Unroasted Green Coffee Extract-Loaded Solid Lipid Nanoparticles for Enhancing Intestinal Permeation

Green coffee bean extract (GCBE) provides diversified health benefits. However, its reported low bioavailability impeded its utilization in various applications. In this study, GCBE-loaded solid lipid nanoparticles (SLNs) were prepared to improve the bioavailability through enhanced intestinal absorption of GCBE. During the preparation of promising GCBE-loaded SLNs, the lipid concentration, surfactant concentration, and co-surfactant amount are crucial that were optimized using the Box-Behnken design, while particle size, polydispersity index (PDI), ζ-potential, entrapment efficiency, and cumulative drug release were the measured responses. GCBE-SLNs were successfully developed by a high shear homogenization technique using geleol as a solid lipid, tween 80 as a surfactant, and propylene glycol as Co-SAA. The optimized SLNs contained 5.8% geleol, 5.9% tween 80, and 80.4 mg PG resulting in a small particle size of 235.7 ± 12.5 nm, reasonably acceptable PDI of 0.417 ± 0.023, and ζ-potential of -15 ± 0.14 mV, with a high entrapment efficiency of 58.3 ± 0.85% and cumulative release of 7575 ± 0.78%. Furthermore, the performance of the optimized GCBE-SLN was evaluated using an ex vivo everted sac model where the intestinal permeation of GCBE was improved due to nanoencapsulation using SLN. Consequently, the results enlightened the auspicious potential of exploiting oral GCBE-SLNs for boosting intestinal absorption of chlorogenic acid.

Phytoecdysteroids and Anabolic Effect of Atriplex dimorphostegia: UPLC-PDA-MS/MS Profiling, In Silico and In Vivo Models

Atriplex dimorphostegia (Saltbush) is an annual halophytic shrub that is widely distributed across various parts of Asia. The current study is the first to report the metabolites profile of the total ethanol extract of the aerial parts of A. dimorphostegia (TEAD), and its anabolic activity together with the isolated 20-hydroxyecdysone (20-HE) in orchidectomized male rats. TEAD was analyzed and standardized utilizing UPLC-PDA-ESI−MS/MS and UPLC-PDA-UV techniques, resulting in tentative identification of fifty compounds including polyphenols, steroids and triterpenoids. In addition, 20-HE was quantified, representing 26.79 μg/mg of the extract. Phytochemical investigation of TEAD resulted in the isolation of 20-HE from the ethyl acetate fraction (EFAD) and was identified by conventional spectroscopic methods of analysis. Furthermore, the anabolic effect of the isolated 20-HE and TEAD was then evaluated using in silico and in vivo models. Molecular docking experiments revealed in vitro selectivity of 20-HE towards estrogen receptors (ERs), specifically ERβ over ERα and androgenic receptor (AR). The anabolic efficacy of TEAD and 20-HE was studied in orchidectomized immature male Wistar rats using the weight of gastrocnemius and soleus muscles. The weights of ventral prostate and seminal vesicles were used as indicators for androgenic activity. Rats administered 20-HE and TEAD showed a significant increase (p = 0.0006 and p < 0.0001) in the net muscle mass compared to the negative control, while the group receiving TEAD showed the highest percentage among all groups at p < 0.0001. Histopathological investigation of skeletal muscle fibers showed normal morphological structures, and the group administered 20-HE showed an increase in cross sectional area of muscle fibers comparable to methandienone and testosterone groups at p > 0.99. A. dimorphostegia exhibited promising anabolic activity with minimal androgenic side effects.

Extended infusion of piperacillin-tazobactam versus intermittent infusion in critically ill egyptian patients: a cost-effectiveness study

Extended infusion of piperacillin/tazobactam over 4 h has been proposed as an alternate mode of administration to the 30-min intermittent infusion to optimize treatment effects in patients with gram-negative bacterial infections. The study aimed to evaluate the extended infusion regimen of piperacillin/tazobactam in standings of efficacy, safety, and cost to the intermittent one in the treatment of gram-negative bacterial infections. A prospective randomized comparative study was performed on 53 patients, 27 in the intermittent infusion group and 26 in the extended infusion group. The primary outcome was the mean number of days to clinical success and the percentage of patients who were clinically cured after treatment. The secondary outcomes included mortality, readmission within 30-days, and cost-effectiveness analysis based on the mean number of days to clinical success. The clinical success rate was comparable in the two groups. Days on extended infusion were significantly lower than intermittent infusion (5.7 vs 8.9 days, respectively, p = 0.0001) as well as days to clinical success (4.6 vs 8.5 days, respectively, p = 0.026). The extended infusion was superior to the intermittent infusion regarding cost-effectiveness ratio ($1835.41 and $1914.09/expected success, respectively). The more cost-effective regimen was the extended infusion. Both regimens had comparable clinical and microbiological outcomes.

Cheminformatics Application in the Phytochemical and Biological Study of Eucalyptus globulus L. Bark as a Potential Hepatoprotective Drug

Natural products are considered as a good source of antifibrotic agents, but identifying and isolating bioactive molecule(s) is still challenging. Fortunately, numerous computational techniques have evolved to save time and efforts in this field. The aim of the current study was to utilize several cheminformatics software to study the chemical and biological features of the bark of Eucalyptus globulus cultivated in Egypt. Sirius software, with the aid of online databases, was used to process liquid chromatography-mass spectrometry (LC-MS) chemical profiling and predict precise molecular formulae, chemical classes, and structures. Accordingly, 37 compounds were tentatively identified, including 15 reported here for the first time from this species. Also, the BioTransformer tool was successfully applied for in silico virtual study of the human metabolism of these compounds, and 1960 different products were obtained through various metabolic pathways. Finally, an electronic library of the identified compounds and their metabolites were developed and docked in silico against eight different protein targets that are involved in the liver fibrosis process. The results revealed that the extract may have a potential hepatoprotective effect through several mechanisms and that the metabolites have the highest binding affinities to the relevant enzymes than their parent compounds. The extract was found to show potent cytotoxic activity against the liver cancer cell lines HEPG2 and HUH-7, and its absorption was enhanced through nanoformulation, as proved using the ex vivo everted gut sac method.

Effects of Metformin Combined With Antifolates on HepG2 Cell Metabolism and Cellular Proliferation

Hepatocellular carcinoma (HCC), one of the most prevalent types of cancers worldwide, continues to maintain high levels of resistance to standard therapy. As clinical data revealed poor response rates, the need for developing new methods has increased to improve the overall wellbeing of patients with HCC. Furthermore, a growing body of evidence shows that cancer metabolic changes are a key feature of many types of human malignancies. Metabolic reprogramming refers to cancer cells’ ability to change their metabolism in order to meet the increased energy demand caused by continuous growth, rapid proliferation, and other neoplastic cell characteristics. For these reasons, metabolic pathways may become new therapeutic and chemopreventive targets. The aim of this study was to investigate the metabolic alterations associated with metformin (MET), an anti-diabetic agent when combined with two antifolate drugs: trimethoprim (TMP) or methotrexate (MTX), and how metabolic changes within the cancer cell may be used to increase cellular death. In this study, single drugs and combinations were investigated using in vitro assays including cytotoxicity assay (MTT), RT-qPCR, annexin V/PI apoptosis assay, scratch wound assay and Seahorse XF analysis, on a human HCC cell line, HepG2. The cytotoxicity assay showed that the IC₅₀ of MET as single therapy was 44.08 mM that was reduced to 22.73 mM and 29.29 mM when combined with TMP and MTX, respectively. The co-treatment of both drugs increased p53 and Bax apoptotic markers, while decreased the anti-apoptotic marker; Bcl-2. Both combinations increased the percentage of apoptotic cells and halted cancer cell migration when compared to MET alone. Furthermore, both combinations decreased the MET-induced increase in glycolysis, while also inducing mitochondrial damage, altering cancer cell bioenergetics. These findings provide an exciting insight into the anti-proliferative and apoptotic effects of MET and anti-folates on HepG2 cells, and how in combination, may potentially combat the aggressiveness of HCC.

Efficacy of pomegranate extract loaded solid lipid nanoparticles transdermal emulgel against Ehrlich ascites carcinoma

The purpose of this work was to incorporate an optimized pomegranate extract loaded solid lipid nanoparticles (PE-SLNs) formula in a transdermal emulgel to evaluate its anticancer effect. The prepared emulgel formulae were evaluated for their physicochemical properties. An ex vivo permeation study was done through mouse skin and the kinetic parameters were determined. Kinetic data showed that the ex vivo permeation of PE from SLNs transdermal emulgel through mouse skin followed non-Fickian diffusion transport. Further, in vivo study was done by applying the optimized PE-SLNs transdermal emulgel on mice skin bearing a solid form of Ehrlich ascites carcinoma (EAC) as well as free PE, control, placebo, and standard groups for comparison. In addition, histopathological examinations of the samples obtained from the EAC mice model were performed. The results proved that application of the selected PE-SLNs emulgel formulation on the mice skin bearing solid tumor revealed statistically significant anticancer effects.

