Preparative isolation and purification of calycosin from Astragalus membranaceus Bge. var. mongholicus (Bge.) Hsiao by high-speed counter-current chromatography

Calycosin Influences the Metabolism of Five Probe Drugs in Rats

Background

Calycosin (CAL), a type of O-methylated isoflavone extracted from the herb Astralagusmembranaceus (AM), is a bioactive chemical with antioxidative, antiphlogistic and antineoplastic activities commonly used in traditional alternative Chinese medicine. AM has been shown to confer health benefits as an adjuvant in the treatment of a variety of diseases.

Aim

The main objective of this study was to determine whether CAL influences the cytochrome P450 (CYP450) system involved in drug metabolism.

Methods

Midazolam, tolbutamide, omeprazole, metoprolol and phenacetin were selected as probe drugs. Rats were randomly divided into three groups, specifically, 5% Carboxymethyl cellulose (CMC) for 8 days (Control), 5% CMC for 7 days + CAL for 1 day (single CAL) and CAL for 8 days (conc CAL), and metabolism of the five probe drugs evaluated using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

Results

No significant differences were observed for omeprazole and midazolam, compared to the control group. T_max and t_1/2 values of only one probe drug, phenacetin, in the conc CAL group were significantly different from those of the control group (T_max h: 0.50±0.00 vs 0.23±0.15; control vs conc CAL). C_max of tolbutamide was decreased about two-fold in the conc CAL treatment group (conc vs control: 219.48 vs 429.56, P<0.001).

Conclusion

Calycosin inhibits the catalytic activities of CYP1A2, CYP2D6 and CYP2C9. Accordingly, we recommend caution, particularly when combining CAL as a modality therapy with drugs metabolized by CYP1A2, CYP2D6 and CYP2C9, to reduce the potential risks of drug accumulation or ineffective treatment.

Rapid Analysis and Guided Isolation of Astragalus Isoflavonoids by UHPLC-DAD-MSn and Their Cellular Antioxidant Defense on High-Glucose-Induced Mesangial Cell Dysfunction

Isoflavonoids, including isoflavones, isoflavans, and pterocarpans, the principal components in Astragalus membranaceus, have a great deal of versatile health-promoting benefits. In this work, as a continuation of our search for bioactive constituents from A. membranaceus, a fast high-performance liquid chromatography-diode array detection-multiple-stage mass spectrometry method was first used to analyze the isoflavonoid profile of A. membranaceus roots extract. Twelve diverse isoflavonoids in subclasses of isoflavones, isoflavans, and pterocarpans present in glycoside/aglycone pair forms were tentatively characterized; of those 12, eight major isoflavonoids were finally isolated and simultaneously quantified by the established fast UHPLC method. Furthermore, the results confirmed for the first time that Astragalus isoflavonoid aglycones could attenuate mesangial cell proliferation and extracellular matrix (ECM) accumulation triggered by high glucose levels, and the primary mechanism might be via protecting intracellular antioxidant enzymes activities and enhancing endogenous antioxidant function to lower levels of cellular oxidative damage induced by high glucose levels. Collectively, diverse Astragalus isoflavonoid antioxidants have the potential to ameliorate high-glucose-induced mesangial cell dysfunction through the regulation of cellular antioxidant defense.

Suppression of A549 cell proliferation and metastasis by calycosin via inhibition of the PKC‑α/ERK1/2 pathway: An in vitro investigation

