bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Fatty acids on the Permeation of Melatonin across Rat and Pig Skin In-vitro and on the Transepidermal Water Loss in Rats In-vivo
Authors: Kandimalla K , Kanikkannan N , Andega S , Singh M
Published: July 2003

Transdermal delivery of melatonin would be advantageous in the treatment of sleep disorders considering the short biological half-life of melatonin and its variable bioavailability via the oral route. This study looked at suitable penetration enhancers for the transdermal permeation of melatonin.

The permeation of melatonin was enhanced by all saturated and unsaturated fatty acids across both rat and porcine skin. There was a parabolic relationship between the carbon chain length of saturated fatty acids and the enhancement of melatonin permeation across rat and porcine skin. For rat skin, the maximum flux was observed with undecanoic acid (45.33 μg cm−2h−1) which enhanced the flux of melatonin 8.6 times compared with the control, whereas lauric acid produced the maximum flux of melatonin (24.98 μg cm−2h−1; 4.7 times) across porcine skin. An increase in the number of double bonds in cis-9-octadecanoic acid increased the flux of melatonin across rat skin. In contrast, with porcine skin, the flux of melatonin decreased as the number of double bonds increased, although the flux values were not statistically significant. Treatment of rats with undecanoic acid, oleic acid and linolenic acid for 3 h using Hill top chamber enhanced the transepidermal water loss significantly. The maximum transepidermal water loss was observed with undecanoic acid and linolenic acid among saturated and unsaturated fatty acids, respectively. Nonanoic acid and myristic acid did not cause a significant change in the transepidermal water loss.

The enhancement effect of saturated fatty acids on the permeation of melatonin was dependent on the chain-length of the fatty acid in both rat and porcine skin. While an increase in the number of double bonds in the fatty acid increased the flux of melatonin in rat skin, no significant difference in the flux was observed with porcine skin. The permeation enhancement of melatonin by saturated and unsaturated fatty acids across rat skin was significantly higher than that of porcine skin. A positive correlation was observed between the permeation enhancement effect of the fatty acids across rat skin in-vitro and the transepidermal water loss in rats in-vivo, suggesting that there is a similarity in the mechanism by which fatty acids enhance the permeation of melatonin and in the enhancement of transepidermal water loss.

We conclude that saturated fatty acids such as undecanoic acid or lauric acid which showed maximum permeation across rat and porcine skin, respectively, may be used as potential penetration enhancers in the development of a transdermal delivery system for melatonin.
Cultured Rabbit Corneal Epithelium Elicits Levofloxacin Absorption and Secretion
Authors: Kawazu Kouichi , Midori Yukari , Ota Atsutoshi
Published: July 2003

Evidence for carrier-mediated transport of levofloxacin in the isolated rabbit cornea has been found. However, it is not known whether this mechanism is located in the epithelium or the endothelium. To resolve this question, we have measured the kinetics of levofloxacin uptake in primary cultures of rabbit corneal epithelial cells.

The results indicate that levofloxacin accumulation was time dependent and a steady state was reached after 30min. Maximal uptake occurred from a solution whose pH was 6.5. The uptake process was stereoselective and concentration dependent. In addition to the uptake, secretion of levofloxacin also occurred.

These results indicate that the corneal epithelium is the site of levofloxacin transport mechanisms, mediating both absorption and secretion.
Characterization of the Carrier-mediated Transport of Levofloxacin, a Fluoroquinolone Antimicrobial Agent, in Rabbit Cornea
Authors: Kawazu Kouichi , Midori Yukari , Shiono Hiromitsu , Ota Atsutoshi
Published: July 2003

The cornea presents a formidable barrier to drug penetration. The fluoroquinolone levofloxacin, which is an effective antimicrobial agent, has the potential to be used in the topical treatment of ocular disease. Thus, we sought to characterize how levofloxacin penetrates the cornea. To perform this characterization, we measured the time dependent permeation of levofloxacin across the isolated rabbit cornea using a diffusion chamber, and compared it with antipyrine fluxes.

Levofloxacin permeation into the receiver epithelial-side bathing solution (pH = 6.5) from the donor endothelial-side (pH = 7.4) reached 3.00nmol cm−2 cornea after 2h, whereas in the opposite direction permeation was 1.89nmol cm−2 cornea. Based on the temperature-dependent effects on permeation, the calculated energy of activation for permeation, Ea, was 31.3kcal mol−1, whereas Ea for antipyrine, a marker of diffusion, was 11.0kcal mol−1. The transport of levofloxacin from epithelium to endothelium was concentration-dependent and had both a linear and saturable component. Evaluation of the kinetic parameters, Jmax, apparent Km and kd showed that they were 38.78 pmol min−1 cm−2, 3.83 mM and 0.0135 μL min−1cm−2, respectively.

These results, coupled with the fact that levofloxacin permeation reached a maximum value at pH 6.5, suggest that levofloxacin transport across the cornea is carrier mediated. However, at present, it cannot be ascertained whether such a system is localized in either the corneal epithelial or the endothelial layer.
The Effect of Pregnenolone 16α-Carbonitrile on the Pharmacokinetics and Metabolism of Dapsone in Rats
Authors: Lu Ming , Poloyac Samuel M , Mcnamara Patrick J , Blouin Robert A
Published: July 2003

The purpose of this study was to evaluate the effect of pregnenolone 16α-carbonitrile (PCN) on the interconversion pharmacokinetics and metabolism of dapsone. To determine microsomal CYP3A activity and protein, eight rats (4 PCN, 4 corn oil) received a 1mg kg−1 intravenous bolus dose of dapsone, followed by blood and urine sampling. The formation clearance of dapsone hydroxylamine (CLf DDS-NOH) was calculated from the obtained samples. Interconversion pharmacokinetics estimates were obtained after 10 rats (5 PCN, 5 control) received 1mg kg−1 dapsone or 1.17 mg kg−1 monoacetyldapsone, with a 24-h wash-out.

