bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvement in site-specific intestinal absorption of furosemide by Eudragit L100-55
Authors: Terao T , Matsuda K , Shouji H
Published: July 2003

Furosemide (frusemide) is a weakly acidic diuretic drug. Its absorption is poor and variable, in part due to its restricted sites of absorption, mainly the stomach. The narrow absorption window of this drug can be explained by pH partition theory. The purpose of this study was to investigate the feasibility of widening the absorption window of furosemide by controlling the pH in distal portions of the gastrointestinal tract with officially used additives. Methacrylate copolymer (Eudragit L100–55), hydroxypropylmethylcellulose phthalate (HP-55) and hydroxypropylmethylcellulose acetate succinate (AS-MF) were selected as additives. The pH of suspensions of these additives was about 4, and the pH was adjusted to about 6–7 by the addition of NaOH. The Eudragit L100–55 suspension was found to be the most resistant to NaOH titration. When Eudragit L100–55 was used in an in-situ ileal loop experiment in rats, the pH of the intestinal contents was significantly reduced, from 7.9 ± 0.1 to 5.7 ± 0.1, and the plasma concentration of furosemide 15 min after administration was about 3 times higher than that in controls, 1.81 ± 0.42 μg mL−1 vs 0.63 ± 0.08 μg mL−1. However, the plasma concentration of [14C] mannitol was not changed by the co-administration of Eudragit L100–55. Furthermore, the AUC of furosemide was significantly increased by a factor of about 1.6 relative to that in controls by the co-administration of Eudragit L100–55, to 21.4 ± 4.0 μg h mL−1 from 13.3 ± 3.9 μg h mL−1, and the gastrointestinal pH in the midgut and ileum was significantly reduced, with most of the furosemide remaining in these segments at 2 h following the oral administration of furosemide with Eudragit L100–55 to rats. These findings clearly demonstrate that the addition of Eudragit L100–55 can increase the absorption of furosemide in distal portions of the gastrointestinal tract. In conclusion, it is feasible to widen the absorption window of furosemide by controlling the pH in distal portions of the gastrointestinal tract by the co-administration of Eudragit L100–55.
Application of pressure-controlled colon delivery capsule to oral administration of glycyrrhizin in dogs
Authors: Shibata Nobuhito , Ohno Tomoya , Shimokawa Tatsuharu , Hu Zhaopeng , Yoshikawa Yukako , Koga Kenjiro , Murakami Masahiro , Takada Kanji
Published: July 2003

A colon delivery system has been used to improve the bioavailability of glycyrrhizin, a glycoside of glycyrrhetic acid. The bioavailability of glycyrrhizin is low when administered in conventional oral galenic dosage forms because glycyrrhizin is enzymatically hydrolysed both in the stomach and in the intestine. It was reasoned that if large amounts of glycyrrhizin were directly delivered to the colon, enzymatic activity should be reduced due to saturation so that intact glycyrrhizin could be absorbed into the systemic circulation. Based on this assumption, pressure-controlled colon delivery capsules (PCDCs) were used as a colon delivery system. Eight types of glycyrrhizin solution were prepared and were introduced into PCDCs. After oral administration of the test PCDCs to beagle dogs, blood samples were obtained over 24 h and plasma glycyrrhizin concentrations were measured by an HPLC method. With PCDCs containing aqueous glycyrrhizin and propylene glycol solutions, plasma glycyrrhizin levels were extremely low and the bioavailabilities of glycyrrhizin were 0.6% and 0.4%, respectively. When Labrasol was added to both types of glycyrrhizin solution, the bioavailability was improved to 4.6 % for aqueous solution and 3.8% for propylene glycol solution. When a surfactant, Polysorbate 80, was added in combination with Labrasol, synergistic effects were not obtained. Furthermore, dose-dependent effects of Polysorbate 80 were not obtained. Labrasol, which is a component of self-emulsifying drug delivery systems (SEDDS), has been shown to strongly improve the bioavailability of glycyrrhizin from the colon.
The effect of selective serotonin reuptake inhibitors (SSRIs) on the pharmacokinetics and metabolism of perazine in the rat
Authors: Daniel Władysława A , Syrek Maciej , Haduch Anna , Wójcikowski Jacek
Published: July 2003

The aim of this study was to investigate the effect of three selective serotonin reuptake inhibitors (SSRIs), fluoxetine, fluvoxamine and sertraline, on the pharmacokinetics and metabolism of perazine in a steady state in rats. Perazine (10 mg kg−1, i.p.) was administered twice daily for two weeks, alone or jointly with one of the SSRIs. Concentrations of perazine and its two main metabolites (N-desmethylperazine and 5-sulfoxide) in the plasma and brain were measured 30 min and 6 and 12 h after the last dose of the drugs. Of the investigated SSRIs, fluoxetine and fluvoxamine significantly increased plasma and brain concentrations of perazine (up to 900% and 760% of the control value, respectively), their effect being most pronounced after 30 min and 6 h. Moreover, simultaneous increases in perazine metabolites concentrations and in the perazine/metabolite concentration ratios were observed. Sertraline elevated plasma and brain concentrations of perazine after 30 min. In-vitro studies with liver microsomes of rats treated chronically with perazine, SSRIs or their combinations showed decreased concentrations of cytochrome P-450 after perazine and a combination of perazine and fluvoxamine (vs control), and increased concentration after a combination of perazine and fluoxetine (vs perazine-treated group). Prolonged treatment with perazine did not significantly change the rate of its own metabolism. Chronic administration of fluoxetine or sertraline, alone or in a combination with perazine, accelerated perazine N-demethylation (vs control or perazine group, respectively). Fluvoxamine had a similar effect. The 5-sulfoxidation of perazine was accelerated by fluvoxamine and sertraline treatment, but the process was inhibited by administration of a combination of perazine and fluoxetine or fluvoxamine (vs control). Kinetic studies using control liver microsomes, in the absence or presence of SSRIs added in-vitro, demonstrated competitive inhibition of both N-demethylation and sulfoxidation by the investigated SSRIs. Sertraline was the most potent inhibitor of perazine N-demethylation but the weakest inhibitor of sulfoxidation. Results of in-vivo and in-vitro studies indicate that the observed interaction between perazine and SSRIs mainly involves competition for an active site of perazine N-demethylase and sulfoxidase. Moreover, increases in the concentrations of both perazine and metabolites measured, produced by the investigated drug combinations in-vivo, suggest simultaneous inhibition of another, yet to be investigated, metabolic pathway of perazine (e.g. aromatic hydroxylation).
Reversible binding of the novel anti-tumour agent 5,6-dimethylxanthenone-4-acetic acid to plasma proteins and its distribution into blood cells in various species
Authors: Zhou Shufeng , Paxton James W , Kestell Philip , Tingle Malcolm D , Kestell Philip
Published: July 2003