Avoiding COVID-19 complications with diabetic patients could be achieved by multi-dose Bacillus Calmette-Guérin vaccine: a case study of beta cells regeneration

Diabetes mellitus (DM) is one of the major risk factors for COVID-19 complications as it is one of the chronic immune-compromising conditions especially if patients have uncontrolled diabetes, poor HbA_1c and/or irregular blood glucose levels. Diabetic patients' mortality rates with COVID-19 are higher than those of cardiovascular or cancer patients. Recently, Bacillus Calmette-Guérin (BCG) vaccine has shown successful results in reversing diabetes in both rats and clinical trials based on different mechanisms from aerobic glycolysis to beta cells regeneration. BCG is a multi-face vaccine that has been used extensively in protection from tuberculosis (TB) and leprosy and has been repositioned for treatment of bladder cancer, diabetes and multiple sclerosis. Recently, COVID-19 epidemiological studies confirmed that universal BCG vaccination reduced morbidity and mortality in certain geographical areas. Countries without universal policies of BCG vaccination (Italy, Nederland, USA) have been more severely affected compared to countries with universal and long-standing BCG policies that have shown low numbers of reported COVID-19 cases. Some countries have started clinical trials that included a single dose BCG vaccine as prophylaxis from COVID-19 or an attempt to minimize its side effects. This proposed research aims to use BCG vaccine as a double-edged weapon countering both COVID-19 and diabetes, not only as protection but also as therapeutic vaccination. The work includes a case study of regenerated pancreatic beta cells based on improved C-peptide and PCPRI laboratory findings after BCG vaccination for a 9 year old patient. The patient was re-vaccinated based on a negative tuberculin test and no scar at the site of injection of the 1^st BCG vaccination at birth. The authors suggest and invite the scientific community to take into consideration the concept of direct BCG re-vaccination (after 4 weeks) because of the reported gene expressions and exaggerated innate immunity consequently. As the diabetic MODY-5 patient (mutation of HNF1B, Val2Leu) was on low dose Riomet^® while eliminating insulin gradually, a simple analytical method for metformin assay was recommended to ensure its concentration before use as it is not approved yet by the Egyptian QC labs.

Dual Targeting of VEGFR2 and C-Met Kinases via the Design and Synthesis of Substituted 3-(Triazolo-thiadiazin-3-yl)indolin-2-one Derivatives as Angiogenesis Inhibitors

The vascular endothelial growth factor receptor 2 (VEGFR2) and c-mesenchymal epithelial transition factor (c-Met) are members of receptor tyrosine kinases which have a crucial role in the process of angiogenesis. Isatin moiety is a versatile group that is shared in many compounds targeting both c-Met and VEGFR2 kinases. In this study, we designed and synthesized different derivatives of substituted 3-(triazolo-thiadiazin-3-yl)indolin-2-one derivatives (6a-y) as dual inhibitors for c-Met and VEGFR2 enzymes. Eight compounds 6a, 6b, 6e, 6l, 6n, 6r, 6v, and 6y were assessed for their anticancer activities against a panel of 58 cancer cell lines according to the US-NCI protocol. Compound 6b revealed the most effective antiproliferative potency (GI %), with broad-spectrum activity against different subpanels of the most NCI 58 tumor cell lines. An in vivo hen's egg-chorioallantoic membrane (HET-CAM) angiogenic study was carried out for 21 compounds 6a, b, d, f, h, i, k-o, t, and 6x to check their mortality and toxicity. At 100 μM concentration, all compounds produced 100% mortality of the chick embryos. At 40 μM concentration, 13 compounds did not exhibit any detectable mortality (nontoxic) and revealed a potent antiangiogenic effect. Seven compounds 6b, 6d, 6f, 6n, 6o, 6t, and 6x significantly decreased the number of blood vessels, and compound 6b was the most effective antiangiogenic agent comparable to dexamethasone. Molecular docking studies were conducted for compound 6b to investigate its mode of interaction within the binding site of both c-Met and VEGFR2 kinases.

Propolis-based niosomes as oromuco-adhesive films: A randomized clinical trial of a therapeutic drug delivery platform for the treatment of oral recurrent aphthous ulcers

Oromuco-adhesive films for buccal delivery of Propolis extract (PPE) entrapped in niosomes, were prepared to treat oral recurrent aphthous ulcer (RAU). PPE was investigated for antimicrobial compounds. Niosomes composed of span60 and cholesterol were evaluated for particles size, polydispersity index (PDI), zeta-potential, entrapment efficiency and in vitro release. The formed oromuco-adhesive films containing niosomal PPE were evaluated for swelling, mucoadhesion and elasticity. 24 patients suffering from RAU were divided equally into medicated and placebo groups and participated in this study to examine the onset of ulcer size reduction, complete healing and pain relief. Ultra-performance liquid chromatography-high resolution mass spectrometry revealed the presence of pinocembrin, pinobanksin, chrysin and galangin as antimicrobial flavonoids with total content of 158.7 ± 0.15 µg quercetin equivalents and phenolic content of 180.8 ± 0.11 µg gallic acid equivalents/mg. Multilamellar niosomes of 176-333 nm displayed entrapment efficiency of 91 ± 0.48%, PDI of 0.676 and zeta potential of -4.99. In vitro release after 8 h from niosomal dispersion and films were 64.05% and 29.09 ± 0.13% respectively. Clinical results revealed duration of film adherence from 2-4 h in the two groups. The onset of ulcer size reduction in medicated group was attained within second and third day, complete healing was achieved within first 10 days of treatment and pain relief lasted for more than 4-5 h, in contrast to the placebo group. This oromuco-adhesive films which offer controlled and targeting drug delivery can be proposed as a new therapeutic strategy in the treatment of oral recurrent aphthous ulcer.

The sole and combined effect of simvastatin and platelet rich fibrin as a filling material in induced bone defect in tibia of albino rats

Statins like simvastatin (SIM) have demonstrated to have pleiotropic actions other than their conventional use as antilipidemic drugs. Also, nowadays natural scaffolds like platelets rich fibrin (PRF) showed promising results on bone regeneration. Aim This study compare the regenerative power of SIM and PRF added locally each as a sole filling material on induced bone defect and evaluate the combined effect using PRF loaded with SIM. MATERIALS AND METHODS: A critical size bone defect was induced in 48 male albino rats of average weight 150-200 g and were divided into 4 groups according to the filling material. Control, PRF, SIM, and SIM/PRF group. Each group was subdivided according to the sacrificing period into two subgroups (one and two-months postoperatively). Tibial specimens were evaluated histologically using masson trichrome (MT) special stain to detect areas of new bone formation, immunohistochemically using anti- BMP2 and anti-VEGF, serum levels of Osteoprotegerin (OPG), RANKL, osteocalcin and alkaline phosphatase enzyme (ALP) were measured one and two months postoperatively using ELISA, Finally bone mineral density (BMD) at the bone defect area was analyzed using digital X-ray one and two-months postoperatively. RESULTS: The percentage of newly formed bone increased significantly in the three groups vs the control group with the highest significant increase (p < 0.001) in the SIM/PRF group one month postoperatively. Also, SIM/PRF group was the only group which showed significant bone maturation two-months postoperatively compared to the other groups. Immunohistochemical analysis showed significant increase in positively stained BMP-2 and VEGF expression (p < 0.001) in the three groups vs the control group with the highest significant increase (p < 0.001) in the SIM/PRF group. Serum bone anabolic markers increased significantly in the SIM and SIM/PRF groups. In contrast, RANKL serum level decreased significantly in the SIM and SIM/PRF group one month postoperatively with no significant decrease in the PRF group vs the control group. Digital X-ray results revealed the highest BMD percent change was found in the SIM/PRF group and showed complete bone healing two-months postoperatively.

Thermoresponsive gels containing gold nanoparticles as smart antibacterial and wound healing agents

Thermoresponsive gels containing gold nanoparticles (AuNPs) were prepared using Pluronic®127 alone (F1) and with hydroxypropyl methylcellulose (F2) at ratios of 15% w/w and 15:1% w/w, respectively. AuNPs were evaluated for particle size, zeta-potential, polydispersity index (PDI), morphology and XRD pattern. AuNP-containing thermoresponsive gels were investigated for their gelation temperature, gel strength, bio-adhesive force, viscosity, drug content, in vitro release and ex-vivo permeation, in addition to in vitro antibacterial activity against bacteria found in burn infections, Staphylococcus aureus. In vivo burn healing and antibacterial activities were also investigated and compared with those of a commercial product using burn-induced infected wounds in mice. Spherical AuNPs sized 28.9-37.65 nm displayed a surface plasmon resonance band at 522 nm, a PDI of 0.461, and a zeta potential of 34.8 mV with a negative surface charge. F1 and F2 showed gelation temperatures of 37.2 °C and 32.3 °C, bio-adhesive forces of 2.45 ± 0.52 and 4.76 ± 0.84 dyne/cm2, viscosities of 10,165 ± 1.54 and 14,213 ± 2.31 cP, and gel strengths between 7.4 and 10.3 sec, respectively. The in vitro release values of F1 and F2 were 100% and 98.03% after 6 h, with permeation flux values of (J1) 0.2974 ± 2.85 and (J2) 0.2649 ± 1.43 (µg/cm2·h), respectively. The formulations showed antibacterial activity with the highest values for wound healing properties, as shown in vivo and by histopathological studies. This study demonstrates that a smart AuNPs thermoresponsive gel was successful as an antibacterial and wound healing transdermal drug delivery system.

