Synthesis and characterization of pyridine-based organic salts: Their antibacterial, antibiofilm and wound healing activities.

In treating wounds, long lasting infection is considered the major impediment. Drugs are rendered ineffective by pathogenic microorganisms via antibiotic resistance and calls for designing and development of new drugs. Herein, we report synthesis of eight different N-alkylated pyridine-based organic salts QAS 1-8 and their antibacterial, antibiofilm and wound healing activities. 3-(2-R-hydrazinecarbonyl)-1-propylpyridinium Bromide was the parent compound while R group was varying in each salt composed of different aromatic aldehyde moieties. In the antibacterial activity against S. aureus and E. coli, amoxicillin shows IC50 near to 25 µg/mL inhibiting 58 ± 0.4% S. aureus while ceftriaxone inhibited 55 ± 0.5% E. coli at a concentration of 10 µg/mL. The highest IC50 (56 ± 0.5% against S. aureus; 55 ± 0.5% against E. coli) was shown by compound QAS 7 at the concentration of 100 µg/mL; followed by the QAS 6 (55 ± 0.5% against E. coli) and QAS 2 (55 ± 0.5% against E. coli). In the antibiofilm activity, QAS 6, QAS 1 and QAS 8 inhibited 58 ± 0.4% S. aureus at a concentration of 75 µg/mL, while QAS 2 inhibited E. coli at the same concentration and amount. QAS 7, 3 and 1 inhibited almost 90% while QAS 6 inhibited 95 ± 1.1%of E. coli at a concentration of 250 µg/mL. Highest MBIC was provided by QAS 7 (52 ± 0.4%) against S. aureus at a concentration of 50 µg/mL that is very near to the standard amoxicillin. Antibacterial and antibiofilm activity results were also supported by the atomic force microscopy (AFM). In the wound healing activity, QAS 8 healed 90.8 ± 4.3% of the wound in 21 days with an average period of epithelialization (POE) of 19 ± 1.4 days; that is far better than povidone iodine ointment (81.5 ± 3.3% of the wound in the 21 days with 22.4 ± 2.9 days of POE). It is concluded from this study that the synthesized compounds QAS 2, 7 and 8 can be used for further mechanistic studies to be employed as antibacterial, antibiofilm and wound healing agents.

Metabolic-Hydroxy and Carboxy Functionalization of Alkyl Moieties in Drug Molecules: Prediction of Structure Influence and Pharmacologic Activity.

Alkyl moieties-open chain or cyclic, linear, or branched-are common in drug molecules. The hydrophobicity of alkyl moieties in drug molecules is modified by metabolic hydroxy functionalization via free-radical intermediates to give primary, secondary, or tertiary alcohols depending on the class of the substrate carbon. The hydroxymethyl groups resulting from the functionalization of methyl groups are mostly oxidized further to carboxyl groups to give carboxy metabolites. As observed from the surveyed cases in this review, hydroxy functionalization leads to loss, attenuation, or retention of pharmacologic activity with respect to the parent drug. On the other hand, carboxy functionalization leads to a loss of activity with the exception of only a few cases in which activity is retained. The exceptions are those groups in which the carboxy functionalization occurs at a position distant from a well-defined primary pharmacophore. Some hydroxy metabolites, which are equiactive with their parent drugs, have been developed into ester prodrugs while carboxy metabolites, which are equiactive to their parent drugs, have been developed into drugs as per se. In this review, we present and discuss the above state of affairs for a variety of drug classes, using selected drug members to show the effect on pharmacologic activity as well as dependence of the metabolic change on drug molecular structure. The review provides a basis for informed predictions of (i) structural features required for metabolic hydroxy and carboxy functionalization of alkyl moieties in existing or planned small drug molecules, and (ii) pharmacologic activity of the metabolites resulting from hydroxy and/or carboxy functionalization of alkyl moieties.

Linking Aromatic Hydroxy Metabolic Functionalization of Drug Molecules to Structure and Pharmacologic Activity.

Drug functionalization through the formation of hydrophilic groups is the norm in the phase I metabolism of drugs for the modification of drug action. The reactions involved are mainly oxidative, catalyzed mostly by cytochrome P450 (CYP) isoenzymes. The benzene ring, whether phenyl or fused with other rings, is the most common hydrophobic pharmacophoric moiety in drug molecules. On the other hand, the alkoxy group (mainly methoxy) bonded to the benzene ring assumes an important and sometimes essential pharmacophoric status in some drug classes. Upon metabolic oxidation, both moieties, i.e., the benzene ring and the alkoxy group, produce hydroxy groups; the products are arenolic in nature. Through a pharmacokinetic effect, the hydroxy group enhances the water solubility and elimination of the metabolite with the consequent termination of drug action. However, through hydrogen bonding, the hydroxy group may modify the pharmacodynamics of the interaction of the metabolite with the site of parent drug action (i.e., the receptor). Accordingly, the expected pharmacologic outcome will be enhancement, retention, attenuation, or loss of activity of the metabolite relative to the parent drug. All the above issues are presented and discussed in this review using selected members of different classes of drugs with inferences regarding mechanisms, drug design, and drug development.

