Orally active carbamate prodrugs of the selective dopamine agonist N-0437: in-vivo activities in the 6-OHDA turning model and in-vitro activities

Tanshinone IIA interacts with DNA by minor groove-binding

Tanshen has long been widely used as a traditional Chinese medicine. Tanshinone IIA (Tan IIA) is the most abundant lipophilic constituent of Tanshen which has antitumor activity but the mechanism is poorly understood. Some preliminary reports hypothesized that it is a DNA intercalator and that the furano-o-quinone moiety could produce free radicals responsible for its cytotoxicity. Here the interaction of Tan IIA with DNA was explored in detail using fluorescence, viscosimetry, and molecular modeling. Tan IIA was found to bind with DNA in the minor groove rather than act as an intercalator. Furthermore, the results of immunofluorescence showed that Tan IIA does not produce free radicals in vivo to damage DNA. The former hypothesis was thus negated. The furan oxygen plays the key role in the antitumor ability of Tan IIA because it is involved in the groove-binding, but not in the production of free radicals. The molecular basis illustrated here could be responsible for all the findings in the structure-relationship studies of tanshinone cytotoxicity.

Antiparkinson prodrugs

Parkinson’s disease (PD) is a progressive, neurodegenerative disorder which involves the loss of dopaminergic neurons of the substantia nigra pars compacta. Current therapy is essentially symptomatic, and L-Dopa (LD), the direct precursor of dopamine (DA), is the treatment of choice in more advanced stages of the disease. Substitution therapy with LD is, however, associated with a number of acute problems. The peripheral conversion of LD by amino acid decarboxylase (AADC) to DA is responsible for the typical gastrointestinal (nausea, emesis) and cardiovascular (arrhythmia, hypotension) side effects. To minimize the conversion to DA outside the central nervous system (CNS) LD is usually given in combination with peripheral inhibitors of AADC (carbidopa and benserazide). In spite of that, other central nervous side effects such as dyskinesia, on-off phenomenon and end-of-dose deterioration still remain. The main factors responsible for the poor bioavailability and the wide range of inter- and intra-patient variations of plasma levels are the drug’s physical-chemical properties: low water and lipid solubility, resulting in unfavourable partition, and the high susceptibility to chemical and enzymatic degradation. In order to improve the bioavailability, the prodrug approach appeared to be the most promising and some LD prodrugs have been prepared in an effort to solve these problems. We report here a review of progress in antiparkinson prodrugs, focusing on chemical structures mainly related to LD, DA and dopaminergic agonists.

Diterpenoids from Salvia miltiorrhiza

The abietane diterpenoid, neocryptotanshinone II, and the known 6,12-dihydroxyabieta-5,8,11,13-tetraen-7-one were isolated as minor components from the roots of Salvia miltiorrhiza. Their structures were established on the basis of spectral evidence.

Risks of reusing coronary angioplasty catheters: results of an experimental study

This experimental study was conducted to evaluate the microbiological and mechanical risks of reusing angioplasty catheters after decontamination and resterilization. The catheters studied were decontaminated in an ultrasound chamber, rinsed, dried, wrapped, and resterilized at 25 or 35 Kgray. Sterility checks performed on catheters cut into three segments concerned bacteria, mushrooms, yeasts, and pyrogens. The surface condition of the balloons was studied by scanning electron microscopy. The mechanical properties analyzed were balloon diameter and bursting pressure and the mean resistance of the catheter body to breakage. Seventy angioplasty catheters of three different types (rapid exchange, coaxial, and on-wire balloon catheter) were tested. Decontamination proved insufficient owing to the persistence of cellular elements on the balloon surface and the presence of pyrogens. Sterility of the material was not ensured with an irradiation of 25 Kgray. It was probable but not certain with 35 Kgray, since an inhibitory effect on micro-organism growth was noted. Mechanical properties were not modified significantly. Our results do not favor the reuse of coronary angioplasty catheters. Better decontamination is desirable but difficult to obtain because of the adhesion of cellular elements to the polymers composing the catheters. Although our results are not necessarily applicable to all resterilization protocols, they indicate that teams desiring to reuse angioplasty material should first test the validity of their procedure for decontamination and resterilization.

Pharmacotherapy of cocaine abuse: preclinical development

Preclinical models of behavioral and toxic effects of cocaine are reviewed and their potential for predicting compounds with efficacy and safety in the medical management of cocaine abuse and toxicity is assessed. Many of the existing models appear to be good predictors of the effects of compounds against specific behavioral or toxicological actions of cocaine. However, the utility of the models for prediction of the efficacy of new therapeutic entities must await clinical validation as no accepted or standard pharmacotherapy currently exists. Preclinical data generated by these models with drugs currently under clinical investigation for cocaine abuse treatment as well as with other compounds are reviewed. These compounds include buprenorphine, bromocriptine, desmethylimipramine, carbamazepine, dopaminergic agonists, antagonists and partial agonists, dopamine reuptake inhibitors, sigma ligands, serotonin antagonists, and excitatory amino acid antagonists. Preclinical information on several drug classes appears sufficiently promising to warrant further evaluation. These include dopamine agonists and partial agonists, D1 receptor antagonists, selective sigma ligands, and modulators of the N-methyl-D-aspartate subtype glutamate receptor.