Results from the interconversion analysis demonstrated that PCN significantly increased systemic clearance (CLs) of dapsone, but not its interconversion. The in-vivo/in-vitro correlation study demonstrated that PCN significantly increased CLs of dapsone (8.55 to 16.39mL min−1; P <0.01) and CLf DDS-NOH (0.13 to 0.18mL min−1; P < 0.01). PCN treatment produced a 69% increase in CYP3A protein, and increased 6β- and 2β-hydroxytestosterone formation rates. Significant correlations were found between CLf DDS-NOH and either 6β- (r2 = 0.925), 2β-hydroxytestosterone (r2 = 0.92), or CYP3A1/2 protein (r2 = 0.60).

We conclude that PCN treatment produces significant increases in CLs (dapsone) and CLf (DDS-NOH) in rats. These changes were not due to changes in the reversible metabolism of dapsone. These results suggest that the formation clearance of dapsone hydroxylamine reflects alterations in CYP3A activity, despite the fact that it accounted for a small part of the systemic clearance of dapsone.
Comparison of Cyclosporin A and Tacrolimus Concentrations in Whole Blood between Jejunal and Ileal Transplanted Rats
Authors: Ogino Yoshinori , Kobayashi Eiji , Fujimura Akio
Published: July 2003

Most immunosuppresive drugs are absorbed from the intestine after oral administration, although there is some difference of bioavailability between ileum and jejunum. Using an orthotopic segmental small bowel transplantation (SBT) model an rats, we studied the pharmacokinetic profiles of cyclosporin A and tacrolimus concentrations after oral intake, comparing jejunal and ileal transplanted rats.

Two types of segmental SBT (jejunal and ileal SBT) in a syngeneic combination were performed. After oral administration of cyclosporin A (10 mg kg−1) or tacrolimus (5 mg kg−1), pharmacokinetic data were obtained from the long-surviving rats transplanted with segmental SBT. To determine the effect of additional bile on cyclosporin absorption, an emulsion of cyclosporin A with fresh bile juice was re-challenged on segmental SBT rats before killing. A histological study was also performed by use of the intestinal grafts from the killed SBT rats.

A higher concentration of cyclosporin A was observed in the ileum-grafted rats than in the rats which received the jejunal grafts. Oral bioavailability of cyclosporin A in ileal SBT rats tended to be increased by addition of fresh bile juice, but that in jejunal SBT rats did not change. On the other hand, there was no significant difference of tacrolimus concentration between jejunum- and ileum-transplanted rats. Histological studies showed that the superficial mucosal layer of both grafts, but especially the ileal graft, was markedly elongated compared with that of normal intestine.

The present study showed that cyclosporin A was more actively absorbed from ileum than from jejunum in SBT, but tacrolimus was absorbed equally from both sites. These data suggest that cyclosporin A concentration is satisfactorily controlled in the segmental ileal graft, while there is no difference of tacrolimus absorption between ileal and jejunal graft.
The Mechanisms of Immune Suppression by High-pressure Stress in Mice
Authors: Fujiwara R , Shibata H , Komori T , Yokoyama M M , Okazaki Y , Ohmori M
Published: July 2003

The effects of high-pressure stress on the induction of anti-sheep red blood cells (SRBC) and of plaque-forming cells (PFC), and on thymus weight, were studied in BALB/c mice in-vivo and in-vitro.

The efficacy of high-pressure stress in suppressing PFC and thymic involution was maximum when the stress was applied 1 h day−1 for 2 days before immunization with SRBC. Both effects were blocked by administration of indomethacin, atropine, naloxone or phentolamine before the first application of stress, whereas hexamethonium and propranolol had no such effect. Hexamethonium, naloxone and propranolol administered before the second application of high-pressure stress blocked both effects. Prostaglandin and acetylcholine given 24 h before application of high-pressure stress caused a marked reduction in PFC count, but not in thymus weight. The reduced PFC count caused by acetylcholine was blocked by pretreatment with indomethacin. When adrenaline was injected 24 h after application of high-pressure stress a marked reduction in PFC was observed, but without thymic involution. When adrenaline was injected 24 h after prostaglandin injection the PFC count was also markedly reduced, but not thymus weight. The decrease in PFC caused by two exposures to stress or one exposure to stress plus injection of adrenaline was blocked by diethylcarbamazine before the second exposure to stress or the injection of adrenaline. In addition, normal spleen cells were induced as suppressor cells when incubated with the serum of stressed mice, but not when supplemented with anti-leukotriene C4, D4 antibody.

These data suggest that mice fall into a pre-stress condition via the release of prostaglandin after the first stress, and then immunosuppression is induced in these prestressed mice via the release of leukotriene C4, D4, caused by the activation of the autonomic nervous system by the second exposure to stress.
Time-dependent Striatal Dopamine Depletion after Injection of 6-Hydroxydopamine in the Rat. Comparison of Single Bilateral and Double Bilateral Lesions
Authors: Ben Valérie , Blin Olivier , Bruguerolle Bernard
Published: July 2003

For future investigation of possible perturbation of circadian rhythm in animal models of Parkinson's disease we needed an animal model providing lasting 80–100% striatal dopaminergic depletion in rats, but without induced mortality. We have thus compared the effects of a single hydroxydopamine bilateral striatal lesion (SB-hydroxydopamine) with those of a double hydroxydopamine bilateral lesion (DB-hydroxydopamine) at the same dose (16 μg/striatum) by HPLC determination of dopamine and 3,4-dihydrophenylacetic acid (dopac) levels in the striatum.

