Coumarin glycosides from Hydrangea paniculata slow down the progression of diabetic nephropathy by targeting Nrf2 anti-oxidation and smad2/3-mediated profibrosis.

BACKGROUND: Water extract of Hydrangea paniculata (HP) stem, rich in coumarin glycosides, has been demonstrated to have renal protective effect in several experimental kidney injury animal models. Currently, it is under pre-clinical development as a class 5 herbal drug against membranous nephropathy. However, whether it also benefits diabetic nephropathy (DN) is not clear. PURPOSE: This study was performed to investigate the protective effect of HP on streptozotocin-induced experimental DN, and further understand its molecular mechanisms. METHODS: In the present study, type 1 diabetes rat model was established by the intraperitoneal injection of streptozotocin. HP was orally administered every day for three months. Biochemical analysis and histopathological staining were conducted to evaluate the renal functions. In vivo pharmacokinetic study was conducted to analyse the metabolites of HP with high blood drug concentration. In vitro assay using these metabolites was performed to analyse their ability to reduce reactive oxygen species (ROS) production induced under high glucose (HG) condition by flow cytometry. Reverse transcription-polymerase chain reaction was conducted to analyse the mRNA level of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and IL6 and western blot was performed to analyse the phosphorylation status of smad 2/3 in HK2 cells under TGFß1 stimulation. RESULTS: The treatment with HP significantly reduced the blood urea nitrogen and serum creatinine content, and urine albumin excretion in diabetic rats, and increased the creatinine clearance rate. Periodic acid-schiff and methenamine staining and immunohistochemistry revealed that HP also ameliorated glomerulosclerosis and tubular vacuolar degeneration, as well as the deposition of fibronectin and collagen IV in the glomeruli. Pharmacokinetic study results revealed that the major coumarin compounds from HP were metabolised into umbelliferone and esculetin. By in vitro assay, umbelliferone and esculetin were found to significantly decrease ROS production induced by HG content, as well as increase the mRNA level of Nrf2. HP and its metabolites also can down-regulate fibronectin secretion in HK2 cells stimulated by TGFß1 and inhibit smad2/3 phosphorylation. CONCLUSION: HP has beneficial effect on DN by increasing Nrf2 expression and inhibiting TGF-smad signal activation. Further, it can be a novel herbal drug against DN.

[Simultaneous determination of daphnetin, daphnoretin, daphneticin in rat plasma by LC-MS/MS and its application in pharmacokinetic study].

To establish HPLC-MS/MS method for simultaneous determination of daphnetin, daphnoretin, and daphneticin in rat plasma after oral and intravenous administration of Daphne giraldii extract, and then use them in the calculation of pharmacokinetic parameters. Six sprague-dawley rats received intragastric administration of D. giraldii extract (daphnetin, daphnoretin and daphneticin were 88.40, 3.24 and 4.28 mg•kg⁻¹, respectively). Their drug plasma concentration was determined by LC-MS/MS with schisandrin as an internal standard to draw plasma concentration-time curve. The pharmacokinetic parameters were calculated by Kinetica 4.4. The results showed that the linear range was 5-1 000 µg•L⁻¹ for daphnetin, daphnoretin and daphneticin, and the method ological test showed conformance to the requirements.The intraday and inter-day variable coefficients (RSD) were both less than 15.0%, indicating that both of legitimate precise and accuracy were consistent with the analysis requirements of biological samples. For daphnetin, the pharmacokinetic parameters Tmax, Cmax, AUC0-t, T1/2 and MRT were 4 h, 858.96 µg•L⁻¹, 10 566.4 µg•L⁻¹â€¢h, 5.19 h and 9.43 h, respectively. For daphnoretin, the pharmacokinetic parameters Tmax, Cmax, AUC0-t, T1/2 and MRT were 2.92 h, 178.00 µg•L⁻¹, 905.89 µg•L⁻¹â€¢h, 3.50 h and 6.95 h, respectively. For daphneticin, the pharmacokinetic parameters Tmax, Cmax, AUC0-t, T1/2 and MRT were 2 h, 36.67 µg•L⁻¹, 355.11 µg•L⁻¹â€¢h, 4.95 h and 8.27 h, respectively. The LC-MS/MS analysis method established in this study was proved to be so accurate and sensitive that it can be applied to the pharmacokinetic study of daphnetin, daphnoretin and daphneticin.

The interaction of auraptene and other oxyprenylated phenylpropanoids with glucose transporter type 4.

