Decaturenol A and known oxalicine related meroterpenoids isolated from Penicillium decaturense RO050, and their new biological activities.

Decaturenol A (1), a new oxalicine related meroterpenoid, has been isolated from Penicillium decaturense RO050 along with seven known compounds (2-8). The structure of 1 was elucidated by spectroscopic data. The effects of isolated compounds (1-8) on endoplasmic reticulum (ER) stress-induced cell death in HT22 hippocampal nerve cells and on the interleukin 10 (IL-10)-induced expression of CD163, a M2 phenotype marker, in human monocyte-derived macrophages were evaluated. While decaturenol A (1) exhibited a protective effect on ER stress-induced cell death in HT22 cells at 10 µM, on the other hand oxalicine A (7) showed cytotoxic activity (IC50 = 5.9 µM). Additionally, decaturenol A (1), decaturins D (2), E (3), and B (4) inhibited the IL-10-induced expression of CD163 each at a concentration of 20 µg/mL.

Mariannamides A and B, new cyclic octapeptides isolated from Mariannaea elegans NBRC102301.

Two new cyclic octapeptides, mariannamides A (1) and B (2), have been isolated from Mariannaea elegans NBRC102301, a Pinus densiflora-derived filamentous fungus. Their structures were elucidated to be cyclo-(l-Leu1-l-Pro1-l-Pro2-l-Leu2-l-Ile1-l-Pro3-l-Val1-l-Ile2) and cyclo-(l-Leu1-l-Pro1-l-Pro2-l-Leu2-l-Ile1-l-Pro3-l-Val1-l-Val2) based on spectroscopic data and Marfey's method. Mariannamide A (1) promoted mRNA expression of sirtuin 1 (SIRT1) in C2C12 cells, a mouse skeletal muscle myoblast cell line, and showed the antimicrobial activity against Escherichia coli and Cryptococcus neoformans.

Identification of glycyrrhizin metabolites in humans and of a potential biomarker of liquorice-induced pseudoaldosteronism: a multi-centre cross-sectional study.

Liquorice [main ingredient, glycyrrhizin (GL)] is widely used as a food sweetener and herbal medicine. Occasionally, liquorice consumption causes pseudoaldosteronism as a side effect which causes oedema, hypokalaemia, and hypertension due to hyperactivity of mineral corticoid receptor. We aimed to detect GL metabolites in human blood and urine samples and to determine the pathological relationship between GL metabolites and pseudoaldosteronism. For this multi-centre, retrospective, cross-sectional study, we recruited patients who had visited Center for Kampo Medicine in Keio University Hospital, Department of Japanese Oriental (Kampo) Medicine in Chiba University Hospital, Clinic of Japanese Oriental (Kampo) Medicine in Kanazawa University Hospital, and Department of Oriental Medicine in Kameda Medical Center from November 2011 to July 2018. We collected laboratory data including concentration of serum potassium, plasma activity of renin and aldosterone, and residual blood and/or urine samples of participants who had experienced symptoms/signs of pseudoaldosteronism in the form of increase in blood pressure and occurrence or aggregation of oedema while taking liquorice-containing herbal preparations, and measured GL metabolites using a highly selective liquid chromatography tandem mass spectrometer system. We registered 97 participants (mean age 60 ± 15 years; male:female 14:83). 18ß-glycyrrhetinic acid (GA) was detected in 67 serum samples (median 122 nM, range 5 nM-1.8 µM) and 18ß-glycyrrhetyl-3-O-sulfate (compound 3) in 68 samples (median 239 nM, range 2 nM-4.2 µM). 3-Monoglucuronyl 18ß-glycyrrhetinic acid, 22α-hydroxy-18ß-glycyrrhetyl-3-O-sulfate-30-glucuronide, 22α-hydroxy-18ß-glycyrrhetyl-3-O-sulfate, and GL itself were not or rarely detected. We could not find any correlation between blood pressure or peripheral oedema and serum concentration of GL metabolites. Sulfotransferase 2A1 catalysed the metabolic reaction of GA to compound 3, a major GL metabolite in human blood. High serum concentration of compound 3 was related to lower renin, aldosterone, and potassium levels, suggesting a pathological relationship between compound 3 and liquorice-induced pseudoaldosteronism. This is the first study to identify the association between a novel metabolite, compound 3, and the incidence of pseudoaldosteronism, highlighting it as a promising biomarker.