Two weeks after neurosurgery, SB-hydroxydopamine and DB-hydroxydopamine induced dopaminergic depletion of at least 81% compared with control groups. After eight weeks striatal dopaminergic depletion was only 60.97% in SB-hydroxydopamine rats, suggesting a compensatory phenomenon, whereas in DB-hydroxydopamine rats dopaminergic loss was stable at 88%. For the DB-hydroxydopamine group the dopac/dopamine ratio was significantly increased at week 2 only, whereas no significant change was observed for other groups. This increase might be explained by increased dopamine turnover.

We have demonstrated that striatal DB-hydroxydopamine injection induces lasting 80–100% neuronal loss, close to that observed in the disease in man, without induced mortality, and provides a tool which meets our experimental requirements.
Oestrogenic Compounds Modulate Cytokine-induced Nitric Oxide Production in Mouse Osteoblast-like Cells
Authors: Van Bezooijen Rutger L , Van Der Bent Chris , Papapoulos Socrates E , Lowik Clemens W G M
Published: July 2003

Nitric oxide (NO) is a mediator of bone metabolism with effects on both bone resorption and formation. Its production by both the constitutive and inducible isoforms of nitric oxide synthase (NOS) is affected by oestrogen in several types of cell and in tissues other than bone cells. Recently, oestrogens were found to increase basal NO production by osteoblasts via enhanced activity or expression, or both, of NOS-3. Inflammatory cytokines, however, increase NO by increasing the expression of NOS-2.

In this study we have examined whether cytokine-induced NO production by osteoblastic cells was affected by oestrogenic compounds by studying the effect of 17β-oestradiol and the anti-oestrogens ICI164,384 and 4-hydroxytamoxifen on cytokine-induced NO production in oestrogen receptor positive MC3T3-E1 osteoblast-like cells. Combinations of the inflammatory cytokines interleukin-1β, tumour necrosis factor-α, and interferon-γ with lipopolysaccharide stimulated NO production up to 11-fold. This cytokine-induced NO production was further increased dose-dependently by the anti-oestrogens ICI164,384 and 4-hydroxytamoxifen (133.3±3.2% and 146.0±13.2%, respectively). 17β-Oestradiol either had no effect on or slightly inhibited cytokine-induced NO production. It did, however, dose-dependently counteract the stimulatory effect of the anti-oestrogens. Concentrations of 17β-oestradiol needed to prevent the stimulatory effect of 4-hydroxytamoxifen were ca tenfold that of ICI164,384.

These findings show that, in addition to the stimulatory effect of oestrogen on basal NO production by NOS-3, cytokine-induced NO production is also affected by oestrogenic compounds in osteoblasts.
Effects of 5-Hydroxytryptamine on the Transintestinal Electrical Activity and Cardiovascular Function of Fawn-hooded Rats In-vivo
Authors: Hardcastle J , Hardcastle P T
Published: July 2003

Fawn-hooded rats, which have abnormal serotonergic function, were used to investigate the receptors involved in 5-hydroxytryptamine (5-HT)-induced intestinal secretion. The effects of 5-HT on secretion by the small intestine and proximal colon, monitored as increased transintestinal electrical activity, and on cardiovascular function, measured as changes in heart rate and blood pressure, were compared in fawn-hooded and Wistar rats.

The maximum fall in heart rate induced by 5-HT (mediated by 5-HT3 receptors) was greater in fawn-hooded than in Wistar rats. ED50 values (the doses resulting in 50% of the maximum effect) for the 5-HT2-mediated increases in systolic pressure were lower for both 5-HT and 5-methoxytryptamine in the fawn-hooded group. The prolonged fall in diastolic pressure mediated by 5-HT1-like receptors was significantly attenuated in fawn-hooded rats, with the maximum responses to 5-HT, 5-methoxytryptamine and 6-hydroxyindalpine reduced to 21%, 42% and 28%, respectively, of the values obtained for Wistar rats. In fawn-hooded rats the small intestine was less sensitive to the effects of 5-HT (ED50=47 nmol kg−1; ED50 for Wistar rats=23nmol kg−1) and the maximum colonic response to 5-methoxytryptamine wasgreater (7.0mV compared with 4.3 mV in Wistar rats), but other indices did not differ for the two strains. The responses to 6-hydroxy-indalpine were similar in fawn-hooded and Wistar rats.

It is concluded that although the cardiovascular response of fawn-hooded rats to 5-HT challenge is very different from that of Wistar rats, this difference is not reflected in marked alterations in 5-HT-induced intestinal secretion. This is consistent with 5-HT stimulating secretion via the activation of several different receptor subtypes so that any changes in the receptor profile in fawn-hooded rats results in little alteration in the overall intestinal response.
Effect of Pretreatment with FTY720 and Cyclosporin on Ischaemia-Reperfusion Injury of the Liver in Rats
Authors: Mizuta Koichi , Ohmori Masami , Miyashita Fujiko , Kitoh Yasuhiko , Fujimura Akio , Mori Masaya , Kanno Takayuki , Hashizume Kohei , Kobayashi Eiji
Published: July 2003

The effect of pretreatment with FTY720 (2-amino-2-[2-(4-octylphenyl)ethyl]-1,3-propane-diol hydrochloride) or cyclosporin, or both, on neutrophil-mediated injury has been examined by use of a rat model of transient clamping of hepatic flow.

Pretreatment with FTY720 alone or with cyclosporin induced a marked reduction of circulatory lymphocytes, whereas the use of these drugs in combination was very effective at suppressing the elevation of the number of peripheral polymorphonuclear neutrophils (PMN) after reperfusion. Pretreatment with cyclosporin, with or without FTY720, significantly reduced hepatic damage, whereas FTY720 alone tended to prolong hepatic damage. Pretreatment of cyclosporin alone, but not in combination with FTY720, significantly reduced the accumulation of PMN and led to lower myeloperoxidase levels in the damaged liver.