The migration and invasion of lung cancer cells into the extracellular matrix contributes to the high mortality rates of lung cancer. The protein kinase C (PKC) and downstream signaling pathways are important in the invasion and migration of lung cancer cells. Calycosin (Cal), an effector chemical from Astragalus has been reported to affect the recurrence and metastasis of cancer cells via the regulation of the protein expression of matrix metalloproteinases (MMPs). The inhibition of Cal on the migration and invasion of A549 cells was investigated in the present study. Cell viability and apoptosis assays were performed using MTT and flow cytometric analyses. A wound healing assay and Transwell invasion assay were performed to evaluate the effect of Cal on A549 cell migration and invasion. Invasion-associated proteins, including MMP-2, MMP-9, E-cadherin (E-cad), integrin β1, PKC-α and extracellular signal-regulated kinase 1/2 (ERK1/2) were detected using western blotting. In addition, PKC-α inhibitor, AEB071, and ERK1/2 inhibitor, PD98059, were used to determine the association between the suppression of PKC-α/ERK1/2 and invasion, MMP-2, MMP-9, E-cad and integrin β1. Cal was observed to suppress cell proliferation and induce apoptosis. There were significant differences between the phorbol-12-myristate-13-acetate (TPA)-induced A549 cells treated with Cal and the untreated cells in the rates of migration and invasion. The levels of MMP-2, MMP-9, E-cad and integrin β1 in the TPA-induced A549 cells changed markedly, compared with the untreated cells. In addition, the suppression of Cal was affected by the PKC inhibitor, AEB071, an ERK1/2 inhibitor, PD98059. The results of the present study indicated that Cal inhibited the proliferation, adhesion, migration and invasion of the TPA-induced A549 cells. The Cal-induced repression of PKC-α/ERK1/2, increased the expression of E-Cad and inhibited the expression levels of MMP-2, MMP-9 and integrin β1, which possibly demonstrates the mechanism underlying the biological anticancer effects of Cal.

A new phenylpropanoid and a new isoflavone glycoside from Shenqi Fuzheng Injection

A new phenylpropanoid and a new isoflavone glycoside were isolated from Shenqi Fuzheng Injection. Their structures were elucidated as (αS)-α-ethenyl-4-hydroxy-3-methoxy-benzenemethanol (1) and calycosin 7-O-[α-d-glucopyranosyl (1 → 4)]-β-d-glucopyranoside (2) by means of spectroscopic methods including UV, IR, HR-ESI-MS, and NMR. The absolute configurations of 1 and 2 were confirmed by quantum chemical calculation and acid hydrolysis.

Strategies of solvent system selection for the isolation of flavonoids by countercurrent chromatography

Flavonoids form a large class of important naturally occurring bioactive compounds. Their isolation and purification from natural sources can sometimes be very difficult and time-consuming when traditional phytochemical techniques are used. Countercurrent chromatography (CCC), a support-free liquid-liquid partition chromatography technique, is very useful for the isolation of polar compounds and its use is increasing in the natural products field. In this paper, we propose strategies of solvent system selection for the isolation of flavonoids by CCC, based on data from the literature, plus incorporation of own practical experiences. The selected references report the isolation of over 300 different flavonoid compounds from more than 100 plant species, using 40 different solvent systems, showing the versatility of this technique. The solvent system hexane-ethylacetate-methanol-water is proposed as a starting point for the separation of samples containing free flavonoids, as it was cited in more than 60% of the papers. A "fine tuning" step is proposed at each level of this solvent family. Other modifications include exchanging the alcohol in the system as well as introducing a fifth solvent. The solvent system ethyl-acetate-butanol-water is proposed as the starting point for glycosylated flavonoids. Other solvent systems are also discussed. The use of gradients is proposed for samples containing both free and glycosylated flavonoids, as the polarity window is larger in these cases. High-speed countercurrent chromatography was used in 89% of the reviewed data.

Preparative isolation and purification of triterpene saponins from Clematis mandshurica by high-speed counter-current chromatography coupled with evaporative light scattering detection

Preparative high-speed counter-current chromatography (HSCCC) coupled with evaporative light scattering detection (ELSD) was successfully applied to the isolation and purification of four triterpene saponins from Clematis mandshurica by one-step separation. The solvent system was composed of ethyl acetate-n-butanol-ethanol-0.05% TFA (5:10:2:20, v/v). The purities of all the saponins obtained were better than 97%. The structures of the compounds were elucidated by the means of spectroscopic methods.

