Microbial transformation of resibufogenin by Curvularia lunata AS 3.4381.

In this paper, the microbial transformation of resibufogenin by Curvularia lunata AS 3.4381 was investigated, and four transformed products were isolated and characterized as 3-epi-resibufogenin (2), 12α-hydroxy-3-epi-resibufogenin (3), 12-oxo-16ß-hydroxy-3-epi-resibufogenin (4), and 12ß,15-epoxy-3-epi-bufalin-14,15-ene (5). Among them, 4 and 5 are new compounds, and isomerization, hydroxylation, and oxidation reactions in microbial transformation process were observed. Additionally, the cytotoxicities of transformed products (2-5) were also investigated.

[Metabolic pathway and metabolites of total diterpene acid isolated from Pseudolarix kaempferi].

The preliminary metabolic profile of total diterpene acid (TDA) isolated from Pseudolarix kaempferi was investigated by using in vivo and in vitro tests. Pseudolaric acid C2 (PC2) was identified as the predominant metabolite in plasma, urine, bile and feces after both oral and intravenous administrations to rats using HPLC-UV and HPLC-ESI/MS(n), and demethoxydeacetoxypseudolaric acid B (DDPB), a metabolite proposed to be the glucoside of PC2 (PC2G), as well as pseudolaric acid C (PC), pseudolaric acid A (PA), pseudolaric acid A O-beta-D glucopyranoside (PAG), pseudolaric acid B O-beta-D glucopyranoside (PBG) and deacetylpseudolaric acid A (DPA) originated from TDA could also be detected. It was demonstrated by tests that the metabolism of TDA is independent of intestinal microflora, and neither of pepsin and trypsin is in charge of metabolism of TDA, TDA is also stable in both pH environments of gastric tract and intestinal tract. The metabolites of TDA in whole blood in vitro incubation were found to be PC2, DDPB and PC2G, which demonstrated that the metabolic reaction of TDA in vivo is mainly occurred in blood and contributed to be the hydrolysis of plasma esterase to ester bond, as well as the glucosylation reaction. These results clarified the metabolic pathway of TDA for the first time, which is of great significance to the in vivo active form and acting mechanism research of P. kaempferi.

Microbial transformation of acetyl-11-keto-boswellic acid by Cunninghamella elegans.

Microbial biotransformation of acetyl-11-keto-boswellic acid by Cunninghamella elegans AS 3.1207 was carried out, and totally four transformed products were isolated. On the basis of the extensive spectral data, their structures were characterized as 7ß-hydroxy-11-keto-boswellic acid (1), 7ß,30-dihydroxy-11-keto-boswellic acid (2), 7ß,16α-dihydroxy-3-acetyl-11-keto-boswellic acid (3), and 7ß,15α,21ß-trihydroxy-3-acetyl-11-keto-boswellic acid (4), respectively. Among them, products 1 and 2 are the new compounds.

Characterization of diterpenoids in the bark of Pseudolarix kaempferi by HPLC-ESI/MSn.

Fragmentation behavior of diterpenoids was investigated by ESI/MSn and the qualitative analysis of diterpenoids in the bark of Pseudolarix kaempferi was performed using high-performance liquid chromatography/ multi-stage mass spectrometry (HPLC-ESI/MSn). The characteristic fragmentation behaviors of the diterpenoids are the cleavages of the lactone ring and C4-O bond. Furthermore, the eliminations of substituent groups at C-18, C-7 and C-8 can also be observed in the MS" (n = 3-4) spectra. For C-4 acetoxy subsititued diterpenoids, [M+Na-60]+ and [M-H-104] are the base peaks of MS2 spectra in the positive and negative ionization modes, respectively. For C-4 hydroxyl subsititued diterpenoids, [M+Na-44]+ and [M-H-62] are the base peaks of MS2 in the positive and negative ionization modes, respectively. For C-18 glucosylated or esterized diterpenoids, [M+Na-44]+ is the base peak of MS2 spectra in positive ionization mode. These fragmentation rules were successfully exploited in the identification of diterpenoids in methanol/water (6:4) extract of P. kaempferi by LC-MS in positive ionization mode. A total of 9 diterpenoids were identified or tentatively characterized, and one of them is reported here for the first time. The described method could be utilized for the sensitive and rapid qualitative analysis of P. kaempferi.

[Metabolic pathway and metabolites of pseudolaric acid B].