The plasma protein binding and distribution in blood cells of the novel anti-tumour agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) has been investigated in-vitro using filtration and an HPLC method to measure DMXAA. DMXAA (500 μm) was extensively bound in plasma from all species with an unbound fraction (fu) of 4.61 ± 1.10 (mouse), 2.59 ± 0.32 (rat), 2.02 ± 0.48 (rabbit) and 2.07 ± 0.23% (human). The binding was concentration dependent with DMXAA concentrations ≥ 1000 μm markedly increasing the fu in the plasma from all species. The estimated number of binding sites in plasma were 2.4 ± 0.2 (mouse), 1.7 ± 0.2 (rat), 0.8 ± 0.1 (rabbit) and 2.1 ± 0.2 (human). The major binding protein in human plasma was albumin, with negligible binding to γ-globulin and α1-acid glycoprotein. There was a significant linear relationship between the bound:free DMXAA concentration ratio (Cb/Cu) and albumin concentration in human serum albumin solution (r = 0.955; P < 0.05) and in healthy human plasma (r = 0.998; P < 0.05), but not in plasma from cancer patients (n = 5), nor across species. In cancer patients (n = 5) DMXAA had a significantly higher (P < 0.05) fu (4.60 ± 0.42%) compared with healthy human plasma (2.07 ± 0.23%). In human plasma, the fu of DMXAA (500 μm) was significantly reduced by 500 μm diazepam (P < 0.05), but not by warfarin, phenylbutazone, salicylic acid, ibuprofen or clofibric acid at that concentration. DMXAA significantly reduced the binding of dansylsarcosine (a Site-II binder) to HSA, but significantly increased the binding of dansylamide (a Site-I binder). Within species, the blood:plasma concentration ratio (CBL/CP) of DMXAA was relatively constant (mouse, 0.581 ± 0.005; rat, 0.667 ± 0.025; rabbit, 0.637 ± 0.019; human, 0.673 ± 0.103) over the range 50–1000 μm, but increased significantly at DMXAA concentrations > 1000 μm in all species except the rabbit. These results indicate that significant alterations in DMXAA plasma binding and distribution into blood cells occur with increasing concentrations of DMXAA in all species, and also that significant interspecies differences exist. It would be more appropriate to compare plasma unbound concentrations when assessing DMXAA exposure in cancer patients or when extrapolating across species.
Synthesis and kinetic evaluation of peptide α-keto-β-aldehyde-based inhibitors of trypsin-like serine proteases
Authors: Lynas John F , Martin S Lorraine , Walker Brian
Published: July 2003

New, synthetic peptide analogues bearing a C-terminal basic α-keto-β-aldehyde moiety were prepared as novel inhibitors of the trypsin-like serine proteases. The compounds, Ac-Leu-Leu-Arg-COCHO, Ac-Arg-Gln-Arg-COCHO and Boc-Val-Leu-Lys-COCHO were evaluated kinetically against trypsin and three other trypsin-like serine proteases, tryptase, plasmin and thrombin, all of which are implicated as mediators of important disease processes. Results illustrate that α-keto-β-aldehydes are potent inhibitors, with similar potency to comparable peptide aldehydes, and intriguingly, appear to act, in some instances, by a novel mechanism of action. Ac-Leu-Leu-Arg-COCHO, an analogue of the natural product leupeptin, is a potent, tight-binding inhibitor of trypsin (Ki(final) = 1.9 μm), plasmin (Ki(final) = 4.9 μm) and tryptase (Ki(final) = 1.2 μm) and an irreversible inactivator of thrombin (k2nd 4500 m−1. min−1). Boc-Val-Leu-Lys-COCHO was found to be a tight-binding inhibitor of its target protease plasmin (Ki(final) = 3.1 μm) and was inactive against thrombin. Ac-Arg-Gln-Arg-COCHO was a slow-binding inhibitor of tryptase (Ki(final) = 1.6 μm) and also irreversibly inactivated trypsin (k2nd = 8920 m−1 min−1). Peptides or peptidomimetics with a C-terminal basic α-keto-β-aldehyde function thus provide a useful new molecular template for the development of new therapeutic agents against a wide range of disorders, such as coagulopathies and asthma, which may be mediated by the aberrant activity of trypsin-like serine proteases.
Characterization and purification of the vitamin K1 2,3 epoxide reductase system from rat liver
Authors: Begent Louise A , Hill Anthony P , Steventon Glyn B , Hutt Andrew J , Pallister Christopher J , Cowell David C
Published: July 2003

