Dimethylene Dioxybiphenyl-2,2′-dicarboxylate Research Articles

A validated HPLC method for the determination of dimethyl‐4,4′‐dimethoxy‐5,6,5′,6′‐dimethylene dioxybiphenyl‐2,2′‐dicarboxylate (DDB) with fluorescence detection in raw material and pill form: application to an in vitro dissolution test and a content uniformity test

A simple, sensitive and rapid HPLC method with fluorescence detection for the determination of dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDB) in the raw material and pill form was developed. Liquid chromatography was performed on a C18 column (250 × 4.6 mm i.d., 5 µm particle size), the mobile phase consisted of methanol and 0.05 M sodium dihydrogen phosphate buffer (80 : 20, v/v), and the apparent pH of the mobile phase was adjusted to 3. The fluorescence detector was operated at excitation/emission wavelengths of 275/400 nm. The proposed method allows the determination of DDB within concentration range 0.1-1.5 µg/mL with a limit of detection of 0.032 µg/mL, a limit of quantification of 0.097 µg/mL and a correlation coefficient of 0.9997. The proposed method has been successfully applied for the analysis of DDB in its pills with a percentage recovery of 98.45 ± 0.32. The method was fully validated according to ICH guidelines. Moreover, the high sensitivity of the method permits its use in an in vitro dissolution test for DDB under simulated intestinal conditions. In addition, the proposed method was extended to a content uniformity test according to USP guidelines.

Derivative spectrophotometric and micellar high performance liquid chromatographic methods for simultaneous determination of silymarin and dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxybiphenyl-2,2′-dicarboxylate (DDB) in raw materials and capsules

First derivative ultraviolet spectrophotometric and micellar high performance liquid chromatographic assay methods were developed and validated for the simultaneous determination of silymarin and dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxybiphenyl-2,2′-dicarboxylate (DDB) in the pure form and in combined capsules. The first derivative (D1) was performed by measuring the amplitudes at 279 and 255 nm for silymarin and DDB, respectively. The calibration graphs were linear in the range of 3–40 μg mL−1 for silymarin and 3–30 μg mL−1 for DDB. An isocratic reversed phase chromatographic assay method was also developed for the determination of both drugs, a C18 column (250 mm × 4.6 mm i.d., 5 μm particle size) was used with a mobile phase composed of 0.17 M sodium dodecyl sulphate, 12% butanol and 0.3% triethylamine, all prepared in 0.02 M phosphoric acid and adjusted to pH 3.5. The flow rate was 1 mL min−1. The effluents were monitored at 288 nm and floctafenine was used as the internal standard. Plots of the peak area ratios of each drug to floctafenine were found to be linear in the range of 1–15 μg mL−1 for silymarin and 1–12 μg mL−1 for DDB. The proposed methods were validated according to ICH guidelines. The methods were successfully applied in the estimation of silymarin and DDB in their combined capsules dosage form.

Efficacy and tolerability of diphenyl-dimethyldicarboxylate plus garlic oil in patients with chronic hepatitis

To investigate the hepatoprotective effect, safety and tolerability of oral preparation comprising dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDB) plus garlic oil (GO) in chronic hepatitis patients. In this double-blind, placebo-controlled clinical trial conducted for 6 weeks with 1-week follow-up, a total of 88 patients with histologically confirmed chronic hepatitis and persistently elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were enrolled and randomly assigned to one of 4 treatment groups: placebo (Group A) and 3 escalating dose groups (2, 3, or 6 study drug capsules a day) (Groups B - D). Each study drug capsule contains 25 mg DDB plus 50 mg GO. Efficacy was assessed by monitoring changes in the circulating activities of ALT and AST as surrogate markers for liver injury. Safety and tolerability were assessed based on the evaluation of clinically adverse events and laboratory test results. Of 88 patients, 83 took at least one dose of study drug and 79 completed the study without any protocol violation. The majority of patients (81/83, 98%) had been infected with HBV. The proportions of patients whose ALT levels returned to normal ranges at Week 6, a primary outcome, were significantly different among 4 groups: 16% (3/19), 41% (9/22), 52% (11/21), and 88% (15/17) in Groups A, B, C, and D, respectively (p < 0.001). The proportions were significantly higher in Groups C (p = 0.022) and D (p < 0.001) but not in Group B compared to Group A. Interestingly, the proportion of Group D was higher than that of Group C (p = 0.034), suggesting a dose-response effect of DDB plus GO on the decrease of ALT levels. The mean ALT levels started to decrease from Week 1 in patients treated with DDB plus GO, whereas no decrease was seen in placebo group. The mean AST levels had a decreasing trend in all doses of DDB plus GO groups. Notably, patients treated with 6 capsules of DDB plus GO daily exhibited the statistically significant decrease in AST levels from Week 3. However, there was no difference in the proportions of patients with the AST decrease to normal ranges after 6-week therapy among 4 groups. The effects of DDB plus GO on decreases in ALT and AST levels lasted until 1 week after completion of treatment. Additionally, the ratios of ALT to AST gradually decreased in patients treated with DDB plus GO over time, suggesting higher degrees of reduction in ALT than in AST in those groups. No clinically meaningful adverse events and laboratory abnormalities were observed during the study period. The 6-week treatment of DDB plus GO lowered serum aminotransferase activities in patients with chronic hepatitis induced by HBV and/or HCV and was well tolerated. For the treatment of viral hepatitis patients, the optimal dose of this preparation was 3 to 6 capsules per day.