BACKGROUND: Glucose transporter 4 (GLUT4) is firmly established to play a pivotal role in glucose metabolism and in particular in modulating the insulin-stimulated glucose transport in several tissues, such as skeletal muscle and adipose tissue. Stimulation of GLUT4 by insulin results in its translocation to the plasma membrane, activation of several kinases, and finally in a large glucose influx into cells. PURPOSE: In this study we investigated the modulating properties of four biologically active oxyprenylated ferulic acid and umbelliferone derivatives and of their unprenylated parent compounds on GLUT-4 mediated glucose uptake and translocation. METHODS: Oxyprenylated phenylpropanoids have been synthesized in high yields and purity by already reported methodologies. All the synthesized chemicals were tested for their capacity to modulate GLUT4 mediated glucose uptake and GLUT4 translocation in L6 rat skeletal myoblasts in the concentration range 0.1 - 10 µM. Insulin (0.1 µM) was used as positive control. Western blot analysis was employed to assess if GLUT4 translocation occurred prior to increase of glucose uptake. Statistical analyses were carried out by the Dunnett multiple comparison test. RESULTS: 4'-Geranyloxyferulic acid (GOFA), 7-isopentenyloxycoumarin, and auraptene (7-geranyloxycoumarin) increased glucose uptake in a concentration-dependent manner, and significant increases were observed at 0.1 µM for GOFA, and 10 µM for 7-isopentenyloxycoumarin, and auraptene. These products also were able to significantly promote the translocation of GLUT4 to the plasma membrane of L6 myotubes. After treatment with compounds for 15 min, the incorporated amounts of GOFA, 7-isopentenyloxucoumarin, and auraptene were 0.15, 0.32, and 1.77 nmols/60-mm culture dish, respectively. A sample of raw Italian propolis, found to be rich in GOFA and auraptene, was also seen to mimic insulin-effect in the concentration range 0.01 - 1.0 mg/ml. CONCLUSIONS: Among the compounds assayed, auraptene showed to possess potentialities to be a potent activator of both translocation of GLUT4 and glucose influx into skeletal muscle cells with the highest bioavailability among effective compounds. Its capacity to modulate sugar metabolism, coupled to its presence in edible Citrus fruits, can be regarded as an additional reason to account for the already known stimulating properties of some vegetable (e.g. bitter orange).

A kinetic study of the main guaco metabolites using syrup formulation and the identification of an alternative route of coumarin metabolism in humans.

For decades guaco species have been empirically used for the treatment of respiratory diseases. However, studies have shown that the toxic and therapeutic effects of the main guaco metabolites are dose-dependent, and none clinical study was done to evaluate the behavior of these substances in humans. In this work, a pilot study measuring the kinetic profile of the main guaco metabolites was performed leading to the knowledge of an alternative route of coumarin metabolism in humans. Initial screenings demonstrated that the administration of 60 mL of guaco syrup (single dose) did not provide sufficient levels of coumarin (COU), 7-hydroxycoumarin (7-HCOU), o-coumaric acid (OCA) and kaurenoic acid (KAU). The pharmacokinetic parameters were calculated by orally administering 60 mL of guaco syrup spiked with 1500 mg of COU. The kinetic study demonstrated that the plasmatic levels of 7-HCOU (considered the main metabolite of COU) were 10 times lower than the levels of COU, and the kinetic profile of 7-HCOU suggests sequential metabolism in the liver with low access of 7-HCOU to the systemic circulation. The study also demonstrated that OCA is one of the main bioavailable metabolites of COU. Therefore, the hydrolysis of the lactone ring forming a carboxylated compound is one of the possible routes of COU metabolism in humans. The half-lives of COU, 7-HCOU and OCA were approximately 4.0, 1.0 and 3.0 h, respectively and there was evidence that the recommended dosage of guaco syrup did not provide sufficient levels of COU, 7-HCOU or OCA to obtain a bronchodilation effect. Clinical studies are necessary to prove the efficacy and safety of products based on guaco.

The effects of Glycyrrhizae uralenis and its major bioactive components on pharmacokinetics of daphnetin in Cortex daphnes in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Glycyrrhizae uralenis (GU) is often prescribed together with Cortex daphnes (CD) in traditional Chinese medicinal practice to increase the efficacy of CD on the treatment of rheumatoid arthritis (RA), but the reasons were still unknown. In order to clarify the rationality of herbaceous compatibility between CD and GU, the comparative evaluations on pharmacokinetic behaviors of daphnetin (a predominantly active ingredient in CD) after intragastric administration of CD and CD-GU (combination of CD and GU) extract were studied. In addition, the effects of glycyrrhizin and liquiritin, active ingredients of Glycyrrhiza triterpenes and Glycyrrhiza flavones respectively, on the pharmacokinetics of daphnetin were also investigated. MATERIALS AND METHODS: Five groups of rats were orally administered with CD extract, CD-GU extract, pure daphnetin, co-administration of daphnetin and glycyrrhizin as well as co-administration of daphnetin and liquiritin at the same single dose of daphnetin (20 mg/kg). The rat plasma concentrations of daphnetin were determined by our developed UPLC-MS/MS method. The pharmacokinetics of daphnetin in above groups were investigated and compared. RESULTS: Comparing with oral administration of CD extract, AUC and Tmax of daphnetin significantly increased after giving CD-GU (p<0.05). In addition, in comparison to daphnetin alone, co-administration of daphnetin with liquiritin significantly increased the AUC and Cmax of daphnetin for ~1.5-fold, while co-administered with glycyrrhizin showed limited impact on the pharmacokinetics of daphnetin. CONCLUSIONS: In this study, it was found that liquiritin, one of the major components of GU, significantly enhanced the bioavailability of the main component daphnetin in CD. In addition, the bioavailability of daphnetin in the CD-GU prescription was also significantly higher than that in CD alone, which could be due to liquiritin. Such results explained the mechanism of the increased efficacy in treating RA with the combined use of CD and GU.