The enzyme vitamin K1 2,3 epoxide reductase is responsible for converting vitamin K1 2,3 epoxide to vitamin K1 quinone thus completing the vitamin K cycle. The enzyme is also the target of inhibition by the oral anticoagulant, R,S-warfarin. Purification of this protein would enable the interaction of the inhibitor with its target to be elucidated. To date a single protein possessing vitamin K1 2,3 epoxide reductase activity and binding R,S-warfarin has yet to be purified to homogeneity, but recent studies have indicated that the enzyme is in fact at least two interacting proteins. We report on the attempted purification of the vitamin K1 2,3 epoxide reductase complex from rat liver microsomes by ion exchange and size exclusion chromatography techniques. The intact system consisted of a warfarin-binding factor, which possessed no vitamin K1 2,3 epoxide reductase activity and a catalytic protein. This catalytic protein was purified 327-fold and was insensitive to R,S-warfarin inhibition at concentrations up to 5 mm. The addition of the S-200 size exclusion chromatography fraction containing the inhibitor-binding factor resulted in the return of R,S-warfarin inhibition. Thus, to function normally, the rat liver endoplasmic reticulum vitamin K1 2,3 epoxide reductase system requires the association of two components, one with catalytic activity for the conversion of the epoxide to the quinone and the second, the inhibitor binding factor. This latter enzyme forms the thiol-disulphide redox centre that in the oxidized form binds R,S-warfarin.
Molecular and functional identification of large neutral amino acid transporters LAT1 and LAT2 and their pharmacological relevance at the blood-brain barrier
Authors: Kido Yasuto , Tamai Ikumi , Uchino Hiroshi , Suzuki Fumio , Sai Yoshimichi , Tsuji Akira
Published: July 2003

We present here the evidence of molecular and functional expression of LAT1 and LAT2, subunits of the large neutral amino acid transporter system L, in cultured brain capillary endothelial cells of the rat. By means of the RT-PCR method, transcripts of LAT1, LAT2 and heavy chain of 4F2 antigen (4F2hc) were detected in rat primary cultured brain capillary endothelial cells (BCECs) and immortalized subline, RBEC1. The uptake properties of RBEC1, such as [3H]leucine and l-[3H]DOPA uptake, were similar to those of primary cultured BCECs. So, RBEC1 may retain almost native properties of the large neutral amino acid uptake activities. [3H]Leucine uptake by RBEC1 showed two saturable components and the Km values of the high- and low-affinity components were 8.92 ± 3.18 and 119 ± 45 μm, respectively. The Km value of the high-affinity component agreed well with that of LAT1 and the amino acid transport selectivity of RBEC1 was similar to that of LAT1. Therefore, it is suggested that LAT1 is important at the blood-brain barrier of rats. Additionally, the Km value of the low-affinity component was similar to that of LAT2. These observations indicate that LAT1 and LAT2 are involved as transporters for large neutral amino acids at the blood-brain barrier. Additionally, we concluded that RBEC1 is useful as an in-vitro model for evaluation of the pharmacological relevance of system L at the blood-brain barrier.
Ruscogenin glycoside (Lm-3) isolated from Liriope muscari improves liver injury by dysfunctioning liver-infiltrating lymphocytes
Authors: Wu Feihua , Cao Jingsong , Jiang Jieyun , Yu Boyang , Xu Qiang
Published: July 2003

The effects of ruscogenin 1-O-[β-d-glucopyranosyl(1 → 2)] [β-d-xylopyranosyl(1 → 3)]-β-d-fucopyranoside (Lm-3) and its aglycone, ruscogenin, on liver injury induced in mice by delayed-type hypersensitivity to picryl chloride have been investigated. Lm-3 and ruscogenin significantly decreased liver injury when given during the effector phase of the delayed-type hypersensitivity reaction. The pretreatment of nonparenchymal cells, but not hepatocytes, with Lm-3 or ruscogenin in-vitro caused a concentration- and time-dependent inhibition against the damage. Lm-3 showed a stronger inhibition against the damage than ruscogenin (IC50: Lm-3 6.3 times 10−10  m, ruscogenin 3.9 times 10−7  m). However, neither Lm-3 nor ruscogenin blocked the hepatotoxic potential of CCl4, when used to pretreat hepatocytes. Moreover, Lm-3 and ruscogenin inhibited concanavalin A-induced lymphocyte proliferation only at high concentrations. These results suggested that Lm-3 and ruscogenin improved the immunological liver injury by selectively causing dysfunction of the liver-infiltrating cells rather than by protecting hepatocyte membranes. Such characteristics would be significant for treating immunologically related liver diseases as well as for developing new drugs.
The influence of plasma on the disinfecting activity of the new antimicrobial agent N-chlorotaurine-sodium in comparison with chloramine T
Authors: Gottardi Waldemar , Hagleitner Magdalena , Nagl Markus
Published: July 2003

The phenomenon of increasing bactericidal activity of N-chlorotaurine in the presence of chlorine-consuming material has been investigated both on a chemical-analytical and microbiological basis using plasma as substrate and chloramine T for comparison. Chlorine consumption assessed by iodometric titration showed a biphasic time-course with a very fast loss of oxidation capacity within one minute (N-chlorotaurine: — 9.3%, chloramine T: −16.8%) followed by a slow loss which could still be detected after 24 h (total loss −61.7% and −74.1%, respectively). Killing curves revealed that an increase in bactericidal activity, in spite of improved consumption, did not occur with all strains, and could be detected only at a certain degree of consumption. Escherichia coli and Pseudomonas aeruginosa showed the most pronounced effect, Streptococcus pyogenes and Proteus mirabilis a medium-sized one, while it was absent in Staphylococcus aureus. With chloramine T, an increase in bactericidal activity could not be proved. The chemical basis of these consumption effects can be reduced to four reaction types: oxidation of thiols; chlorine substitution of activated C-H compounds; transhalogenation; and hydrolytic degradation of N-chloro-α-amino acids and -peptides emerging by transhalogenation. The initial fast loss of oxidation capacity can be attributed mainly to oxidation of thiols, while the subsequent slower decrease is caused by the other types of reaction. The increase in bactericidal activity, on the other hand, can be explained by transhalogenation, leading to the formation of more bactericidal N-chloro compounds by which the loss of N-chlorotaurine is over-compensated.
Active intestinal secretion of new quinolone antimicrobials and the partial contribution of P-glycoprotein
Authors: Naruhashi Kazumasa , Tamai Ikumi , Inoue Natsuko , Muraoka Hiromi , Sai Yoshimichi , Suzuki Nagao , Tsuji Akira
Published: July 2003