In conclusion, pretreatment with cyclosporin, with or without FTY720, reduced hepatic damage after warm ischaemia-reperfusion, whereas pretreatment with FTY720 alone tended to prolong this damage.
Modulation of Nitric Oxide-dependent Vascular and Platelet Function In-vitro by the Novel Phosphodiesterase Type-V Inhibitor, ONO-1505
Authors: Laight David W , Anggärd Erik E , Carrier Martin J
Published: July 2003

We have characterized the in-vitro modulation of both nitric oxide (NO)-dependent vasodilator activity and anti-platelet function by the novel type-V phosphodiesterase inhibitor, ONO-1505 (4-[2-(2-hydroxyethoxy)ethylamino]-2-(1H-imidazol-1-yl)-6-methoxyquinazoline methanesulphonate).

ONO-1505 elicited vasorelaxation in the rat isolated aorta. If the concentration of ONO-1505 was ≤10 μM the vasorelaxation was abolished by NG-nitro-L-arginine methyl ester (L-NAME), by methylene blue, and by endothelial denudation. Furthermore, pretreatment of the rat isolated aorta for 10 min with ONO-1505 in the presence of L-NAME potentiated vasorelaxation to the NO-donor, sodium nitroprusside. Similarly, ONO-1505, although having no effect on adenosine diphosphate (ADP)-induced rat platelet aggregation in-vitro, augmented established anti-aggregatory effects of sodium nitroprusside.

The data therefore show that the novel phosphodiesterase V inhibitor ONO-1505 augments endogenous and exogenous nitrovasodilator activity in-vitro; they also imply modulation of the NO pathway in the haemodynamic actions of this compound, previously reported in-vivo.
In-vivo and In-vitro Assessment of the Free-radical-scavenger Activity of Ginkgo Flavone Glycosides at High Concentration
Authors: Hibatallah Jalila , Carduner Charlotte , Poelman Marie-Christine
Published: July 2003

Free radicals are involved in numerous skin diseases, especially inflammatory reactions and photosenescence. To identify possible free-radical scavenging by an original terpenefree Ginkgo biloba extract containing 33% Ginkgo flavone glycosides, mostly quercetin and kaempferol derivatives, we studied its activity by means of in-vitro and in-vivo experiments, using superoxide dismutase (SOD) as a positive control.

By means of an in-vitro electron-spin resonance (ESR) assay we compared the activity of the Ginkgo extract with that of its two aglycones, quercetin and kaempferol. Quercetin and Ginkgo extract had significant antioxidant properties without pro-oxidant effect. In contrast, kaempferol, above an optimum antioxidant concentration, behaved as a pro-oxidant. The in-vivo experiments were conducted on an anti-inflammatory model. The cutaneous blood flux which reflects the skin inflammatory level was recorded by means of a laser Doppler perfusion imager. The data confirmed the free-radical-scavenging property of both Ginkgo extract and SOD. The Ginkgo extract significantly inhibited (37%) cutaneous blood flux to the same extent as SOD.

These data confirmed the antioxidant property of Ginkgo extract. A complementary spin-trapping technique would enable identification of the free radicals involved. This Ginkgo extract should be useful for protection of the skin against free radicals.
Isolation of Opioid-active Compounds from Tabernaemontana pachysiphon leaves
Authors: Ingkaninan K , Ijzerman A P , Taesotikul T , Verpoorte R
Published: July 2003

A procedure for prefractionation of crude plant extracts by centrifugal partition chromatography (CPC) has been developed to enable rapid identification of known-positive compounds or false-positive compounds and to increase the chance of identifying minor unknown-active compounds. The study explored the use of CPC as a tool in the prefractionation step before investigation of bioactivity.

Fractions obtained by CPC from an ethanolic extract of Tabernaemontana pachysiphon Stapf (Apocynaceae) were screened by means of an opiate-receptor-binding assay and an adenosine A1-receptor-binding assay. Fractions containing fatty acids, which had false-positive effects on the assay, were identified, as were unknown-positive fractions from which two opioid-active compounds, tubotaiwine and apparicine, were subsequently isolated. The affinities (Ki) of tubotaiwine and apparicine at the opiate receptor were 1.65 ± 0.81 and 2.65 ± 1.56 μmol, respectively. Both alkaloids had analgesic activity in the abdominal constriction test in mice.

CPC prefractionation led to the rapid isolation of two opioid-active compounds, tubotaiwine and apparicine, from the unknown-positive fraction; false-positive fractions were rapidly identified. Both tubotaiwine and apparicine had affinity for adenosine receptors in the micromolar range and also had in-vivo analgesic activity in mice.
Anti-inflammatory and Antinociceptive Effects in Rodents of the Essential Oil of Croton cajucara Benth
Authors: Bighetti Eliete J B , Hiruma-Lima Clélia A , Gracioso Juliano S , Brito Alba R M Souza
Published: July 2003

The plant Croton cajucara Benth. (Euphorbiaceae) is widely used in Amazonian folk medicine for the treatment of a wide range of illnesses. In this investigation the analgesic and anti-inflammatory properties of the essential oil from the bark of C. cajucara Benth., administered orally, were determined in several standard rodent models of pain and inflammation.