An integrated strategy based on UPLC-DAD-QTOF-MS for metabolism and pharmacokinetic studies of herbal medicines: Tibetan "Snow Lotus" herb (Saussurea laniceps), a case study.

ETHNOPHARMACOLOGICAL RELEVANCE: Saussurea laniceps Hand.-Mazz. (SL) has long been used under the herbal name Tibetan "Snow Lotus" for the treatment of rheumatoid arthritis, stomachache and dysmenorrhea in Tibetan folk medicine. Since herbal medicine (HM) is a synergistical system with multiple components, both of the metabolism and pharmacokinetic studies of HM are interdependent. This study aimed to develop an integrated strategy based on the UPLC-DAD-QTOF-MS technique for metabolism and pharmacokinetic studies of HM. MATERIAL AND METHODS: SL was used here as a test herb to verify the feasibility of the proposed strategy. SL was administered to rats, then, the blood plasma, urine and feces were analyzed to determine the metabolic profiles. Using our strategy, umbelliferone and scopoletin were evaluated to be the key bioactive components. Their pharmacokinetic parameters were measured and biotransformation pathways were elucidated. RESULTS: After oral administration of SL to rats, 17 components in blood, 10 components in urine and 2 components in feces were identified and characterized using our UPLC-DAD-QTOF-MS method. Umbelliferone, scopoletin and their metabolites were found to be the major components involved in the metabolism process. Literature reports also suggest that umbelliferone and scopoletin are responsible for the therapeutic effects of SL, thus these two components were selected as the active markers for pharmacokinetic study. In the test of validity, the established method presented good linearity with R(2)>0.99. The relative standard deviation value was below 13.9% for precision, and recovery studies for accuracy were found to be within the range 91.8-112.5%. CONCLUSION: The present strategy offers, simultaneously, precision in quantitative analysis (metabolism study) and accuracy in quantitative analysis (pharmacokinetic study) with greater efficiency and less costs, which is therefore reliably used for integrated metabolism and pharmacokinetic studies of HM.

Evaluation of percutaneous absorption of esculetin: effect of chemical enhancers.

Percutaneous transdermal absorption of esculetin (6,7-dihydroxycoumarin), an oxidative damage inhibitor, was evaluated by means of in vitro permeation studies in which vertical Franz-type diffusion cells and pig ear skin were employed. To determine the absorption of esculetin, we validated a simple, accurate, precise, and rapid HPLC-UV method. Additionally, the effects of several percutaneous enhancers were studied. Pretreatment of porcine skin was performed with ethanol (control vehicle), decenoic acid, oleic acid, R-(+)-limonene, and laurocapram (Azone®) (5% in ethanol, w/w, respectively). Pretreatment of skin with oleic acid or laurocapram led to statistically significant differences in the transdermal flux of esculetin with respect to controls. Of the two enhancers, laurocapram showed the greatest capacity to enhance the flux of esculetin across pig skin.

[Effects of glycyrrhiza extract on pharmacokinetics property of daphnetin in rats].

OBJECTIVE: To research the influence of glycyrrhiza extract on the pharmacokinetics characteristic parameters of daphnetin, which was aimed to explore the rationality of concert application of drugs. METHOD: The rats received intragastric administration of daphnetin and glycyrrhiza extract containing the same daphnetin respectively. The blood concentration of daphnetin was assayed by LC-MS. The data was processed by program DAS2.1.1. RESULT: Glycyrrhiza extract can reduce the t(1/2), tmax and Ke of daphnetin, while increased the Ka and AUC(0-infinity). CONCLUSION: Glycyrrhiza extract promoted the oral absorption of daphnetin, slowed down the elimination and increased the biological availability.

Silkworm as a model animal to evaluate drug candidate toxicity and metabolism.