Transport of quinolone antimicrobials and the contribution of the secretory transporter P-glycoprotein were studied in-vivoand in-vitro. In rat intestinal tissue (Ussing chambers method) and human Caco-2 cells (Transwell method), grepafloxacin showed secretory-directed transport. In both experimental systems, the secretory-directed transport was decreased by ciclosporin A, an inhibitor of P-glycoprotein, and probenecid, an inhibitor of anion transport systems. This suggested the contribution of P-glycoprotein and anion-sensitive transporter(s). The involvement of P-glycoprotein was investigated by using a P-glycoprotein over-expressing cell line, LLC-GA5-COL150, and P-glycoprotein-gene-deficient mice (mdr1a(—/—)/1b(—/—) mice). LLC-GA5-COL150 cells showed secretory-directed transport of grepafloxacin, while the parent cell line, LLC-PK1, did not. The secretory-directed transport of sparfloxacin and levofloxacin was also detected in LLC-GA5-COL150 cells. In the mdr1a(—/—)/1b(—/—) mice, the intestinal secretory clearance was smaller than that in wild-type mice after intravenous administration of grepafloxacin. Moreover, the absorption from an intestinal loop in mdr1a(—/—)/1b(—/—) mice was larger than that in wild-type mice. Accordingly, it appears that some quinolones are transported by secretory transporters, including P-glycoprotein. The involved transporters function in-vivo not only to transport grepafloxacin from blood to intestine but also to limit its intestinal absorption.
Taurocholic acid-induced secretion in normal and cystic fibrosis mouse ileum
Authors: Hardcastle J , Hardcastle P T , Chapman J , Taylor C J
Published: July 2003

Bile acids cause secretion throughout the intestinal tract and this process contributes to maintaining the fluidity of intestinal contents. In cystic fibrosis (CF) defective intestinal secretion can lead to excessive dehydration of the luminal contents and the development of clinical symptoms. This study was designed to investigate bile acid-induced secretion in mouse ileum and to determine whether this process was defective in CF. Taurocholic acid-induced secretion was monitored as a rise in short-circuit current (SCC) in ileal sheets from normal (Swiss MF1) and transgenic CF mice. Taurocholic acid increased the SCC in both intact and stripped ileal sheets from Swiss MF1 mice. This effect was due to a stimulation of electrogenic Cl− secretion as it was inhibited by Cl−-free conditions, serosal furosemide (frusemide), mucosal diphenylamine-2-carboxylic acid (DPC) and increased serosal K+ concentration, without being affected by reduced mucosal Na+ concentration. Taurocholic acid-induced secretion was inhibited by tetrodotoxin, indicating the involvement of a neural pathway, but this did not include capsaicin-sensitive afferent neurons or muscarinic cholinoreceptors. Mucosal mast cells also contributed to the response. Responses in tissues from transgenic wild-type mice were similar to those obtained with Swiss MF1 animals, but ilea from CF mice exhibited a lower basal SCC with significantly reduced secretory responses to acetylcholine and taurocholic acid. We concluded that taurocholic acid induces ileal secretion by a mechanism that entails activation of enteric nerves and degranulation of mucosal mast cells. Impaired bile acid-induced secretion in CF may contribute to luminal dehydration.
Confirmation of the anxiolytic-like effect of dihydrohonokiol following behavioural and biochemical assessments
Authors: Maruyama Yuji , Kuribara Hisashi , Kishi Eiko , Weintraub Susan T , Ito Yoshihisa
Published: July 2003

Previous studies in this laboratory revealed that dihydrohonokiol-B (DHH-B; 3′-(2 propenyl)-5-propyl-(1,1′-biphenyl)-2,4′-diol), a partially reduced derivative of honokiol, was an effective anxiolytic-like agent in mice at an oral dose of 0.04 mg kg−1, and at higher doses, when evaluated by the elevated plus-maze test. The aim of this study was to further confirm the anxiolytic-like effect of DHH-B using an additional behavioural procedure (Vogel's conflict test in mice) and a biochemical assessment (in-vitro determination of muscimol-stimulated 36Cl− uptake into mouse cortical synaptoneurosomes). As in earlier experiments, DHH-B (0.04–1 mg kg−1, p.o.) was shown to prolong the time spent in the open-sided arms of the elevated plus-maze in a dose-dependent manner. Moreover, in the Vogel's conflict test, DHH-B (5 mg kg−1, p.o.) significantly increased punished water intake. In tests with mouse cerebral cortical synaptoneurosomes, 10 and 30 μm of DHH-B significantly increased 36Cl− influx in the absence of muscimol. In the presence of 25 μm muscimol, the addition of 1 μm DHH-B led to significant enhancement of 36Cl− uptake, while 30 μm DHH-B was required to further stimulate the 36Cl− uptake induced by 250 μm muscimol. The results of these studies confirm that DHH-B is a potent anxiolytic-like agent and that GABAA receptor-gated Cl−-channel complex is involved in the anxiolytic-like efficacy of DHH-B.
Comparison of suppressive potency between prednisolone and prednisolone sodium succinate against mitogen-induced blastogenesis of human peripheral blood mononuclear cells in-vitro
Authors: Sugiyama Kentaro , Kawada Tomie , Sato Hiroshi , Hirano Toshihiko
Published: July 2003

