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Background and Objectives: Saliva is a patient-friendly matrix for therapeutic drug monitoring (TDM) but is infrequently used in routine care. This is due to the uncertainty of saliva-based TDM results to inform dosing. This study aimed to retrieve data on saliva–plasma concentration and subsequently determine the physicochemical properties that influence the excretion of drugs into saliva to increase the foundational knowledge underpinning saliva-based TDM. Methods: Medline, Web of Science and Embase (1974–2023) were searched for human clinical studies, which determined drug pharmacokinetics in both saliva and plasma. Studies with at least ten subjects and five paired saliva–plasma concentrations per subject were included. For each study, the ratio of the area under the concentration–time curve between saliva and plasma was determined to assess excretion into saliva. Physicochemical properties of each drug (e.g. pKa, lipophilicity, molecular weight, polar surface area, rotatable bonds and fraction of drug unbound to plasma proteins) were obtained from PubChem and Drugbank. Drugs were categorised by their ionisability, after which saliva-to-plasma ratios were predicted with adjustment for protein binding and physiological pH via the Henderson–Hasselbalch equation. Spearman correlation analyses were performed for each drug category to identify factors predicting saliva excretion (α = 5%). Study quality was assessed by the risk of bias in non-randomised studies of interventions tool. Results: Overall, 42 studies including 40 drugs (anti-psychotics, anti-microbials, immunosuppressants, anti-thrombotic, anti-cancer and cardiac drugs) were included. The median saliva-to-plasma ratios were similar for drugs in the amphoteric (0.59), basic (0.43) and acidic (0.41) groups and lowest for drugs in the neutral group (0.21). Higher excretion of acidic drugs (n = 5) into saliva was associated with lower ionisation and protein binding (correlation between predicted versus observed saliva-to-plasma ratios: R2 = 0.85, p = 0.02). For basic drugs (n = 21), pKa predicted saliva excretion (Spearman correlation coefficient: R = 0.53, p = 0.02). For amphoteric drugs (n = 10), hydrogen bond donor (R = − 0.76, p = 0.01) and polar surface area (R = − 0.69, p = 0.02) were predictors. For neutral drugs (n = 10), protein binding (R = 0.84, p = 0.004), lipophilicity (R = − 0.65, p = 0.04) and hydrogen bond donor count (R = − 0.68, p = 0.03) were predictors. Drugs considered potentially suitable for saliva-based TDM are phenytoin, tacrolimus, voriconazole and lamotrigine. The studies had a low-to-moderate risk of bias. Conclusions: Many commonly used drugs are excreted into saliva, which can be partly predicted by a drug's ionisation state, protein binding, lipophilicity, hydrogen bond donor count and polar surface area. The contribution of drug transporters and physiological factors to the excretion needs to be evaluated. Continued research on drugs potentially suitable for saliva-based TDM will aid in adopting this person-centred TDM approach to improve patient outcomes. [ABSTRACT FROM AUTHOR]

Here, we show that 3,5-bis[(1E)-2-(2,6-dichlorophenyl)ethenyl]-1H-pyrazole 2l depolymerizes microtubules and reduces the number of growing tips of microtubules. The fluorescence recovery after photobleaching experiment in live MCF-7 cells showed that pyrazole 2l suppresses spindle microtubule dynamics. Further, the compound inhibits chromosome movements, activates the spindle assembly checkpoint and blocks mitosis in MCF-7 cells. Pyrazole 2l treatment induced cell death in a variety of pathways. Pyrazole 2l induces cell death independent of BubR1 and p53 levels of MCF-7 cells upon microtubule depolymerization. Further, pyrazole 2l increases the interaction between NF-κB and microtubules and enhances the nuclear localization of NF-κB at its half-maximal proliferation inhibitory concentration while a high concentration of the compound reduced the nuclear localization of NF-κB. Interestingly, the compound exerted significantly stronger antiproliferative effects in cancerous cells than in non-cancerous cells. The results indicated that pyrazole 2l inhibits mitosis by targeting microtubules, induces several types of cell death stimuli and suggests its potential as a lead in developing anticancer agent. [ABSTRACT FROM AUTHOR]

The drug discovery process is a rocky path that is full of challenges, with the result that very few candidates progress from hit compound to a commercially available product, often due to factors, such as poor binding affinity, off-target effects, or physicochemical properties, such as solubility or stability. This process is further complicated by high research and development costs and time requirements. It is thus important to optimise every step of the process in order to maximise the chances of success. As a result of the recent advancements in computer power and technology, computer-aided drug design (CADD) has become an integral part of modern drug discovery to guide and accelerate the process. In this review, we present an overview of the important CADD methods and applications, such as in silico structure prediction, refinement, modelling and target validation, that are commonly used in this area. [ABSTRACT FROM AUTHOR]

