Recent Developments in the Antimicrobial Potential of Some Nitrogenous Heterocycles and their SAR Studies: A Review.

BACKGROUND: Infection remains a significant global health concern, with millions of new cases and deaths occurring due to infectious diseases. Currently, chemoprophylaxis and chemotherapy are the primary treatments, but side effects and toxicities pose challenges. Pathogenic microorganisms have developed resistance to antimicrobial medications. Nitrogen containing heterocyclic scaffolds possess the potential in drug discovery and are explored in various fields like pharmaceuticals, cosmetics, and agrochemicals. To minimize antimicrobial drug resistance, there is a need to design potent, safer antimicrobial lead compounds with higher selectivity and minimal cytotoxicity. OBJECTIVES: The present review aims to outline several recent developments in medicinal chemistry aspect of nitrogenous heterocyclic derivatives with the following purposes: (1) To cast light on the recent literature reports of the last eight years ranging from 2015 to 2023 describing anti-microbial potential of nitrogen-containing heterocyclic derivatives which includes pyrazole, pyrazoline, imidazole, tetrazole and quinoline; (2) To brief the recent developments in the medicinal chemistry of nitrogenous heterocyclic derivatives that is directed towards their anti-microbial profile; (3) To summarize the complete correlation of structural features of nitrogenous heterocyclic molecules with the pharmacological action including in silico as well as mechanistic studies to provide thoughts accompanying the generation of lead molecules. METHODS: Antimicrobial potential of nitrogenous heterocyclic molecules has been displayed by relating the structural features of various lead candidates with their in vitro as well as in vivo antimicrobial outcomes. In contrast, in silico computational analysis from different articles also helped to predict the SAR of potent molecules. RESULTS: Nitrogen containing heterocycles are involved in a range of natural to synthetic analogues with keen antimicrobial potency. It is an emerging need to generate new nitrogenous heterocyclic molecules in order to tackle the drug resistance in micro-organisms with more targeted selectivity as well as specificity. CONCLUSION: To limit the side effects associated with them and to combat the microbes acquired resistance towards the current drug regimen, novel nitrogenous heterocycle based antimicrobial agents are essential to be developed. This review connects the structural units present in lead compounds with their promising antimicrobial action.

Unveiling the phyto-restorative potential of ethereal distillates for atopic dermatitis: an advanced therapeutic approach.

Atopic dermatitis is acknowledged as a vital inflammatory disorder associated with the integumentary system of the body and is characterized by the formation of thick reddish-grey scars and erythema formation on skin, prevalent amidst the populace. Numerous synthetic drugs are available for treatment like antihistamines, immunosuppressants, glucocorticoids etc., but contrarily, essential oil therapy is exclusively lime lighted to favour the purpose. The utilization of available engineered drugs, possess the marked adverse effects owing to prolonged duration of therapy and therefore, essential oils are explored well and proved to exhibit the anti-eczematic, anti-inflammatory and antipruritic properties. Ethereal distillates own the assorted and selective therapeutic properties attributable to presence of bioactive compounds liable to treat this torturous and integumentary disorder, likely lavender oil, patchouli oil, frankincense oil etc., have been found to exert their pharmacological actions by impeding the liberation and action of inflammatory mediators and immunological hyperactivities that are engaged in exacerbating this idiopathic illness. The current attempt provided the update with the aim to bring forth the naturally originated treatment that is pertinent to provide the invulnerable therapy by circumventing the noxious symptoms i.e. erythema formation and inflamed lesions.

Dissociative Photoionization of Dimethylpyridines and Trimethylpyridine at 266 nm: Dynamics of Methyl Radical Release.

The 266 nm photolysis of various positional isomers of dimethylpyridines and trimethylpyridine was investigated by measuring the translational energy distribution of the methyl radical following {sp2}C-C{sp3} bond dissociation. The observed translational energy distribution is attributed to the dissociative photoionization in the cationic ground state following [1 + 1 + 1] three-photon absorption. The translational energy distribution profiles of the methyl radical were broad with the maximum translation energy in excess of 2 eV, which originates due to the dissociation of {sp2}C-C{sp3} bond ortho to the N atom in the ring. The dynamics of {sp2}C-C{sp3} bond dissociation in the cationic ground state of methylpyridines is marginally dependent on the number and position of the methyl groups; similar to xylenes, however, it is site-selective with the preferential cleavage of C-C bond in the ortho position to the pyridinic nitrogen atom, which is attributed to the relative stability of the resulting radical cation.

Flexible piezo-resistive strain sensors using all-polydimethylsiloxane based hybrid nanocomposites for wearable electronics.