Clinically, both prednisolone and prednisolone sodium succinate are widely used as immunosuppressive agents for the treatment of various allergic disorders. However, whether prednisolone sodium succinate itself has immunosuppressive or anti-inflammatory effects is unclear, and prednisolone sodium succinate may exhibit its efficacy only after hydrolytic conversion to prednisolone in-vivo. If this is the case, the impairment of prednisolone sodium succinate conversion to prednisolone in some clinical conditions may attenuate the efficacy of prednisolone sodium succinate. We therefore compared the pharmacological efficacy of prednisolone with that of prednisolone sodium succinate in-vitro using human peripheral blood mononuclear cells (PBMCs). PBMCs were obtained from 5 healthy subjects and 1 patient with pneumonia. The cells were incubated in the presence of concanavalin A and the cell growth was estimated by 3-(4,5-dimethyl thiazo-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Both prednisolone and prednisolone sodium succinate dose-dependently suppressed PBMC blastogenesis. Mean (s.d.) prednisolone and prednisolone sodium succinate IC50 (concentration of drug that gave 50% inhibition of cell growth) values were 580.0 (1037.9) and 3237.1 (4627.3) nm, respectively. The ratio of prednisolone IC50/prednisolone sodium succinate IC50 ranged from 0.005 to 0.230. Thus, prednisolone sodium succinate potency was markedly lower than that of prednisolone. After incubation of PBMCs with 100 μm prednisolone sodium succinate, 22.7–42.9 μm prednisolone was liberated into the culture medium, as determined by HPLC. The ratio of prednisolone liberation from prednisolone sodium succinate was not affected by the presence of fetal bovine serum or PBMC, or both, in the culture medium. These results suggested that the PBMC-suppressive effects of prednisolone sodium succinate might be due, at least partially, to prednisolone liberated from prednisolone sodium succinate into the culture medium. Prednisolone sodium succinate can be converted to prednisolone in the absence of serum or PBMCs, but the ratio of this conversion was very slow (t£frac12; > 4 days). Therefore, impairment of the enzymatic conversion of prednisolone sodium succinate to prednisolone in some pathological conditions such as liver diseases may result in attenuation of the clinical efficacy of prednisolone sodium succinate.
Uptake of quinolones by in-vitro human monocyte derived macrophages
Authors: Dorian Martine , Grellet Jean , Saux Marie C
Published: July 2003

We have developed an in-vitro model of monocyte-derived macrophage (MDMØ) to compare fluoroquinolone uptake in monocytes and derived macrophages. Monocyte-derived macrophages were obtained in-vitro by cultivating freshly isolated monocytes for seven days in RPMI 1640 medium, containing foetal calf serum and Rhu granulocyte-macrophage colony stimulating factor. Final suspensions contained 95% viable cells and 63% macrophages. Intra-macrophagic accumulation of ciprofloxacin, ofloxacin or sparfloxacin was measured at equilibrium after 30-min incubation in the presence of 16–18 μg mL−1 antibiotic. The results revealed low intra-cellular accumulation of ofloxacin in MDMØ (intracellular/extracellular ratio: IC/EC = 1.7). Ciprofloxacin and sparfloxacin uptake was significantly higher. The IC/EC ratios were only slightly increased in macrophages when compared with monocytes under the same experimental conditions. These results suggest that maturation of monocyte to macrophage has only a limited effect on basal quinolone uptake. Monocytic maturation cannot explain the important differences between fluoroquinolone accumulation in monocytes and tissue macrophages. Cell activation may be a greater determinant.
Effects of steroidal and non-steroidal antiphlogistic drugs on eicosanoid synthesis in irritated skin: studies with the isolated perfused bovine udder
Authors: Bäumer Wolfgang , Kietzmann Manfred
Published: July 2003

Using the isolated perfused bovine udder as an in-vitro model of skin inflammation, the effects of topically administered arachidonic acid on prostaglandin and leukotriene synthesis have been shown previously. In this study, the effects of indometacin (indomethacin) and clobetasol-17-propionate (administered topically) as well as flunixin meglumine and meloxicam (administered via the perfusion fluid) have been studied. Compared with controls, arachidonic acid caused a significant increase in the dermal prostaglandin E2 (PGE2) and peptidoleukotriene (LTC4/D4/E4) concentration. Topical treatment with indometacin (1.6 mg cm−2) and clobetasol-17-propionate (90 μg cm−2), which were administered 60 min before arachidonic acid administration, inhibited the inflammatory reaction. Flunixin meglumine (1 μg mL−1 perfusion fluid) was administered 30 min after and meloxicam (3 μg mL−1 perfusion fluid) was administered 60 min before arachidonic acid application. Three hours after arachidonic acid administration, a significant inhibition of PGE2 synthesis was induced by flunixin. In contrast, meloxicam showed only a slight effect. The effect of flunixin was comparable with in-vivo results. It is known from animal studies that anti-inflammatory effects of meloxicam are obvious within up to 6 h after treatment. Therefore, the incomplete effect of meloxicam may be explained pharmacokinetically. In conclusion, the described in-vitro model seems to be suitable for studies of pharmacological effects on eicosanoid synthesis in the skin.
Specific inhibition of Type II inosine monophosphate dehydrogenase activity of Tmolt4 T cell human leukaemia cells by 3-methoxy and di-benzohydroxamic acids, maleic hydrazide and malonic acids
Authors: Hall I H , Barnes B J , Ward E S , Wheaton J R , Izydore R A
Published: July 2003