Kurarinone from Sophora Flavescens Roots Triggers ATF4 Activation and Cytostatic Effects Through PERK Phosphorylation.

In response to cellular stresses, activating transcriptional factor 4 (ATF4) regulates the expression of both stress-relieving genes and apoptosis-inducing genes, eliciting cell fate determination. Since pharmacological activation of ATF4 exerts potent anti-tumor effects, modulators of ATF4 activation may have potential in cancer therapy. We herein attempted to identify small molecules that activate ATF4. A cell-based screening to monitor TRB3 promoter activation was performed using crude drugs used in traditional Japanese Kampo medicine. We found that an extract from Sophora flavescens roots exhibited potent TRB3 promoter activation. The activity-guided fractionation revealed that kurarinone was identified as the active ingredient. Intriguingly, ATF4 activation in response to kurarinone required PKR-like endoplasmic reticulum kinase (PERK). Moreover, kurarinone induced the cyclin-dependent kinase inhibitor p21 as well as cytostasis in cancer cells. Importantly, the cytostatic effect of kurarinone was reduced by pharmacological inhibition of PERK. These results indicate that kurarinone triggers ATF4 activation through PERK and exerts cytostatic effects on cancer cells. Taken together, our results suggest that modulation of the PERK-ATF4 pathway with kurarinone has potential as a cancer treatment.

Identification of Lycopodium Alkaloids Produced by an Ultraviolet-Irradiated Strain of Paraboeremia, an Endophytic Fungus from Lycopodium serratum var. longipetiolatum.

12- epi-Lycopodine (1), a Lycopodium alkaloid, along with lycopodine (2) and huperzine A (3), were discovered in the mycelium of Paraboeremia sp. Lsl3KI076, a UV-irradiated strain of Paraboeremia sp. Lsl3, an endophytic fungus from Lycopodium serratum Thunb. var. longipetiolatum Spring. Additionally, a trace of 1 was isolated from Phlegmariurus nummulariifolius (Blume) Ching, and the structure was elucidated on the basis of spectroscopic data. This is the first report proving that a new naturally occurring Lycopodium alkaloid can be obtained from an endophytic fungus.

A glucosyltransferase specific for 4-hydroxy-2,5-dimethyl-3(2H)-furanone in strawberry.

4-Hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) is a key aroma compound in Fragaria × ananassa (strawberry). A considerable amount of HDMF is converted into HDMF ß-D-glucoside and accumulated in mature strawberry fruits. Here we isolated a novel UDP-glucose: HDMF glucosyltransferase, UGT85K16 from Fragaria × ananassa. UGT85K16 preferentially glucosylated the hydroxyl group of HDMF and its structural analogs. Although UGT85K16 also catalyzed the glucosylation of vanillin, its affinity and efficiency toward HDMF was higher. The expression of UGT85K16 mRNA correlated with the accumulation of HDMF and its glucoside in Fragaria × ananassa plants. These results suggest that UGT85K16 might be UDP-glucose: HDMF glucosyltransferase in strawberries. ABBREVIATIONS: DMMF: 2,5-dimethyl-4-methoxy-3(2H)-furanone; EHMF: 2(5)-ethyl-4-hydroxy-5(2)-methyl-3(2H)-furanone; GBV: glycosidically bound volatile; HDMF: 4-hydroxy-2,5-dimethyl-3(2H)-furanone; HMF: 4-hydroxy-5-methyl-3(2H)-furanone; HMMF: 4-hydroxy-5-methyl-2-methylene-3(2H)-furanone; PSPG: Plant secondary product glycosyltransferase; RT-PCR: reverse transcription-PCR; OMT: O-methyltransferase; UGT: UDP-glycosyltransferase.