We report flexible piezo-resistive strain sensors composed of silver nanoparticle (Ag NP), graphene nanoplatelet (GNP), and multi walled carbon nanotube (MWCNT)-based ternary conductive hybrid nanocomposites as an active sensing layer fabricated using a simple solution processing method on flexible polydimethylsiloxane (PDMS) substrates. The electrical characteristics have been studied in PDMS-based flexible devices having three different kinds of structures, namely Ag NPs/MWCNT/PDMS, GNP/PDMS and Ag NPs/GNP/PDMS. The microscopic analysis of the hybrid nanocomposites is undertaken using field emission scanning electron microscopy. The diameter of the CNTs is found to be in the range of 20-40 nm, whereas the length is determined to be 100-800 nm. The average diameter and length of the GNPs are observed to be 30-50 nm and 100-500 nm, respectively. The crystallite size of the silver nanoparticles in the Ag NPs/MWCNT/PDMS and Ag NPs/GNP/PDMS-based nanocomposites is determined to be 22.8 nm and 29.1 nm, respectively. The prepared sample of Ag NPs shows four distinct peaks in the X-ray diffraction pattern, which correspond to the (111), (200), (220), and (311) face-centered cubic (FCC) crystalline planes. Raman spectroscopy is undertaken to study the fundamental physical properties and chemical analysis of the nanocomposites. Ag NPs/GNP/PDMS-based sensors exhibit superior performance in terms of sensitivity, response and recovery time during breathing/unbreathing analysis. The large surface area of the Ag NPs and GNPs promotes uniform distribution of Ag NPs to fill into the porous GNP surface, thereby facilitating high contact area along with better electron transport in the Ag NPs/GNP/PDMS hybrid nanocomposite-based sensors. The gauge factor (GF), response and recovery time of the Ag NPs/GNP/PDMS hybrid nanocomposite-based sensors are determined to be 221, 130 ms and 119 ms, respectively. The ternary conductive nanocomposite-based sensors are free from the drawbacks of binary nanocomposite-based sensors where the high percolation threshold and poor mechanical behaviour lead to the degradation of the device performance.

Ab initio anharmonic analysis of complex vibrational spectra of phenylacetylene and fluorophenylacetylenes in the acetylenic and aromatic C-H stretching region.

Vibrational spectra in the acetylenic and aromatic C-H stretching regions of phenylacetylene and fluorophenylacetylenes, viz., 2-fluorophenylacetylene, 3-fluorophenylacetylene, and 4-fluorophenylacetylene, were measured using the IR-UV double resonance spectroscopic method. The spectra, in both acetylenic and aromatic C-H stretching regions, were complex exhibiting multiple bands. Ab-initio anharmonic calculations with quartic potential using B97D3/6-311++G(d,p) and vibrational configuration interaction were able to capture all important spectral features in both the regions of the experimentally observed spectra for all four molecules considered in the present work. Interestingly, for phenylacetylene, the spectrum in the acetylenic C-H stretching region emerges due to anharmonic coupling of modes localized on the acetylenic moiety along with the other ring modes, which also involve displacements on the acetylenic group, which is in contrast to what has been proposed and propagated in the literature. In general, this coupling scheme is invariant to the fluorine atom substitution. For the aromatic C-H stretching region, the observed spectrum emerges due to the coupling of the C-H stretching with C-C stretching and C-H in-plane bending modes.

Formulation Development and Investigations on Therapeutic Potential of Nanogel from Beta vulgaris L. Extract in Testosterone-Induced Alopecia.

The objective of the present study was to develop a novel nanogel containing Beta vulgaris L. hydroalcoholic extract and assess its efficacy for treating testosterone-induced alopecia. Beta vulgaris L. leaf hydroalcoholic extract nanogel (BVEN) was prepared by ionic gelation method, incorporated in carbopol 934 gel. Optimization of particle size and entrapment efficiency as the responses was carried out by central composite design response surface methodology. Prepared nanoparticles were evaluated for entrapment efficiency, particle size, zeta potential, polydispersity index, Fourier transform infrared spectroscopy, transmission electron microscopy, and differential scanning calorimetry. Nanogel was evaluated for pH, colour, appearance and homogeneity, viscosity, spreadability, in vitro release study, and stability studies. Further, 2.5% and 5% BVEN were also evaluated for antialopecic activity in Swiss albino mice by using parameters as hair growth initiation, testosterone content, total protein, prostate weight measurement, hair follicular density, anagen/telogen ratio, and histopathological studies. The resulting nanoparticles had better entrapment efficiency with particle size of 274 nm, polydispersity index of 0.259, and zeta potential of +28.8. BVEN pH 6.5, drug content, i.e., quercetin 99.84 ± 1.30% and stigmasterol 99.89 ± 1.52%, spreadability 20.3 ± 0.5925 g cm/sec, and viscosity 110 × 105 cps were observed. Stability studies showed that nanogel was stable at 4°C ± 2°C/60% ± 5% RH. It was found that 5% BVEN showed better antialopecic activity as compared to 2.5% BVEN.

Dynamics of Methyl Radical Formation Following 266 nm Dissociative Photoionization of Xylenes and Mesitylene.