Antitumor Agents. 293. Nontoxic Dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylenedioxybiphenyl-2,2′-dicarboxylate (DDB) Analogues Chemosensitize Multidrug-Resistant Cancer Cells to Clinical Anticancer Drugs

Novel dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxybiphenyl-2,2'-dicarboxylate (DDB) analogues were designed and synthesized to improve their chemosensitizing action on KBvin (vincristine-resistant nasopharyngeal carcinoma) cells, a multidrug resistant cell line overexpressing P-glycoprotein (P-gp). Structure-activity relationship analysis showed that aromatic and bulky aliphatic side chains at the 2,2'-positions effectively and significantly sensitized P-gp overexpressing multidrug resistant (MDR) cells to anticancer drugs, such as paclitaxel (TAX), vincristine (VCR), and doxorubicin (DOX). DDB derivatives 16 and 23 showed 5-10 times more effective reversal ability than verapamil (VRP) for TAX and VCR. Analogue 6 also exhibited five times greater chemosensitizing effect against DOX than VRP. Importantly, no cytotoxicity was observed by the active DDB analogues against both non-MDR and MDR cells, suggesting that DDB analogues serve as novel lead compounds for the development of chemosensitizers to overcome the MDR phenotype. The mechanism of action studies demonstrated that effective inhibition of P-glycoprotein by DDB analogues dramatically elevated the cellular concentration of anticancer drugs.

Pharmacokinetic interaction between liquiritigenin (LQ) and DDB: Increased glucuronidation of LQ in the liver possibly due to increased hepatic blood flow rate by DDB

It has been reported that both liquiritigenin (LQ) and dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylenedioxybiphenyl-2,2′-dicarboxylate (DDB) have a hepatoprotective effect, and administration of both drugs together shows additive protective effect against acute liver injuries. Therefore, the pharmacokinetic interaction between LQ and DDB in rats was studied. LQ (20 and 50 mg/kg for the i.v. and p.o. administration, respectively), DDB (10 mg/kg for both i.v. and p.o. administration), and both drugs together were once administered intravenously or orally to rats. After the i.v. administration of both drugs together, the Cl nr and AUC of LQ were significantly faster (by 30.5%) and smaller (by 22.5%), respectively, than those of without DDB due to the faster hepatic blood flow rate by DDB. After the p.o. administration of both drugs together, the AUC of LQ was comparable to that of without DDB due to negligible effect of DDB on intestinal metabolism of LQ. The pharmacokinetic parameters of DDB after both i.v. and p.o. administration were not altered by LQ, indicating that LQ did not considerably affect the pharmacokinetics of DDB in rats.