Small-molecular-weight benzohydroxamic and malonic acids and maleic hydrazide proved to be potent inhibitors of the activity of human Tmolt4 leukaemia Type II IMP (inosine monophosphate) dehydrogenase (IMPDH) activity. They were competitive inhibitors with respect to IMPDH demonstrating Ki values in the range 2.57–41.3 μm, less than half the values of the IC50 (μm) for the inhibition of Type II IMPDH. The IC50 μm values positively correlated with the ability of each compound to inhibit crude IMPDH activity, de-novo purine and DNA syntheses and growth of the T leukaemia cell line. Compounds were not inhibitors of Type I IMPDH. Type I IMPDH predominates in normal resting cells compared with Type II which is found in rapidly proliferating cells. Discovery of agents which would selectivity target IMPDH found in proliferating cells should eliminate any antineoplastic therapeutic toxic effects in normal cells of the body.
Radical scavenging and xanthine oxidase inhibitory activity of phenolic compounds from Bridelia ferruginea stem bark
Authors: Cimanga K , Ying L , De Bruyne T , Apers S , Cos P , Hermans N , Bakana P , Tona L , Kambu K , Kalenda D T , Pieters L , Berghe D Vanden , Vlietinck A J
Published: July 2003

Bridelia ferruginea Benth. (Euphorbiaceae) is a subtropical medicinal plant widely used in traditional African medicine against various diseases, including rheumatic pains. Seven of its constituents (3-O-methylquercetin (1), 3,7,3′,4′-tetra-O-methylquercetin (rutisin, 2), myricetin (3), 3′,4′,5′-tri-O-methylmyricetin (ferrugin, 4), 3,3′,4′,5′-tetra-O-methylmyricetin (5), quercetin 3-O-glucoside (6), and a biflavanol gallocatechin-[4′-O-7]-epigallocatechin (7)) have been evaluated in-vitro in the xanthine-xanthine oxidase enzymatic system for inhibition of xanthine oxidase and radical scavenging activity. Results indicated that compounds 1, 3, 4 and 6 exhibited, at different levels, xanthine oxidase inhibiting and superoxide scavenging activity at micromolar concentrations, whereas compound 7 showed scavenging activity only. Compounds 2 and 5 were inactive in both cases. Study of the structure-activity relationship demonstrated that for flavonoids the xanthine oxidase inhibitory activity was reduced by methylation of the hydroxyl functionality at C-3 and in rings A and B. These results may partly explain and support the use of B. ferruginea stem bark for the treatment of rheumatic pains in traditional medicine.
Inhibition of chemical carcinogenesis by berberine in rats and mice
Authors: Anis K V , Rajeshkumar N V , Kuttan Ramadasan
Published: July 2003

Berberine, an alkaloid isolated from the plant Berberis aristata, has been found to inhibit significantly the carcinogenesis induced by 20-methylcholanthrene (200 μg/0.1 mL/mouse) or N-nitrosodiethylamine (NDEA; 0.02% NDEA in distilled water, 2.5 mL/animal by gavage, five days a week for 20 weeks) in a dose-dependent manner in small animals. Administration of berberine (0.5, 2.5 or 5.0 mg kg−1) could reduce significantly the incidenceof tumour in animals after an injection of 20-methylcholanthrene and increased their life span compared with the control. When berberine (10, 25 or 50 mg kg−1) was administered simultaneously with NDEA, the markers of liver injury (liver weight, γ-glutamyl transpeptidase activity and glutathione S-transferase level) were reduced significantly compared with animals treated with NDEA only, which resulted in all the values being elevated. A similar decrease was noted inthe serum levels of lipid peroxide, bilirubin and glutamate pyruvate transaminase. Morphology of liver tissue and levels of marker enzymes indicated that berberine offered protection against chemical carcinogenesis.
St John's wort (Hypericum perforatum L.): a review of its chemistry, pharmacology and clinical properties
Authors: Barnes Joanne , Anderson Linda A , Phillipson J David
Published: July 2003

The chemical composition of St. John's wort has been well-studied. Documented pharmacological activities, including antidepressant, antiviral, and antibacterial effects, provide supporting evidence for several of the traditional uses stated for St John's wort. Many pharmacological activities appear to be attributable to hypericin and to the flavonoid constituents; hypericin is also reported to be responsible for the photosensitive reactions that have been documented for St. John's wort. With regard to the antidepressant effects of St John's wort, hyperforin, rather than hypericin as originally thought, has emerged as one of the major constituents responsible for antidepressant activity. Further research is required to determine which other constituents contribute to the antidepressant effect.

Evidence from randomised controlled trials has confirmed the efficacy of St John's wort extracts over placebo in the treatment of mild-to-moderately severe depression. Other randomised controlled studies have provided some evidence that St John's wort extracts are as effective as some standard antidepressants in mild-to-moderate depression. There is still a need for further trials to assess the efficacy of St John's wort extracts, compared with that of standard antidepressants, particularly newer antidepressant agents, such as the selective serotonin reuptake inhibitors (recent comparative studies with fluoxetine and sertraline have been conducted). Also, there is a need for further studies in well-defined groups of patients, in different types of depression, and conducted over longer periods in order to determine long-term safety. St John's wort does appear to have a more favourable short-term safety profile than do standard antidepressants, a factor that is likely to be important in patients continuing to take medication.

Concerns have been raised over interactions between St John's wort and certain prescribed medicines (including warfarin, ciclosporin, theophylline, digoxin, HIV protease inhibitors, anticonvulsants, selective serotonin reuptake inhibitors, triptans, oral contraceptives); advice is that patients taking these medicines should stop taking St John's wort, generally after seeking professional advice as dose adjustment of conventional treatment may be necessary.
Tissue distribution of radioactivity following intranasal administration of radioactive microspheres
Authors: Eyles J E , Spiers I D , Williamson E D , Alpar H O
Published: July 2003