The 266 nm dissociative photoionization of three xylene isomers and mesitylene leading to the formation of methyl radical was examined. The total translational energy distribution profiles [P(ET)] for the methyl radical were almost identical for all of the three isomers of xylene and mesitylene, while a substantial difference was observed for the corresponding P(ET) profile of the co-fragment produced by loss of one methyl group in m-xylene. This observation is attributed to the formation of the methyl radical from alternate channels induced by the probe. The P(ET) profiles were rationalized based on the dissociation of {sp2}C-C{sp3} bond in the cationic state, wherein the {sp2}C-C{sp3} bond dissociation energy is substantially lower relative to the neutral ground state. The dissociation in the cationic state follows a resonant three-photon absorption process, resulting in a maximum translational energy of about 1.6-1.8 eV for the photofragments in the center-of-mass frame. Fitting of the P(ET) profiles to empirical function reveals that the dynamics of {sp2}C-C{sp3} bond dissociation is insensitive to the position of substitution but marginally dependent on the number of methyl groups.

Dipole moment enhanced π-π stacking in fluorophenylacetylenes is carried over from gas-phase dimers to crystal structures propagated through liquid like clusters.

The aggregates of monofluorinated phenylacetylenes in the gas-phase, investigated using the IR-UV double resonance spectroscopic method in combination with extensive structural search and electronic structure calculations, reveal the formation of liquid-like clusters with a π-stacked dimeric core. The structural assignment based on the IR spectra in the acetylenic and aromatic C-H stretching regions suggests that, unlike the parent non-fluorinated phenylacetylene, the substitution of a F atom on the phenyl ring increases the dipole moment, leading to robustness in the formation of a ππ stacked dimer, which propagates incorporating C-Hπ_{Ar/Ac} and C-HF interactions involving both acetylenic and aromatic C-H groups. The structural evolution of fluorophenylacetylene aggregates in the gas phase shows marginal effects due to fluorine atom position on the phenyl ring, with substitution in the para-position tending towards phenylacetylene. The present study signifies that the ππ stacked dimers act as a nucleus for the growth of higher clusters to which other molecular units are added predominantly via the {Ar}_C-Hπ_{Ar} type of interaction and the dominant interactions present in the crystal structures gradually emerge with increasing cluster size. Based on these features, gas-phase clusters of fluorophenylacetylene are hypothesized as "liquid-like clusters" acting as intermediates in the generation of various polymorphic forms starting from a ππ stacked dimer as the core molecular unit.

An updated review on the Oenothera genus.

Oenothera genus (Onagraceae) has been used as a folk remedy since ancient times for the treatment of asthma, gastrointestinal disorders, neuralgia, skin diseases, and hepatic and kidney diseases. Different chemical constituents like lipids, flavonoids, tannins, steroids and triterpenes have been isolated from this genus. The various notable pharmacological activities reported from the genus are antioxidant, cytotoxic, antibacterial, antiviral, anti-inflammatory, antihyperlipidaemic, thrombolytic and antidiarrhoeal. The present paper is to summarize the worldwide reported biological activities and phytoconstituents associated with this genus for about 50 years and highlight the medicinally important species belonging to this genus so that these species can be further explored and used as therapeutic agents for various diseases.

Evaluation of the antinociceptive activity of Amaranthus hybridus Linn. root extracts.

The work evaluated the antinociceptive activity of Amaranthus hybridus Linn. root extracts using the central and peripheral antinociceptive experimental animal models. The oral administration of ethanol and aqueous root extracts (100 and 200 mg/kg) produced significant (p < 0.01) and dose dependent results compared to their respective controls. The aqueous extract (200 mg/kg) produced more inhibition of abdominal writhes in mice than the other test extracts. Both the test extracts significantly (p < 0.01) and dose dependently increased the hot plate pain threshold in mice but the aqueous extract (200 mg/kg) was exhibiting more increase in pain threshold than the other test doses of extracts. Dose dependent and significant (p < 0.01) reduction of painful sensation in mice tail immersion test due to oral administration of test doses was also observed. Oral acute toxicity study indicated the non toxic nature of root extracts. The present investigation revealed that ethanol and aqueous root extracts of A. hybridus Linn. possess significant and dose dependent central and peripheral antinociceptive activity justifying its traditional use in treating conditions associated with painful conditions.

Automated small tilt-angle measurement using Lau interferometry.

A technique for a tilt-angle measurement of reflecting objects based on the Lau interferometry coupled with the moire readout has been proposed. A white-light incoherent source illuminates a set of two gratings, resulting in the generation of the Fresnel image due to the Lau effect. The Fresnel image is projected onto a reflecting object. The image reflected from the object is superimposed onto an identical grating, which results in the formation of a moiré fringe pattern. The inclination angle of moiré fringes is a function of tilt angle of the object. Theory and experimental arrangement of the proposed technique is presented and results of the investigation are reported.