Bioactivity-directed isolation, identification of diuretic compounds from Polyporus umbellatus

Solvent effect on the absorption and fluorescence of ergone: determination of ground and excited state dipole moments

The effect of solvents on the absorption and emission spectra of ergone has been studied in various solvents at 298 K. The bathochromic shift was observed in absorption and fluorescence spectra with the increase of solvents polarity, which implied that transition involved was π→π*. And the normalized transition energy value E(T)(N) showed some scattering when plotted versus Δν. The ground state and excited state dipole moments were calculated by quantum-mechanical second-order perturbation method as a function of the dielectric constant (ε) and refractive index (n). The result was found to be 1.435 D and 2.520 D in ground state and excited state respectively. And also, the density functional calculations were used to obtain the ground state and excited state dipole moments for it has proven to be suitable for calculating electronic excitation energy. And the result is consistent with the experimental.

Ergosta-4,6,8(14),22-tetraen-3-one isolated from Polyporus umbellatus prevents early renal injury in aristolochic acid-induced nephropathy rats

OBJECTIVES

Aristolochic acid (AA) nephropathy, first reported as Chinese herbs nephropathy, is a rapidly progressive tubulointerstitial nephropathy that results in severe anemia, interstitial fibrosis and end-stage renal disease. Tubulointerstitial injury was studied in a rat model of AA nephropathy to determine whether ergosta-4,6,8(14),22-tetraen-3-one (ergone) treatment prevents early renal injury in rats with aristolochic acid I-induced nephropathy.

METHODS

Early renal injury via renal interstitial fibrosis was induced in rats by administration of aristolochic acid I (AAI) solution intragastrically for 8 weeks. Ninety-six rats were randomly divided into four groups (n = 24/group): (1) control (2) AAI (3) AAI + ergone (10 mg/kg) and (4) AAI + ergone (20 mg/kg). Blood and urine samples were collected and rat were sacrificed for histological assessment of the kidneys on at the end of weeks 2, 4, 6 and 8.

KEY FINDINGS

AAI caused progressive elevation of blood urea nitrogen, creatinine, potassium, sodium, chlorine, proteinuria and urinary N-acetyl-β-D-glucosaminidase (NAG). Ergone suppressed elevation of blood urea, nitrogen, creatinine, proteinuria and urinary NAG to some degree, but the AAI-ergone-treated group did not differ from AAI-treated group for body weight, serum potassium, sodium and chlorine. The progress of the lesions in the kidney after AAI administration was also observed by histopathological examinations, but kidneys from rats of AAI-ergone-treated group displayed fewer lesions.

CONCLUSIONS

Ergone treatment conferred protection against early renal injury in a rat model of AA nephropathy. Early administration of ergone may prevent the progression of renal injury and the subsequent renal fibrosis in AA nephropathy.

Studies of Interaction between Ergosta‐4,6,8(14),22‐tetraen‐3‐one (Ergone) and Human Serum Albumin by Molecular Spectroscopy and Modeling

Our previous experimental results have shown that ergosta‐4,6,8(14),22‐tetraen‐3‐one (ergone) is one of the main bioactive components of Polyporus umbellatus. The efficacy of ergone binding to human serum albumin (HSA) is critical for pharmacokinetic behavior of ergone. The interactions between ergone and HSA under simulative physiological conditions were investigated by the methods of fluorescence spectroscopy, absorption and circular dichroism spectroscopy. Fluorescence data revealed that the fluorescence quenching of HSA by ergone was the result of the formation of the ergone‐HSA complex. According to the modified Stern‐Volmer equation, the binding constants (Ka) between ergone and HSA were determined. The thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS) for the reaction were calculated to be 0.989 kJ mol‐1 and 11.214 J mol‐1 K‐1, indicating that the hydrogen bonds and hydrophobic interactions played a dominant role in the binding of ergone to HSA. The conformational investigation showed that the presence of ergone decreased the α‐helical content of HSA and induced the slight unfolding of the polypeptides of protein. Furthermore, displacement experiments using warfarin and ibuprofen indicated that ergone could bind to site I of HSA, which was also in agreement with the results of the molecular modeling.