Effects of Osthol Isolated from Cnidium monnieri Fruit on Urate Transporter 1.

(1) Background: Crude drugs used in traditional Japanese Kampo medicine or folk medicine are major sources of new chemical entities for drug discovery. We screened the inhibitory potential of these crude drugs against urate transporter 1 (URAT1) to discover new drugs for hyperuricemia. (2) Methods: We prepared the MeOH extracts of 107 different crude drugs, and screened their inhibitory effects on URAT1 by measuring the uptake of uric acid by HEK293/PDZK1 cells transiently transfected with URAT1. (3) Results: We found that the extract of the dried mature fruit of Cnidium monnieri inhibited urate uptake via URAT1. We isolated and identified osthol as the active ingredient from this extract. Osthol noncompetitively inhibited URAT1 with an IC50 of 78.8 µM. We evaluated the effects of other coumarins and found that the prenyl group, which binds at the 8-position of coumarins, plays an important role in the inhibition of URAT1. (4) Conclusions: Cnidium monnieri fruit may be useful for the treatment of hyperuricemia or gout in traditional medicine, and its active ingredient, osthol, is expected to be a leading compound for the development of new drugs for hyperuricemia.

Anti-Tumorigenic Activity of Chrysin from Oroxylum indicum via Non-Genotoxic p53 Activation through the ATM-Chk2 Pathway.

The p53 tumor suppressor plays critical roles in cell cycle regulation and apoptotic cell death in response to various cellular stresses, thereby preventing cancer development. Therefore, the activation of p53 through small molecules is an attractive therapeutic strategy for the treatment of cancers retaining wild-type p53. We used a library of 700 Myanmar wild plant extracts to identify small molecules that induce p53 transcriptional activity. A cell-based screening method with a p53-responsive luciferase-reporter assay system revealed that an ethanol extract of Oroxylum indicum bark increased p53 transcriptional activity. Chrysin was isolated and identified as the active ingredient in the O. indicum bark extract. A treatment with chrysin increased p53 protein expression and the p53-mediated expression of downstream target genes, and decreased cell viability in MCF7 cells, but not in p53-knockdown MCF7 cells. We also found that chrysin activated the ATM-Chk2 pathway in the absence of DNA damage. Hence, the inactivation of the ATM-Chk2 pathway suppressed p53 activation induced by chrysin. These results suggest the potential of chrysin as an anti-cancer drug through the activation of p53 without DNA damage.

Identification of metabolites in human and rat urine after oral administration of Xiao-Qing-Long-Tang granule using ultra high performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry.

Xiao-Qing-Long-Tang is a traditional Chinese formula used for the treatment of cold syndrome, bronchitis, and nasal allergies for thousands of years. However, the in vivo integrated metabolism of its multiple components and the active chemical constituents of Xiao-Qing-Long-Tang remain unknown. In this study, a method using ultra high performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry was established for the detection and identification of the metabolites in human and rat urine after oral administration of Xiao-Qing-Long-Tang. A total of 19 compounds were detected or tentatively identified in human urine samples, including eight prototypes and 11 metabolites. Also, a total of 50 compounds were detected or tentatively identified in rat urine samples, including 15 prototypes and 35 metabolites detected with either a highly sensitive extracted ion chromatogram method or the MSE determination using Mass Fragment software. Our results indicated that phase Ⅱ reactions (e.g. glucuronidation and sulfation) were the main metabolic pathways of flavones, while phase I reactions (e.g. demethylation and hydroxylation) were the major metabolic reaction for alkaloids, lignans, and ginger essential oil. This investigation provided important structural information on the metabolism of Xiao-Qing-Long-Tang and provided evidence to obtain a more comprehensive metabolic profile.