Pomegranate extract-loaded solid lipid nanoparticles: design, optimization, and in vitro cytotoxicity study

Background

Pomegranate extract (PE) is a natural product with potent antioxidant and anticancer activity because of its polyphenols content. The main purpose of this study was to maximize the PE chemotherapeutic efficacy by loading it in an optimized solid lipid nanoparticles (SLNs) formula.

Materials and methods

The influence of independent variables, which were lipid concentration (X₁), surfactant concentration (X₂) and cosurfactant concentration (X₃), on dependent ones, which were particle size (Y₁), polydispersity index (Y₂), zeta potential (Y₃), entrapment efficiency (Y₄) and cumulative % drug release (Y₅), were studied and optimized using the Box–Behnken design. Fifteen formulations of PE-SLNs were prepared using hot homogenization followed by ultra-sonication technique. Response surface plots, Pareto charts and mathematical equations were produced to study the impact of independent variables on the dependent quality parameters. The anti-proliferative activity of the optimized formula was then evaluated in three different cancer cell lines, namely, MCF-7, PC-3 and HepG-2, in addition to one normal cell line, HFB-4.

Results

The results demonstrated that the particle sizes ranged from 407.5 to 651.9 nm and the entrapment efficiencies ranged from 56.02 to 65.23%. Interestingly, the 50% inhibitory concentration of the optimized formula had more than a 40-fold improved effect on the cell growth inhibition in comparison with its free counterpart. Furthermore, it was more selective against cancer cells than normal cells particularly in MCF-7 breast cancer cells.

Conclusion

These data proved that nanoencapsulation of PE enhanced its anticancer efficacy. Therefore, our results suggested that a PE-loaded SLNs optimized-formula could be a promising chemo therapeutic agent.

Honey-based hydrogel: In vitro and comparative In vivo evaluation for burn wound healing

Honey was used to treat wounds since ancient times till nowadays. The present study aimed at preparing a honey-based hydrogel and assay its antimicrobial properties and wound healing activity; in-vitro and in-vivo. Topical honey hydrogel formulations were prepared using three honey concentrations with gelling agents; chitosan and carbopol 934. The prepared formulae were evaluated for pH, spreadability, swelling index, in-vitro release and antimicrobial activity. The pH and spreadability were in the range of 4.3–6.8 and 5.7–8.6 cm, respectively. Chitosan-based hydrogel showed higher in-vitro honey release with diffusional exponent ‘n ≤ 0.5 indicates Fickian diffusion mechanism. Hydrogel formulae were assessed for in-vitro antimicrobial activity using Disc Diffusion antibiotic sensitivity test against common burn infections bacteria; Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumonia and Streptococcus pyogenes. The 75% honey-chitosan hydrogel showed highest antimicrobial activity. This formula was tested for in-vivo burn healing using burn-induced wounds in mice. The formula was evaluated for burn healing and antibacterial activities compared to commercial product. 75% honey-chitosan hydrogel was found to possess highest healing rate of burns. The present study concludes that 75% honey-chitosan hydrogel possesses greater wound healing activity compared to commercial preparation and could be safely used as an effective natural topical wound healing treatment.

Modulation of NAD(P)H:quinone oxidoreductase by vanadium in human hepatoma HepG2 cells

Recent studies demonstrated the carcinogenicity and the mutagenicity of vanadium compounds. In addition, vanadium (V(5+)) was found to enhance the effects of other genotoxic agents. However, the mechanism by which V(5+) induce toxicity remain unknown. In the current study we examined the effect of V(5+) (as ammonium metavanadate, NH(4)VO(3)) on the expression of NAD(P)H: quinone oxidoreductase 1 (NQO1) in human hepatoma HepG2 cells. Therefore, HepG2 cells were treated with increasing concentrations of V(5+) in the presence of two NQO1 inducers, the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and isothiocyanate sulforaphane (SUL). Our results showed that V(5+) inhibited the TCDD- and SUL-mediated induction of NQO1 at mRNA, protein and activity levels. Investigating the effect of V(5+) at transcriptional levels revealed that V(5+) significantly inhibited the TCDD- and SUL-mediated induction of antioxidant responsive element (ARE)-dependent luciferase reporter gene expression. In addition, V(5+) was able to decrease the TCDD- and SUL-induced nuclear accumulation of nuclear factor erythroid 2-related factor-2 (Nrf2) without affecting Nrf2 mRNA or protein levels. Looking at the post-transcriptional level, V(5+) did not affect NQO1 mRNA stability, thus eliminating the possible role of V(5+) in decreasing NQO1 mRNA levels through this mechanism. In contrast, at post-translational level, V(5+) was able to significantly decrease NQO1 protein half-life. The present study demonstrates for the first time that V(5+) down-regulates NQO1 at the transcriptional and post-translational levels in the human hepatoma HepG2 cells via AhR- and Nrf2-dependent mechanisms.

Relative hypoglycemic effect of insulin suppositories in diabetic beagle dogs: optimization of various concentrations of sodium salicylate and polyoxyethylene-9-lauryl ether

The effect of insulin suppositories containing different amounts and concentrations of sodium salicylate (50, 100 mg) and polyoxyethylene-9-lauryl ether (POELE 1, 3, 4%), respectively, on the plasma glucose concentration of diabetic beagle dogs was investigated after rectal administration. Comparison of the effects of these formulations was made with that produced after subcutaneous insulin injections. Insulin suppositories containing sodium salicylate (50 mg) produced a maximum reduction of plasma glucose concentration (Cmax) of 55 +/- 11%, an area under the curve (AUC) of 252 +/- 59% reduction h; and a relative hypoglycemia (RH) of 49 +/- 12% relative to subcutaneous injection of insulin (4 U/kg). Increasing sodium salicylate to 100 mg/suppository did not improve the hypoglycemic effect of insulin suppositories further. Investigation of the influence of insulin suppositories containing different concentrations of the nonionic surfactant POELE (1, 3, 4%) showed that; the suppositories containing the lowest concentration (1%) produced the highest hypoglycemic effect with a Cmax of 68%, AUC of 332 +/- 67% reduction h, and RH of 55 +/- 11%. Incorporation of sodium salicylate 50mg in insulin suppositories containing 1% POELE did not improve further the effects found with these suppositories. In conclusion, a relative hypoglycemic effect of about 50-55% can be achieved using insulin suppositories containing Witepsol W35 as a base, insulin (5 U/kg), and sodium salicylate (50 mg) or POELE (1%) as rectal absorption enhancers.

Embryonic subcellular distribution of 13-cis- and all-trans-retinoic acid indicates differential cytosolic/nuclear localization

Isotretinoin (13-cis-retinoic acid [13CRA], Accutane) is used for the treatment of dermatological diseases. Isotretinoin is, however, teratogenic in animals and humans. The mechanism of action of its teratogenicity is still not clearly identified. It has little or no binding properties to cytosolic retinoid-binding proteins or nuclear retinoid receptors (RAR, RXR). One hypothesis is that the teratogenicity of 2 approximately equipotent teratogenic doses of 13CRA and all-trans-retinoic acids (ATRA) could mainly be correlated to ATRA in the nuclei, where the retinoic acid receptors (RARs) are located. To test this hypothesis, female mice at gestational day 11 were treated with approximately equipotent teratogenic doses of 13-cis-retinoic acid (100 mg/kg orally) or all-trans-retinoic acid (10 mg/kg orally) and sacrificed 1 h and 4 h after administration. Embryos were homogenized and centrifuged into 4 fractions, and the purity of the fractions was tested by quantification of marker constituents for various cell compartments. We analyzed, by RP-HPLC, nuclear, mitochondrial, microsomal, and cytosolic fractions, as well as embryo homogenate and maternal plasma. After treatment with 13-cis-retinoic acid, this substance was mainly located in the nuclear fraction of the embryo (approximately 82%), whereas all-trans-retinoic acid, after ATRA treatment, was mainly located in the cytosolic supernatant (approximately 64%). The binding to cellular retinoid-binding protein (CRABP) may limit the access of ATRA to the nucleus, in contrast to 13CRA, which does not bind to CRABP. The concentration of ATRA in the nuclear fraction was similar after administration of either 13CRA or ATRA. The teratogenic activity of 13-cis-retinoic acid could therefore be explained by its access to the nucleus and its possible conversion to all-trans-retinoic acids, which will interact with the nuclear retinoid receptors.

