Studies on the mechanism of action of local anesthetics on proton translocating ATPase from Mycobacterium phlei

Dibasic Derivatives of Phenylcarbamic Acid against Mycobacterial Strains: Old Drugs and New Tricks?

In order to provide a more detailed view on the structure⁻antimycobacterial activity relationship (SAR) of phenylcarbamic acid derivatives containing two centers of protonation, 1-[2-[({[2-/3-(alkoxy)phenyl]amino}carbonyl)oxy]-3-(dipropylammonio)propyl]pyrrolidinium oxalates (1a⁻d)/dichlorides (1e⁻h) as well as 1-[2-[({[2-/3-(alkoxy)phenyl]amino}carbonyl)oxy]-3-(di-propylammonio)propyl]azepanium oxalates (1i⁻l)/dichlorides (1m⁻p; alkoxy = butoxy to heptyloxy) were physicochemically characterized by estimation of their surface tension (γ; Traube's stalagmometric method), electronic features (log ε; UV/Vis spectrophotometry) and lipophilic properties (log kw; isocratic RP-HPLC) as well. The experimental log kw dataset was studied together with computational logarithms of partition coefficients (log P) generated by various methods based mainly on atomic or combined atomic and fragmental principles. Similarities and differences between the experimental and in silico lipophilicity descriptors were analyzed by unscaled principal component analysis (PCA). The in vitro activity of compounds 1a⁻p was inspected against Mycobacterium tuberculosis CNCTC My 331/88 (identical with H37Rv and ATCC 2794, respectively), M. tuberculosis H37Ra ATCC 25177, M. kansasii CNCTC My 235/80 (identical with ATCC 12478), the M. kansasii 6509/96 clinical isolate, M. kansasii DSM 44162, M. avium CNCTC My 330/80 (identical with ATCC 25291), M. smegmatis ATCC 700084 and M. marinum CAMP 5644, respectively. In vitro susceptibility of the mycobacteria to reference drugs isoniazid, ethambutol, ofloxacin or ciprofloxacin was tested as well. A very unique aspect of the research was that many compounds from the set 1a⁻p were highly efficient almost against all tested mycobacteria. The most promising derivatives showed MIC values varied from 1.9 μM to 8 μM, which were lower compared to those of used standards, especially if concerning ability to fight M. tuberculosis H37Ra ATCC 25177, M. kansasii DSM 44162 or M. avium CNCTC My 330/80. Current in vitro biological assays and systematic SAR studies based on PCA approach as well as fitting procedures, which were supported by relevant statistical descriptors, proved that the compounds 1a⁻p represented a very promising molecular framework for development of 'non-traditional' but effective antimycobacterial agents.

Pharmacokinetics and pharmacodynamics of lignocaine: A review

Lignocaine is an essential drug on World Health Organisation essential drug list, considered efficacious, safe and cost-effective for any health-care system. Despite its ubiquitous use in medicine and surgery, there are few detailed reviews of its pharmacokinetics and pharmacodynamics. Being an amide-type local anesthetic and Class 1b antiarrhythmic, lignocaine is most frequently used clinically for its anesthetic and antiarrhythmic benefits. However, lignocaine has important antinociceptive, immuno-modulating, and anti-inflammatory properties. Information pertaining to the pharmacokinetics and pharmacodynamics of lignocaine was examined by performing a literature search of PubMed, Embase and MEDLINE (via Ovid), pharmacology textbooks and online sources. We present a focused synopsis of lignocaine’s pharmacological composition, indications for use and mechanisms of action, focusing on its anti-inflammatory, immuno-modulating and analgesia effects. In addition we review the dosing regimes and infusion kinetics of lignocaine in the clinical setting. Finally, we review the evidence for ligocaine’s modulation of the inflammatory response during major surgery and its specific effects on cancer recurrence. These indirect effects of local anesthetics in tumor development may stem from the reduction of neuroendocrine responses to the stress response elicited by major surgery and tissue damage, enhanced preservation of immune-competence, in addition to opioid-sparing effects of modulating tumor growth.

Liposomal bupivacaine and clinical outcomes

In the multimodal approach to the management of postoperative pain, local infiltration and regional blocks have been increasingly utilized for pain control. One of the limitations of local anesthetics in the postoperative setting is its relatively short duration of action. Multivesicular liposomes containing bupivacaine have been increasingly utilized for their increased duration of action. Compared with bupivacaine HCl, local infiltration of liposomal bupivacaine has shown to have an increase in duration of action and causes delay in peak plasma concentration. In this article, we attempt to review the clinical literature surrounding liposomal bupivacaine and its evolving role in perioperative analgesia. This new bupivacaine formation may have promising implications in postoperative pain control, resulting in increased patient satisfaction and a decrease in both hospital stay and opioid-induced adverse events (AEs). Although more studies are needed, the preliminary clinical trials suggest that liposomal bupivacaine has predictable pharmacokinetics, a similar side effect profile compared with bupivacaine HCl, and is effective in providing increased postoperative pain control.