We observed that pretreatment with essential oil significantly reduced the latency of sleeping time evoked by pentobarbital compared with the control group (P < 0.001). Doses of 100 or 1000 mg kg−1 also increased the sleeping time induced by pentobarbital (30.9 ± 3.91 and 52.1 ± 15.6 min, respectively) compared with the negative control (12.4 ± 4–27 min). We investigated the antinociceptive effect of the essential oil in chemical (acetic acid) and thermal (hot-plate) models of nociception in mice. Dipyrone (200 mg kg−1) and the highest doses of the essential oil (1000 mg kg−1) significantly inhibited acetic acid-induced abdominal constriction in mice (5.00 ± 1.38 and 6.8 ± 2.1 constrictions, respectively) compared with the negative control (33.1 ± 2). The same dose of essential oil also raised the pain thresholds of mice in the hot-plate test and significantly (P < 0.05) increased the latency at all observation times. In acetic acid-induced abdominal constriction in mice pretreatment of the animals with naloxone (5 mg kg−1) significantly reversed the analgesic effect of morphine and of the essential oil at the highest dose (1000 mg kg−1).

The essential oil of C. cajucara was also investigated for its anti-inflammatory properties. At the lowest dose (100 mg kg−1) the essential oil had anti-inflammatory effects in animal models of acute (carrageenin-induced paw oedema in mice) and chronic (cotton pellet granuloma) inflammation. The essential oil at doses of 50, 100 and 200 mg kg−1 significantly and dose-dependently inhibited carrageenan-induced oedema (49 ± 5; 37 ± 5; 34 ± 8 mg, respectively) compared with the negative control (74 ± 8 mg). The essential oil (100 mg kg−1) also inhibited chronic inflammation by 38% whereas diclofenac inhibited it by 36%. However, the essential oil did not inhibit the migration of neutrophils into the peritoneal cavity.

These data show that the essential oil from C. cajucara contains compounds that had a significant antinociceptive effect when the oil was administered at the highest dose. This effect seems to be related to interaction with the opioid system. The essential oil also had a significant anti-inflammatory effect in acute and chronic inflammation models when administered at lower doses. This effect seems to be related to cyclooxygenase inhibition.
Investigation of Plants used in Jamaican Folk Medicine for Anti-bacterial Activity
Authors: Facey Petrea C , Pascoe Keith O , Porter Roy B , Jones Alcia D
Published: July 2003

We have started a systematic scientific study of folklore medicinal plants currently used as alternative medicine in Jamaican society. In this initial study, extracts of plants widely used by the islanders are studied for antibacterial activity against five common pathogens; Streptococcus group A, Staphylococcus aureus, Proteus mirabilis, Pseudomonas aeruginosa and Escherichia coli.

These studies revealed that 25% (approx.) of the plant extracts had antimicrobial activity against at least one of the microbes used. Subsequent to these observations, extracts from Mikania micrantha were examined in detail. This led to the isolation of two sesquiterpenoids, mikanolide and dihydromikanolide, with activity against S. aureus and C. albicans.

The results suggest that traditional folk medicine could be used as a guide in our continuing search for new natural products with potential medicinal properties.
Fluorimetric Determination of Ampicillin by use of Non-toxic Catalysts. Estimation of β-Lactamase Activity and Parameters
Authors: Baker W L
Published: July 2003

A fluorescence assay based on the use of biological reducing agents as catalysts rather than heavy metal ions has been developed for estimation of ampicillin concentrations.

The assay is based on the conversion of ampicillin to its penicilloate, by treatment with sodium hydroxide, then neutralization, dilution with 0.5 M acetate buffer at pH4 and heating for 30 min at 100°C in the presence of ascorbic acid (0.5 mg) and EDTA (50 μM). Reduced glutathione, cysteine and N-acetylcysteine also catalysed the development of fluorescence. A practical sensitivity range of 0.5–50 μM ampicillin was used. The assay was used to estimate ampicillin in some biological solutions to which the antibiotic has been added. Milk, blood serum, trypticase soy broth and nutrient broth containing 25 μM antibiotic assayed at 18.5, 21.7, 16.5 and 14.7 μM, respectively, with standard deviations between 1.2 and 0.7%. The low results were attributed to binding of some ampicillin by proteins or peptides which were removed by pretreatment. Urine containing 5 mM ampicillin assayed at 4.97 mM with a standard deviation of 3%. A modification of the procedure was used to measure β-lactamase activity against ampicillin in several organisms in a fixed time assay. Kinetic parameters of a commercial β-lactamase preparation from Bacillus cereus could also be determined by an additional modification. In both instances a correction was required for the intrinsic fluorescence of ampicillin remaining in the solution. The preparation examined had a Michaelis constant (Km) of 0.32 mM, a maximum velocity (Vcat) of 5398 μmol ampicillin hydrolysed mg−1 min−1, an apparent catalytic constant (Kcat, turnover number) of 20220 s−1 and a Kcat/Km ratio of 0.63 times 107 M−1 S−1.

The major advantage of using this assay technique is that toxic metals are not used in the development of fluorescence so it is more environmentally acceptable. The technique is useful for examining β-lactamase activity against ampicillin and might be useful for pharmaceutical products—for determining available therapeutic levels and for monitoring the activity of penicillin acylase against the penicilloate of ampicillin.
Evaluation and Prediction of Drug Permeation
Authors: Pagliara Alessandra , Reist Marianne , Geinoz Sandrine , Carrupt Pierre-Alain , Testa Bernard
Published: July 2003