Contribution of a significant first-pass effect of dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxybiphenyl-2,2′-dicarboxylate in the liver to its poor bioavailability in rats

Abstract Objectives The objective of this study was to investigate the mechanism responsible for the poor oral bioavailability of dimethyl-4′,4′-dimethoxy-5,6,5′,6′-dimethylene dioxy-biphenyl-2,2′-dicarboxylate (DDB), a hepatoprotective agent, in rats. Methods DDB was intravenously administered to rats at doses of 0.2-1 mg/kg. To determine the hepatic first-pass effect in rats, DDB (1 mg/kg) was administered via the pyloric vein and the femoral vein. Direct measurement of intestinal permeability was attempted using Caco-2 cell monolayers and rat intestinal epithelium. Key findings A moment analysis indicated that the volume of distribution and clearance remained unchanged with the magnitude of the dose, indicating that DDB exhibited linear pharmacokinetics. When the area under the curve for DDB after administration to the pyloric vein was compared with that after femoral vein administration, the ratio (FH) was found to be 0.294, indicating a significant first-pass effect for DDB. The permeability of DDB was high in the rat intestine (1.78 ± 0.229 × 10−5 cm/s) and in Caco-2 cell monolayers (6.8 ± 0.70 × 10−5 cm/s), suggesting that DDB, in soluble form, was readily permeable across the intestinal epithelium. Conclusions These observations indicated that despite the fact that DDB was readily permeable to the intestinal epithelium, a significant first-pass metabolism was associated with its pharmacokinetics in rats.

Contribution of a significant first-pass effect of dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxybiphenyl-2,2′-dicarboxylate in the liver to its poor bioavailability in rats

The objective of this study was to investigate the mechanism responsible for the poor oral bioavailability of dimethyl-4',4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDB), a hepatoprotective agent, in rats. DDB was intravenously administered to rats at doses of 0.2-1 mg/kg. To determine the hepatic first-pass effect in rats, DDB (1 mg/kg) was administered via the pyloric vein and the femoral vein. Direct measurement of intestinal permeability was attempted using Caco-2 cell monolayers and rat intestinal epithelium. A moment analysis indicated that the volume of distribution and clearance remained unchanged with the magnitude of the dose, indicating that DDB exhibited linear pharmacokinetics. When the area under the curve for DDB after administration to the pyloric vein was compared with that after femoral vein administration, the ratio (F(H)) was found to be 0.294, indicating a significant first-pass effect for DDB. The permeability of DDB was high in the rat intestine (1.78 +/- 0.229 x 10(-5) cm/s) and in Caco-2 cell monolayers (6.8 +/- 0.70 x 10(-5) cm/s), suggesting that DDB, in soluble form, was readily permeable across the intestinal epithelium. These observations indicated that despite the fact that DDB was readily permeable to the intestinal epithelium, a significant first-pass metabolism was associated with its pharmacokinetics in rats.

Validated stability-indicating HPLC method for the determination of dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxybiphenyl-2,2′-dicarboxylate (DDB) and its degradation products

High-performance liquid chromatographic method was developed for the quantitative determination of dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxybiphenyl-2,2′-dicarboxylate (DDB) and its degradation products. Forced degradation studies were performed on bulk sample of DDB using acid (1N hydrochloric acid), alkaline (0.1N sodium hydroxide), oxidation (0.33% hydrogen peroxide), heat (70 °C) and photolytic degradation. The chromatographic method was fine tuned using the samples generated from forced degradation studies. Good resolution between the peaks corresponds to degradation products and the analyte was achieved on 5 μm ODS column (Luna, Phenomenex, USA). The mobile phase consists of a mixture of acetonitrile and water (60:40, v/v). Quantitation was achieved with UV detection at 235 nm based on peak area. The proposed HPLC method was utilized to investigate the kinetics of acidic, alkaline and oxidative degradation processes of DDB at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy were calculated. The pH-rate profiles of degradation of DDB in Britton–Robinson buffer solutions within the pH range 2–11 were studied. The developed method was validated with respect to linearity, accuracy, precision, robustness and forced degradation studies prove the stability-indicating power of the method.