ATP synthase and the actions of inhibitors utilized to study its roles in human health, disease, and other scientific areas

ATP synthase, a double-motor enzyme, plays various roles in the cell, participating not only in ATP synthesis but in ATP hydrolysis-dependent processes and in the regulation of a proton gradient across some membrane-dependent systems. Recent studies of ATP synthase as a potential molecular target for the treatment of some human diseases have displayed promising results, and this enzyme is now emerging as an attractive molecular target for the development of new therapies for a variety of diseases. Significantly, ATP synthase, because of its complex structure, is inhibited by a number of different inhibitors and provides diverse possibilities in the development of new ATP synthase-directed agents. In this review, we classify over 250 natural and synthetic inhibitors of ATP synthase reported to date and present their inhibitory sites and their known or proposed modes of action. The rich source of ATP synthase inhibitors and their known or purported sites of action presented in this review should provide valuable insights into their applications as potential scaffolds for new therapeutics for human and animal diseases as well as for the discovery of new pesticides and herbicides to help protect the world's food supply. Finally, as ATP synthase is now known to consist of two unique nanomotors involved in making ATP from ADP and P(i), the information provided in this review may greatly assist those investigators entering the emerging field of nanotechnology.

Anti-inflammatory properties of local anesthetics and their present and potential clinical implications

Development of new local anesthetic agents has been focused on the potency of their nerve-blocking effects, duration of action and safety and has resulted in a substantial number of agents in clinical use. It is well established and well documented that the nerve blocking effects of local anesthetics are secondary to their interaction with the Na+ channels thereby blocking nerve membrane excitability and the generation of action potentials. Accumulating data suggest however that local anesthetics also possess a wide range of anti-inflammatory actions through their effects on cells of the immune system, as well as on other cells, e.g. microorganisms, thrombocytes and erythrocytes. The potent anti-inflammatory properties of local anesthetics, superior in several aspects to traditional anti-inflammatory agents of the NSAID and steroid groups and with fewer side-effects, has prompted clinicians to introduce them in the treatment of various inflammation-related conditions and diseases. They have proved successful in the treatment of burn injuries, interstitial cystitis, ulcerative proctitis, arthritis and herpes simplex infections. The detailed mechanisms of action are not fully understood but seem to involve a reversible interaction with membrane proteins and lipids thus regulating cell metabolic activity, migration, exocytosis and phagocytosis.

[Molecular mechanism of action of local anesthetics]

The main target of local anaesthetics on nervous tissue is the sodium channel. Molecular biology and electrophysiology have shown different mechanisms of action on this sodium channel, which depend on the chemical structure and electrostatic charge of the local anaesthetic molecule. There are two main types of action, shown up on the isolated axon, a direct one on the sodium channel itself and an alteration in the lipids surrounding the channel. These effects have been shown on the isolated axon and explain the anaesthetic effect by an inhibition of the sodium current. Experimental studies have also shown the effects of local anaesthetics on different organelles within the cell, and so on intracellular metabolism. Mitochondrial energetic metabolism, and therefore ATP synthesis, is reduced by local anaesthetics at several levels. The respiratory enzyme chain is inhibited by small concentrations of local anaesthetic, especially NADH dehydrogenase and ubiquinone succinate dehydrogenase. Moreover, local anaesthetics increase the mitochondrial membrane permeability to protons, thus removing the moving force behind ATPase activity in ATP synthesis; this leads to a drastic fall in available energy. This effect is further increased by a direct inhibition of ATPase and ATP/ADP translocation. Other enzyme systems of other organelles are also disturbed by local anaesthetics, such as the endoplasmic reticular Ca++ ATPase, which is inhibited, so altering the calcium concentration within the cytosol. Local anaesthetics also inhibit lipolysis and glycogenesis. Receptors such as the acetylcholine receptors are blocked by local anaesthetics. The mechanism of action of these drugs on all these protein systems is two-fold: an alteration of protein structure, but also of the lipids surrounding them.(ABSTRACT TRUNCATED AT 250 WORDS)

Stoichiometry and dissociation constants for interaction of tetracaine with mitochondrial adenosinetriphosphatase as determined by fluorescence

The stoichiometry and dissociation constants for the interaction of tetracaine with chloroform-released ATPase prepared from beef heart mitochondria were determined from the enhancement of tetracaine fluorescence intensity that occurs upon binding. There is a single class of approximately 60 thermodynamically equivalent binding sites on ATPase for tetracaine; these have a microscopic dissociation constant of 4.9 X 10(-4) M at 25 degrees C under solvent conditions that are similar to those used for enzyme assay. Analysis of enzyme kinetic data according to a partial noncompetitive scheme gave an inhibitor constant for tetracaine of 4.8 X 10(-4) M. The numerical agreement between the dissociation constant and the inhibitor constant shows that the filling of the same class of sites is probably responsible for both the enzyme inhibition and the fluorescence enhancement. The sites are hydrophobic, as evidenced by the blue shift and the magnitude of the fluorescence enhancement that occur upon binding.