Pharmacokinetics of ergosterol in rats using rapid resolution liquid chromatography-atmospheric pressure chemical ionization multi-stage tandem mass spectrometry and rapid resolution liquid chromatography/tandem mass spectrometry

Rapid resolution liquid chromatography/tandem multi-stage mass spectrometry (RRLC-MS(n)) and rapid resolution liquid chromatography/tandem mass spectrometry (RRLC/MS/MS) methods were developed for the identification and quantification of ergosterol and its metabolites from rat plasma, urine and faeces. Two metabolites (ERG1 and ERG2) were identified by RRLC/MS(n). The concentrations of the ergosterol were determined by RRLC/MS/MS. The separation was performed on an Agilent Zorbax SB-C18 with the mobile phase consisting of methanol and water (containing 0.1% formic acid). The detection was carried out by means of atmospheric pressure chemical ionization mass spectrometry in positive ion mode with multiple reaction monitoring (MRM). Linear calibration curves were obtained in the concentration range of 7-2000, 6-2000 and 8-7500 ng/mL for plasma, urine and faecal homogenate, respectively. The intra- and inter-day precision values (RSD) were below 10%. The method was applied to the pharmacokinetic properties and elimination pathway of ergosterol in rats.

Ergosta-4,6,8(14),22-tetraen-3-one induces G2/M cell cycle arrest and apoptosis in human hepatocellular carcinoma HepG2 cells

BACKGROUND

Mushrooms have been used in Asia as traditional foods and medicines for a long time. Ergosta-4,6,8(14),22-tetraen-3-one (ergone) is one of the well-known bioactive steroids, which exists widely in various medicinal fungi such as Polyporus umbellatus, Russula cyanoxantha, and Cordyceps sinensis. Ergone has been demonstrated to possess cytotoxic activity. However, the molecular mechanisms by which ergone exerts its cytotoxic activity are currently unknown.

METHODS

In the present study, ergone possessed a remarkable anti-proliferative activity toward human hepatocellular carcinoma HepG2 cells. We assayed the cell cycle by flow cytometry using PI staining; investigated the exposure of phosphatidylserine at the outer layer of the cytoplasmic membrane by the FITC-annexin V/PI staining; observed the nuclear fragmentation by Hoechst 33258 staining and studied the protein expression of Bax, Bcl-2, p-53, procaspase-3, -8, -9, PARP and cleaved PARP by Western blotting analysis.

RESULTS

Cells treated with ergone showed typical markers of apoptosis: G2/M cell cycle arrest, chromatin condensation, nuclear fragmentation, and phosphatidylserine exposure. Furthermore, PARP-cleavage; activation of caspase-3, -8, -9; up-regulation of Bax and down-regulation of Bcl-2 were observed in HepG2 cells treated with ergone, which show that both the intrinsic and extrinsic apoptotic pathways are involved in ergone-induced apoptosis in HepG2 cells. Ergosta-4,6,8(14),22-tetraen-3-one induces G2/M cell cycle arrest and apoptosis in HepG2 cells in a caspase-dependent manner.

GENERAL SIGNIFICANCE

In this study, we reported for the first time that ergone-induced apoptosis through activating the caspase. These results would be useful for the further utilization of many medicinal fungi in cancer treatment.

Quantitative HPLC method and pharmacokinetic studies of ergosta-4,6,8(14),22-tetraen-3-one, a natural product with diuretic activity from Polyporus umbellatus

A simple and specific HPLC method with dual wavelength UV detection for the determination of ergosta-4,6,8(14),22-tetraen-3-one (ergone) in rat plasma was developed and proved to be efficient. The method used ergosterol as internal standard (IS). Following a single-step protein precipitation, the analyte and IS were separated on an Inertsil ODS-3 column with a mobile phase containing methanol-water (99:1, v/v) at a flow rate of 1 mL/min. The analytes were detected by using UV detection at wavelength of 350 (ergone) and 283 (IS) nm, respectively. The calibration curve was linear over the range of 0.1-2.0 µg/mL and the lower limit of quantification was 0.1 µg/mL. The intra-day and inter-day precision studies showed good reproducibility with RSD less than 8.5%. The intra-day and inter-day accuracy ranged from 95.6 to 104%. Mean extraction recovery was above 95% at the low, medium and high concentrations. The present HPLC-UV method was simple and reliable. The method described herein had been successfully applied for the pharmacokinetic studies in male SD rats after administration of 20 mg/kg dose of solution of ergone.