Effect of different bile salts on the relative hypoglycemia of witepsol W35 suppositories containing insulin in diabetic Beagle dogs

Insulin suppositories were formulated using Witepsol W35 as a base to investigate the effect of various bile salts/acids on the plasma glucose concentration of diabetic beagle dogs. Comparison of the effect of these formulations was made with that produced by insulin subcutaneous injections. Of the bile salts/acids studied, incorporation of 100 mg of deoxycholic acid (DCA), sodium cholate (NaC), or sodium deoxycholate (NaDC) with insulin (10 U/Kg) showed that suppositories containing NaDC produced the highest area under the curve (AUC) and relative hypoglycemia (RH) of 290 +/- 83 mg%h and 28% +/- 8.1%, respectively. To study the optimum amount of NaDC in insulin suppositories to produce the highest RH, 50-200 mg/suppository were used, and we found that 150 mg NaDC produced 35% +/- 13% RH. We also studied the influence of different doses of insulin (5-20 U/kg) in the presence of NaDC (100 mg). It was found that increase of the insulin dose was accompanied by an increase in AUC and maximum reduction in plasma glucose level Cmax. A combination of NaDC (100 mg) and NaC (50 mg) produced an AUC of 252 +/- 13mg%h and an RH of 49% +/- 2.6%, which were higher than produced by either of its individual components (NaC 50 mg or NaDC 100 mg) when used alone or when compared with an equivalent amount of NaDC (150 mg). When the effect of sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC) was studied, it was found that an insulin suppository containing 100 mg of either NaTC or NaTDC produced an RH equivalent to that produced previouslY with a mixture of NaDC (100 mg) and NaC (50 mg). On the other hand, NaC (50 mg) did not improve the hypoglycemic effect of NaTC any further. In conclusion, a relative hYpoglycemia of about 50% can be reached using insulin suppositories containing Witepsol W35 as a base and NaDC plus NaC (100 mg plus 50 mg, respectively), NaTDC (100mg), or NaTC (100 mg) as rectal absorption enhancers of insulin. A desirable hypoglycemia, expressed as Cmax, and/or AUC can be reached by adjusting the insulin dose in the formulation according to the degree of hyperglycemia.

Synergistic teratogenic effects induced by retinoids in mice by coadministration of a RARalpha- or RARgamma-selective agonist with a RXR-selective agonist

To study the interaction of retinoid-induced limb defects and cleft palate on day 11 of gestation, a RXR-selective agonist (AGN191701, an arylpropenyl-thiophene-carboxylic acid derivative, 20 mg/kg orally) was coadministered with a RARalpha-agonist (Am580, an arylcarboxamidobenzoic acid derivative, 5 mg/kg orally) to NMRI mice. AGN191701 was neither fetotoxic nor teratogenic at the dose used but potentiated Am580-induced limb defects and cleft palate and prevented Am580-induced fetal weight retardation. These results suggest that Am580-induced limb defects and probably cleft palate on day 11 of gestation may be mediated via RARalpha-RXR heterodimerization, particularly in the absence of toxicokinetic interactions. AGN191701 was also coadministered with a RARgamma-agonist (CD437, an adamantyl-hydroxyphenyl naphthoic acid derivative, 15 mg/kg orally) on days 8 and 11 of gestation to investigate which CD437-induced defects are mediated via RARgamma-RXR heterodimerization. On day 8 of gestation, AGN191701 potentiated CD437-induced embryolethality, exencephaly, spina bifida aperta, cleft palate, and tail defects, as well as visceral and skeletal defects, but not micrognathia. On day 11 of gestation, the incidence of CD437-induced cleft palate and limb defects was also potentiated when coadministered with the RXR agonist. These results suggest that synergistic teratogenic effects can be induced by coadministration of two receptor-selective retinoids, indicating the importance of RARalpha-RXR and RARgamma-RXR heterodimers in producing structural defects during organogenesis.

Selective agonists of retinoic acid receptors: comparative toxicokinetics and embryonic exposure

Three biologically active synthetic retinoids were investigated that bind selectively to retinoic acid receptors RARs (alpha, beta and gamma). The retinoids were previously demonstrated to have different teratogenic effects in the mouse in terms of potency and regioselectivity. The teratogenic potency rank order (alpha >beta >gamma) was found to be more or less compatible with the receptor binding affinities and transactivation potencies of the retinoid ligands to their respective receptors. The RARalpha agonist (Am580; CD336) induced a wide spectrum of malformations; CD2019 (RARbeta agonist) and especially CD437 (RARgamma agonist) produced more restricted defects. In the current study we tried to address whether the differences in teratogenic effects are solely related to binding affinity and transactivation differences or also due to differences in embryonic exposure. Therefore, transplacental kinetics of the ligands were assessed following administration of a single oral dose of 15 mg/kg of either retinoid given to NMRI mice on day 11 of gestation. Am580 was rapidly transferred to the embryo resulting in the highest embryonic exposure [embryo to maternal plasma area under the time vs concentration curve (AUC)(0-24 h )ratio (E/M) was 1.7], in accordance with its highest teratogenic potency. The low placental transfer of CD2019 (E/M of 0.3) was compatible with its lower teratogenic potential. Of major interest was the finding that the CD437, though being least teratogenic, exhibited considerable embryonic exposure (E/M of 0.6). These findings suggest that both the embryonic exposure and receptor binding transactivation selectivity are crucial determinants of the teratogenicity of these retinoid ligands.

Effect of streptozotocin-induced hyperglycaemia on intravenous pharmacokinetics and acute cardiotoxicity of doxorubicin in rats

The present study was designed to investigate the pharmacokinetics and acute cardiotoxicity of doxorubicin (DOX) after intravenous (i.v.) administration (15 mg kg(-1)) to streptozotocin (STZ)-induced hyperglycaemic and normoglycaemic male Wistar albino rats. In STZ diabetic rats the area under the serum DOX time-concentration curve (AUC(0-24 h)) increased (13.35+/-1.33 compared with 7.13+/-0.71 microg h(-1) ml(-1); P<0.0001) and plasma and renal DOX clearance decreased. The DOX accumulation in STZ-induced diabetic rat heart (12.7+/-1.2 microg g(-1)) was increased (P<0.05) compared with non-diabetic hearts (11.0+/-0.9 microg/g), 24 h after DOX administration. Serum creatine phosphokinase (CPK) activity showed 25% increase in peak level in STZ diabetic rats compared to non-diabetic rats. DOX produced a reduction in heart rate of anaesthetized non-diabetic (20%) and diabetic (14%) rats 1 and 2 h after its administration, respectively. Isolated atria of diabetic rats were more sensitive to the negative chronotropic effect of DOX (150 microm). These preliminary results indicate that hyperglycaemia may alter the pharmacokinetics and acute cardiotoxicity of DOX and suggest that i.v. doses of DOX in diabetic patients may need to be modified if the present data could be extrapolated to humans.

Inhibition of benzo(a)pyrene-induced forestomach carcinogenesis in mice by thymoquinone

The modulating effect of thymoquinone (TQ) on benzo(a)pyrene (BP)-induced forestomach tumours was investigated in female Swiss albino mice, receiving oral administration of BP at a dose of 1 mg twice weekly for 4 weeks. Administration of 0.01% of TQ in drinking water 1 week before, during and after BP treatment until the end of the experiment resulted in significant suppression of BP-induced tumourigenesis when compared with the group receiving BP alone. TQ inhibited both BP-induced forestomach tumour incidence and multiplicity by 70% and 67%, respectively. Lipid peroxide accumulation and decreased glutathione (GSH) content and glutathione-S-transferase (GST) and DT diaphorase activities were observed in the liver of BP-treated tumour-bearing mice. TQ alone showed a significant induction in the enzyme activities of hepatic GST and DT diaphorase. Mice treated with TQ along with BP showed almost normal hepatic lipid peroxides and GSH levels, and normal enzyme activities compared to the control group. The present data may indicate the potential of TQ, the main constituent of the volatile oil of Nigella sativa seed, as a powerful chemopreventive agent against BP-induced forestomach tumours in mice. The possible modes of action of TQ may be through its antioxidant and anti-inflammatory activities, coupled with enhancement of detoxification processes.

Metabolism of retinaldehyde isomers in pregnant rats: 13-cis- and all-trans-retinaldehyde, but not 9-cis-retinaldehyde, yield very similar patterns of retinoid metabolites

Retinaldehyde (RAL), a key intermediate in retinoid metabolism, acts as a retinoic acid (RA) precursor, but is also reduced to retinol (ROH), which can subsequently be esterified to retinyl esters, the storage form of vitamin A. Limited information is available on the metabolism of geometric isomers of RAL as well as on the transplacental distribution of their metabolites, including RA isomers. Such information would be very helpful for the assessment of the teratogenic potency of RAL isomers, as teratogenesis represents a major side effect of retinoid use in pharmacotherapy. In the present study we examined concentrations of retinoids in plasma, maternal tissues, and embryos of pregnant rats 2 h after a single oral dose (100 mg/kg body weight) of all-trans-, 13-cis-, or 9-cis-RAL on gestational day 13. The main findings of this study were the very similar patterns of retinoid metabolites (consisting of retinoids with mainly the all-trans-configuration) after administration of all-trans- and 13-cis-RAL, and the high concentrations of 9-cis-RA, 9,13-dicis-RA, and 9-cis-retinoyl-beta-D-glucuronide after dosing with 9-cis-RAL. In addition, all-trans-RA as a RAL metabolite reached the embryos to a much greater extent than any of its cis-isomers. The results are discussed in view of in vitro data on enzymes involved in the biotransformation of RAL isomers.

