate and determine two bioactive triterpenes in five Chinese herbs. It is concluded that this method could be used for rapid and accurate qualitative and quantitative analysis of the two bioactive triterpenes in Chinese herbs.

Development of a new HPLC method with precolumn fluorescent derivatization for rapid, selective and sensitive detection of triterpenic acids in fruits

Triterpenic acids are widespread in plants and have multiplicity of biological properties. Unfortunately the method for accurate analysis of these compounds remains poorly investigated. This study proposed a highly sensitive and selective precolumn derivatization method for accurate determination of five triterpenic acids (betulinic acid, betulonic acid, maslinic acid, ursolic acid and oleanolic acid) in fruits using acridone-9-ethyl-p-toluenesulfonate (AETS) as fluorescent labeling reagent by HPLC with fluorescence detection (FLD). Response surface methodology was employed to optimize the derivatization reaction, ensuring the sufficient labeling of the analyzed components. The rapid separation of five triterpenic acids could be achieved in as little as 16 min. This developed method offered the exciting detection limits of 1.68-2.04 ng/mL. When applied to several popular fruits in China, it revealed satisfactory applicability and reproducibility. This developed method also exhibits powerful potential for accurate detection of triterpenic acids from other foodstuffs and nature products.

Application of metabonomic analytical techniques in the modernization and toxicology research of traditional Chinese medicine

In the recent years, a wide range of metabonomic analytical techniques are widely used in the modern research of traditional Chinese medicine (TCM). At the same time, the international community has attached increasing importance to TCM toxicity problems. Thus, many studies have been implemented to investigate the toxicity mechanisms of TCM. Among these studies, many metabonomic-based methods have been implemented to facilitate TCM toxicity investigation. At present, the most prevailing methods for TCM toxicity research are mainly single analysis techniques using only one analytical means. These techniques include nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS), etc.; with these techniques, some favourable outcomes have been gained in the toxic reaction studies of TCM, such as the action target organs assay, the establishment of action pattern, the elucidation of action mechanism and the exploration of action material foundation. However, every analytical technique has its advantages and drawbacks, no existing analytical technique can be versatile. Multi-analysed techniques can partially overcome the shortcomings of single-analysed techniques. Combination of GC-MS and LC-MS metabolic profiling approaches has unravelled the pathological outcomes of aristolochic acid-induced nephrotoxicity, which can not be achieved by single-analysed techniques. It is believed that with the further development of metabonomic analytical techniques, especially multi-analysed techniques, metabonomics will greatly promote TCM toxicity research and be beneficial to the modernization of TCM in terms of extending the application of modern means in the TCM safety assessment, assisting the formulation of TCM safety norms and establishing the international standards indicators.

Rapid and novel discrimination and quantification of oleanolic and ursolic acids in complex plant extracts using two-dimensional nuclear magnetic resonance spectroscopy-Comparison with HPLC methods

A novel strategy for NMR analysis of mixtures of oleanolic and ursolic acids that occur in natural products is described. These important phytochemicals have similar structure and their discrimination and quantification is rather difficult. We report herein the combined use of proton-carbon heteronuclear single-quantum coherence ((1)H-(13)C HSQC) and proton-carbon heteronuclear multiple-bond correlation ((1)H-(13)C HMBC) NMR spectroscopy, in the identification and quantitation of oleanolic acid (OA) and ursolic acid (UA)in plant extracts of the Lamiaceae and Oleaceae family. The combination of (1)H-(13)C HSQC and (1)H-(13)C HMBC techniques allows the connection of the proton and carbon-13 spins across the molecular backbone resulting in the identification and, thus, discrimination of oleanolic and ursolic acid without resorting to physicochemical separation of the components. The quantitative results provided by 2D (1)H-(13)C HSQC NMR data were obtained within a short period of time ( approximately 14min) and are in excellent agreement with those obtained by HPLC, which support the efficiency of the suggested methodology.