Liquiritigenin, an aglycone of liquiritin in Glycyrrhizae radix, prevents acute liver injuries in rats induced by acetaminophen with or without buthionine sulfoximine

Glycyrrhizae radix has been used as one of the oldest and most frequently employed botanicals in both western and oriental countries. Previously, we showed that liquiritigenin (LQ), an aglycone of liquiritin in G. radix, exerts cytoprotective effects against heavy metal-induced toxicity in vitro. This study investigated in vivo protective effects of LQ against acute liver injuries induced by acetaminophen (APAP) or APAP plus buthionine sulfoximine (BSO). Liver injuries were assessed by blood biochemistry and histopathology in rats administered with LQ purified from the acid hydrolyates of liquiritin singly (p.o. or i.v., 2–4 days) or in combination with dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylenedioxybiphenyl-2,2′-dicarboxylate (DDB), a synthetic derivative of Schisandrin C in Fructus shizandrae, and exposed to APAP or APAP + BSO. LQ treatments (oral) effectively decreased liver injuries induced by a single dose of APAP, as evidenced by decreases in hepatic necrosis and inflammation as well as plasma alanine aminotransferase and lactate dehydrogenase activities. LQ, when intravenously applied, enhanced hepatoprotective effect with a greater potency. APAP + BSO led to severe liver injuries, resulting in lethality. LQ pretreatments significantly reduced the potentiated liver necrosis, decreasing mortality. In spite of the improvement in blood biochemistry, DDB failed to protect the liver from injuries induced by APAP or APAP + BSO. Combined treatments of rats with LQ and DDB showed some additive protective effect. The present study demonstrates that LQ efficaciously protects the liver from acute injuries induced by APAP or from APAP-induced severe injuries during GSH deficiency, indicating that LQ is one of the principal cytoprotective components comprised in G. radix.

Garlic oil and DDB, comprised in a pharmaceutical composition for the treatment of patients with viral hepatitis, prevents acute liver injuries potentiated by glutathione deficiency in rats

A pharmaceutical composition PENNEL ® comprising garlic oil (GO) and dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxybiphenyl-2,2′-dicarboxylate (DDB) as ingredients active for phase II enzyme induction and liver protection, respectively, has been used as a curative preparation for patients with acute or chronic viral hepatitis. In spite of the wide clinical use of PENNEL ® in Asian and Middle Eastern countries, whether GO + DDB treatment synergistically protects the liver from injuries potentiated by GSH deficiency compared to the individual treatment has not been determined. This study investigated the effects of GO + DDB in comparison with each ingredient alone on chemical-induced liver injury potentiated by a GSH depleting agent. Rats that had been daily pretreated with GO + DDB, GO, DDB, ursodesoxycholic acid or silymarin for 6 days were exposed to buthionine sulfoximine (BSO) and then injected with a single dose of CCl 4. The effects of the agents on acute liver toxicities induced by BSO, CCl 4 or BSO + CCl 4 were assessed by blood biochemistry and histopathology. GO + DDB pretreatment effectively prevented increases in plasma aminotransferases or lactate dehydrogenase activities in rats exposed to BSO + CCl 4, compared to GO or DDB treatment alone. Whereas BSO potentiated CCl 4-induced liver injuries as evidenced by elevations in central necrosis, hepatocyte degeneration and inflammation, pretreatment with GO + DDB abrogated BSO + CCl 4-induced liver injuries more efficaciously than did that with GO or DDB. The hepatoprotective effect of GO + DDB was superior to that of ursodesoxycholic acid or silymarin. Also, blood biochemistry indicated that GO + DDB pretreatment prevented increases in plasma triglyceride contents in rats insulted with CCl 4 or BSO + CCl 4. The present study demonstrated that GO + DDB, when daily pretreated for six consecutive days, exerted synergistic protection of the liver from chemical-induced injury potentiated by the condition of GSH deficiency, and has additional advantages in lowering the plasma lipids.

DDB liver drug as a novel ionophore for potentiometric barium (II) membrane sensor

Dimethyl-4,4-dimethoxy-5,6,5′,6′-dimethylene dioxy biphenyl-2,2-dicarboxylate (DDB) liver drug is used as a novel ionophore in plasticized poly (vinyl chloride) (PVC) matrix membrane sensors for barium ions. Optimum performance characteristics are displayed by membrane sensor incorporating DDB ionophore, potassium tetrakis(4-chlorophenyl)borate as lipophilic salt, and o-nitrophenyloctyl ether as plasticizer. The sensor exhibits a linear response over the concentration range 10 −1–10 −5 mol l −1 BaCl 2 with a Nernstian slope of 30 mV per decade and high selectivity towards Ba 2+ with respect to Li +, Na +, K +, Rb +, NH 4 +, Mg 2+, Ca 2+, Sr 2+, Mn 2+, Co 2+, Ni 2+, Cd 2+, Al 3+, La 3+, and Ce 3+ ions. The sensor response is stable over a wide pH range (4–9) and the lifetime is about 2 months. The proposed sensor is successfully applied to the determination of Ba 2+contents of some rocks.