Effect of adenosine on pulmonary circulation of rabbits

The effect and mechanism of action of adenosine on the pulmonary circulation of rabbits were studied. Adenosine (10(-5)-10(-3) M) produced a concentration-dependent decrease in pulmonary arterial tension of precontracted pulmonary arterial rings. Removal of endothelium (denuded) augmented the adenosine-induced vasodilation in the pulmonary arterial rings. Theophylline (5 x 10(-5) M), an adenosine receptor antagonist, reduces the vasodilation induced by adenosine in intact and denuded rings. Pretreatment of the pulmonary rings with the cyclooxygenase inhibitor indomethacin (5 x 10(-6) M) significantly attenuated the adenosine-induced relaxation in denuded but not in the intact pulmonary arterial rings. Methylene blue (5 x 10(-5) M), a guanylate cyclase inhibitor, significantly reduced the relaxation induced by adenosine in both the intact and the denuded arterial rings. Adenosine significantly attenuated the pressor responses of serotonin and acetylcholine in the intact and denuded rabbit's pulmonary arterial rings. The results of this study indicate that adenosine induces pulmonary vasodilation and that functional endothelium is not required to evoke this dilation. In addition, guanylate cyclase activity and the generation of cGMP is essential for adenosine to induce vasodilation in the rabbit lung. Furthermore, the results of this study may suggest that adenosine could be used to reduce the severity of pulmonary hypertension and possibly pulmonary edema.

Enhanced generation of leukotriene B4 and superoxide radical from calcium ionophore (A23187) stimulated human neutrophils after priming with interferon-alpha

The present study was designed to investigate the effect of interferon-alpha ( INF-alpha) on the production of leukotrienes (LTs) and superoxide radicals when intact human neutrophils were stimulated with calcium ionophore (A23187). A reverse phase high performance liquid chromatography and UV spectroscopy were employed to detect and quantitate the released LTs; namely LTC4, LTB4 and its trans isomers, 6-trans LTB4 and 12-epi-6-trans LTB4. Preincubation of intact human neutrophils at 37 degrees C for 30 min with INF-alpha and stimulation with calcium ionophore A23187 for 1 min enhanced significantly the formation of LTB4. Preincubation of intact human neutrophils with INF-alpha and subsequent stimulation with calcium ionophore A23187 also enhanced significantly superoxide radical generation that reduced nitroblue tetrazolium into blue formazan. The in vivo effect of INF-alpha in rats demonstrated that the higher dose of INF-alpha that induced superoxide radical and LTB4 by A23187 stimulated intact human neutrophil in vitro, also induced a significant decrease in white blood cells and RBCs started at 4 h after i.p administration. The differential white blood cell count revealed that, the prime target for INF-alpha is the white blood cells of myeloid origin. These results might demonstrate the modulatory effects of INF-alpha on granulocyte functions.

Effect of Cremophor EL on the pharmacokinetics, antitumor activity and toxicity of doxorubicin in mice

Cremophor EL (CR) is a solubilizing agent and a modulator of P-glycoprotein (P-gp)-mediated anticancer multidrug resistance. The present study was undertaken to evaluate whether doxorubicin (Dox) pharmacokinetics, therapeutic activity and cardiotoxicity in Swiss albino mice is modified when combined with CR treatment. CR (2.5 ml/kg, i.p) given simultaneously with Dox (20 mg/kg, i.p.) increased Dox levels in plasma, heart, liver and kidneys of healthy mice. Using an Ehrlich ascites carcinoma (EAC)-bearing mice experimental model, CR (2.5 ml/kg) improved the survival and antitumor activity of Dox. The enhanced antitumor activity of Dox was related to a significant increase in EAC tumor cellular Dox content by CR. Furthermore, CR (1 microg/ml) potentiated the in vitro cytotoxicity of Dox in cultured EAC cells. In healthy mice, Dox-induced mortality was markedly reduced by simultaneous treatment with CR. CR enhanced DOX-induced increase in plasma lactate dehydrogenase, creatine phosphokinase (CPK) and CPK-MB isozyme activities, as well as the cardiac malondialdehyde level. CR also increased Dox-induced focal necrotic myocardial lesions. These findings suggest that CR increased DOX antitumor activity and cardiotoxicity as a result of enhancing its bioavailability, and decreased Dox-induced mortality in mice by a mechanism not yet defined.

Hypoglycemic effect of oral insulin in diabetic rabbits using pH-dependent coated capsules containing sodium salicylate without and with sodium cholate

The hypoglycemic effect of oral insulin (20 U and 40 U) capsules coated with a pH-dependent soluble polymer (Eudragit S100) and containing sodium salicylate (50 mg) without and with sodium cholate (50 mg) was studied in alloxan-hyperglycemic rabbits and compared with that of s.c. insulin injection (20 U). The capsules containing 20 U insulin + sodium salicylate (50 mg) produced a significant reduction in plasma glucose level to 82 and 73% of initial values at 2 and 3 hr after administration, respectively. The blood glucose level slowly returned to normal values at 5 hr. The AUC0-5 hr was 73.7 +/- 43.5 mg.hr/dl compared to 242 +/- 70.5 mg.hr/dl for insulin (20 U, s.c.) with a relative hypoglycemia of 30.4%. A higher dose of oral insulin (40 U) + sodium salicylate (50 mg) was more effective in reducing plasma glucose level which steadily decreased and reached 56% of the initial value by 5 hr (AUC0-5 hr = 132 +/- 41.5 mg.hr/dl and relative hypoglycemia = 27.3%). Sodium cholate (50 mg), however, slightly improved sodium salicylate effect producing an AUC0-5 hr of 139 +/- 37.3 mg.hr/dl with relative hypoglycemia of 28.7%. The relative hypoglycemia of pH-dependent coated capsules reached in the present experiment is the highest found so far.

Promotion of oral insulin absorption in diabetic rabbits using pH-dependent coated capsules containing sodium cholate

The hypoglycemic effect of oral insulin (40 U) capsules coated with a pH-dependent soluble polymer (Eudragit S100) and containing various doses of sodium cholate (20, 50, 100 mg) was studied in alloxan-hyperglycemic rabbits and compared with that of s.c. insulin injection (20 U). Sodium cholate (20 and 50 mg/capsule) produced a dose-related enhancement of an insulin-induced decrease in the blood glucose level. Insulin capsules containing sodium cholate (50 mg/capsule) produced a steady reduction of the blood glucose level reaching 69% of the initial values (P < 0.01) by 3 h and 48% (P < 0.001) by 5 h after administration. This capsule produced an AUC0-5 h of 125 +/- 14.8 mg.h/dl with relative hypoglycemia (R.H.) of 25.8% compared with insulin s.c. The capsules containing sodium cholate (100 mg), however, did not significantly (P > 0.05) improve the hypoglycemic effect of insulin more than the smaller dose (50 mg/capsule) producing an AUC and R.H. of 135 +/- 12.3 mg.h/dl and 27.9%, respectively. The capsule coated with Eudragit S100 and containing insulin mixed with sodium cholate seems to be a promising formulation to overcome the unavailability of oral insulin.

RARalpha-mediated teratogenicity in mice is potentiated by an RXR agonist and reduced by an RAR antagonist: dissection of retinoid receptor-induced pathways

To dissect the complex pattern of retinoid-induced developmental defects, an RXR-selective agonist (AGN191701, an arylpropenyl-thiophene-carboxylic acid derivative) was coadministered with an RARalpha-selective agonist (Am580, an arylcarboxamidobenzoic acid derivative) to NMRI mice on Day 8.25 of gestation. AGN191701 was neither fetotoxic nor teratogenic at the doses used, but potentiated Am580-induced resorptions, spina bifida aperta, micrognathia, kidney hypoplasia, dilated bladder, undescended testis, atresia ani, tail malformations, fused ribs, and fetal weight retardation. These effects were generally reduced by coadministration of an RAR-selective antagonist (CD2366, an adamantyl-methoxyphenyl-heptatrienoic acid derivative). The incidence of other defects induced by an RARalpha-selective agonist such as exencephaly or cleft palate was neither greatly affected by the RXR-selective agonist nor by the antagonist. These results suggest that some malformations such as the posterior neural tube defect spina bifida as well as urogenital defects may be mediated via liganded RARalpha-RXR heterodimerization, while other defects such as the anterior neural tube defect exencephaly as well as cleft palate are induced by different mechanisms.