A major challenge confronting the pharmaceutical scientist is to optimize the selective and efficient delivery of new active entities and drug candidates. Successful drug development requires not only optimization of specific and potent pharmacodynamic activity, but also efficient delivery to the target site. Following advances in rational drug design, combinatorial chemistry and high-throughput screening techniques, the number of newly discovered and promising active compounds has increased dramatically in recent years, often making delivery problems the rate-limiting step in drug research. To overcome these problems, a good knowledge of the pharmacokinetic barriers encountered by bioactive compounds is required. This review gives an overview of the properties of relevant physiological barriers and presents some important biological models for evaluation of drug permeation and transport. Physicochemical determinants in drug permeation and the relevance of quantitative and qualitative approaches to the prediction and evaluation of passive drug absorption are also discussed.
Biochemical and Pharmacological Characteristics of a Newly Synthesized H+/K+-ATPase Inhibitor, YJA20379-8, 3-Butyryl-4-[R-1-methylbenzylamino]-8-ethoxy-1,7-naphthyridine, in pigs and rats
Authors: Sohn Sang Kwon , Chang Man Sik , Choi Wahn Soo , Chung Young Kuk , Kim Kyu Bong , Woo Tae Wook , Lee Seok Bong , Park Chong Jeun
Published: July 2003

We have investigated the effect of the newly synthesized proton-pump inhibitor YJA20379-8, 3-butyryl-4-[R-1-methylbenzylamino]-8-ethoxy-1,7-naphthyridine, on gastric mucosal proton pump (H+/K+-ATPase) activity, gastric acid secretion and gastric lesions in experimental animals.

In lyophilized pig gastric microsomes, YJA20379-8 was shown to inhibit H+/K+-ATPase activity; the inhibitory effect was not affected by pH, the IC50 (dose resulting in 50% inhibition) being 28.0 μM and 30.0 μM at pH 6.4 and pH 7.4, respectively. The effect was fully reversed by dilution and subsequent washing of the incubation mixtures of H+/K+-ATPase and YJA20379-8, suggesting the reversible nature of the enzyme inhibition. In pylorus-ligated rats, YJA20379-8 administered by different routes (intraduodenal, subcutaneous, intravenous or oral) resulted in dose-dependent suppression of basal gastric acid secretion. The duration of antisecretory action of 30 mg kg−1 YJA20379-8 given intraduodenally was very brief (less than 7 h). Pretreatment with YJA20379-8 also dose-dependently prevented gastric lesions induced by absolute ethanol and water-immersion stress in rats.

These results suggest that YJA20379-8 might exert its antiulcer activity partly by reversible suppression of acid secretion and partly by protecting the gastric mucosa against ulcerative stimuli.
Inclusion Complexation of the Sunscreen Agent 2-Ethylhexyl-p-dimethylaminobenzoate with Hydroxypropyl-β-cyclodextrin: Effect on Photostability
Authors: Scalia Santo , Villani Silvia , Casolari Alberto
Published: July 2003

The interaction between the UV filter, 2-ethylhexyl-p-dimethylaminobenzoate, and unmodified and modified α-, β- or γ-cyclodextrins was studied in water by phase-solubility analysis.

Of the cyclodextrins available, only hydroxypropyl-β-cyclodextrin caused a marked increase in the aqueous solubility of 2-ethylhexyl-p-dimethylaminobenzoate. The data from the solubility study indicated the formation of a 1:1 (sunscreen-cyclodextrin) complex. The inclusion of the sunscreen agent into the hydroxypropyl-β-cyclodextrin cavity was confirmed by thermal analysis and by nuclear magnetic resonance spectroscopy. Irradiation-induced degradation of 2-ethylhexyl-p-dimethylaminobenzoate was reduced by complexation with hydroxypropyl-β-cyclodextrin, this effect being more pronounced in solution (the extent of degradation was 25.5% for the complex compared with 54.6% for free 2-ethylhexyl-p-dimethylaminobenzoate) than in the emulsion vehicle (the extent of degradation was 25.1% for the complex compared with 33.4% for free 2-ethylhexyl-p-dimethylaminobenzoate).

Although photodegradation of the sunscreen agent is significantly reduced by formation of the inclusion complex it is important to design a suitable vehicle. Inclusion of 2-ethyl-hexyl-p-dimethylaminobenzoate-DMAB into the hydroxypropyl-β-cyclodextrin cavity limits interaction of the UV filter with the skin reducing the side-effects of the formulation.
Absorption of Vitamin K2 by Dogs after Oral Administration of a Soft Gelatin Capsule Formulation Containing a New Emulsion-type Vehicle
Authors: Amemiya Tohru , Mizuno Satoshi , Hayashi Yayoi , Yuasa Hiroaki , Watanabe Jun
Published: July 2003

This study has evaluated the performance of a newly developed vehicle for administration of a drug in a soft gelatin capsule. The absorption of vitamin K2 in dogs after oral administration of the vitamin in a soft gelatin capsule containing the newly developed vehicle was compared with absorption after administration of a control formulation prepared by encapsulating the contents of a commercially available vitamin K2 capsule (Glakay capsules 15 mg) in the same type of soft gelatin.

Under non-fasted conditions the profile of the plasma concentration of vitamin K2 against time for the test formulation was comparable with that for the control formulation in non-fasted dogs. Under fasted conditions, however, both the maximum concentration (Cmax) and the area under the plot of concentration against time (AUC) were significantly smaller for the test formulation than for the control formulation. The Cmax and AUC for the test formulation were about 10 times larger for non-fasted dogs than for fasted dogs whereas values for the control formulation were about twice as large. These results suggest that both formulations might require the presence of food or digestive fluid components, or both, for better absorption of vitamin K2. It seems that although the performances of the test and control formulations were comparable in the presence of these components, the control formulation works better in their absence. It should be also noted that, in contrast with the results from the absorption tests, the dispersibility of the test vehicle in water was much better than that of the control vehicle. This suggests that dispersibility does not significantly affect vitamin K2 absorption.

