Toxicity studies and anti-arthritic effect of mandelic acid (2-hydroxy -2-phenyl acetic acid) using in vitro and in vivo techniques.

The major concern to search for new anti-arthritic drugs is primarily to prevent systemic complications and to maintain quality of life. As these drugs are prescribed for long duration so the objective is to ensure their safety in terms of toxicity. By keeping in view this concept, the present study was investigated to determine new anti-arthritic potential using in-vitro and in-vivo methods. The in-vitro tests comprised of protein denaturation (BSA and egg albumin) and Human Red Blood cell (HRBC) membrane stabilization assays at 50-6400µg/mL, for in-vivo testing, formaldehyde-induced arthritic rats were treated with 40, 80 and 160mg/kg mandelic acid. Mandelic acid (MA) inhibited the protein denaturation and stabilized the membrane of HRBC in a concentration dependent manner. Likewise, mandelic acid exhibited dose dependent reduction in paw volume induced by formaldehyde. For acute and sub-acute treatment, MA did not show any sign of toxicity and mortality in each rat and LD50 might be greater than 2000mg/kg. In addition, histopathological assessment presented slight increased interstitial spaces in the kidney, disorganization of glomerulus, dilated sinusoids at highest dose 800mg/kg which were not observed in sub-chronic therapy. Hence, these results conclude that mandelic acid has the potential to treat rheumatoid arthritis with observed no significant signs of toxicity and should be tested further to determine anti-arthritic mechanism of drug action at cellular level.

An in cellulo-activated multicolor cell labeling approach used to image dying cell clearance.

Dying cell clearance is critical for myriad biological processes such as tissue homeostasis. We herein report an enzyme-activated fluorescence cell labeling approach and its use for multicolor imaging of dying cell clearance. Diacetylated 4-hydroxymandelic acid (DHA)-conjugated dyes give rise to reactive quinone methides upon deacetylation in live cells, which in turn covalently labels cellular proteins. With partner cells tagged with distinct fluorescence, apoptotic cell clearance by Raw 264.7 macrophages and epithelial HeLa cells was captured by confocal microscopy, showing the potential of DHA-based cell labeling for investigating cell-cell interactions.

Sulfation of the 3,4-methylenedioxymethamphetamine (MDMA) metabolites 3,4-dihydroxymethamphetamine (DHMA) and 4-hydroxy-3-methoxymethamphetamine (HMMA) and their capability to inhibit human sulfotransferases.

3,4-Methylenedioxymethamphetamine (MDMA, Ecstasy) is excreted in human urine mainly as conjugates of its metabolites 3,4-dihydroxymethamphetamine (DHMA) and 4-hydroxy-3-methoxymethamphetamine (HMMA). The glucuronidation kinetics of HMMA showed high capacities, but also high K(m) values, unlikely to be reached after recreational user's doses. Therefore, the aim of the present work was to investigate the sulfation of DHMA and HMMA by human sulfotransferases (SULTs) in pooled human liver cytosol (pHLC). The kinetic data showed deviation from typical Michaelis-Menten kinetics. The overall efficiency for HMMA sulfation was calculated to be 2-10 times higher than for glucuronidation. As the sulfation of both MDMA metabolites showed substrate inhibition effects, their inhibitory potential towards typical sulfation reactions in pHLC was tested. The following substrates for typical sulfation reactions were used: nitrophenol, dopamine, estradiol, and dehydroepi androsten dione. Inhibition was observed towards dopamine sulfation by DHMA and HMMA, but not by MDMA. The 1/V vs. 1/S plots indicated a mixed-type or competitive inhibition model for DHMA and HMMA, respectively. In conclusion, the presented data indicated that sulfation of HMMA should be the major conjugation reaction observed in humans. Furthermore, both, DHMA and HMMA, were identified as inhibitors of dopamine sulfation.

The styrene metabolite, phenylglyoxylic acid, induces striatal-motor toxicity in the rat: influence of dose escalation/reduction over time.

Exposure to the industrial solvent, styrene, induces locomotor and cognitive dysfunction in rats, and parkinsonian-like manifestations in man. The antipsychotic, haloperidol (HP), well known to induce striatal toxicity in man and animals, and styrene share a common metabolic pathway yielding p-fluoro phenylglyoxylic acid and phenylglyoxylic acid (PGA), respectively. Using an exposure period of 30 days and the vacous chewing movement (VCM) model as an expression of striatal-motor toxicity, we found that incremental PGA dosing (220-400 mg/kg) significantly increased VCMs up to day 25, but decreased to control levels shortly after reaching maximum dose. However, a diminishing dose of PGA (400-200 mg/kg) did not evoke an immediate worsening of VCMs but precipitated a significant increase in VCMs following dosage reduction to 200 mg/kg on day 22. PGA exposure, therefore, compromises striatal-motor function that is especially sensitive to changes in exposure dose. Longer alternating dose exposure studies are needed to establish whether motor dysfunction is progressive in severity or longevity. These findings are of significance for the environmental toxicology of styrene in the chemical industry.

Noninvasive evaluation of brain muscarinic receptor occupancy of oxybutynin, darifenacin and imidafenacin in rats by positron emission tomography.