Subchronic toxicity studies of Radix Astragali extract in rats and dogs

Radix Astragali extract (RAE) is obtained from Astragalus membranaceus. It consists of Astragalus polysaccharide and Astragalus membranaceus saponins. In the study, we observed the subchronic toxicity of RAE in Sprague-Dawley rats and beagle dogs to evaluate the safety dosage range in clinical application. These subjects were daily administered of RAE by intra-peritoneum or vein for three consecutive months. General index were observed such as food-intake, behavior, body weight, hematological parameters, etc. Body weight, the weight of principal organ and hematology index are normal in experimental groups and control groups. The hematological biochemistry examination and histopathology examination of experimental groups are similar to control groups. In conclusion, our studies clearly demonstrated that RAE was safe without any distinct toxicity and side effects, the safety dosage range is 5.7-39.9g/kg for rats and 2.85-19.95g/kg for beagle dogs, which is equal to 70 or 35 times of that of human (0.57g/kg, say, average BW 70kg), respectively.

Development of an efficient method for the preparative isolation and purification of chlorophyll a from a marine dinoflagellate Amphidinium carterae by high-speed counter-current chromatography coupled with reversed-phase high-performance liquid chromatography

In our research into chlorophylls of marine dinoflagellates, chlorophyll a was separated rapidly from the hexane extract of Amphidinium carterae in three steps. The first step was silica gel column chromatography, where elution was performed with 0-50% ethyl acetate in n-hexane. The second was high-speed counter-current chromatography using a two-phase solvent system consisting of n-hexane-ethyl acetate-methanol-water (5:5:5:1, v/v), and the third step was preparative reversed-phase high-performance liquid chromatography using a solvent system of acetone-water (89:11, v/v). HPLC analysis showed that the purity of chlorophyll a from the second step was over 83%, and after the third it was over 99%. Thirty milligrams of chlorophyll a was isolated from a crude sample of 250 mg of chlorophylls, and its structure was identified by analyzing its MS, 1H NMR and 13C NMR spectra.

Development of a gradient elution preparative high performance liquid chromatography method for the recovery of the antibiotic ertapenem from crystallization process streams

A gradient elution preparative chromatography method was developed for the recovery of the antibiotic ertapenem from crystallization mother-liquor streams. The preparative HPLC method that was developed on the lab-scale employs an analytical size column of conventional dimensions (25 cm x 0.46 cm) packed with Kromasil C8 stationary phase. Gradient elution was used with aqueous acetic acid and acetonitrile as mobile phases. A target of processing approximately 30 mg of ertapenem per half an hour at a flow rate of 1.5 mL/min with high yield and adequate rejection of all major impurities was achieved. This corresponds to a productivity of approximately 0.6 kg ertapenem as free acid per kilogram of stationary phase per day (kkd). The scalability of the method was demonstrated by using a 5 cm i.d. column configuration to generate 10 g of purified ertapenem. This work complements a previous study improving on the productivity and throughput of the method by employing gradient elution and the use of crystallization to remove some key impurities that are chromatographically difficult to resolve [A. Vailaya, P. Sajonz, O. Sudah, V. Capodanno, R. Helmy, F.D. Antia, J. Chromatogr. A 1079 (2005) 80].

Preparative isolation and purification of rupestonic acid from the Chinese medicinal plant Artemisia rupestris L. by high-speed counter-current chromatography

Rupestonic acid was purified for the first time by high-speed counter-current chromatography from a dichloromethane extract of the traditional Chinese medicinal plant Artemisia rupestris L. The separation was performed in two steps with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (6:4:3.5:6.5, v/v) with 0.5% acetic acid in stationary-phase. From 200 mg of the crude extract, 27.9 mg of rupestonic acid was obtained at over 98% purity as determined by HPLC analysis, and its chemical structure was confirmed by MS, 1H and 13C nuclear magnetic resonance.