5-substituted-2-thiohydantoin analogs as a novel class of antitumor agents

Certain series of 2-thiohydantoin derivatives, carrying various substituents at position 5 such as 5-bromo-2-thienylmethylene, 5-(2-carboxyphenylthio)-2-thienylmethylene and 2-methylene-4H-thieno[2,3-b][1]benzothiopyran-4-one, were evaluated for their antitumor activity. Compound 5-(5-bromo-2-thienylmethylene)-3-morpholinomethyl-2-(2,3,4,6 -tetra-O-acetyl -beta-D-glucopyranosylthio)hydantoin proved to possess a broad spectrum antitumor activity against a wide range of different human cell lines of nine tumor subpanels causing both cytostatic and cytotoxic effects, resulting in full panel median growth inhibition (GI50) and total growth inhibition (TGI), with a median lethal concentration (LC50) at 15.1, 41.7 and 83.2 microM, respectively. On the other hand, compound 5-(5-bromo-2-thienylmethylene)-2-thiohydantoin and compound 5-(5-bromo-2-thienylmethylene)-3-phenyl-2- (2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl-thio)hydantoin showed potential selectivity against leukemia cell lines. Further derivatization of these compounds, deduced from the obtained tentative structure-activity relationships, may lead to more potent agents.

All-trans-retinoyl-beta-glucuronide is a potent teratogen in the mouse because of extensive metabolism to all-trans-retinoic acid

All-trans-retinoyl-beta-D-glucuronide (all-trans-RAG) is a water-soluble derivative of all-trans-retinoic acid (all-trans-RA) and has been characterized as an endogenous metabolite of vitamin A in rat bile and kidney. All-trans-RAG was previously demonstrated to be a major metabolite after application of all-trans-RA in several species (mouse, rat, rabbit, monkey); all-trans-RAG was described in these experiments to exhibit a very low placental transfer to the embryo. Because retinoid-like activity has been found after application of all-trans-RAG in vivo as well as in several in vitro systems, and because of its low placental transfer, this glycoconjugate appeared to be an interesting retinoid with possible therapeutic activity, but reduced teratogenicity. Here we investigated the teratogenic activity of all-trans-RAG in comparison to all-trans-RA in mice, and performed accompanying pharmacokinetic studies. Surprisingly, all-trans-RAG was more teratogenic than equimolar doses of all-trans-RA following subcutaneous application on day 11 of gestation in the mouse (20 mumol/kg body weight). Pharmacokinetic studies revealed that all-trans-RAG was extensively hydrolyzed to all-trans-RA and that the plasma area under the concentration-time curve (AUC) of all-trans-RA following all-trans-RAG application exceeded the plasma AUC value of all-trans-RA following application of all-trans-RA. Extensive hydrolysis of all-trans-RAG was also observed after intravenous application of this glycoconjugate. Transfer of all-trans-RAG to the embryo was low, but transfer was high to maternal organs such as the liver and kidney. These in vivo studies suggest that all-trans-RAG serves as a precursor of all-trans-RA by the intravenous and subcutaneous routes, and application of all-trans-RAG results in high and teratogenic in vivo exposure to all-trans-RA.

Further branching of valproate-related carboxylic acids reduces the teratogenic activity, but not the anticonvulsant effect

In the present study, compounds derived from the anticonvulsant drug valproic acid (VPA, 2-n-propylpentanoic acid) and analogues known to be teratogenic were synthesized with an additional carbon-branching in one of the side chains. The substances were tested for their ability to induce anticonvulsant activity and sedation in adult mice, and neural tube defects (exencephaly) in the offspring of pregnant animals (Han:NMRI mice). In all cases, the rates of exencephaly, embryolethality, and fetal weight retardation induced by the methyl-branched derivatives were very low when compared to those of the parent compounds. These novel compounds exhibited anticonvulsant activity which was not significantly different from that of VPA. Neurotoxicity was considerably lower for some compounds as compared to VPA. Anticonvulsant activity and neurotoxicity of branched short chain fatty acids are far less structure-dependent and not related to teratogenic potency. Within this series of compounds, (+/-)-4-methyl-2-n-propyl-4-pentenoic acid and (+/-)2-isobutyl-4-pentenoic acid exhibited the most favorable profile in regard to high anticonvulsant effect, low sedation, and teratogenicity. Valproic acid analogues with additional methyl branching may be valuable antiepileptic agents with low teratogenic potential.

Fully automated determination of selective retinoic acid receptor ligands in mouse plasma and tissue by reversed-phase liquid chromatography coupled on-line with solid-phase extraction

A fully automated reversed-phase HPLC method was developed for the quantitative assay of three retinoids (Am-580, CD-2019 and CD-437) which selectively activate the retinoic acid receptors RAR alpha, RAR beta and RAR gamma, respectively. Mouse plasma, embryo and maternal tissues were prepared for injection by on-line solid-phase extraction (SPE) and valve-switching techniques. Following automatic injection, the sample was loaded on preconditioned disposable cartridges, cleaned-up and then transferred onto the analytical column to be eluted in the backflush mode, separated by gradient elution and detected by UV, while a new cartridge was concomitantly conditioned. The overall recovery was quantitative allowing for external standardization. The calibration curves were linear in all biological samples tested so far, with a correlation coefficient (r) >0.99. The intra-day precision was < or = 7.8% (n = 5-6) and the inter-day variability was < or = 9.4% (n = 3). The lower limit of detection was 2.5 ng/ml or ng/g for CD-2019 and CD-437, and 5 ng/ml for Am-580 with a S/N ratio of 5 using a sample weight of 25 microliters or mg. The method is now in routine use in our laboratory for the assessment of the pharmacokinetic profiles of these retinoids. The small sample size required, the simple sample preparation and the rapid analysis with high degree of automation make this method convenient for microanalysis of biological samples both in animal and human studies.

Effect of praziquantel on serum glucose and insulin levels in normal and hyperglycemic rats

The effects of praziquantel (CAS 55268-74-1) on serum glucose and insulin levels in normoglycemic and hyperglycemic rats were studied. Also the combined effect of praziquantel and glibenclamide (CAS 10238-21-8) on oral glucose tolerance in rats was investigated. Praziquantel, given orally in a dose of 250 mg/kg, significantly increased serum glucose level in hyperglycemic rats without changing serum insulin level. After oral glucose load, praziquantel produced a significant increase in serum glucose level and antagonized the hypoglycemic action of glibenclamide. These results indicate that praziquantel significantly increased serum glucose level in both hyperglycemic rats and after glucose load. Since insulin levels are not significantly altered by praziquantel, the hyperglycemic effect of this drug may be attributed to inhibition of peripheral glucose utilization. Care should be taken if praziquantel is prescribed to diabetic patients.

Pattern of retinoid-induced teratogenic effects: possible relationship with relative selectivity for nuclear retinoid receptors RAR alpha, RAR beta, and RAR gamma

Retinoic acid, an oxidative metabolite of vitamin A, is involved in the control of many biological processes including embryonic development. Excess as well as deficiency of retinoids were found to be teratogenic. The effects of retinoids in normal as well as abnormal development may be mediated by two members of retinoid receptors, the RAR's and RXR's, which exhibit a specific temporal and spatial expression during development. The significance of the retinoid receptors was investigated here by studying the teratogenic effects of retinoid ligands with relative selectivity for binding and transactivation of the retinoic acid receptors RAR alpha, RAR beta and RAR gamma. Pregnant NMRI mice were administered 5 or 15 mg/kg of CD 336 (Am 580) (alpha-ligand), CD 2019 (beta-ligand), CD 437 (gamma-ligand) or 37.5 mg/kg all-trans-retinoic acid in 25% Cremophor EL on day 8.25 or day 11 of gestation by gastric intubation. External, visceral and skeletal malformations were observed on day 18 of gestation. The order of teratogenic potency was: alpha-ligand > beta-ligand > gamma-ligand. In addition, these retinoids also produced a different spectrum of defects. The alpha-ligand induced the most varied defects including severe ear, mandible, and limb malformations. The beta-ligand induced defects of the urinary system and liver in greater frequency than expected from its relative potency. The gamma-ligand preferentially induced ossification deficiencies and defects of the sternebrae and vertebral body. Our results show that these three retinoids, which were previously demonstrated to exhibit retinoid-like activities in several systems, exert differing teratogenic activities, in regard to both potency and regioselectivity: we hypothesize that the relative selectivity for binding and transactivation of the three retinoic acid receptors could possibly be related to the differences of teratogenic effects observed in this study. The low potency of the gamma-ligand may lead the way to interesting new retinoids with improved therapeutic ratio.

Methionine reduces the valproic acid-induced spina bifida rate in mice without altering valproic acid kinetics

The antiepileptic drug valproic acid (VPA) is an established human teratogen causing spin bifida aperta. We recently developed a mouse model in which spina bifida aperta and occulta are induced with VPA. In a search for protection against neural tube defects, we investigated the effect of methionine on the incidence of VPA-induced spina bifida in the mouse. To induce spina bifida, we injected VPA (350 mg VPA-Na/kg body weight) subcutaneously three times on d 9 of gestation at 0, 6 and 12 h. In some mice, L-methionine (3 x 70 mg/kg body weight) was injected intraperitoneally 30 min before each VPA administration. When fetuses were examined on d 18, methionine treatment slightly reduced the VPA-induced spina bifida aperta rate from 5 to 1% (P > 0.05, no significant difference). The incidence of VPA-induced spina bifida occulta (90%) was significantly lower (28%) when methionine was also administered (P < 0.05). Examination on d 10 showed that the number of embryos in the mice administered VPA and methionine having an open neuroporus posterior was significantly lower than in mice administered VPA alone (P < 0.05). Pharmacokinetic studies indicated that VPA concentrations in maternal plasma and embryo did not differ between the two groups. Methionine reduces VPA-induced spina bifida in mice without altering VPA kinetics.