AIMS: The current study was conducted to evaluate, by the noninvasive positron emission tomography (PET), the binding of antimuscarinic agents used to treat overactive bladder (OAB) to muscarinic receptors in rat brain. MAIN METHODS: Muscarinic receptor occupancy in the rat brain after the intravenous (i.v.) injection of oxybutynin, darifenacin and imidafenacin was evaluated by using a small animal PET system, and compared with the results by ex vivo autoradiographic and ex vivo radioligand binding experiments. KEY FINDINGS: In PET study, the i.v. injection of oxybutynin but not darifenacin or imidafenacin at pharmacological doses decreased significantly binding potential (BP) of (+)N-[(11)C]methyl-3-piperidyl benzilate ([(11)C](+)3-MPB) in the rat cerebral cortex and corpus striatum in a dose-dependent manner. Similarly, in the in vivo autoradiographic experiment, oxybutynin dose-dependently reduced binding of [(11)C](+)3-MPB in the brain, whereas darifenacin and imidafenacin did not. Following the i.v. injection of oxybutynin, darifenacin and imidafenacin, there was a similar degree of binding to muscarinic receptors in the bladder as demonstrated by a significant increase in apparent dissociation constant (K(d)) values for specific [N-methyl-(3)H]scopolamine methyl chloride ([(3)H]NMS) binding. Significant binding of muscarinic receptors in the brain was observed after the injection of oxybutynin but not darifenacin or imidafenacin. SIGNIFICANCE: Oxybutynin but not darifenacin or imidafenacin has potential side effects on the central nervous system (CNS) in patients with OAB. The results reveal the noninvasive characterization of brain receptor occupancy by PET to be a powerful tool for precise evaluation of adverse CNS effects of antimuscarinic agents in pre-clinical and clinical evaluations.

[Synthesis of new mandelic acid derivatives with preservative action. Synthesis and acute toxicity study]. / Sinteza unor noi derivati ai acidului mandelic cu actiune conservanta. Sinteza si studiul toxicitatii acute.

Starting from the antiseptic action of DL mandelic acid, there were synthesized a series of esters of the mandelic acid, esters which could have preservative action. This study present the synthesis, structure validation and the acute toxicity study, for the new synthesized compounds. The esters were obtained by acylating 4-hydroxybenzoic acid propyl, ethyl, methyl esters and salicylic acid with the DL mandelic chloride (that was protected initially by the hydroxylic group). The structure of the synthesized compounds was confirmed by quantitative elemental analysis and RMN 1H spectral measurements. The acute toxicity was determined for two of the esters, who proved to had a preservative action (previously studied) and indicated that these esters have a small toxicity.

Mandelic acid condensation polymer: novel candidate microbicide for prevention of human immunodeficiency virus and herpes simplex virus entry.

Presently marketed vaginal barrier methods are cytotoxic and damaging to the vaginal epithelium and natural vaginal flora when used frequently. Novel noncytotoxic agents are needed to protect men and women from sexually transmitted diseases. One novel candidate is a mandelic acid condensation polymer, designated SAMMA. The spectrum and mechanism of antiviral activity were explored using clinical isolates and laboratory-adapted strains of human immunodeficiency virus (HIV) and herpes simplex virus (HSV). SAMMA is highly effective against all CCR5 and CXCR4 isolates of HIV in primary human macrophages and peripheral blood mononuclear cells. SAMMA also inhibits infection of cervical epithelial cells by HSV. Moreover, it exhibits little or no cytotoxicity and has an excellent selectivity index. SAMMA, although not a sulfonated or sulfated polymer, blocks the binding of HIV and HSV to cells by targeting the envelope glycoproteins gp120 and gB-2, respectively, and also inhibits HSV entry postattachment. SAMMA is an excellent, structurally novel candidate microbicide that warrants further preclinical evaluation.

Agents for the treatment of overactive detrusor. VI. Synthesis and pharmacological properties of acetamide derivatives bearing cyclic amines in N-substituents.

With the aim of improving of the efficacy and decreasing the side effects of oxybutynin (1), N-[(tetrahydro-3- or 4-pyridyl)methyl]-, N-(4-piperidyl)-, and N-(3- or 4-piperidylalkyl)-2-hydroxyacetamides (3a-n, 4a-g) and the related carboxamides (3o-r, 4h-k, 13', 17) were synthesized and evaluated for inhibitory activity against urinary bladder rhythmic contraction in rats and for mydriatic activity in rats. Some of these compounds were superior to oxybutynin in both inhibitory activity against bladder contraction and selectivity between inhibitory activity against bladder contraction and mydriatic activity. Among them, N-[(1,2,3,6-tetrahydro-4-pyridyl)methyl]- and N-[(1,2,3,6-tetrahydro-1-methyl-4-pyridyl)methyl]-2-hydroxy-2,2- diphenylacetamide (3e, 3f) exhibited the most potent inhibitory activity against bladder contraction (ED30 = 0.005 and 0.003 mg/kg i.v., respectively). Judging from the effect of 3e on detrusor contraction in vitro in guinea-pigs, it appeared that the inhibitory activity of 3e against bladder contraction in vivo was related mainly to its inhibitory activity against detrusor contraction in vitro induced with carbachol (antimuscarine-like activity). The selectivity (20-fold) of 3e between inhibitory activity against bladder contraction and mydriatic activity was greatly superior to that (0.48-fold) of oxybutynin. Compound 3e was synthesized by debenzylation (method E or F) of the corresponding N-[[1-(4-methoxybenzyl)-tetrahydro-4-pyridyl]methyl] derivative (3k), which was prepared by acylation (method B) of the corresponding (tetrahydro-4-pyridyl)methylamine (7k) or by reduction (method D) of the corresponding pyridinium chloride (14k) with NaBH4.