The anti-fibrogenic effect of a pharmaceutical composition of [5-(2-pyrazinyl)-4-methyl-1,2-dithiol-3-thione] (oltipraz) and dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDB).

Liver fibrosis is a prepathological state wherein damaged liver tissues in chronic liver diseases, such as hepatitis, are not repaired to normal tissues, but converted to fibrous tissue. 5-(2-Pyrazinyl)-4-methyl-1,2-dithiol-3-thione (oltipraz), a cancer chemopreventive agent, is effective against a wide variety of chemical carcinogens. Recently, we reported that oltipraz inhibits liver fibrogenesis (Kang et al., 2002). In the present study, the effects of oltipraz in combination with dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDB) on dimethylnitrosamine (DMN)-induced liver fibrogenesis were assessed in rats. Oltipraz (30 mg/kg body weight, p.o., 3 times per week for 4 weeks) was found to inhibit the increases in plasma ALT, AST and bilirubin by DMN, whereas DDB (30 mg/kg body weight, p.o., 3 times per week for 4 weeks) attenuated the increases in the plasma ALT and bilirubin. The lowered plasma protein and albumin contents in DMN-treated rats were completely restored by oltipraz, but not by DDB. DDB decreases liver cell injury and inflammation through inhibition of nuclear factor-kB. DMN increased the accumulation of liver collagen, as indicated by the increase in the 4-hydroxyproline content in liver homogenates, which was reduced by treatment with oltipraz, but not by DDB. Given the differential effect between oltipraz and DDB, the potential enhancement of antifibrotic efficacy by the drugs was assessed in the animal model. Despite the minimal effect of DDB on DMN-induced fibrogenesis, DDB (5-25 mg/kg), administered together with oltipraz (25-5 mg/kg), showed an additive protective effect against hepatotoxicity and fibrosis induced by DMN, which was shown by the blood chemistry parameters and histopathological analysis. The adequate composition ratio of oltipraz to DDB was 5:1. These results provide information on the pharmaceutical composition, comprising of oltipraz and DDB as the active components, for the treatment and/or prevention of liver fibrosis and cirrhosis.

Inhibition of lipopolysaccharide-induced I-kappaB degradation and tumor necrosis factor-alpha expression by dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDB): minor role in hepatic detoxifying enzyme expression.

Dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate (DDB) is active against a variety of hepatotoxins and has been used as a curative agent for patients with acute and chronic viral hepatitis. Effects of DDB on the expression of xenobiotic-metabolizing enzymes and on nuclear factor-kappaB (NF-kappaB) activation and tumor necrosis factor-alpha (TNF-alpha) production by lipopolysaccharide (LPS), an endotoxin involved in inflammatory responses, were examined in rats and in RAW264.7 cells to investigate mechanistic aspects. Expression of hepatic cytochrome P450s, microsomal epoxide hydrolase and glutathione S-transferases was determined by immunoblot and Northern blot analyses. Activation of hepatic NF-kappaB and I-kappaBalpha degradation was assessed by gel mobility shift and immunoblot analyses, respectively. LPS-induced TNF-alpha expression was monitored in rats and in RAW264.7 cells by enzyme-linked immunosorbent assay and/or reverse transcription-polymerase chain reaction analysis. DDB failed to alter the expression of hepatic cytochrome P450 1A and 2C11, microsomal epoxide hydrolase and glutathione S-transferases in rats with slight inhibition of P450 2E1 expression, but induced P450 2B1/2. Pretreatment of rats with DDB prevented LPS-induced hepatic I-kappaBalpha degradation and the resultant NF-kappaB activation, and inhibited the LPS-induced plasma TNF-alpha protein and hepatic TNF-alpha mRNA expression in a dose-dependent manner. LPS-induced I-kappaBalpha degradation and TNF-alpha production were also inhibited by DDB in RAW264.7 cells, which was consistent with the results in rats. The present study demonstrated that DDB may inhibit inflammatory responses in association with reduction of NF-kappaB activation through prevention of I-kappaBalpha degradation and subsequent TNF-alpha production, but not with modulation of the detoxifying enzyme expression.