Application of preparative high-speed counter-current chromatography for separation of methyl gallate from Acer truncatum Bunge

Preparative separation of methyl gallate in leaves extract of Acer truncatum Bunge was conducted using high-speed counter-current chromatography (HSCCC) with a solvent system composed of ethyl acetate-ethanol-water at volume ratios of 5:1:5 (v/v/v). In a single operation, 57.5 mg of methyl gallate was obtained from 120 mg of the extract. HPLC analyses of the counter-current chromatography (CCC) fraction revealed that the methyl gallate was having over 97% purity. Its structure was identified by 1H NMR and 13C NMR.

Isolation of quercetin-3-O-l-rhamnoside from Acer truncatum Bunge by high-speed counter-current chromatography

Preparative high-speed counter-current chromatography (HSCCC) was successfully used for isolation and purification of quercetin-3-O-L-rhamnoside from the ethyl acetate extract of the leaves of Acer truncatum Bunge using a two-phase-system composed of ethyl acetate-ethanol-water at a volume ratio of 5:1:5 (v/v/v). In a single operation, 41.9mg of quercetin-3-O-L-rhamnoside was obtained from 366mg of the crude extract. High-performance liquid chromatography (HPLC) analyses of the CCC fraction revealed that the purity of quercetin-3-O-L-rhamnoside was over 96%. Its structure was identified by MS, 1H NMR and 13C NMR. Quercetin-3-O-L-rhamnoside was obtained from this plant for the first time.

Preparative isolation and purification of gastrodin from the Chinese medicinal plant Gastrodia elata by high-speed counter-current chromatography

Gastrodia elata Blume is a famous Chinese medicinal plant, which has been widely used for the treatment of rheumatism, epilepsy, paralysis, hemiplegia, lumbago, headache and vertigo. High-speed counter-current chromatography was successfully used for the first time for the preparative isolation and purification of the bioactive component gastrodin from G. elata Blume. The crude gastrodin was obtained by extraction with ethanol from the dried roots of G. elata Blume under sonication. Preparative high-speed counter-current chromatography with a two-phase solvent system composed of n-butanol-ethyl acetate-water (2:3:5, v/v/v) was successfully performed yielding 48 mg gastrodin at 96% purity from 500 mg of the crude extract (10.3% gastrodin) with the recovery of approximately 90% in a one-step separation.

Preparative isolation and purification of coumarins from Angelica dahurica (Fisch. ex Hoffm) Benth, et Hook. f (Chinese traditional medicinal herb) by high-speed counter-current chromatography

A preparative high-speed counter-current chromatography (HSCCC) method for isolation and purification of coumarins from Angelica dahurica (Fisch. ex Hoffin) Benth, et Hook. f(Baizhi in Chinese) was successfully established by using n-hexane-methanol-water as the two-phase solvent system in gradient elution mode. The upper phase of n-hexane-methanol-water (5:5:5, v/v) was used as the stationary phase of HSCCC. The mobile phase used in HSCCC was the lower phase of n-hexane-methanol-water (5:5:5, v/v) and n-hexane-methanol-water (5:7:3, v/v) that was changed in gradient. Three major components including imperatorin, isoimperatorin and oxypeucedanine were isolated, each at over 98% purity as determined by high-performance liquid chromatography (HPLC). The peak fractions of HSCCC were identified by 1H-NMR and 13C-NMR.

Application of high-speed counter-current chromatography to the preparative separation and purification of baicalin from the Chinese medicinal plant Scutellaria baicalensis

Baicalin was separated and purified for the first time from the traditional Chinese medicinal plant Scutellaria baicalensis Georgi by high-speed counter-current chromatography. Crude baicalin was obtained by extraction with methanol-water (70:30, v/v) from S. baicalensis Georgi. The separation was performed in two steps with a two-phase solvent system composed of n-butanol-water (1:1, v/v), in which the lower phase was used as the mobile phase at a flow-rate of 1.0 ml min(-1) in the head-to-tail elution mode. A total of 37.0 mg of baicalin at 96.5% purity was yielded from 200 mg of the crude baicalin (containing 21.6% baicalin) with 86.0% recovery as determined by HPLC analysis.