The metabolic profile of pseudolaric acid B (PB) was investigated by using in vivo and in vitro tests. Pseudolaric acid C2 (PC2) was identified as the specific metabolite of PB in plasma, urine, bile and feces using HPLC and HPLC-ESI/MS(n) after both oral and intravenous administration to rats, and almost no prototype was detected in all kinds of samples. The metabolic behaviors of PB orally administered in rats treated with antibiotics to eliminate intestinal microflora were identical with those in untreated rats, demonstrating that the metabolism of PB is independent of intestinal microflora. PB was stable in 48 h respective incubation with artificial gastric juice and artificial intestinal juice, suggesting that neither pepsin nor trypsin is in charge of metabolism of PB, and also demonstrating that PB is stable in both pH environments of gastric tract and intestinal tract. In vitro research on metabolism of PB in rat liver microsomes incubation revealed that little PB was metabolized and that the proposed metabolites were the demethoxy and demethoxydecarboxy products of the prototype. The amount of metabolites was extremely low compared with the prototype, indicating that liver microsomes are not responsible for the metabolism of PB either. PB was gradually metabolized into PC2 during 1 h in whole blood incubation in vitro, and the metabolic process showed dynamically dependent manner with incubation time. Once absorbed into blood, PB was quickly metabolized into PC2, accordingly, little prototype was detected in all kinds of samples. The metabolism was attributed to the rapid hydrolysis of C-19 ester bond by plasma esterase. These results clarified the metabolic pathway of PB for the first time, which was of great significance to identify the in vivo active form and interpret acting mechanism of the active compounds of P. kaempferi.

Microbial biotransformation of cryptotanshinone by Cunninghamella elegans and its application for metabolite identification in rat bile.

Cryptotanshinone (1) is one of the major bioactive constituents in Salvia miltiorrhiza Bunge. Preparative-scale biotransformation of cryptotanshinone by Cunninghamella elegans (AS 3.2082) produced three new products, which were identified as (3R,15R)-3-hydroxycryptotanshinone (2), (3S,15R)-3-hydroxycryptotanshinone (3), and (4S,15R)-18-hydroxycryptotanshinone (4), respectively. The structural elucidation was based primarily on 1D and 2D NMR and HR-ESI-MS analyses. The absolute configuration of these three products was confirmed by comparison of their circular dichroism spectra with those of the known compounds. These biotransformed metabolites were used as for the comparison of in vivo metabolites in rat bile sample after intravenous administration and they are identical to three of the minor hydroxylated metabolites in vivo, which suggested that microbial biotransformation model was a useful and feasible approach for the preparation of mammalian metabolites in trace.

Analysis of phenolic compounds in Epimedium plants using liquid chromatography coupled with electrospray ionization mass spectrometry.

A new method based on HPLC coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) has been established for the analysis of phenolic compounds in Epimedium plants. The characteristic fragmentation pathways of 29 phenolic compounds were studied, and 126 compounds were identified or tentatively characterized based on their mass spectra from fourteen samples including the aerial samples and the underground parts of the seven species. Furthermore, the differences in phenolic compound profiles between different Epimedium plants and two parts of the seven species were reported for the first time. Due to their significant chemical differences, these Epimedium species should be used separately in clinical practice.

Simultaneous determination and pharmacokinetics of five bufadienolides in rat plasma after oral administration of Chansu extract by SPE-HPLC method.

A sensitive and rapid solid-phase extraction-high performance liquid chromatography (SPE-HPLC) method has been developed for the determination of five bufadienolides, arenobufagin, teliocinobufagin, cinobufotalin, cinobufagin and resibufogenin in rat plasma and applied to a pharmacokinetic study in rats after oral administration of Chansu extract (Venenum Bufonis). Plasma samples were pretreated with solid-phase extraction using Extract-Clean cartridges, and the extracts were analyzed by a reversed-phase C(18) column on a HPLC system with photodiode array detection (DAD). The calibration curves were linear over the range of 0.10-1.66 microg/ml for arenobufagin, 0.03-1.20 microg/ml for telocinobufagin, 0.01-0.62 microg/ml for cinobufotalin, 0.03-0.70 microg/ml for cinobufagin and 0.02-2.57 microg/ml for resibufogenin, respectively. The limit of quantification was 1.1 ng/ml for arenobufagin, 0.3 ng/ml for telocinobufagin, 9.7 ng/ml for cinobufotalin, 8.8 ng/ml for cinobufagin, 7.7 ng/ml for resibufogenin, respectively. The established method could be easily applied to the determination and pharmacokinetic studies of five bufadienolides in rat plasma after oral administration of Chansu extract.

Detection, characterization and identification of phenolic acids in Danshen using high-performance liquid chromatography with diode array detection and electrospray ionization mass spectrometry.

By using HPLC-diode array detection-electrospray ion trap tandem mass spectrometry (HPLC-DAD-ESI-MS(n)) in negative ion mode, we have analyzed the fragmentation pathways of 11 phenolic acids which were isolated from Danshen. Then the extract of Danshen was analyzed, and a total of 42 phenolic acids, including sixteen new minor constituents, were identified or tentatively identified for the first time. A new solid-phase extraction (SPE) method, new HPLC separation method, new liquid chromatography (LC)-MS and LC-MS(n) (n=3-5) data and proposed fragmentation pathways, LC retention time for phenolic acids are reported.

