The preparation of the porous graphene materials with controllable porosity basically depends on the design of porous architectures. The development of three‐dimensional (3D) graphene materials from ...two‐dimensional (2D) graphene sheets can harness the unique physical and electrical properties of graphene, but the challenges lie on the design and synthesis of nanoporous graphene with controlled engineering. In this work, two organic aromatic molecules viz., 2‐amino‐3‐hydroxypyridine and phloroglucinol were targeted for the development of porous graphene nanostructures. The synthesis process was designed in such a way that both the molecules having ─OH and ─NH2 groups at ortho position and 3 ─OH groups at 1, 3, 5 positions, respectively, can generate pores along with the development of graphenic lattice during heat treatment. The optimization of reaction conditions viz., time and temperature was done and the chemistry of formation of porous natured graphenic lattice was discussed. Interestingly, the results indicate that both the organic molecules have the potential to develop porous graphenic structures within their lattice at relatively low temperatures without using any additional reagents and reaction conditions. It is suggested that the structure of organic precursor is a critical factor which needs to be optimized to produce porous graphenes.
The present work deals with the design and synthesis of porous graphene from organic precursors under normal atmospheric conditions. The results suggest that apart from synthesis methods and reaction conditions, the structure of organic precursor is a critical factor which requires to be optimized in order to develop porous graphenic structure.
The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of 2-Amino-3-Hydroxypyridine, which is reported to function as an oxidative hair dye ingredient. The Panel reviewed ...relevant animal and human data provided in this safety assessment, and concluded that 2-Amino-3-Hydroxypyridine is safe in the present practices of use and concentration for use in oxidative hair dye formulations.
The asymmetric unit of the title compound, C5H7N2O+·C4H4NO4S−, contains one cation and one anion. The 6-methyl-2,2,4-trioxo-2H,4H-1,2,3-oxathiazin-3-ide anion adopts an envelope conformation with the ...S atom as the flap. In the crystal, the anions and cations are held together by N—H...O, N—H...N, O—H...O and C—H...O hydrogen bonds, thus forming a three-dimensional structure. The Hirshfeld surface analysis and fingerprint plots reveal that the crystal packing is dominated by O...H/H...O (43.1%) and H...H (24.2%) contacts.
At the present time, there is a growing interest in metal-based anticancer agents. Metal complexes exhibit many valuable clinical properties, however, due to toxicity, only a few clinically useful ...complexes have been discovered. It has been demonstrated that synthetic vanadium complexes exhibit many biological activities, including anti-cancer properties, however, cellular and molecular mechanisms still are not fully understood.
This investigation examined the potential effects of three newly synthesized oxidovanadium(IV) complexes with 2-amino-3-hydroxypyridine against pancreatic cancer cells.
We measured cytotoxicity by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, antiproliferative activity by bromodeoxyuridine assay and necrosis as well as late apoptosis by lactate dehydrogenase assay. Reactive oxygen species generation, apoptosis and mitochondrial membrane potential were determined by a flow cytometry technique. Cell morphology was evaluated by using a transmission electron microscope.
The results showed that oxidovanadium(IV) complexes were cytotoxic on pancreatic cancer cells (PANC-1 and MIA PaCa2) over the concentration range of 12.5-200μM, following 48h incubation. Additionally, the cellular mechanism of cytotoxic activity of 2-NH2-3-OH(py)H4V2O2(pmida)2·6H2O (V3) complex was dependent on ROS generation, induction apoptosis with simultaneous disruption of mitochondrial membrane potential.
We have proven that oxidovanadium (IV) complexes show therapeutic potential in pancreatic cancer therapy. The results of our research will help to understand the cellular mechanisms of the cytotoxic activity of the vanadium complexes and will allow a more effective design structure of new vanadium-based compounds in the future.
Background
p‐Phenylenediamine (PPD) is the primary patch test screening agent for hair dye contact allergy, and approximately 100 different hair dye chemicals are allowed.