The aim of this study was to increase understanding of the kinetics of microparticle distribution and elimination following intranasal application. To do this we investigated the in-vivo distribution of radioactivity following intranasal instillation of scandium-46 labelled styrene-divinyl benzene 7-μm-diameter microspheres. Groups of BALB/c mice received 0.250 mg (47.5 kBq) particles suspended in either 50-μl or 10-μl volumes of phosphate buffered saline. The in-vivo distribution of radioactivity was influenced by the volume of liquid that was used to instil the microsphere suspension. Comparatively large (50 μl) administration vehicle volumes resulted in substantial bronchopulmonary deposition (∼ 50% of administered dose). Intranasal instillation of microspheres suspended in 10-μl volumes tended to restrict particle deposition initially to the nasal cavity. For both administration vehicle volumes tested, the radioactivity per unit mass of excised nasal-associated lymphoid tissue (NALT) was found to be consistently elevated relative to other tissues. This corroborates the findings of other workers who have previously identified NALT as an active site of microparticle accumulation following intranasal application. Elimination via the alimentary canal was the principal fate of intranasally applied radiolabeled material. No significant concentration of radioactivity within excised gut-associated lymphoid tissue (GALT) (Peyer's patches) was noted. At latter time points we observed, in mice that received the 50-μl volume particle suspension nasally, accumulation of potentially relevant quantities of radioactivity in the liver (0.3% after 576 h) and spleen (0.04% after 576 h). Thus, our data corroborate the notion that epithelial membranes in the lung are probably less exclusive to the entry of microparticulates into systemic compartments than are those mucosae in the gastrointestinal tract or nasopharynx. This effect may contribute to the effectiveness of pulmonary delivered antigen-loaded microparticles as humoral immunogens.
The change in characteristics of microcrystalline cellulose during wet granulation using a high-shear mixer
Authors: Suzuki Tatsuya , Kikuchi Hiroshi , Yamamura Shigeo , Terada Katsuhide , Yamamoto Keiji
Published: July 2003

The objective of this study was to investigate the mechanism of hard granule formation and to demonstrate the applicability of X-ray diffraction methods for studying the polymeric pharmaceutical excipients. Using a high-shear mixer, microcrystalline cellulose (MCC) was granulated with water as the granulating liquid. The hardness of the MCC granules increased with granulation time and the amount of water added. The specific surface area measured by the N2 adsorption method was reduced during the process. Crystallite size of cellulose, calculated by Scherrer's equation adapted for wide angle X-ray diffraction method, decreased with granulation time and with increasing amounts of water added. Debye plots for X-ray small scattering patterns suggested that the average magnitude of the continuous solid region in MCC granules became significantly greater, whereas the specific surface area of the MCC granules, calculated from Debye plots, became smaller in comparison with that of intact MCC. These findings suggested that the long-chain structures in MCC were disrupted, resulting in smaller units with shorter chain lengths due to the strong shear force of the impeller. These smaller units then form a network within the granules. Thus, MCC granules are strengthened with longer granulation time and greater amounts of water, resulting in a more intricate network. The change in MCC chain length and physical structure can be experimentally detected using the small-angle X-ray scattering and wide-angle powder X-ray diffraction methods.
Water quantitatively induces the mucoadhesion of liquid crystalline phases of glyceryl monooleate
Authors: Lee Jaehwi , Young Simon A , Kellaway Ian W
Published: July 2003

The possible role of water inthe mucoadhesion phenomenon exhibitedby the liquid crystalline phases of glyceryl monooleate was investigated using an in-vitro tensile strength technique. The mucoadhesion of the liquid crystalline phases of glyceryl monooleate was found to occur following uptake of water. The mucoadhesive force of the cubic phase was consistent since it is not capable of taking up additional water. An increase in pre-load period greatly facilitated the mucoadhesion of glyceryl monooleate (0% w/w initial water content), suggesting that the mucoadhesion is dependent upon the extent of the dehydration of the substrate. A good linear relationship between initial water content of the liquid crystalline phases and mucoadhesive force led to the conclusion that the mucoadhesive force increased with decreasing initial water concentration. Rheological properties of the liquid crystalline phases were also studied to allow a correlation between physical changes and mucoadhesion of the liquid crystalline phases, revealing that higher water concentrations in the liquid crystalline phases led to a more ordered structure that showed less mucoadhesion. The results of this study indicated that the mucoadhesive force ofthe liquid crystalline phases of glyceryl monooleate is determined by the capability to take up water from a water-rich environment. It may, therefore, be advantageous to use the lamellar phase as a buccal drug carrier as opposed to the relatively less mucoadhesive cubic phase.
Percutaneous absorption of the montoterpene carvone: implication of stereoselective metabolism on blood levels
Authors: Jäger Walter , Mayer Marion , Reznicek Gottfried , Buchbauer Gerhard
Published: July 2003

The purpose of this study was to determine whether an enantioselective difference in the metabolism of topically applied R-(—)- and S-(+)-carvone could be observed in man. In a previous investigation we found that R-(—)- and S-(+)-carvone are stereoselectively biotransformed by human liver microsomes to 4R,6S-(—)- and 4S,6S-(+)-carveol, respectively, and 4R,6S-(—)-carveol is further glucuronidated. We therefore investigated the metabolism and pharmacokinetics of R-(—)- and S-(+)-carvone in four healthy subjects using chiral gas chromatography as the analytical method. Following separate topical applications at a dose of 300 mg, R-(—)- and S-(+)-carvone were rapidly absorbed, resulting in significantly higher Cmax levels for S-(+)-carvone (88.0 vs 23.9 ng mL−1) and longer distribution half-lives (t2α1) (19.4 vs 7.8 min), resulting in 3.4-fold higher areas under the blood concentration-time curves (5420 vs 1611 ng min mL−1). The biotransformation products for both enantiomers in plasma were below detection limit. Analysis of control- and β-glucuronidase pretreated urine samples, however, revealed a stereoselective metabolism of R-(—)-carvone to 4R,6S-(—)-carveol and 4R,6S-(—)-carveol glucuronide. No metabolites could be found in urine samples after S-(+)-carvone application. These data indicate that stereoselectivity in phase-I and phase-II metabolism has significant effects on R-(—)- and S-(+)-carvone pharmacokinetics. This might serve to explain the increased blood levels of S-(+)-carvone.
In-vivo kinetics of the interaction between midazolam and erythromycin in rats, taking account of metabolic intermediate complex formation
Authors: Takedomi Sayuri , Matsuo Hirotami , Yamano Katsuhiro , Ohtani Hisakazu , Sawada Yasufumi
Published: July 2003

