Anticonvulsant activity, teratogenicity and pharmacokinetics of novel valproyltaurinamide derivatives in mice

Fetal protective effect of Indonesian propolis from Apis mellifera against rifampicin-pyrazinamide induced impaired pregnancy in BALB/c mice

OBJECTIVES

Anti-tuberculosis drugs rifampicin and pyrazinamide combination in pregnancy can cause morphological, visceral and skeletal damage. Several studies showed that propolis improves pregnancy outcomes. This study aims to determine the fetal protective effect of propolis in BALB/c mice given the anti-tuberculosis drug combination rifampicin and pyrazinamide.

METHODS

A total of 21 pregnant mice were randomly divided into three groups: the normal group (N) was given distilled water as a vehicle, the positive control group (RP) were given rifampicin 15 mg/kg BW, pyrazinamide 35 mg/kg BW and the treatment group (IP) were given rifampicin 15 mg/kg BB, pyrazinamide 35 mg/kg BW and propolis 400 mg/kg BW. The treatment was given during the period of organogenesis, from day 6 to day 15. Laparotomy was performed on the 18th day of pregnancy. Maternal and fetal body weight, fetal length, number of fetuses, and skeletal defects of fetuses were used as parameters to identify the teratogenic effect. All data were analyzed using the ANOVA.

RESULTS

All groups significantly differed between maternal and fetal body weights (p<0.05). The administration of rifampicin-pyrazinamide and propolis during pregnancy did not significantly affect the number of fetuses (p>0.05). The administration of propolis protects the fetus from skeletal abnormalities. While in the RP and IP groups, we can find resorption sites and haemorrhagic.

CONCLUSIONS

This study may suggest the protective effects of propolis against rifampicin pyrazinamide-induced impaired pregnancy.

Post-stroke Delivery of Valproic Acid Promotes Functional Recovery and Differentially Modifies Responses of Peri-Infarct Microglia

The specific role of peri-infarct microglia and the timing of its morphological changes following ischemic stroke are not well understood. Valproic acid (VPA) can protect against ischemic damage and promote recovery. In this study, we first determined whether a single dose of VPA after stroke could decrease infarction area or improve functional recovery. Next, we investigated the number and morphological characteristic of peri-infarct microglia at different time points and elucidated the mechanism of microglial response by VPA treatment. Male Sprague-Dawley rats were subjected to distal middle cerebral artery occlusion (dMCAo) for 90 min, followed by reperfusion. Some received a single injection of VPA (200 mg/kg) 90 min after the induction of ischemia, while vehicle-treated animals underwent the same procedure with physiological saline. Infarction volume was calculated at 48 h after reperfusion, and neurological symptoms were evaluated. VPA didn’t significantly reduce infarct volume but did ameliorate neurological deficit at least partially compared with vehicle. Meanwhile, VPA reduced dMCAo-induced elevation of IL-6 at 24 h post-stroke and significantly decreased the number of CD11b-positive microglia within peri-infarct cortex at 7 days. Morphological analysis revealed that VPA therapy leads to higher fractal dimensions, smaller soma size and lower circularity index of CD11b-positive cells within peri-infarct cortex at both 2 and 7 days, suggesting that VPA has core effects on microglial morphology. The modulation of microglia morphology caused by VPA might involve HDAC inhibition-mediated suppression of galectin-3 production. Furthermore, qPCR analysis of CD11b-positive cells at 3 days post-stroke suggested that VPA could partially enhance M2 subset polarization of microglia in peri-infarct cortex. Analysis of VPA-induced changes to gene expressions at 3 days post-stroke implies that these alternations of the biomarkers and microglial responses are implicated in the upregulation of wound healing, collagen trimmer, and extracellular matrix genes within peri-infarct cortex. Our results are the first to show that a low dose of VPA promotes short-term functional recovery but does not alter infarct volume. The decreases in the expression of both IL-6 and galectin-3 might influence the morphological characteristics and transcriptional profiles of microglia and extracellular matrix remodeling, which could contribute to the improved recovery.

Taurine and its analogs in neurological disorders: Focus on therapeutic potential and molecular mechanisms

Taurine is a sulfur-containing amino acid and known as semi-essential in mammals and is produced chiefly by the liver and kidney. It presents in different organs, including retina, brain, heart and placenta and demonstrates extensive physiological activities within the body. In the several disease models, it attenuates inflammation- and oxidative stress-mediated injuries. Taurine also modulates ER stress, Ca2+ homeostasis and neuronal activity at the molecular level as part of its broader roles. Different cellular processes such as energy metabolism, gene expression, osmosis and quality control of protein are regulated by taurine. In addition, taurine displays potential ameliorating effects against different neurological disorders such as neurodegenerative diseases, stroke, epilepsy and diabetic neuropathy and protects against injuries and toxicities of the nervous system. Several findings demonstrate its therapeutic role against neurodevelopmental disorders, including Angelman syndrome, Fragile X syndrome, sleep-wake disorders, neural tube defects and attention-deficit hyperactivity disorder. Considering current biopharmaceutical limitations, developing novel delivery approaches and new derivatives and precursors of taurine may be an attractive option for treating neurological disorders. Herein, we present an overview on the therapeutic potential of taurine against neurological disorders and highlight clinical studies and its molecular mechanistic roles. This article also addresses the neuropharmacological potential of taurine analogs.