Gas chromatography-mass spectrometry designation and prediction of metabolic dealkylation and hydroxylation reactions in xenobiotics exemplified by tramadol.

Metabolic dealkylation and hydroxylation reactions in xenobiotics are common and may take place at different sites in the molecules. Sometimes confusion may arise as to the nature and site of the resulting metabolic change when there is more than one potential site. The use of GC-MS in resolving the problem has been demonstrated by using tramadol as example. Human urine samples containing tramadol and its metabolites were extracted under basic pH conditions and analyzed by GC-MS, in the electron impact and chemical ionization modes, before and after trimethylsilyl (TMS) derivatization. By recognizing the mass-to-charge ratios of molecular and base-peak ions in the mass spectra, it was possible to predict and designate sites of demethylation and hydroxylation in tramadol metabolites. In addition to the designation of the known tramadol metabolites, the practice has led to the tentative characterization of hydroxytramadol and norhydroxytramadol as new metabolites of tramadol in humans. Possible extension of the modus operandi to other xenobiotics was discussed.

Preliminary investigation of novel tetra-tailed macrocycle amphiphile based nano-vesicles for amphotericin B improved oral pharmacokinetics.

Supramolecular macrocycles-based drug delivery systems are receiving wider recognition due to their self-assembly into nanostructures with unique characteristics. This study reports synthesis of resorcinarene-based novel and biocompatible amphiphilic supramolecular macrocycle that self-assembles into nano-vesicular system for Amphotericin B (Am-B) delivery, a model hydrophobic drug. The macrocycle was synthesized through a two-step reaction and was characterized with 1 H NMR and mass spectrometric techniques. Its biocompatibility was assessed in cancer cell lines, blood and animals. Its critical micelle concentration (CMC) was determined using UV spectrophotometer. Am-B loaded in novel macrocycle-based vesicles were examined according to their shape, size, surface charge, drug entrapment efficiency and excepients compatibility using atomic force microscope (AFM), Zetasizer, HPLC and FT-IR spectroscopy. Drug-loaded vesicles were also investigated for their in-vitro release, stability and in-vivo oral bioavailability in rabbits. The macrocycle was found to be nontoxic against cancer cells, haemo-compatible and safe in mice and revealed lower CMC. It formed mono-dispersed spherical shape vesicles of 174.4 ± 3.78 nm in mean size. Vesicles entrapped 92.05 ± 4.39% drug and were stable upon storage with gastric-simulated fluid and increased the drug oral bioavailability in rabbits. Results confirmed novel macrocycle as biocompatible vesicular nanocarrier for enhancing the oral bioavailability of lipophilic drugs.

Target urinary analytes for the gas chromatographic- mass spectrometric detection of procyclidine and benzhexol in drug abuse cases.

The two antiparkinsonian drugs procyclidine and benzhexol are presently finding considerable favor for their euphoric hallucinogenic effects among drug abusers in some countries. In anticipation of their possible scheduling in national drug laws, gas chromatography-mass spectrometry (GC-MS) methods for their detection in urine will be required. However, because of uncertainty of the metabolic fate of the two drugs in humans, the urinary target analytes for GC-MS detection were not well defined. The problem was addressed in the present study in which it was found that mono-hydroxy metabolites, where hydroxylation took place at the cyclohexane ring in both drugs, could be endorsed as the major target analytes. The metabolites could only be detected as the mono- and/or di-trimethylsilyl (TMS) derivatives. The predominance of either derivative depended on the temperature and time of heating with the derivatizing reagent. Because of the basic properties of the hydroxy metabolites, analytic method optimization was needed for their detection in urine included extraction under basic pH conditions. Urine hydrolysis with ß-glucuronidase did not have an effect on the recovery of the metabolites, but was usually performed in search for other drugs. Because of the relative abundance of ions, the electron impact mass spectra of the mono-TMS derivatives and the chemical ionization (CI) mass spectra of the mono- and di-TMS derivatives of the hydroxy metabolites of both drugs were found to be more structurally informative. The CI mass spectra of the di- TMS derivatives have the additive advantage of being potentially useful for quantitative analysis.

The GC-MS detection and characterization of neopine resulting from opium use and codeine metabolism and its potential as an opiate-product-use marker.

Neopine, a minor opium alkaloid and an isomer of codeine (also known as beta-codeine), has been detected in both the urine of opium users and pharmaceutical codeine users. The characterization of neopine was achieved by comparison of the mass spectra and GC retention times of the trimethylsilyl derivative. The presence of neopine in the urine of pharmaceutical codeine users was attributed to the metabolism of codeine through a double bond migration in ring C, from the 7-8 to the 8-14 position. The potential use of the alkaloid as a confirmation marker of opium and/or pharmaceutical codeine use and the ability to differentiate these from heroin use has been discussed.