To evaluate the feasibility of using the silkworm as a model animal for screening drug candidates, we examined whether the lethal dose of cytotoxic chemicals in silkworm, Bombyx mori, were consistent with those in mammals, and compared the metabolic pathways of these drugs between silkworms and mice. The lethal dose levels of cytotoxic chemicals in silkworms were consistent with those in mammals. We examined the fate of model drugs, 4-methyl umbelliferone, umbelliferone, and 7-ethoxycoumarine, in silkworm larvae. The half-life of 4-methyl umbelliferone in the silkworm larvae hemolymph was 7.0+/-0.1 min, similar to that in mouse blood. In silkworm larvae, 4-methyl umbelliferone was conjugated with glucose, whereas in mammals it is conjugated with glucuronate or sulfate. These results are consistent with a previous report that UDP-glucosyltransferase catalyzes the conjugation of 4-methyl umbelliferone. The glucose-conjugation reaction of 4-methyl umbelliferone was observed in microsomal fractions of fat bodies isolated from silkworms. Furthermore, most umbelliferone and 7-ethoxycoumarine injected into the hemolymph of silkworms was eliminated through the feces in the glucose-conjugated form. These findings suggest that chemicals are metabolized through a pathway common to both mammals and silkworms: reaction with cytochrome P450, conjugation with hydroxylated compounds, and excretion.

[Absorption and transport of 6 coumarins isolated from the roots of Angelica pubescens f. biserrata in human Caco-2 cell monolayer model].

OBJECTIVE: To study the absorption and transepithelial transport of six coumarins (umbelliferone, osthole, columbianadin, columbianetin acetate, angelol-A and angelol-B, isolated from the roots of Angelica pubescens f. biserrata) in the human Caco-2 cell monolayer model. METHODS: The in vitro cultured human colon carcinoma cell line, Caco-2 cell monolayer model, was applied to study the absorption and transport of the six coumarins from apical (AP) to basolateral (BL) side and from BL to AP side. The six coumarins were measured by reversed-phase high-performance liquid chromatography (HPLC) coupled with ultraviolet absorption detector. Transport parameters and apparent permeability coefficients (P(app)) were calculated and compared with those of propranolol as a control substance of high permeability and atenolol as a control substance of poor permeability. The transport mechanism of angelol-B was assayed by using iodoacetamide as a reference standard to inhibit ATP-dependent transport and MK571 as a well-known inhibitor of MRP2. RESULTS: The absorption and transport of six coumarins were passive diffusion as the dominating process. The P(app) values of umbelliferone, osthole, columbianadin, columbianetin acetate, angelol-A and angelol-B from AP to BL side were (2.679+/-0.263) x 10(-5), (1.306+/-0.324) x 10(-5), (0.595+/-0.086) x 10(-6), (2.930+/-0.410) x 10(-6), (1.532+/-0.444) x 10(-5) and (1.413+/-0.243) x 10(-5) cm/s, and from BL to AP side were (3.381+/-0.410) x 10(-5), (0.898+/-0.134) x 10(-5), (0.510+/-0.183) x 10(-6), (0.222+/-0.025) x 10(-6), (1.203+/-0.280) x 10(-5) and (0.754+/-0.092) x 10(-5) cm/s, respectively. In this assay, the P(app) value of propranolol was 2.18 x 10(-5) cm/s and the P(app) value of atenolol was 2.77 x 10(-7) cm/s. Among the 6 coumarins, the P(app) values of umbelliferone, osthole, angelol-A and angelol-B from AP to BL side were identical with that of propranolol, and columbianadin and columbianetin acetate lied between propranolol and atenolol. When replaced the HBSS with EBSS, and iodoacetamide or MK-591 were used in the experiment, the P(app) of angelol-B had no statistical difference as compared with the control group. In the mean total recoveries, umbelliferone was (83.31+/-3.52)%, angelol-A was (77.39+/-7.38)%, osthole, columbianadin and angelol-B were between 50% to 65%, and columbianetin acetate was lower than 10%. The accumulation rates of osthole and columbianadin in the Caco-2 cells were (36.15+/-5.87)% and (53.90+/-4.39)%, respectively. CONCLUSION: The absorption and transport of umbelliferone, osthole, columbianadin, columbianetin acetate, angelol-A and angelol-B are passive diffusion as the dominating process in Caco-2 cell monolayer model. Umbelliferone, osthole, angelol-A and angelol-B are estimated to be highly absorbed compounds, and columbianadin and columbianetin acetate are estimated to be moderately absorbed compounds. In the Caco-2 cells, osthol and columbianadin appear to accumulate, and columbianetin acetate may be metabolized. The absorption and transport of angelol-B are not influenced by the change of pH and the presence of iodoacetamide or MK571.