Gabapentin prevents oxaliplatin-induced mechanical hyperalgesia in mice.

Oxaliplatin, a platinum-based chemotherapy drug, frequently causes acute and chronic peripheral neuropathies including mechanical hyperalgesia. These adverse effects hinder anticancer therapy with the drug. In this study, we examined several drugs that might prevent oxaliplatin-induced peripheral neuropathy. Single intraperitoneal (i.p.) injection of oxaliplatin (10 mg/kg) induced cold allodynia (acetone test) and mechanical hyperalgesia (von Frey test). Gabapentin, but not simvastatin and atorvastatin, prevented oxaliplatin-induced mechanical hyperalgesia without affecting cold allodynia. Moreover, oxaliplatin caused phosphorylation of cofilin protein in the spinal cord, which has been shown to be involved in the neuropathic hyperalgesia. This increased phosphorylation of cofilin was also attenuated by gabapentin treatment. These results suggest that gabapentin is useful for relieving oxaliplatin-induced mechanical hyperalgesia and that the pathogenic mechanisms of cold allodynia and mechanical hyperalgesia differ.

3-Monoglucuronyl glycyrrhretinic acid is a possible marker compound related to licorice-induced pseudoaldosteronism.

One of the most common adverse effects of traditional Japanese kampo and traditional Chinese medicine is pseudoaldosteronism caused by licorice. In this review, the authors describe the mechanisms of licorice-induced pseudoaldosteronism by the pharmacokinetics of chemical constituents and its metabolites containing licorice. Glycyrrhizin (GL), the main constituent of licorice, is absorbed as glycyrrhetinic acid (GA), which is a metabolite of GL produced by enterobacteria before its release into the circulation. Circulating GA is metabolized in the liver to become 3-monoglucuronyl-glycyrrhetinic acid (3MGA), which is excreted into the bile via multidrug resistance protein 2 (Mrp2). If Mrp2 function is damaged for some reason, 3MGA is secreted from the liver into the circulation, and excreted into the urine via organic anion transporters expressed at the basolateral side of tubular epithelial cells. Circulating GA cannot be excreted into the urine since GA binds highly to serum albumin and thus does not pass through glomerular filtration and is not a substrate of transporters expressed on tubular epithelial cells. Licorice-induced pseudoaldosteronism develops due to the inhibition of type 2 11ß-hydrosteroid dehydrogenase (11ß-HSD2) which results in the accumulation of cortisol in tubular epithelial cells that activate mineral corticoid receptors to stimulate the excretion of potassium that results in hypokalemia. GA, unlike 3MGA, cannot pass through tubular epithelial cells and cannot inhibit the enzyme in the cells. Therefore, 3MGA may be a genuine causative agent for licorice-induced pseudoaldosteronism. When licorice is used, 3MGA in plasma or urine could function as a marker compound to prevent the adverse effects.

A rapid method for simultaneous determination of 52 marker compounds in Xiao-Qing-Long-Tang by ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

Xiao-Qing-Long-Tang (XQLT) is a classical Chinese medicine formula. It is generally used for the treatment of common cold, bronchial asthma, and allergic rhinitis in Asia. In this study, a multicomponent quantification fingerprinting approach based on ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry has been developed for the analysis of compounds in XQLT in 14.5 min. A total of 52 compounds were identified by co-chromatography of sample extract with authentic standards and comparing the retention time, UV spectra, molecular ions and characteristic fragment ions with those of authentic standards, or tentatively identified by MS(E) determination along with Mass Fragment software. Moreover, the method was validated for the simultaneous quantification of 16 components in XQLT commercial products. The method is practical for comprehensive standardization of XQLT and holistic comparison of its commercial products from different manufacturers.