Multi-drug resistance is increasing in the pathogenic bacterium S. pneumoniae, which is mainly responsible for meningitis and community-acquired pneumonia (CAP), highlighting the need for new anti-pneumococcal agents. We have identified a potential anti-pneumococcal agent, enol 3, which acts by hindering the cell division process by perturbing Z-ring dynamics inside the cell. Enol 3 was also shown to inhibit FtsZ polymerization and induce its aggregation in vitro but does not affect the activity of tubulin and alkaline phosphatase. Docking studies show that 3 binds near the T7 loop, which is the catalytic site of FtsZ. Similar effects on Z-ring and FtsZ assembly were observed in B. subtilis, indicating that 3 could be a broad-spectrum anti-bacterial agent useful in targeting Gram-positive bacteria. In conclusion, compound 3 shows strong anti-pneumococcal activity, prompting further pre-clinical studies to explore its potential. [ABSTRACT FROM AUTHOR]

This study investigated the effect of 2-methylimidazole (2-MIM) addition on the fluorescence of ethyl-7-hydroxy-2-oxo-2H-chromene-3-carboxylate using low-cost density functional theory (DFT) and Time-Dependent DFT calculations on single crystal X-ray geometries of ethyl-7-hydroxy-2-oxo-2H-chromene-3-carboxylate hydrate (1), 2-MIM (2), and the 1 : 1 co-crystal of (1) and (2), (3). At low concentrations (1 : 1–1 : 10) of 2-MIM, the fluorophore shows a decrease in the fluorescence intensity, but at higher concentrations (above 1 : 10) the fluorescence excitation maximum shifted from 354 nm to 405 nm, with a significant emission intensity increase. The changed excitation and emission profile at high concentrations is due to the deprotonation of the coumarin's phenolic group, which was confirmed by the increased shielding of the aromatic protons in the titration 1H NMR spectra. The experimental fluorescence data between the 1 : 1 and 1 : 10 ratios agreed with the theoretical fluorescence data, with a redshift and decreased intensity when comparing (1) and (3). The data indicated that combining the fluorophore with 2-MIM increased levels of vibronic coupling between 2-MIM and the fluorophore decreasing de-excitation efficiency. These increased vibronic changes were due to charge transfer between the fluorophore and 2-MIM in (3). The subtle movement of the proton, H(5) toward N(2′) (0.07 Å) caused a significant decrease in fluorescence due to electron density distribution (EDD) changes. This was identified by comparison of the EDD in the excited (S1) and ground (S0) states plotted as an isosurface of EDD difference. For the higher concentrations, an alternative excitation pathway was explored by modifying the crystal geometry of (3) based on 1H NMR spectroscopy data to resemble excitoplexes. Theses excitoplex geometries reflected the fluorescence profile of the fluorophore with high concentrations of 2-MIM; there were dramatic changes in the theoretical fluorescence pathway, which was 100% vibronic coupling compared to 15.31% in the free fluorophore. At this concentration, the de-excitation pathway causes remodelling of the lactone ring via stretching/breaking the C＝O bond in the S1 causing increased fluorescence by movement of the transition dipole moment. These results reflect previous studies, but the methods used are less experimentally and computationally expensive. This study is among the first to explain charge transfer fluorescence using crystalline geometries. This study will be of interest to the fields of crystal engineering and fluorescence spectroscopy. [ABSTRACT FROM AUTHOR]

Paracetamol (PCM) has two well-documented polymorphic forms at room temperature; monoclinic Form I is more stable than the other orthorhombic Form II. Form II exhibits improved tabletting properties compared to Form I due to low shearing forces; however, difficulties in its manufacture have limited its use in industrial manufacture. Previous studies have found that the introduction of a co-former to form co-crystals would allow the PCM molecule to exist in a conformation similar to that of the orthorhombic form while being more stable at room temperature. Experimental charge density analysis of the paracetamol-4,40-bipyridine (PCM-44BP) co-crystal system, and its constituent molecules, has been carried out to examine the forces that drive the formation and stabilisation of the co-crystal, while allowing PCM to maintain a packing motif similar to that found in Form II. It is hoped studies on this well-known compound will help apply the knowledge gained to other drug molecules that are less successful. The PCM molecules in the co-crystal were found to exhibit similar packing motifs to that found in Form I, however, intercalation of the 44BP molecule between the PCM layers resulted in a shallower angle between molecular planes, which could result in the required lateral shear. Topological analysis identified more weak interactions in the co-crystal compared to the individual molecules, thus allowing for greater stability as evidenced by the lattice energies. Weak interactions in the PCM-44BP co-crystal were found to range in strength from 4.08-84.33 kJ·mol-1, and this variety allowed the PCM-44BP planes to be held together, while a weak π-π interaction (15.14 kJ·mol-1) allowed lateral shear to occur, thus mimicking the planes found in Form II PCM and offering the possibility of improved tabletting properties. A comparison of integrated atomic charges between partitions of the PCM molecules in the single and co-crystal found that the hydroxyl and amide groups were involved in greater hydrogen bonding in the co-crystal, resulting in a charge redistribution across the molecule evidenced by a larger molecular dipole moment (μ = 12.34D). These findings, in addition to the co-crystal having the largest lattice energy, form a potential basis with which to predict that the co-crystal exhibits improved solubility and stability profiles. It is anticipated that these findings will contribute to improvements in the formulation and other physical properties of PCM and other pharmaceutical compounds. [ABSTRACT FROM AUTHOR]