Determination of Dimethyl-4,4′-Dimethoxy-5,6,5′,6′-Dimethylene Dioxybiphenyl-2,2′-Dicarboxylate in Human Serum by High Performance Liquid Chromatography

ABSTRACT Dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxybiphenyl-2,2′-dicarboxylate (DDB) has been shown to improve liver function in chronic hepatitis patients. Despite the fact that the oral bioavailability for DDB appears to be low and variable, the intestinal absorption of the drug is not well understood because of the lack of sensitivity and inadequate separation of DDB from endogenous peaks derived from the serum in previously developed HPLC assays. The present study describes a reliable HPLC method for DDB in serum samples for normal dose human bioavailability trials. A deproteinated serum sample was subjected to a solid-phase extraction procedure. The residue of the Sep-Pak eluent was reconstituted in acetonitrile and an aliquot was directly injected onto an octadecyl silica column (4 μm, 250 x 4.5mm I.D.). The mobile phase consisting of acetonitrile and water (52.5% acetonitrile in water, v/v), was delivered at a flow rate of lml/min, and DDB elution from the HPLC column was monitored by UV absorption at 278nm. The assay was linear in the range of 5-100ng DDB/ml serum with inter-day and intra-day variation less than 14.3 and 13.2 %, respectively. To determine whether the HPLC assay can be utilized in normal dose bioavailability studies, human serum samples (1ml each) were obtained from a typical normal dose bioavailability study (oral capsule for DDB; 15 mg as DDB) and analyzed for DDB. The drug was readily detectable in all samples from 30min to 720min after administration. Therefore, these data indicate that this HPLC assay is readily applicable to a normal dose pharmacokinetic study of DDB in human subjects.

Effect of dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxybiphenyl-2,2'- dicarboxylate (DDB) on chemical-induced liver injury.

The effects of orally administered dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylene-dioxybiphenyl-2,2'-d icarboxylate (DDB) on the hepatotoxicity induced by carbon tetrachloride, acetaminophen or ethanol were investigated in rats and mice. Either single or repeated DDB pretreatment (50 or 200 mg/kg) did not alter the hepatotoxicity induced by carbon tetrachloride (0.2 or 1.0 ml/kg, i.p.) in female rats as indicated by increases in the activity of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and sorbitol dehydrogenase (SDH) in serum. The hepatotoxicity of acetaminophen (350 mg/kg, i.p.) was also unaffected in male mice pretreated with DDB (50 mg/kg/d) for a week. However, DDB administration (50 mg/kg/d for 7 d) decreased the hepatic fatty degeneration induced by repeated ethanol treatment (0.75 g/kg, i.p., x2 times a day for a week) in rats as shown by the accumulation of triglycerides and cholesterol in the liver. Malondialdehyde (MDA) formation in liver homogenates was inhibited by DDB treatment. The significance of the action of DDB on alcoholic fatty liver generation in clinical settings is discussed.

Reversing effect of dimethyl-4,4'-dimethoxy-5,6,5', 6'-dimethylenedioxybiphenyl-2,2'-dicarboxylate (DDB) on the phenotypes of human hepatocarcinoma cells line.

When human Bel-7402 hepatocarcinoma cell line grew in a medium containing 10(-4) M dimethyl-4,4'-dimethoxy-5,6,5', 6'-dimethylenedioxybiphynyl-2,2'-dicarboxylate (DDB), the secretion of alpha-fetoprotein (AFP) was significantly lower than the control cells, whereas the albumin (ALB) secretion was markedly higher. The activity of gamma-glutamultranspepeidase (gamma-GT) in DDB-treated cells markedly decreased in comparison with the control cells. On the contrary, the activity of tyrosine-alpha-ketoglutarate transaminase (TAT) was higher in DDB-treated cells than in control cells. DDB (10(-4) M) could significantly increase the content of cAMP in Bel-7402 cells, and also enhance the expression of anti-oncogene p53. The results suggest that DDB has reversing effects on the phenotypes of the human Bel-7402 hepatocarcinoma cell line.