Effects of Hovenia dulcis fruit and peduncle extract on alcohol metabolism.

ETHNOPHARMACOLOGICAL RELEVANCE: The dried fruit and peduncle of Hovenia dulcis Thunberg (Rhamnaceae) (HD) has been used as a folk medicine to treat liver disease, detoxify alcoholism, and prevent and cure hangovers. AIM OF THE STUDY: We investigated the pharmacology of HD on the kinetics of EtOH and on the enzymes related to alcohol metabolism to seek the scientific evidence of HD to prevent hangover, the effectiveness as a folk medicine. MATERIALS AND METHODS: EtOH was orally administered 30 min after oral administration of HD boiling water extract in rats. Then, the profiles of blood EtOH concentrations were measured. Mice were reared with food containing powdered HD for 7 days, and the activities of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) in liver were measured. Hepa1c1c7 cells were cultured with the medium containing HD extract, and the activities of ADH and ALDH were measured. RESULTS: HD extract reduced the blood EtOH concentrations in rats and induced the activities of ADH and ALDH and mRNA and protein expressions of ADH1B, ALDH1A1, and ALDH2 in the liver of mice and Hepa1c1c7 cells. Dihydromyricetin, one of the ingredients of HD, significantly induced the activities of ADH and ALDH in Hepa1c1c7 cells, however, the fractions containing hydrophilic organic compounds with small molecular weight contributed the most of the activities of HD extract. CONCLUSIONS: We clarified the experimental pharmacological evidences of HD as a folk medicine to detoxify alcoholism and prevent hangovers.

Mineral crude drug mirabilite (Mangxiao) inhibits the occurrence of colorectal cancer by regulating the Lactobacillus-bile acid-intestinal farnesoid X receptor axis based on multiomics integration analysis.

Mineral crude drug has revolutionized the treatment landscape in precision oncology niche that leads to the improvement in therapeutic efficiency on various tumor subtypes. Mangxiao (MX), a mineral crude drug in traditional Chinese medicine, has been used for treating gastrointestinal diseases for thousands of years. However, the action mechanisms are still ambiguous. Here, we attempt to explore inhibitory roles and associated pharmacological mechanisms of MX upon colorectal cancer (CRC) in APCMin/+ male mice by integrating metabolomics, 16S rDNA sequencing analyses, and metagenomic-based microbiota analysis. We found that MX can significantly inhibit the occurrence of CRC through the regulation of the dysregulated gut microbe metabolism. Furthermore, the correlation analysis of metabolomes and 16S rDNA revealed that MX could restore the disorders of gut microbes by specifically enriching the abundance of Lactobacilli to improve bile acid metabolism, which further activated the farnesoid X receptor (FXR) in CRC mice, then the improvement of gut dysbiosis could inhibit the development of CRC. Collectively, our effort confirmed MX has the capacity to intervene the development of CRC and further discovered that it targets Lactobacillus-bile acid-intestinal FXR axis, which can be regarded as a candidate medicine for future drug discovery and development against CRC.

Involvement of cardiac glycosides targeting Na/K-ATPase in their inhibitory effects on c-Myc expression via its transcription, translation and proteasomal degradation.

Cardiac glycosides (CGs) have been used for decades to treat heart failure and arrhythmic diseases. Recent non-clinical and epidemiological findings have suggested that CGs exhibit anti-tumor activities. Therefore, CGs may be repositioned as drugs for the treatment of cancer. A detailed understanding of the anti-cancer mechanisms of CGs is essential for their application to the treatment of targetable cancer types. To elucidate the factors associated with the anti-tumor effects of CGs, we performed transcriptome profiling on human multiple myeloma AMO1 cells treated with periplocin, one of the CGs. Periplocin significantly down-regulated the transcription of MYC (c-Myc), a well-established oncogene. Periplocin also suppressed c-Myc expression at the protein levels. This repression of c-Myc was also observed in several cell lines. To identify target proteins for the inhibition of c-Myc, we generated CG-resistant (C9) cells using a sustained treatment with digoxin. We confirmed that C9 cells acquired resistance to the inhibition of c-Myc expression and cell proliferation by CGs. Moreover, the sequencing of genomic DNA in C9 cells revealed the mutation of D128N in α1-Na/K-ATPase, indicating the target protein. These results suggest that CGs suppress c-Myc expression in cancer cells via α1-Na/K-ATPase, which provides further support for the anti-tumor activities of CGs.