In conclusion, although the new vehicle did not perform better than the control vehicle in terms of vitamin K2 absorption, the performance of the control formulation was comparable for non-fasted dogs. Because the new vehicle contains considerably less surfactant than the vehicles currently used in soft gelatin capsules, it could be a safer alternative for use under non-fasted conditions.
Statistical Moments for Placental Transfer of Solutes in Man
Authors: Bernus Iren , Roberts Michael S , Rasiah Rohan L , Mortimer Robin H
Published: July 2003

The placental transfer of red blood cells and solutes in man has been investigated by statistical moment analysis, using the impulse-response technique. Model compounds of different lipophilicity (sucrose, water, antipyrine, propranolol and labetalol) were injected with a vascular reference (labelled red blood cells) as boluses into either the foetal or maternal circulation of a single-pass perfused placental lobule. Maternal and foetal venous outflow fractions were collected at intervals ranging from 1 to 600s. Perfusion was conducted at maternal flow rates of 4 and 6 mL min−1 and foetal flow rates of 2 and 3 mL min−1, respectively, to yield a constant materno-foetal flow ratio of 2. The outflow concentration-time profile curves were analysed by statistical moment analysis.

The sum of foetal and maternal recovery was close to 100% for red blood cells, sucrose, water and antipyrine, but lower for propranolol and labetalol. The mean transit time (MTT) values ranged from 20 to 500s. The normalized variance (CV2) for red blood cells in the foetal and maternal circulation of the placenta were in the ranges 2.31 to 3.86 and 2.00 to 2.03, respectively.

The shape of the outflow concentration-time proifles after bolus input is consistent with that of vascular residence time models such as the dispersion model. The heterogeneity in red blood cell transit times, as defined by CV2, is greater than in either the perfused leg or perfused liver.
Effect of Oral Administration of Fennel (Foeniculum vulgare) on Ciprofloxacin Absorption and Disposition in the Rat
Authors: Zhu M , Wong P Y K , Li R C
Published: July 2003

The aim of this study was to investigate the possibility of a drug-drug interaction between ciprofloxacin and fennel (Foeniculum vulgare) in a rat model.

Pharmacokinetic assessment of ciprofloxacin was performed in two groups of male Sprague-Dawley rats. One group (n=5) received 20 mg kg−1 antibiotic orally with concomitant oral dosing of the aqueous fennel extract (2 g herb kg−1) whereas the controls (n=5) received 20 mg kg−1 oral ciprofloxacin. Blood and urine samples were collected over 6 and 24 h, respectively, for quantitation of ciprofloxacin by HPLC. A non-com-partmental model was employed for pharmacokinetic analysis. Major ingredients and metal cations in the fennel extract were determined. Compared with the control, maximum plasma concentration, area under the curve and urinary recovery of ciprofloxacin were significantly (P<0.05) lower, by 83, 48 and 43%, respectively, in rats receiving concomitant dosing of the two agents. The relative bioavailability of ciprofloxacin, under the influence of fennel, was estimated to be 0.52. In addition, its apparent volume of distribution and terminal elimination half-life were significantly (P<0.05) increased, from 30.8±11.1 (L kg−1) and 2.0±0.4 (h) to 143.8±31.6 (L kg−1) and 5.2±2.0 (h), respectively. Although none of the organic components of fennel seemed to cause this interaction, the total amount of ten metal cations measured was found to be 13 mg g−1.

Significant interaction between ciprofloxacin and fennel was observed in this study. Absorption, distribution and elimination of ciprofloxacin were all affected. These changes might be because of the formation of a more lipophilic ciprofloxacin chelate in the presence of relatively large amounts of metal cations. If, therefore, the two therapeutic agents are used concurrently, an adequate dosing interval is needed to ensure the efficacy of ciprofloxacin.
Superconductivity of Ternary Metal Compounds Prepared at High Pressures
Authors: Shirotani Ichimin
Published: July 2003

Various ternary metal phosphides, arsenides, antimonides, silicides and germanides have been prepared at high temperatures and high pressures. These ternary metal compounds can be classified into four groups: [1] metal-rich compounds MM′4X2 and [2] MM′X, [3] non-metal-rich compounds MXX′ and [4] MM′4X12 (M and M′ = metal element; X and X′ = non-metal element). We have studied the electrical and magnetic properties of these materials at low temperatures, and found many new superconductors with the superconducting transition temperature (Tc) of above 10 K. The metal-rich compound ZrRu4P2 with a tetragonal structure showed the superconducting transition at around 11 K, and had an upper critical field (Hc2) of 12.2 tesla (T) at 0 K. Ternary equiatomic compounds ZrRuP and ZrRuSi crystallize in two modifications, a hexagonal Fe2P-type structure [h-ZrRuP(Si)] and an orthorhombic Co2P-type structure [o-ZrRuP(Si)]. Both h-ZrRuP and h-ZrRuSi have rather high Tc values of above 12 K; on the contrary, Tc of o-ZrRuP and o-ZrRuSi is about 4 K. The alloys ZrRu1−xRhxP were prepared at high temperatures and at high pressures. The superconductivity and the crystal structure of the alloys are very sensitive to the content of Rh atoms. The Hc2 values of h-ZrRuP, h-HfRuP, h-ZrRuSi and h-ZrRuAs are 14–16 T at 0 K. The coherence length of these compounds is below 50 Å. ZrRhSi with the Co2P-type structure and ZrRuGe with a TiFeSi-type structure showed the superconductivity at around 10.5 K. Tc’s of MoNiP with the Fe2P-type structure and MoRuP with the Co2P-type structure were over 15 K. Both compounds have the highest Tc among the metal phosphides. Non-metal-rich compound NbPS showed the Tc of 13 K and the high Hc2 of 17 T. This Hc2 value is the highest among the phosphide superconductors. The Debye temperature and the density of states at the Fermi level for NbPS are 330 K and 0.51 states/eV-atom, respectively. Filled skutterudites LnRu4X12 (Ln = La and Pr, X = P, As and Sb) with a cubic structure show interesting superconductivity behavior at low temperatures. LaRu4As12 had the highest Tc of 10.3 K among the skutterudite compounds. PrRu4As12 with the magnetic element Pr transformed to a superconductor at around 2.4 K. Superconducting properties of various ternary metal compounds prepared at high pressure are discussed.
Introduction of P450, Peroxidase, and Catalase Activities into Myoglobin by Site-Directed Mutagenesis: Diverse Reactivities of Compound I
Authors: Watanabe Yoshihito , Ueno Takafumi
Published: July 2003