Ethanol potentiates valproic acid-induced neural tube defects (NTDs) in mice due to toxicokinetic interactions

Both the antiepileptic drug valproic acid (VPA) and ethanol interfere with fetal folate metabolism, which may contribute to their mechanism of teratogenesis. Therefore, the possible interaction between VPA and ethanol was investigated in mice. Ethanol (2 x 2.5 g/kg) was given orally 4 and 1 h prior to VPA (300 and 400 mg/kg, SC) in day 8.25 pregnant NMRI mice. Fetuses were examined for exencephaly, embryolethality, and fetal weight retardation on day 18 of gestation. Higher doses of ethanol (2 x 5 g/kg, orally) at day 7.5 and 8 of gestation resulted in 22% embryolethality and 1.7% exencephaly with no effect on fetal weight. Ethanol, however, increased VPA (400 mg/kg, SC)-induced exencephaly, embryolethality, and fetal weight retardation. It also increased VPA (300 mg/kg, SC)-induced exencephaly without affecting embryotoxicity. A minimum of two oral doses of 2.5 g/kg ethanol, 1 and 4 h, or 1 and 6 h prior to VPA administration were needed to produce maximum potentiation of the effects observed. These ethanol doses increased plasma VPA levels of day 8.25 pregnant mice given 400 mg/kg VPA to values comparable to the levels of mice given only VPA at a higher dose level (500 mg/kg). The incidence of exencephaly was increased from 35% for VPA (400 mg/kg) to 59% when VPA was given with ethanol. This incidence was similar to that of 60% for the high dose of VPA (500 mg/kg) administered without ethanol. Maternal plasma ethanol concentration peaked at 193, 196, and 183 mg/dL 15, 30, and 60 min, respectively, after oral ethanol administration (2.5 g/kg), and fell to 110 mg/dL by 2 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of zinc on the anti-inflammatory and ulcerogenic activities of indometacin and diclofenac

In the present study, the potential anti-inflammatory activity of zinc sulfate (zinc) has been examined in rats with acute and chronic inflammation. Additionally, we studied the effect of the concurrent administration of zinc on the anti-inflammatory activity of indometacin and diclofenac and their gastric side effects. Oral or subcutaneous administration of zinc (25 and 15 mg/kg, respectively) significantly reduced carrageenan-induced paw edema. Subcutaneous co-administration of zinc (15 mg/kg) and indometacin (5 mg/kg) or diclofenac (10 mg/kg) resulted in a further reduction in paw edema which was more than either that produced by either agent alone. However, after oral co-administration of zinc and diclofenac the reduction in paw edema was not significantly different from that produced by either zinc or diclofenac alone. In rats with chronic inflammation, the administration of zinc (5 mg/kg s.c. for 7 days) proved as effective as either indometacin (3 mg/kg) or diclofenac (5 mg/kg). Co-administration of zinc with indometacin or diclofenac did not affect the level of activity of either drug. Co-administration of zinc did not affect the ulcerogenic effect of indometacin expressed as the ulcer index. In contrast to indometacin, administration of zinc markedly reduced the ulcerative action of diclofenac. In conclusion, zinc supplementation may contribute significantly to the treatment of inflammation. The combination of zinc with other anti-inflammatory drugs may provide beneficial additive effects and reduce their gastric hazards, particularly with diclofenac.

Identification of 9,13-dicis-retinoic acid as a major plasma metabolite of 9-cis-retinoic acid and limited transfer of 9-cis-retinoic acid and 9,13-dicis-retinoic acid to the mouse and rat embryos

9-Cis-retinoic acid (9-cis-RA) has been proposed to be the endogenous ligand of retinoid X receptors. We examined the plasma pharmacokinetics of 9-cis-RA and its metabolites in nonpregnant female NMRI mice after oral dosing with 50 mg 9-cis-RA/kg body weight. Furthermore, we studied the metabolism of 9-cis-RA and its transfer to the embryo following oral administration of the precursor 9-cis-retinaldehyde (9-cis-RAL; 100 mg/kg body weight) to pregnant mice and rats on gestational days 11 and 13, respectively. Following 9-cis-RA administration, plasma levels of 9-cis-RA reached their maximum within 40-60 min and then declined in a monoexponential manner with an apparent half-life of 64 +/- 32 min. A great variety of polar metabolites of 9-cis-RA was found; among them, the beta-glucuronides of 9-cis-RA (9-cis-RAG) and of 9-cis-4-oxo-RA (9-cis-4-oxo-RAG) could be identified. A further prominent polar metabolite of 9-cis-RA in mouse plasma was shown to be an additional RA isomer (distinct from 13-cis-RA and all-trans-RA) whose concentrations weeesimilarly high as those of 9-cis-RA.(ABSTRACT TRUNCATED AT 250 WORDS)

Interactions of a novel catecholamine, GP-2-128, with adrenoceptors

GP-2-128 is a novel catecholamine designed for transdermal iontophoretic delivery in patients with limited mobility to prevent deconditioning and muscular wasting. We characterized the interactions of this agent with alpha- and beta-adrenoceptors in vitro. In electrically stimulated rat left atria, GP-2-128 produced a concentration-dependent increase in contractile force. pD2 values for GP-2-128, isoproterenol (ISO), and dobutamine (DOB) were 10.6 +/- 0.12, 8.55 +/- 0.02, and 7.0 +/- 0.20, respectively. Metoprolol caused a shift in the concentration-effect curves for the three agonists. In spontaneously beating rat right atria, pD2 values of GP-2-128, ISO, and DOB are 10.4 +/- 0.24, 8.82 +/- 0.18, and 6.92 +/- 0.18, respectively. The affinity constant (KA) of GP-2-128, ISO, and DOB for cardiac beta 1-adrenoceptors was determined by competition binding assays to be 8.09, 6.04 and 4.49, respectively. In guinea pig trachea precontracted with histamine, GP-2-128 and ISO produced a concentration-dependent relaxation. pD2 values were 10.0 +/- 0.1 and 8.2 +/- 0.1, respectively. DOB was more potent than GP-2-128 in contracting isolated rat aortic rings (alpha 1 effect) and in displacing [3H]rauwolscine (alpha 2 effect). We also studied the interactions of GP-2-128 and ISO with the atypical beta-adrenoceptors (beta 3) in guinea pig ilea and rat and hamster adipocytes. Both agents inhibited twitches produced by transmural nerve stimulation in the presence of 10(-5) M nadolol. The EC30 for GP-2-128 and ISO at this atypical receptor site were 4.25 x 10(-10) and 5.05 x 10(-8) M, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticonvulsant and neurotoxic activities of twelve analogues of valproic acid

Twelve racemic analogues of the antiepileptic drug valproic acid (VPA) were tested and compared with VPA for anticonvulsant activity by the subcutaneous pentylenetetrazol (PTZ) seizure threshold test and for neurotoxicity by the rotorod test. Four compounds produced maximal anticonvulsant activity (100% protection) in equimolar doses (1.5 mmol/kg) to VPA and two compounds showed a similar effect with lower doses (1.0 mmol/kg). Four compounds produced lower activity (38-80% protection), and two compounds showed no anticonvulsant activity at the dose used (1.5 mmol/kg). Two of the 12 compounds, (+/-)-2-n-propyl-4-hexynoic acid (11) and (+/-)-4-methyl-2-n-propyl-4-pentenoic acid (12), showed no sedation at doses that produced the maximum anticonvulsant effect. For the first time we succeeded to develop two compounds with higher protective index and safety ratios than VPA. Compound 11 had a longer duration of action and higher protective index but a lower safety ratio than 12. Comparisons of the anticonvulsant and minimal neurotoxic effects of these compounds with their calculated lipophilicity (C log P) revealed that compounds with the desired high anticonvulsant activity and minimal neurotoxicity showed C log P values between 1.84 and 2.64 and had nine carbon atoms (in contrast to eight carbon atoms for VPA).

Trimethoprim potentiates valproic acid-induced neural tube defects (NTDs) in mice

The antiepileptic drug valproic acid (VPA) may produce NTDs because of interference with folate metabolism. Therefore, the possible interactions of VPA with the dihydrofolate reductase inhibitor trimethoprim (TM) was investigated. The combination of TM with sulfamethoxazol is used for treatment of urinary infections, the most common complications of pregnancy. TM (80 and 160 mg/kg) was given i.p. and orally, 0.5 and 1 h, respectively, prior to valproic acid (VPA, 300 and 400 mg/kg, s.c.) in day 8 pregnant NMRI mice. Fetuses were examined for exencephaly, resorptions, and fetal weight retardation on day 18 of gestation. TM (160 mg/kg, i.p.) produced no exencephaly or embryolethality, but increased fetal weight. Administration of TM (80 mg/kg, i.p.) increased VPA-induced exencephaly and fetal weight retardation but not embryolethality. Exencephaly rates induced by VPA (300 and 400 mg/kg) were 4% and 12.9% and were increased by coadministration of TM to 22.7% and 42.5%, respectively (P < 0.01). Oral TM also increased VPA-induced exencephaly and fetal weight retardation but with lower potency than i.p. injection. The observed effects were not due to altered VPA pharmacokinetics. These results support the view that VPA-induced neural tube defects may be mediated via an interaction with folate metabolism, and advise against TM-use in VPA-treated epileptics during pregnancy.