Pharmacological properties of dibenzo[ a, c]cyclooctene derivatives isolated from Fructus Schizandrae chinensis III. Inhibitory effects on carbon tetrachloride-induced lipid peroxidation, metabolism and covalent binding of carbon tetrachloride to lipids

Fructus Schizandrae, a traditional Chinese tonic, has been shown to lower the elevated serum glutamic pyruvic transaminase (SGPT) levels of patients with chronic viral hepatitis and several of its components decrease the hepatotoxicity of carbon tetrachloride (CCl 4) in animals. This paper deals with the mechanism of protection against CCl 4-hepatotoxicity of these compounds as well as of DDB, a synthetic analogue of Schizandrin (Sin) C. Of the seven components, Sin B and C, Schizandrol (Sol) B, Schizandrer (Ser) A and B, as well as dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylenedioxy-biphenyl-2,2′-dicarboxylate (DDB) were shown to inhibit CCl 4-induced lipid peroxidation and [ 14C]Cl 4 covalent binding to lipids of liver microsomes from phenobarbital(PB)-treated mice. The compounds also decreased carbon monoxide (CO) production and cofactor (NADPH, oxygen) utilization during CCl 4 metabolization by liver microsomes. It may be postulated, therefore, that the hepatoprotective effect of certain components isolated from Fructus Schizandrae as well as DDB is due to their inhibitory effect on CCl 4-induced lipid peroxidation and the binding of CCl 4-metabolites to lipids of liver microsomes.

Pharmacological properties of dibenzo[ a,c]cyclooctene derivatives isolated from Fructus Schizandrae chinensis I. Interaction with rat liver cytochrome P-450 and inhibition of xenobiotic metabolism and mutagenicity

Seven compounds isolated from Fructus Schizandrae chinensis, a traditional Chinese tonic, which is also able to decrease liver lesions by hepatoxic chemicals, are named Schizandrin (Sin) A, B and C, Schizandrol (Sol) A and B and Schizandrer (Ser) A and B. They are dibenzo[ a,c]cyclooctene derivatives. Dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylenedioxy-biphenyl-2,2′-dicarboxylate (DDB) is an intermediate for synthesizing Sin C. The interactions of these compounds with rat liver microsomes in vitro have been investigated. Sol A and Sol B gave type I difference spectrum, the other six compounds gave ‘reverse type I’ difference spectrum. When Schizandrins or DDB were incubated with NADPH-reduced microsomes, Sin B, Sin C, Sol B, Ser A and Ser B generated dual Soret peaks at 455–460 nm and 425–430 nm, the other three compounds caused a difference spectrum without 455 nm peak. All these compounds more or less inhibit liver microsomal hydroxylation of benzo[ a]pyrene (BP) demethylation of aminopyrine. Sin B, Sol B and DDB decreased mutagenicity of BP in Ames test.

Pharmacological properties of dibenzo[ a,c]cyclooctene derivatives isolated from Fructus Schizandrae chinensis II. Induction of phenobarbital-like hepatic monooxygen ases

Schizandrin (Sin) A, B and C, Schizandrol (Sol) A and B and Schizandrer (Ser) A and B were isolated from Fructus Schizandrae chinensis, a traditional Chinese tonic. These components are the derivatives of dibenzo[ a,c]cyclooctene. Dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylenedioxy-biphenyl-2,2′-dicarboxylate (DDB) is an intermediate for synthesizing Sin C. The effect of these compounds on rat liver microsomal monooxygenases and epoxide hydrolase has been studied. Among these compounds, Sin B, Sin C, Sol B and DDB significantly increased rat liver cytochrome P-450 concentration, NADPH-cytochrome c reductase, benzphetamine and aminopyrine demethylase activities. The four compounds also markedly stimulated proliferation of smooth endoplasmic reticulum of liver cells. Metyrapone (1 mM) inhibited to a same extent (about 50%) the activity of aminopyrine demethylase of microsomes from rats treated by Sin B, Sin C, Sol B, DDB and phenobarbital (PB). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of liver microsomal preparations showed that Sin B and Sol B induce a major protein band of P-450 similar to that induced by PB. In addition, the effect of Sin B-, Sol B- and DDB-treated rat liver microsomes on [G- 3H]benzo[ a]pyrene (BP) metabolism and covalent binding of reactive metabolites to DNA, in vitro, resembles that of PB. Dual induction of rats by Sol B and BP decreased mutagenicity of BP.