Metabolism and excretion of kakkalide and its metabolites in rat urine, bile, and feces as determined by HPLC/UV and LC/MS/MS.

This study investigated the metabolic fate of kakkalide (irisolidone 7-xylosylglucoside), a major isoflavone found in extracts of Pueraria lobata flowers, and in rat urine, bile, and feces. Using HPLC/UV or LC/MS/MS methods, seven metabolites, tectorigenin-7-O-glucuronide, tectorigenin-7-O-sulfate, tectorigenin-4'-O-sulfate, 6-OH biochanin A-glucuronide, irisolidone-7-O-glucuronide, tectorigenin, and irisolidone were identified in rat urine after oral administration of kakkalide. Furthermore, irisolidone-7-O-glucuronide was found in bile, and irisolidone and kakkalide were found in feces. An HPLC/UV method for simultaneous quantification of all the metabolites and kakkalide in urine, bile, and feces was developed using daidzein or apigenin as the internal standard. Over a 72-h period, 13.2 ± 2.8 % of the kakkalide was excreted as seven metabolites in urine. Over the same time period, irisolidone-7-O-glucuronide excretion in bile accounted for 3.8 ± 1.1 % of the dose, while kakkalide and irisolidone excretion in feces accounted for 2.1 ± 0.7 % and 0.7 ± 0.1 % of the dose, respectively. The results indicate that urine is the primary route of kakkalide elimination in vivo and that extensive metabolism may be one of the reasons for the low bioavailability of kakkalide.

Heating or ginger extract reduces the content of Pinellia ternata lectin in the raphides of Pinellia tuber.

Pinellia tuber, the dried tuber of Pinellia ternata, causes a very strong acridity sensation in the oral and laryngopharynx mucosa when taken orally in its unprocessed form. In traditional Chinese medicine (TCM), this sensation has been called "toxicity", and Pinellia tuber must be processed using ginger extract, licorice, or alum. In Japanese traditional Kampo medicine, since "toxicity" can be eliminated by decocting, it should not be processed. However, little is known about the mechanism underlying the "detoxification" of Pinellia tubers. In this study, we produced murine antiserum using recombinant P. ternata lectin (PTL), developed an immuno-fluorescence staining method for PTL in the needle-shaped crystals (raphides) that were prepared by petroleum ether extraction (PEX) from Pinellia tuber, and elucidated the mechanism of the processing of Pinellia tuber using heat or ginger extract. After heating the raphides in water, the amount of PTL contained in the raphides was significantly reduced by the immunostaining, although the shape of the raphides was not changed. Incubating raphides with dried ginger extract also significantly reduced the amount of PTL in the raphides in a concentration-dependent manner. By the activity-guided fractionation of ginger extract, the active ingredients in the ginger extract were oxalic acid, tartaric acid, malic acid, and citric acid. Among these four organic acids, oxalic acid mainly contributed to the effect of dried ginger extract by its content in ginger extract and its activity. These results exhibit scientific evidences for the traditional theories of processing to "detoxify" Pinellia tuber in TCM and Kampo medicine.

Inhibitory effect of Bofutsushosan (Fangfengtongshengsan) extract on the absorption of fructose in rats and mice.