In order to retard the rate of development of antibacterial resistance, the causative agent must be identified as rapidly as possible, so that directed patient treatment and/or contact precautions can be initiated. This review highlights the challenges associated with the detection and identification of pathogenic bacteria, by providing an introduction to the techniques currently used, as well as newer techniques that are in development. Focusing on the chemical basis for these techniques, the review also provides a comparison of their advantages and disadvantages. [ABSTRACT FROM AUTHOR]

Experimental charge density distribution studies of two polymorphic forms of piroxicam, β-piroxicam (1) and piroxicam monohydrate (2), were carried out via high-resolution single crystal X-ray diffraction experiments and multipole refinement. The asymmetric unit of (2) consists of two discrete piroxicam molecules, (2a) and (2b), and two water molecules. Geometry differs between (1) and (2) due to the zwitterionic nature of (2) which results in the rotation of the pyridine ring around the C(10)–N(2) bond by approximately 180°. Consequently, the pyridine and amide are no longer co-planar and (2) forms two exclusive, strong hydrogen bonds, H(3)…O(4) and H(2)…O(3), with bond energies of 66.14 kJ mol−1 and 112.82 kJ mol−1 for (2a), and 58.35 kJ mol−1 and 159.51 kJ mol−1 for (2b), respectively. Proton transfer between O(3) and N(3) in (2) results in significant differences in surface electrostatic potentials. This is clarified by the calculation of atomic charges in the zwitterion that shows the formally positive charge of the pyridyl nitrogen which is redistributed over the whole of the pyridine ring instead of concentrating at N–H. Similarly, the negative charge of the oxygen is distributed across the benzothiazine carboxamide moiety. The multipole derived lattice energy for (1) is −304 kJ mol−1 and that for (2) is −571 kJ mol−1, which is in agreement with the experimentally determined observations of higher solubility and dissolution rates of (1) compared to (2). [ABSTRACT FROM AUTHOR]

The ursane triterpenoids, asiatic acid 1 and madecassic acid 2, are the major pharmacological constituents of Centella asiatica, commonly known as Gotu Kola, which is used traditionally for the treatment of anxiety and for the improvement of cognition and memory. Using the two-electrode voltage-clamp technique, these triterpenes, and some semisynthetic derivatives, were found to exhibit selective negative modulation of different subtypes of the GABAA receptor expressed in Xenopus laevis oocytes. Despite differing by only one hydroxyl group, asiatic acid 1 was found to be a negative modulator of the GABA-induced current at α1 β2 γ2L, α2 β2 γ2L and α5 β3 γ2L GABAA receptors, while madecassic acid 2 was not. Asiatic acid 1 exhibited the greatest effect at α1 β2 γ2L ( IC50 37.05 μ m), followed by α5 β3 γ2L ( IC50 64.05 μ m) then α2 β2 γ2L ( IC50 427.2 μ m) receptors. Conversion of the carboxylic acid group of asiatic acid 1 to a carboxamide group (2 α,3 β,23-trihydroxy-urs-12-en-28-amide 5) resulted in enhanced inhibition at both the α1 β2 γ2L ( IC50 14.07 μ m) and α2 β2 γ2L receptor subtypes ( IC50 28.41 μ m). The results of this study, and the involvement of α5-containing GABAA receptors in cognition and memory, suggest that asiatic acid 1 may be a lead compound for the enhancement of cognition and memory. [ABSTRACT FROM AUTHOR]

The charge density distribution in 2,2′-dihydroxy-1,1′-naphthalazine (Pigment Yellow 101; P.Y.101) has been determined using high-resolution X-ray diffraction and multipole refinement, along with density functional theory calculations. Topological analysis of the resulting densities highlights the localisation of single/double bonds in the central C=N–N=C moiety of the molecule in its ground state. The density in the N–N is examined in detail, where we show that very small differences between experiment and theory are amplified by use of the Laplacian of the density. Quantification of hydrogen bonds highlights the importance of the intramolecular N–H…O interaction, known to be vital for retention of fluorescence in the solid state, relative to the many but weak intermolecular contacts located. However, a popular method for deriving H-bond strengths from density data appears to struggle with the intramolecular N–H…O interaction. We also show that theoretical estimation of anisotropic displacements for hydrogen atoms brings little benefit overall, and degrades agreement with experiment for one intra-molecular contact. [ABSTRACT FROM AUTHOR]