The enantioselective teratogenicity of 2-n-propyl-4-pentynoic acid (4-yn-VPA) is due to stereoselective intrinsic activity and not differences in pharmacokinetics

The present study was designed to investigate whether there are pharmacokinetic reasons for the enantioselective teratogenicity of R(+)-4-yn-VPA (low potency) and S(-)-4-yn-VPA (high potency). A gas chromatographic method was employed to determine 4-yn-VPA enantiomers in maternal plasma, brain, erythrocytes and in the embryo and decidua/extraembryonic membranes of the mouse following a single intraperitoneal dose of 300 mg/kg (+/-)-4-yn-VPA-Na on day 9 of gestation. Furthermore, the pharmacokinetics of R- and S-4-yn-VPA were studied in maternal plasma of day-8 pregnant mice following intraperitoneal administration of 300 and 500 mg (+/-)-4-yn-VPA-Na/kg body wt., respectively. No significant difference in the pharmacokinetic profiles of the two enantiomers was detected in either the maternal organism or in the embryonic compartments. Thus, the two enantiomers reach the embryo in comparable concentrations during the sensitive period of organogenesis, but exhibit very different teratogenic activities. This study therefore indicates that the stereoselective teratogenicity of 4-yn-VPA is due to differences in intrinsic activities and not due to differences in the pharmacokinetics of the enantiomers.

Effect of supplementation with folinic acid, vitamin B6, and vitamin B12 on valproic acid-induced teratogenesis in mice

The effect of administration of folinic acid, vitamin B6 + vitamin B12, and their combination on valproic acid (VPA)-induced teratogenesis was studied in NMRI mice. VPA (500 mg/kg, sc) was injected on Day 8 of gestation and the vitamins (two dose levels) were injected ip 1 hr before, immediately before, and 1 hr after VPA administration. Folinic acid significantly reduced VPA-induced resorptions (21-24%), and palate, rib, and sternebral malformations. Exencephaly and spina bifida occulta were also reduced (14 and 40%, respectively), but the difference was not statistically significant. On the other hand, vitamin B6 + vitamin B12 significantly reduced VPA-induced exencephaly (23%), spina bifida occulta (80%), palate and rib malformations, kidney abnormalities, and fetal weight retardation. A combination of the three vitamins was effective in reducing VPA-induced exencephaly (23-30%), spina bifida occulta (60%), and palate and rib malformations. The protection against VPA-induced malformations was not complete and was not always dose related, and the reduction in exencephaly rate was only significant in the absence of a reduction in resorption rate. Full-length cleft palate, sternebral malformations, and retarded sternebral and caudal ossification were, however, increased by the high dose of combined vitamin administration. The present study supports the view that VPA-induced teratogenesis may be mediated via an interaction with folate metabolism. Although folinic acid and vitamin B6 + vitamin B12 can effectively reduce VPA malformations, the protection was not complete, which may suggest the involvement of other factors. Furthermore, the dose levels should be carefully chosen since high doses of the combined vitamins can actually increase the incidence of certain defects.

Methotrexate increases valproic acid-induced developmental toxicity, in particular neural tube defects in mice

The hypothesis that valproic acid-induced dysmorphogenesis may be due to an interference of this drug with folate metabolic pathways was further investigated by a study of a possible interaction of valproic acid (VPA) and the established folate antagonist methotrexate (MTX). The dihydrofolate reductase inhibitor MTX (1.25 and 2.5 mg/kg, i.p.) was injected 15 min prior to VPA (300 and 400 mg/kg, s.c.) in day 8 pregnant NMRI mice. Fetuses were examined for exencephaly, resorption, and fetal weight retardation on day 18 of gestation. MTX produced no exencephaly or reduction in fetal weight, and the 2.5-mg/kg dose caused 56% resorption. Higher doses (5-20 mg/kg) produced embryolethality and fetal weight retardation, but no exencephaly. VPA (300 and 400 mg/kg) administration resulted in 3.4% and 12.6% exencephaly and 9% and 19% resorptions, respectively. Coadministration of MTX with VPA significantly increased VPA-induced resorption and exencephaly rates as well as fetal weight retardation. Exencephaly induced by VPA 400 mg/kg was increased to 29.5% and 24.1% (P < 0.01 and P < 0.05) when given with 1.25 and 2.5 mg/kg MTX, respectively. MTX (2.5 mg/kg i.p.) did not alter transplacental VPA (400 mg/kg, s.c.) pharmacokinetics. These results support the view that VPA-induced teratogenesis may be mediated by interaction with folate metabolism.

Maternal factors influencing development of embryos from mice superovulated with gonadotropins

In NMRI mice superovulation with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) increased mating rate, number of implantation sites, rate of advanced and delayed resorptions, as well as retarded sternebral ossification and cleft palate. On day 3 of gestation in preimplantation embryos, cell number and mitotic index were lower after superovulation than after spontaneous ovulation. However, when preimplantation embryos from superovulated and control females were transferred on day 3 of pregnancy to pseudopregnant recipients (10 embryos per female) no differences could be detected between the two groups of fetuses at term. The results of the embryo transfer experiments indicate that abnormal embryonic development after superovulation with gonadotropins is predominantly induced by effects of the hormone treatment on the maternal uterine environment.

Amniotic fluid cholinesterase of valproate-induced exencephaly in the mouse: an animal model for prenatal diagnosis of neural tube defects

After a single administration of the antiepileptic drug valproic acid (VPA; i.p.:600 mg/kg) on day 8 of gestation in the mouse embryotoxicity and amniotic fluid (AF) cholinesterase (ChE) were evaluated on day 16 of gestation. VPA treatment induced an increase in embryolethality, neural tube defects (exencephaly), cleft palate, deformed vertebrae, open eyes, and a reduction in fetal weight. In VPA-exposed fetuses AF total ChE (TChE) activity of exencephalic fetuses was higher than that of normal fetuses. However, in 3 out of 110 normal fetuses of the control group TChE activity was found in the AF. There was no correlation between blood contamination of AF and its TChE activity, either in non-exencephalic control or treated embryos. Using ethopropazine as a "pseudo"-ChE inhibitor in vitro, the percentage of acetyl-ChE in blood-contaminated AF was similar to that of fetal rather than maternal serum, indicating that AF was contaminated with fetal and not with maternal blood. VPA-induced exencephaly in mice may provide an animal model to further investigate biochemical markers for prenatal diagnosis of neural tube defects.

Studies on the teratogenic effects of different oral preparations of caffeine in mice

Caffeine in doses up to 250 mg/kg per day in drinking water or up to 150 mg/kg per day in sustained release pellets was administered to pregnant mice. Apart from a low incidence of cleft palate, in the 50 mg/kg and 150 mg/kg caffeine pellet groups no gross abnormalities were observed which were attributable to caffeine treatment. The most important effect observed was a reduction in fetal weight. Retarded ossification particularly of the supraoccipital bones was observed in fetuses when caffeine (150 mg/kg) was administered in drinking water but not when the same dose was given as a sustained release pellet. Analysis of caffeine blood level data showed that the total exposure from the pellets was greater than from the drinking water. It would thus appear that the effect on the supraoccipital bones is an indirect one mediated through reduced food and water intake of the dams when caffeine is administered in drinking water.

Effect of prenatal phenytoin administration on postnatal development of the rat: a behavioral teratology study

Adult pregnant Wistar rats were treated with phenytoin (100 Mg/kg) orally from day 7 to 19 of pregnancy, and a control group was pair-fed during the whole treatment period. Within 24 hours after parturition , the offspring were culled to six to eight per litter and reared by fostering or cross-fostering. The physical and behavioral development of the offspring was observe up to 90 days of age. There was a reduced survival of the offspring and a reduction in body weight which persisted to the end of the experiment, though both of these effects could be reduced by cross-fostering. Certain neurological defects were also seen in the prenatal phenytoin group. For example, there was a delay of up to 15 days in the development of the dynamic righting reflex, a decrease in ability of offspring to stay on a rotating rod, and a decrease in ability to walk along elevated parallel rods. There seemed also to be some loss of cliff avoidance. However, there was no change in the development of crawling and walking activities at 9-21 days of age, and no important changes were observed in a head dipping test or in a conditioned avoidance test at 26-34 days. There was a significant decrease in brain weight of the treated group at age 3 days which remained significantly lower than the controls even at 90 days, but no change in the brain/body weight ratio. There was no difference in cerebellar DNA content.