Comparative teratogenicity analysis of valnoctamide, risperidone, and olanzapine in mice

OBJECTIVES

Based on the recent findings from animal studies, it has been proposed that the therapeutic use of valnoctamide, an anxiolytic drug developed in the early 1960s, be extended to treat other neurological disorders such as epilepsy and bipolar disease. Given the scarcity of adequate data on its prenatal toxicity, a comparative teratogenicity study of valnoctamide and two of the most commonly used drugs to treat bipolar disorder, risperidone and olanzapine, was carried out in a mouse model system.

METHODS

Pregnant dams were treated with the aforementioned three drugs at the dose levels calculated as an equal proportion of the respective LD50 values of these drugs. The main reproductive indices examined included the numbers of implantations and resorptions, viable and dead fetuses, and fetal gross, visceral and skeletal abnormalities.

RESULTS

The outcomes of the present study indicated that olanzapine was the most teratogenic of the three drugs, inducing maternal-, embryo-, and fetotoxicity. Risperidone also exerted a significant prenatal toxicity, but its adverse effect was less pronounced than that induced by olanzapine. Valnoctamide did not show any teratogenic effect, even when used in relatively higher dosages than olanzapine and risperidone. The observed increased skeletal abnormalities in one of the valnoctamide treatment groups were nonspecific and, as such, signaled a modest developmental delay rather than an indication that the compound could induce structural malformations.

CONCLUSIONS

Under our experimental conditions, valnoctamide demonstrated the lowest prenatal toxicity of the three tested drugs.

Advances in drug design based on the amino Acid approach: taurine analogues for the treatment of CNS diseases

Amino acids are well known to be an important class of compounds for the maintenance of body homeostasis and their deficit, even for the polar neuroactive aminoacids, can be controlled by supplementation. However, for the amino acid taurine (2-aminoethanesulfonic acid) this is not true. Due its special physicochemical properties, taurine is unable to cross the blood-brain barrier. In addition of injured taurine transport systems under pathological conditions, CNS supplementation of taurine is almost null. Taurine is a potent antioxidant and anti-inflammatory semi-essential amino acid extensively involved in neurological activities, acting as neurotrophic factor, binding to GABA A/glycine receptors and blocking the excitotoxicity glutamate-induced pathway leading to be a neuroprotective effect and neuromodulation. Taurine deficits have been implicated in several CNS diseases, such as Alzheimer’s, Parkinson’s, epilepsy and in the damage of retinal neurons. This review describes the CNS physiological functions of taurine and the development of new derivatives based on its structure useful in CNS disease treatment.

Valproic Acid: second generation

The manuscript focuses on structure-activity relationship studies of CNS-active compounds derived from valproic acid (VPA) that have the potential to become second-generation VPA drugs. Valproic acid is one of the four most widely prescribed antiepileptic drugs (AEDs) and is effective (and regularly approved) in migraine prophylaxis and in the treatment of bipolar disorders. Valproic acid is also currently undergoing clinical trials in cancer patients. Valproic acid is the least potent of the established AEDs and its use is limited by two rare but potentially life-threatening side effects, teratogenicity and hepatotoxicity. Because AEDs treat the symptoms (seizure) and not the cause of epilepsy, epileptic patients need to take AEDs for a long period of time. Consequently, there is a substantial need to develop better and safer AEDs. To become a successful second-generation VPA, the new drug should possess the following characteristics: broad-spectrum antiepileptic activity, better potency than VPA, lack of teratogenicity and hepatotoxicity, and a favorable pharmacokinetic profile compared with VPA including a low potential for drug interactions.

Preclinical Profiling and Safety Studies of ABT-769: A Compound with Potential for Broad-spectrum Antiepileptic Activity

PURPOSE

The objective of this study was to characterize the antiseizure and safety profiles of ABT-769 [(R)-N-(2 amino-2-oxoethyl)spiro[2,5]octane-1-carboxamide].

METHODS

ABT-769 was tested for protection against maximal electroshock and pentylenetetrazol-induced seizures in the mouse and for suppression of electrically kindled amygdala seizures and spontaneous absence-like seizures in the rat. The central nervous system safety profile was evaluated by using tests of motor coordination and inhibitory avoidance. The potential for liver toxicity was assessed in vitro by using a mitochondrial fatty acid beta-oxidation assay. Teratogenic potential was assessed in the mouse.