Development of the fingerprints for the quality of the roots of Salvia miltiorrhiza and its related preparations by HPLC-DAD and LC-MS(n).

High-performance liquid chromatographic (HPLC) fingerprints were developed for identification of both lipophilic and hydrophilic components of the roots of Salvia miltiorrhiza and four related preparations. These samples were separated with an Agilent Zorbax Extend C(18) reserved-phase column (5 microm, 250 mm x 4.6 mm) by linear gradient elution using water-phosphoric acid (100:0.026, v/v) and acetonitrile as mobile phase. The flow rate was 0.8 ml/min and the detector wavelength was set at 280 nm. Mean chromatograms and correlation coefficients of samples were calculated by the software "Similarity Evaluation System for Chromatographic Fingerprint of TCM". The correlation coefficients of Danshen and Fufang Danshen tablets (FDT) samples were in the range of 0.352-0.993 and 0.768-0.987, respectively. The correlation coefficients of Compound Danshen dripping pills (CDDP), Danshen injection (DSI) and Xiangdan injection (XDI) samples were higher than 0.928, 0.850 and 0.960, respectively. It was the first time to identify 34 peaks by comparing with standard compounds and using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS(n)) technique. All results indicated that the developed fingerprint assay could be readily utilized as a quality control method for S. miltiorrhiza and its related preparations.

Identification of tanshinones and their metabolites in rat bile after oral administration of TTE-50, a standardized extract of Salvia miltiorrhiza by HPLC-ESI-DAD-MSn.

TTE-50 is a standardized extract of Salvia miltiorrhiza which mainly consisted of tanshinones. A sensitive and specific method using liquid chromatography-diode array detection-electrospray ionization (ESI) ion trap mass spectrometry was established for the study of the constituents and metabolites of TTE-50 in rat bile sample after oral administration. The bile samples were extracted with ethyl acetate (EtOAc) of three-fold volume for three times. The chromatographic separation was carried out on a Zorbax Extend-C18 column with a gradient elution program whereas acetonitrile-water was used as mobile phase. Mass spectra were acquired in positive ionization mode and data-dependant scan was used for the identification of the tanshinones and metabolites in the bile samples. Identification and structural elucidation of the tanshinones and their metabolites in bile samples were performed by comparing their retention-times and full scan MS(n) spectra with those of reference compounds and data in the literatures. Sixteen tanshinones in TTE-50 along with seventeen phase I metabolites were identified simultaneously. The metabolic modification could take place in the C-4 side chain of tanshinone IIA, from methyl to primary alcohol, then to aldehyde group was proposed for the first time. The established method was valuable for the study of the metabolism of complex system such as herbal extracts or traditional Chinese medicine (TCM) formula.

HPLC determination of four triterpenoids in rat urine after oral administration of total triterpenoids from Ganoderma lucidum.

A sensitive and simple high-performance liquid chromatography (HPLC) method was applied for the quantitative determination of four major triterpenoids (ganoderic acids C(2), B, K and H) in rat urine after oral administration of total triterpenoids from Ganoderma lucidum. The urine sample was extracted with dichloromethane-ethyl acetate (90:10) after acidification by hydrochloric acid (0.2 mol/ml). Chromatographic separation was achieved on a Zorbax SB-C(18) column (250 mm x 4.6 mm, 5 microm) at 35 degrees C, with a linear gradient of acetonitrile and 0.03% aqueous phosphoric acid (v/v), at a flow rate of 1.2 ml/min. The four triterpenoids and internal standard (hydrocortisone) were detected at a wavelength 252 nm. The within- and between-day assay coefficients of variation for the four triterpenoids in urine were less than 9% and the extraction recovery of this method was higher than 90%. Using this method, the excretion profile of the triterpenoids in rat urine after oral administration of total triterpenoids of G. lucidum was revealed for the first time.

High-performance liquid chromatographic determination of tanshinones in the roots of Salvia miltiorrhiza and related traditional chinese medicinal preparations.