To predict, quantitatively, the extent of drug interaction during repeated administration of a metabolic inhibitor, we analysed the effects of erythromycin treatment under several regimens on the area under the concentration curve (AUC) of midazolam in rats. Midazolam was administered into the portal vein 12 h after erythromycin treatment for 1, 2 or 3 days, or 12, 24, 36, 48, 72 and 96 h after erythromycin treatment for 4 days, and the plasma-concentration profiles of midazolam were analysed to assess the AUC. Moreover, the contents of total cytochrome P450 and inactive metabolic intermediate (MI) complex were simultaneously quantitated. While the AUC value of midazolam was not affected by the administration of erythromycin for 1 day, repeated administration of erythromycin evoked an increase in AUC ratio (AUC in erythromycin-treated rats/AUC in vehicle-treated rats), which reached a maximum value of 1.99 at 12 h after 4 days' treatment with erythromycin. The total content of cytochrome P450 in liver microsomes was unaffected by erythromycin treatment. Although the MI complex was undetectable after 1 day's treatment with erythromycin, its content increased with duration of erythromycin treatment, and the complex disappeared after the end of erythromycin treatment with a half-life of 12.3 h. In conclusion, the interaction between erythromycin and midazolam could be well predicted when the formation of MI complex in the liver was taken into account.
Synthesis of flavonoids and their effects on aldose reductase and sorbitol accumulation in streptozotocin-induced diabetic rat tissues
Authors: Lim Soon Sung , Jung Sang Hoon , Ji Jun , Shin Kuk Hyun , Keum Sam Rok
Published: July 2003

Aldose reductase, the key enzyme of the polyol pathway, and oxidative stress are known to play important roles in the complications of diabetes. A drug with potent inhibition of aldose reductase and oxidative stress, therefore, would be a most promising drug for the prevention of diabetic complications. The purpose of this study was to develop new compounds with these dual-effects through synthesis of chalcone derivatives and by examining the structure-activity relationships on the inhibition of rat lens aldose reductase as well as on antioxidant effects. A series of 35 flavonoid derivatives were synthesized by Winget's condensation, oxidation, and reduction of appropriate acetophenones with appropriate benzaldehydes. The inhibitory activity of these derivatives on rat lens aldose reductase and their antioxidant effects, measured using Cu2+ chelation and radical scavenging activities on 1,1-diphenyl-picrylhydrazyl in-vitro, were evaluated. Their effect on sorbitol accumulation in the red blood cells, lenses and sciatic nerves of streptozotocin-induced diabetic rats was also estimated. Among the new flavonoid derivatives synthesized, those with the 2′,4′-dihydroxyl groups in the A ring such as 2,4,2′,4′-tetrahydroxychalcone (22), 2,2′,4′-trihydroxychalcone (11), 2′,4′-dihydroxy-2,4-dimethylchalcone (21) and 3,4,2′,4′-tetrahydroxychalcone (18) were found to possess the highest rat lens aldose reductase inhibitory activity in-vitro, their IC50 values (concentration of inhibitors giving 50% inhibition of enzyme activity) being 1.6 times 10−7, 3.8 times 10−7, 4.0 times 10−7 and 4.6 times 10−7 M, respectively. All of the chalcones tested except 3, 18, 23 with o-dihydroxy or hydroquinone moiety showed a weak free radical scavenging activity. In the in-vivo experiments, however, compound 18 with o-dihydroxy moiety in the B ring showed the strongest inhibitory activity in the accumulation of sorbitol in the tissues. It also showed the strongest activity in transition metal chelation and free radical scavenging activity. Of the 35 4,2′-dihydroxyl and 2′,4′-dihydroxyl derivatives of flavonoid synthesized, including chalcone, flavone, flavanone, flavonol and dihydrochalcone, some chalcone derivatives synthesized were found to possess aldose reductase inhibition and antioxidant activities in-vitro as well as inhibition in the accumulation of sorbitol in the tissues in-vivo. 3,4,2′,4′-Tetrahydroxychalcone (18, butein) was the most promising compound for the prevention or treatment of diabetic complications.
Design, synthesis and biological evaluation of a sulfonylcyanoguanidine as thromboxane A2 receptor antagonist and thromboxane synthase inhibitor
Authors: Dogné Jean-Michel , Wouters Johan , Rolin Stéphanie , Michaux Catherine , Pochet Lionel , Durant François , Delarge Jacques , Masereel Bernard
Published: July 2003

The synthesis and the structure of N-isopropyl-N′-[2-(3′-methylphenylamino)-5-nitrobenzenesulfonyl] urea (14) was drawn from two thromboxane A2 receptor antagonists structurally related to torasemide. Compound 14 showed an IC50 value of 22 nm for the thromboxane A2 (TXA2) receptor of human washed platelets. Compound 14 prevented platelet aggregation induced by arachidonic acid (0.6 mm) and U-46619 (1 μm) with an IC50 value of 0.45 and 0.15 μm, respectively. Moreover, 14 relaxed the rat isolated aorta and guinea-pig trachea precontracted by U-46619, a TXA2 agonist. Its efficacy (IC50) was 20.4 and 5.47 nm, respectively. Finally, 14 (1 μm) completely inhibited TXA2 synthase of human platelets. The pKa value and the crystallographic data of 14 were determined and used to propose an interaction model between the TXA2 antagonists related to torasemide and their receptor.