Bofutsushosan (BTS; fangfengtongshengsan in Chinese) is a formula in traditional Japanese Kampo and Chinese medicine comprising 18 crude drugs and used to treat obesity and metabolic syndrome. In our previous study, BTS boiling water extract inhibited the uptake of fructose absorbed via glucose transporter 5 into cultured cells. In this study, the inhibitory effect of BTS extract on the absorption of fructose from the intestine was investigated in vivo. The extract of BTS was orally administered to rats at doses equivalent to 25-fold of the daily dose for humans. One minute after sample administration, fructose was orally administered and blood samples were collected from the jugular vein 0.5, 1, 1.5, 2, and 4 h after the administration of fructose. The absorption of fructose from the intestine was significantly reduced by treatment with BTS extract, and this in vivo study reproduced previous in vitro results. Subsequently, the blood samples were collected from the portal vein 30 min after the oral administration of fructose in mice. BTS extract significantly reduced fructose absorption in mice, and compared the effect of modified BTS samples by removing one to several crude drugs from BTS. We found that the dried rhizome of Rheum palmatum (RR) significantly contributed to the inhibitory effect of BTS on fructose absorption. We found sennoside A to be the active ingredient of RR for the inhibition of fructose absorption, and that its effect almost saturated at a dose of 3 mg/kg. These results support the action mechanisms of BTS when used for the treatment of obesity in clinics and drug stores.

Antitubercular activity of disulfiram, an antialcoholism drug, against multidrug- and extensively drug-resistant Mycobacterium tuberculosis isolates.

The antimycobacterial activities of disulfiram (DSF) and diethyldithiocarbamate (DDC) against multidrug- and extensively drug-resistant tuberculosis (MDR/XDR-TB) clinical isolates were evaluated in vitro. Both DSF and DDC exhibited potent antitubercular activities against 42 clinical isolates of M. tuberculosis, including MDR/XDR-TB strains. Moreover, DSF showed remarkable bactericidal activity ex vivo and in vivo. Therefore, DSF might be a drug repurposed for the treatment of MDR/XDR-TB.

3-Monoglucuronyl-glycyrrhretinic acid is a substrate of organic anion transporters expressed in tubular epithelial cells and plays important roles in licorice-induced pseudoaldosteronism by inhibiting 11ß-hydroxysteroid dehydrogenase 2.

Licorice (glycyrrhiza root) has been used as a herbal medicine worldwide with its main active constituent being glycyrrhizin (GL). Licorice sometimes causes adverse effects such as inducing pseudoaldosteronism by inhibiting type 2 11ß-hydroxysteroid dehydrogenase (11ß-HSD2) caused by glycyrrhetinic acid (GA), a major metabolite of GL. In this study we compared the inhibitory effects of GA, GL, and 3-monoglucuronyl-glycyrrhetinic acid (3MGA), another metabolite of GL, on 11ß-HSD2 activity by using microsomes and rat kidney tissue slices. GA, 3MGA, and GL inhibited 11ß-HSD2 in rat kidney microsomes, with IC(50) values of 0.32, 0.26, and 2.2 µM, respectively. However, the inhibitory activity of these compounds was reduced markedly, in the slices, in a medium containing 5% bovine serum albumin. Assays using human embryonic kidney 293 cells with transient transformation in transporter genes showed that 3MGA is a substrate of human organic anion transporter (OAT) 1, human OAT3, and human organic anion-transporting peptide 4C1, whereas GA is not. When GA (100 mg/kg/day) was administered orally for 16 days to Eisai hyperbilirubinemic rats, plasma concentrations and urinary excretion of 3MGA were significantly higher, whereas the activity of 11ß-HSD2 in kidney microsomes was significantly lower compared with Sprague Dawley rats. These results suggest that 3MGA is actively transported into tubules through OATs, resulting in the inhibition of 11ß-HSD2. Because the plasma level of 3MGA depends on the function of hepatic transporters, monitoring 3MGA levels in plasma or urine may be useful for preventing pseudoaldosteronism when licorice or GL is prescribed to patients.