Objectives
To examine ...whether PPD is an optimal screening agent for diagnosing hair dye allergy or whether other clinically important sensitizers exist.
Methods
Two thousand nine hundred and thirty‐nine consecutive patients in 12 dermatology clinics were patch tested with five hair dyes available from patch test suppliers. Furthermore, 22 frequently used hair dye ingredients not available from patch test suppliers were tested in subgroups of ∼ 500 patients each.
Results
A positive reaction to PPD was found in 4.5% of patients, and 2.8% reacted to toluene‐2,5‐diamine (PTD), 1.8% to p‐aminophenol, 1% to m‐aminophenol, and 0.1% to resorcinol; all together, 5.3% (n = 156). Dying hair was the most frequently reported cause of the allergy (55.4%); so‐called ‘temporary henna’ tattoos were the cause in 8.5% of the cases. p‐Methylaminophenol gave a reaction in 20 patients (2.2%), 3 of them with clinical relevance, and no co‐reaction with the above five well‐known hair dyes.
Conclusions
Hair dyes are the prime cause of PPD allergy. PPD identifies the majority of positive reactions to PTD, p‐aminophenol and m‐aminophenol, but not all, which justifies additional testing with hair dye ingredients from the used product.
The popularity of hair dyes use has been increasing regularly throughout the world as per the demand of hair coloring fashion trends and other cosmetic products. 2-Amino-3-hydroxypyridine (A132) is ...widely used as a hair dye ingredient around the world. We are reporting first time the phototoxicity mechanism of A132 under ambient environmental UV-B radiation. It showed maximum absorption in UV-B region (317nm) and forms a photoproduct within an hour exposure of UV-B irradiation. Photocytotoxicity of A132 in human keratinocytes (HaCaT) was measured by mitochondrial (MTT), lysosomal (NRU) and LDH assays which illustrated the significant reduction in cell viability. The role of reactive oxygen species (ROS) generation for A132 phototoxicity was established photo- chemically as well as intracellularly. Noteworthy, formation of tail DNA (comet assay), micronuclei and cyclobutane pyrimidine dimers (CPDs) (immunocytochemistry) formation confirmed the photogenotoxic potential of dye. Cell cycle study (sub-G1peak) and staining with EB/AO revealed the cell cycle arrest and apoptosis. Further, mitochondrial mediated apoptosis was corroborated by reduced MMP, release of cytochrome c and upregulation of caspase-3. Release of mitochondrial Smac/DIABLO in cytoplasm demonstrated the caspase dependent apoptotic cell death by photolabile A132 dye. In-addition increased Bax/Bcl2 ratio again proved the apoptosis. Thus, study suggests that A132 induces photogenotoxicity, phototoxicity and apoptotic cell death through the involvement of Smac/DIABLO in mitochondrial apoptosis via caspase dependent manner. Therefore, the long term use of A132 dye and sunlight exposure jointly increased the oxidative stress in skin which causes premature hair loss, damage to progenitor cells of hair follicles.