Two new ceramides, (3S,4S,5R)-3-octadecanoylamino-4-hydroxy-5-dodecane-2,3,4,5-tetrahydrofuran (1) and (3S,4S,5R)-3-[(2R)-2-hydroxyhexacosanoylamino]-4-hydroxy-5-[(4E)-dodecane-4-ene]-2,3,4,5-tetrahydrofuran (2), together with eight known compounds, eleutheroside A (3), eleutheroside B (4), eleutheroside E (5), 7-hydroxy-6-methoxy-coumarin (6), 6,7-dimethoxycoumarin (7), 5α,8α-epidioxyergosta-6,22-dien-3-ol (8), stigmasterol (9) and rutin (10), were isolated from the fruit pulp ofAcanthopanax senticosus(Rupr. et Maxim) Harms. Their structures were elucidated by means of physicochemical properties and spectroscopic methods (1D, 2D NMR and MS). [ABSTRACT FROM PUBLISHER]

The experimental electron density distribution (EDD)in 8-hydroxyquinoline cocrystallized with salicylic acid, 1, has been determined from a multipole refinement of high-resolutionX-ray diffraction data collected at 100 K. The experimental EDD iscompared with theoretical densities resulting from high-level ab initioand BHandH calculations using Atoms in Molecules theory. 1crystallizes in the triclinic crystal system, and the asymmetricunit consists of a neutral salicylic acid molecule, a salicylate anion,and an 8-hydroxyquinolinium cation exhibiting a number of inter- andintramolecular hydrogen bonds and π–π interactions.Topological analysis reveals that π–π interactionsare of the “closed-shell” type, characterized by ratherlow and flat charge density. In general, the agreement of the topologicalvalues (ρbcpand ∇2ρbcp) between experiment and theory is good, with mean differencesof 0.010 e Å–3and 0.036 e Å–5, respectively. The energetics of the π–π interactionshave been estimated, and excellent agreement is observed between therelative energy and the strength of π-stacking derived fromthe Espinosa approach, with an average difference of only 4.4 kJ mol–1. [ABSTRACT FROM AUTHOR]

A new triterpenoid, 3,4-seco-lupane-20(29)-ene-3,28-dioic acid (1), together with three known lignans, (-)-schisandrin B (2), (-)-sesamin (3) and (-)-syringaresinol (4), was isolated from the pulp of Acanthopanax senticosus (Rupr. et Maxim) Harms. Their structures were elucidated by means of physicochemical properties and spectroscopic methods (1D, 2D-NMR and MS). [ABSTRACT FROM AUTHOR]

Bryostatin structures share a commonality of a central bryophan ring, but each differs due to two groups (R1 and R2) that are attached to the bryophan ring via ester bonds. This research examines the impact that conditions such as UV light, acidic and basic conditions can have on the bryostatin structure in the presence of octanoic acid and water. Mass spectrometry (MS) measurements suggest that bryostatin can easily rearrange into various structures under natural conditions by reacting with carboxylates that are ubiquitous in nature. A second set of measurements suggest bryostatin can be hydrolyzed by water, a reaction that has significant implications in both medicinal applications and extraction procedures. [ABSTRACT FROM AUTHOR]

The 1,3-dipolar cycloaddition of azomethine ylides is a versatile and efficient tool for the construction of five-membered nitrogen heterocycles. When the azomethine ylide is conjugated with double bonds other pericyclic pathways become available, including 1,5- or 1,7-electrocyclizations, with the latter 8π-electron process having only recently emerged as a potentially useful method for the formation of seven-membered heterocycles. Under special structural circumstances, multistep rearrangements can also be observed. In this account, a summary of our work on the exploration and development of 1,7-electrocyclizations of azomethine ylides is presented. 1 Introduction 2 Electrocyclizations 2.1 Reaction of β-Phenylcinnamaldehyde with Amino Acids: The First 1,7-Electrocyclization of Nonstabilized Azomethine Ylides 2.2 Synthesis of Azepines from Unsaturated Aldehydes and Sarcosine via 1,7-Electrocyclizations 2.3 Electrocyclizations of Stabilized Azomethine Ylides 2.4 Electrocyclizations of Azomethine Ylides onto a N=O Double Bond 3 Conclusions [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and initial evaluation of novel chromogenic substrates with potential in the detection and differentiation of cultured bacterial colonies are described. The substrates were readily hydrolysed by specific aminopeptidase activity to release the chromogen, 9-(4′-aminophenyl)-10-methylacridinium salt, which provided a clear visual indication of the presence of the corresponding bacteria. [Copyright &y& Elsevier]