Rapid resolution liquid chromatography-mass spectrometry and high-performance liquid chromatography-fluorescence detection for metabolism and pharmacokinetic studies of ergosta-4,6,8(14),22-tetraen-3-one

Ergosta-4,6,8(14),22-tetraen-3-one (ergone) from many medicinal plants has been demonstrated to possess a variety of pharmacological activities in vivo and in vitro, including cytotoxic, diuretic and immunosuppressive activity. Metabolism and pharmacokinetic studies on rat were conducted for ergone. Rapid resolution liquid chromatography with atmospheric pressure chemical ionization tandem multi-stage mass spectrometry (RRLC-APCI-MS(n)) and high-performance liquid chromatography with fluorescence detection (HPLC-FLD) methods were applied for the identification and quantification of ergone and its metabolite from rat plasma, faeces and urine. A metabolite was identified by RRLC-DAD-APCI-MS(n): 22,23-epoxy-ergosta-4,6,8(14)-triaen-3-one (epoxyergone). The concentrations of the analyte with its metabolites were determined by HPLC-FLD at excitation wavelength of 370 nm and emission wavelength of 485 nm. The samples were deproteinized with methanol after addition of camptothecin as internal standard (IS). The analysis was performed on a Diamonsil C18 column (150 mm x 4.6 mm x 5 microm) with a mobile phase gradient consisting of methanol and water at a flow rate of 1 mL min(-1). The assay was linear over the concentration range of 42-1500, 36-7500 and 42-1500 ng mL(-1) for plasma, faecal homogenate and urine respectively. The absolute recoveries were found to be 97.0+/-1.2%, 98.1+/-0.7% and 96.6+/-1.8% for plasma, faecal homogenate and urine respectively. The intra-day and inter-day relative standard deviations (RSD) were less than 10%. The previous HPLC-MS/MS method is not affordable for most laboratories because of the specialty requirement and high equipment cost. However, the HPLC-FLD method is economic and operating simply for quantitative determination of ergone and its metabolite in rat plasma, faeces and urine. In addition, liquid chromatography coupled with ion trap multi-stage mass spectrometry is becoming a useful technique for ergone metabolite identification.

A fast and sensitive HPLC-MS/MS analysis and preliminary pharmacokinetic characterization of ergone in rats

A fast and sensitive HPLC-APCI-MS/MS method was developed for the determination of ergosta-4,6,8(14),22-tetraen-3-one (ergone) in rat plasma. The plasma sample containing ergone and ergosterol (internal standard) were simply treated with acetone to precipitate and remove proteins and the isolated supernatants were directly injected into the HPLC-APCI-MS/MS system. Chromatographic separation was performed on a 1.8microm Zorbax SB-C18 column (100mm x 3.0mm) with a 97:3 (v/v) mixed solution of methanol and 0.1% aqueous formic acid being used as mobile phase. Quantification was performed by multiple selected reactions monitoring (MRM) of the transitions with (m/z)(+) 393-268 for ergone and (m/z)(+) 379-69 for the IS. The method was validated in the concentration range of 5-1600ng/mL for ergone. The precision of the assay (RSD%) was less than 10.5% at all concentrations levels within the tested range and adequate accuracy, and the limit of detection was 1.5ng/mL. The absolute recoveries of both ergone and ergosterol from the plasma were more than 95%. The developed method has been successfully applied to the pharmacokinetic study of the drug in SD rats.

1β-hydroxylfriedelin, a new natural pentacylic triterpene from the sclerotia of Polyporus umbellatus

A new pentacylic triterpene, 1β-hydroxylfriedelin, has been isolated from the sclerotia of Polyporus umbellatus (Pers.) Fries (Polyporaceae) together with 18 known compounds (2–19). The structures of these compounds were elucidated on the basis of spectral data.