Qualitative and quantitative analysis in quality control of traditional Chinese medicines

Separation techniques with high efficiency and sensitive detection have been widely used for quality control of traditional Chinese medicines (TCMs). High-performance liquid chromatography, gas chromatography, and capillary electrophoresis are commonly used to separate various components in TCMs. Ultraviolet detection, fluorescence detection, evaporative light-scattering detection, mass spectrometry and nuclear magnetic resonance can be applied to separation techniques for qualitative and quantitative analysis of TCMs. The development of quality control for TCMs based on quantitative and qualitative analysis from 2000 to 2007 are reviewed; the fingerprint technique is also discussed due to its broad application in the quality control of TCMs. Prospects for further research based on our primary results are also discussed.

Ultrasound-assisted extraction and silylation prior to gas chromatography–mass spectrometry for the characterization of the triterpenic fraction in olive leaves

One of the most important fractions of bioactive compounds isolated from plants is that formed by triterpenic compounds, which have proved to be anti-bacterial, antifungal, anti-inflammatory, cytotoxic and anti-tumour. A method for leaching and determination of the main triterpenic compounds (oleanolic acid, ursolic acid, uvaol, erythrodiol) in olive leaves is here presented. Quantitative leaching was obtained with ethanol as leachant and ultrasonic assistance for 20 min, a very short time as compared to conventional procedures by maceration, which usually requires at least 5 h. After isolation, an aliquot of the ethanolic leachate was silylated to derivatize the analytes prior to gas chromatography-mass spectrometry analysis. Silylation reaction was also assisted with ultrasound in order to accelerate the derivatization step, which only required 5 min--a dramatic shortening in comparison to conventional silylation of terpenic compounds with derivatization times ranging from 30 min to 3 h. The proposed method has demonstrated to be useful for isolation and characterization of the triterpenic fraction in plants; the capability of ultrasound to assist sample preparation (acceleration of leaching and derivatization) has also been proved.

Use of liquid chromatography-atmospheric pressure chemical ionization-ion trap mass spectrometry for identification of oleanolic acid and ursolic acid in Anoectochilus roxburghii (wall.) Lindl

Oleanolic acid (OA) and ursolic acid (UA) are the two important bioactive compounds in Anoectochilus roxburghii (wall) Lindl (A. roxburghii), which has been used as a traditional Chinese medicine. So far, there has been no report to indicate that A. roxburghii contains these two bioactive compounds. It is necessary to develop an effective method to extract and analyze OA and UA in A. roxburghii. In this paper, a quantitative method, consisting of supercritical fluid extraction (SFE) followed by liquid chromatography-atmospheric pressure chemical ionization-ion trap mass spectrometry (LC-APCI-IT-MS) analysis, was developed for identification of OA and UA in A. roxburghii. The extraction was carried out by using CO(2) as the supercritical fluid and ethanol as the modifier before LC separation. The mobile phase used for LC separation consisted of acetic acid (1%, v/v), water (15%, v/v) and methanol (84%, v/v), and the elution was performed at a flow rate of 0.8 ml/min. The mass spectrometer was operated in APCI(+) mode with selected ion monitoring (SIM) to quantify OA and UA at m/z 439.4. Under optimum conditions, the linear responses of OA and UA were obtained in the concentration range of 0.5-80 (r = 0.9992) and 0.5-50 microg/ml (r = 0.9989) with the detection limits of 0.125 and 0.085 microg/ml, respectively. The proposed method has been used for the identification and quantitation of OA and UA in a real A. roxburghii sample.

Optimization of CZE for analysis of phytochemical bioactive compounds

Advantages of CZE such as high efficiency, low cost, short analysis time, and easy implementation result in its wide applications for analysis of phytochemical bioactive compounds (e.g. flavonoids, alkaloids, terpenoids, phenolic acid, saponins, anthraquinones and coumarins). However, several aspects, including sample preparation, separation, and detection have significant effects on CZE analysis. Therefore, optimization of these procedures is necessary for development of the method. In this review, sample preparation such as extraction method and preconcentration, separation factors including buffer type, concentration and pH, additives, voltage and temperature, as well as detection, e.g. direct and indirect UV detection, LIF and MS were discussed for optimization of CZE analysis on phytochemical bioactive compounds. The optimized strategies were also reviewed.