RESULTS

ABT-769 blocked maximal electroshock, subcutaneous pentylenetetrazol and intravenous pentylenetetrazol-induced seizures with median effective dose (ED50) values of 0.25, 0.38, and 0.11 mmol/kg, p.o., respectively. No tolerance was evident in the intravenous pentylenetetrazol test after twice-daily dosing of ABT-769 (0.3 mmol/kg, p.o.) for 4 days. ABT-769 blocked absence-like spike-wave discharge (ED50, 0.15 mmol/kg, p.o.) and shortened the cortical and amygdala afterdischarge duration of kindled seizures (1 and 3 mmol/kg, p.o.). The protective indices (ED50 rotorod impairment/ED50 seizure protection) were 4.8, 3.2, and 10.9 in the maximal electroshock, subcutaneous pentylenetetrazol and intravenous pentylenetetrazol seizure tests, respectively. ABT-769 did not affect inhibitory avoidance performance (0.1-1 mmol/kg, p.o.). ABT-769 did not affect mitochondrial fatty acid beta-oxidation or induce neural tube defects.

CONCLUSIONS

ABT-769 is an efficacious antiseizure agent in animal models of convulsive and nonconvulsive epilepsy and has a favorable safety profile. ABT-769 has a broad-spectrum profile like that of valproic acid. Its profile is clearly different from those of carbamazepine, phenytoin, lamotrigine, topiramate, vigabatrin, and tiagabine.

Tetramethylcyclopropyl Analogue of a Leading Antiepileptic Drug, Valproic Acid. Synthesis and Evaluation of Anticonvulsant Activity of Its Amide Derivatives

Although valproic acid (VPA) is an extensively used antiepileptic drug for treatment of various kinds of epilepsies, it has been proven to possess two life-threatening side effects: hepatotoxicity and teratogenicity. Amide and urea derivatives of 2,2,3,3-tetramethylcyclopropanecarboxylic acid (TMCA) were prepared to discover lead compounds with clinical potential. In the amide and alkylamide series of TMCA derivatives, N-methoxy-2,2,3,3-tetramethylcyclopropanecarboxamide (21) was one of the most active compounds, having the subcutaneous metrazol test (scMet) ED50 values of 35 mg/kg in rats and 74 mg/kg in mice. In the maximal electroshock-induced seizure test (MES), this compound had ED50 values of 108 mg/kg in rats and 115 mg/kg in mice. Compound 21 was 18.5 and 4.5 times more potent than VPA in the corresponding rat tests. The most active compound in the series of urea derivatives was 2,2,3,3-tetramethylcyclopropanecarbonylurea (25), possessing MES ED50 values of 29 mg/kg in rats and 90 mg/kg in mice. In the scMet test this compound had ED50 values of 92 mg/kg in rats and 125 mg/kg in mice. The median toxic dose (TD50) in rats was 538 mg/kg, providing compound 25 with a wide safety margin and a protective index (TD50/ED50) of 18.5 in the MES test, which is about 12 times greater than that of VPA. Compounds 21 and 25 have the potential for development as novel potent and safe central nervous system active drugs with a broad spectrum of antiepileptic activity.

Teratogenicity of valproate conjugates with anticonvulsant activity in mice

Valproic acid (VPA) is an effective antiepileptic medication, the use of which in females of childbearing age is complicated by its ability to induce birth defects, including neural tube defects (NTDs), in exposed embryos. In experimental settings, VPA reproducibly induces NTDs in laboratory animals such as the highly inbred SWV/Fnn mice. In search of new, efficacious derivatives of VPA that lack toxicity, the conjugates of VPA with amantadine (VPA-AMA) and N-3-aminopropyl-2-pyrrolidinone (VPA-PYR) have been synthesized and evaluated for their anticonvulsant activity. In the present study, the authors evaluated the teratogenicity potential of VPA-AMA and VPA-PYR using a well-established mouse model for antiepileptic drug teratogenicity. All tested compounds were injected intraperitoneally to pregnant dams on gestational day 8.5, and the fetuses examined on day 18.5. At the highest dose tested (3.61 mmol/kg), VPA-PYR was maternally lethal, whereas VPA-AMA induced excessive embryonic lethality. At a dose of 2.20 mmol/kg, VPA-PYR was not teratogenic to the exposed embryos; VPA-AMA induced NTDs in 8.2% of embryos, VPA caused 5.5% NTDs. 0.80 mmol/kg amantadine induced NTDs in 2.2% of the exposed fetuses. In conclusion, VPA-AMA has a comparable teratogenicity as does VPA, and it is proposed that the teratogenicity of VPA-AMA is due to the parent compound. Additional studies are needed to fully define and understand the structure-teratogenicity relationships of VPA analogues.