We have prepared several myoglobin (Mb) mutants which are protein models for peroxidase, P450, and catalase. In most cases, the distal site of Mb was modified by site-directed mutagenesis on the basis of mechanisms of peroxidase, P450, and catalase reactions. The most important feature of the Mb mutants is the direct observation of their active intermediates, so called compound I. Under catalytic oxidations of sulfides and styrene by H2O2, up to 97% of enantioselectivity was observed. Introduction of an aromatic substrate, tryptophan, near the heme by the site directed mutagenesis of Mb allowed us to proceed almost stoichiometric aromatic hydroxylation. In addition, compound I of Mb mutants exhibit the catalase activity. These results demonstrate that the compound I of Mb mutants are capable to proceed all of the peroxidase, P450, and catalase reactions.
Intramolecular Electron Transfer of Cytochrome c Modified with N,N,N′,N″,N″-Diethylenetriaminepentaacetatocobaltate(III)
Authors: Tsukahara Keiichi , Iida Nao , Kaida Yuka , Takashima Hiroshi , Mizobe Maya , Arakawa Ryuichi
Published: July 2003

Horse heart cytochrome c (cytc) modified with an N,N,N′,N″,N″-diethylenetriaminepentaacetatocobaltate(III) ion, [cytcIII{CoIII(dtpa)}], was prepared and characterized. The major component of singly modified [cytcIII{CoIII(dtpa)}] contains a [CoIII(dtpa)] ion at Lys13, of which the ε-amino group is linked with a carboxylate ion of dtpa. A one-electron reduced protein, [cytcII{CoIII(dtpa)}], was prepared by reduction with a methylviologen-radical cation, which was produced in situ by a photoreduction using a tris(2,2′-bipyridine)ruthenium(II) ion in the presence of disodium dihydrogen ethylenediaminetetraacetate at 25 °C, pH 7.5 (0.010 mol dm−3 tris(hydroxymethyl)aminomethane–HCl buffer), and an ionic strength of 0.50 mol dm−3 (NaCl). The reaction of [cytcII{CoIII(dtpa)}] to form [cytcIII{CoII(dtpa)}] was very slow, and was followed by conventional spectrophotometry. The reaction was of first order in the protein and the first-order rate constant ((3.1 ± 0.5) × 10−4 s−1) was independent of the concentration of the protein, indicating that the intramolecular electron-transfer (ET) process is predominant. The reaction mechanism is discussed on a through-bond or through-space pathway. The slow intramolecular ET rate might arise not only from the long distance, but also from the large reorganization energy for the Co(III)/Co(II) couple.
Equation of State for Free Energy of Homogeneous Nucleation in Supersaturated Lennard-Jones Vapor Phase Derived by Monte Carlo Simulations
Authors: Yamada Yuri , Kataoka Yosuke
Published: July 2003

We estimated the free energy of homogeneous nucleation in supersaturated Lennard-Jones vapor phase by using Monte Carlo simulations. The nucleation free energy of an N-particle cluster is obtained as the difference between the free energies of the cluster phase and the monomer phase in an N-particle system. In the previous papers, we estimated the Helmholtz free energy of the nucleation by MC calculations under a fixed volume per particle, V/N = 43.2 σ3, and the equation of state of the nucleation energy as a function of cluster size and temperature. In this study, we carried out some additional MC calculations under different volumes per particle and took into consideration the pressure to estimate the Gibbs free energy of the nucleation. Then we established the equations of state of the Helmholtz and Gibbs free energies of nucleation as a function of cluster size, temperature, and volume or pressure.
Photoinduced Electron Transfer from Tetrathienylethylenes to Fullerenes (C60/C70): Tetrathienylethylene-Dendrimer Effect
Authors: Yamanaka Ken-ichi , Fujitsuka Mamoru , Ito Osamu , Aoshima Toshihide , Fukushima Takanori , Miyashi Tsutomu
Published: July 2003

Photoinduced electron-transfer processes between C60/C70 and tetrathienylethylenes (TTE’s) in benzonitrile have been studied by measuring the transient absorption spectra in the Vis/NIR regions using nanosecond laser photolysis. The absorption bands of the radical anions of C60/C70 (C60•−/C70•−) and radical cations of TTE’s (TTE’s•+) were observed with the decay of the triplet states of C60/C70 (3C60*/3C70*), indicating that electron transfer takes place via 3C60*/3C70*. In addition, formation of the dication of TTE (TTE2+) was confirmed by its characteristic absorption band at 680 nm. The TTE2+ is formed by the stepwise collision of TTE with 3C60*/3C70*. By the substitutions with the MeS groups at the thienyl rings of TTE, the efficiencies and rates of the electron-transfer processes became higher than those of TTE with the PhS groups. For dendrimer TTE’s, the photoinduced electron-transfer processes also took place via 3C60*/3C70*, although the efficiencies and rates were decreased with an increase in the dendrimer generation. After forward electron transfer, the back electron transfer processes were observed between separately solvated C60•−/C70•− and TTE’s•+ even for the dendrimer TTE’s, which suggest that outer-sphere back electron-transfer took place in the backward processes.