PURPOSE: This paper describes a validated high-performance liquid chromatographic method to quantitate four tanshinones as markers; dihydrotanshinone I, cryptotanshinone, tanshinone I and tanshinone IIA for use in the quality control of the roots of Salvia miltiorrhiza and its related traditional Chinese medicinal preparations. METHODS: Separation was achieved using a Zorbax Extend C18 reserved-phase column (5microm, 250*4.6mm) at 20 degrees with a gradient mixture of deionized water and acetonitrile at a flow rate of 1.2ml/min. RESULT: The limits of quantitation were 0.13, 0.08, 0.06 and 0.05microg/ml for dihydrotanshinone I, cryptotanshinone, tanshinone I and tanshinone IIA, respectively. This method provided good reproducibility and sensitivity for the quantification of four tanshinones with overall RSD values for intra-day and inter-day precision and accuracy better than 3.8% and higher than 94.9%, respectively. The recovery of the method was 95.4-104.4% for all the tanshinones and showed good linearity (r>0.9998) over a relatively wide concentration range. CONCLUSIONS: This assay was successfully applied to the determination of four tanshinones in the roots of Salvia miltiorrhiza and its related traditional Chinese medicinal preparations. The results indicated that the HPLC assay could be readily utilized as a quality control method for the roots of Salvia miltiorrhiza and its related traditional Chinese medicinal preparations.

[Study on the metabolite of stilbene glucoside in mice by liquid chromatography tandem-mass spectrometry].

AIM: To study the metabolite of stilbene glucoside in the Chinese traditional medicine Polygonum multiflornm in mice and elucidate its chemical structure by liquid chromatography tandem-mass spectrometry. METHODS: The stilbene glucoside was injected into the tail vein of mice. Blood samples were collected from artery in the eyepit. The methanol-protein-precipitated plasma sample was introduced into the liquid chromatography-tandem mass spectrometer directly. The analytical column was C18 column (250 mm x 4.6 mm ID, 5 microns). The mobile phase consisted of acetonitrile-methanol-water-formic acid (15:18:66:1) for ES+, acetonitrile-methanol-water (15:18:67) for ES-. The UV detection wavelength was set at 320 nm. The mass ion source type was ESI. HV capillary was 3 kV. The dry gas was nitrogen gas and the flow rate was set at 318 L.h-1. The ion source temperature was 150 degrees C. RESULTS: The stilbene glucoside and its metabolite were separated completely under the chromatography condition. The ions at m/z 600 and m/z 605 were detected under positive ion polarity while the ions at m/z 581 and m/z 402 were detected under negative ion polarity. CONCLUSION: It was proposed that the metabolite of stilbene glucoside injected in vein was its glucuronide conjugate.

Characterization of compounds from the roots of Saposhnikovia divaricata by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry.

In this study, four types of compounds including coumarins, chromones, furoylmethyl amino acid derivative and benzofuran glycoside were isolated from the roots of Saposhnikovia divaricata. The electrospray ionization (ESI) mass spectral fragmentation pathways of these compounds were proposed. In particular, the ESI-MS(n) fragmentation behavior of linear dihydrofurocoumarins, dihydrofuro- and dihydropyranochromones were deduced in detail. For the linear dihydrofurocoumarins, the fragmentation was triggered by the initial loss of the C-4' substituting group. Then, the characteristic ions were observed followed by the losses of 15, 18, 28 and 46 Da. It is noteworthy that the elimination of H(2)O (18 Da) from the cleavage of the dihydrofuran ring is reported for the first time. For the linear dihydrofurochromones, characteristic eliminations of 18, 48 and 72 Da were observed. The loss of 18 Da could arise from two different fragmentation pathways, and the observed ion was composed of a mixture of two different structural ions. For the linear dihydropyranochromones, it was found that the dihydropyran ring was converted into the pyran ring by the elimination of the C-3' substituting group. This fragmentation was followed by the diagnostic losses of 18, 28, 42 and 54 Da in tandem mass spectrometry. The above fragmentation rules were successfully applied for the analysis of the chemical constituents of the roots of Saposhnikovia divaricata. A total of 32 compounds were identified or tentatively characterized by HPLC/DAD/ESI-MS(n). Among them, eight compounds were new and seven compounds were reported from that genus for the first time.

HPLC method for comparative study on tissue distribution in rat after oral administration of salvianolic acid B and phenolic acids from Salvia miltiorrhiza.

A sensitive and selective high-performance liquid chromatography method was developed and validated to determine the prototype of salvianolic acid B and the metabolites of phenolic acids (protocatechuic acid, vanillic acid and ferulic acid) in rat tissues after oral administration of total phenolic acids and salvianolic acid B extracted from the roots of Salvia miltiorrhiza, respectively. The tissue samples were treated with a simple liquid-liquid extraction prior to HPLC. Analysis of the extract was performed on a reverse-phase C(18) column with a mobile phase consisting of acetonitrile and 0.05% trifluoracetic acid. The calibration curves for the four phenolic acids were linear in the given concentration ranges. The intra-day and inter-day relative standard deviations in the measurement of quality control samples were less than 10% and the accuracies were in the range of 88-115%. The average recoveries of all the tissues ranged from 78.0 to 111.8%. This method was successfully applied to evaluate the distribution of the four phenolic acids in rat tissues after oral administration of total phenolic acids of Salvia miltiorrhiza or salvianolic acid B and the possible metabolic pathway was illustrated.