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•Photodegradation of A132 and formation of novel photoproduct•Involvement of ROS in A132 phototoxicity•Role of ROS in DNA damage, CPD and micronuclei formation•Release of Smac/DIABLO from mitochondria during apoptosis•Caspase 3 dependent apoptotic cell death
Four novel N2O2 type Schiff base metal complexes of Cu(II), Ni(II), Co(II) and Zn(II) have been synthesized from a new Schiff base ligand derived from 4-aminoantipyrine, salicylaldehyde and ...2-amino-3-hydroxy- pyridine. The ligand and its complexes have been characterized on the basis of Elemental analyses, Magnetic susceptibility, FAB Mass, UV-Vis., IR, ¹H-NMR, ESR and CV spectral studies, as well as conductivity data. On the basis of spectral studies, a square-planar geometry for the complexes has been proposed. The ESR spectrum of Cu(II) complex was recorded at LNT and its salient features are reported. The in vitro antimicrobial activity of the investigated compounds was tested against the bacteria such as Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and fungi Candida albicans and Rhizopus stolonifer. The data indicate that most of the metal complexes have higher antimicrobial activity than the free ligand. DNA cleavage experiments performed on calf thymus DNA plasmids using metal complexes in the presence of H2O2 showed that all the complexes afford a pronounced DNA cleavage
Flavonoids, with high antioxidant activity in fruits and vegetables, are natural vegetable dyes synthesized from phenylalanine. They are very essential for human health due to their activity as free ...radical acceptors. In this paper, the availability in the determination of quercetin (Que), galangin (Gal), 3-hydroxyflavone (3HF), and chrysin (Chr) of a modified glassy carbon (GC) sensor electrode using 2-amino-3-hydroxypyridine (AHP) was examined separately and simultaneously by cyclic voltammetry (CV). Surface characterization of modified electrodes was performed using CV, electrochemical impedance spectroscopy, and scanning electron microscopy techniques. The modification of AHP onto the GC electrode surface was carried out between −150 and +600 mV potential range using 100 mV s
−1
scanning rate with 30 cycles. The binding of flavonoid derivatives onto the modified surface was performed between +300 and +1,700 mV potential range using 100 mV s
−1
scanning rate with 10 cycles. The usability of the modified electrode was examined in the determination of some flavonoids by square wave voltammetry. From the experimental results, it was found out that Que, 3HF, and Chr; Gal, 3HF, and Chr; and 3HF and Chr can be determined simultaneously by using an AHP-modified GC sensor electrode. Also, these molecules can easily be determined separately by using the modified electrode.
Mixed ligand Ni(II), Cu(II) and Zn(II) complexes of 2-amino-3-hydroxypyridine and imidazoles were synthesized and characterized by spectral techniques. The thermogravimetric studies under nitrogen ...revealed the presence of coordinated water molecules, and gave metal oxide as final solid residue. Morphology of the complexes was investigated by SEM. Potentiometric study in aqueous solution identified MABH, MAB and MAB
2 species. The complexes have
in vitro biological activities against bacteria, fungi and yeast.
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► Several Ni(II), Cu(II) and Zn(II)-AHP-imidazole complexes were synthesized. ► The complexes were characterized by elemental, spectral and magnetic moment data. ► TG–DTA analyses show interesting decomposition patterns in these complexes. ► Morphology of the metal complexes was investigated by SEM. ► Potentiometric study identified MABH, MAB and MAB
2 species in aqueous solution.
Several mixed ligand Ni(II), Cu(II) and Zn(II) complexes of 2-amino-3-hydroxypyridine (AHP) and imidazoles viz., imidazole (him), benzimidazole (bim), histamine (hist) and
l-histidine (his) have been synthesized and characterized by elemental and spectral (vibrational, electronic,
1H NMR and EPR) data as well as by magnetic moment values. On the basis of elemental analysis and molar conductance values, all the complexes can be formulated as MABCl except histidine complexes as MAB. Thermogravimetric studies reveal the presence of coordinated water molecules in most of the complexes. From the magnetic measurements and electronic spectral data, octahedral structure was proposed for Ni(II) and Cu(II)-AHP-his, tetrahedral for Cu(II)-AHP-him/bim/hist, but square planar for the Cu(II)-AHP complex. The
g
∥/
A
∥ calculated supports tetrahedral environment around the Cu(II) in Cu(II)-AHP-him/bim/hist and distorted octahedral for Cu(II)-AHP-his complexes. The morphology of the reported metal complexes was investigated by scanning electron micrographs (SEM). The potentiometric study has been performed in aqueous solution at 37
°C and
I
=
0.15
mol
dm
−3 NaClO
4. MABH, MAB and MAB
2 species has been identified in the present systems. Proton dissociation constants of AHP and stability constants of metal complexes were determined using MINIQUAD-75. The most probable structure of the mixed ligand species is discussed based upon their stability constants. The
in vitro biological activity of the complexes was tested against the Gram positive and Gram negative bacteria, fungus and yeast. The oxidative DNA cleavage studies of the complexes were performed using gel electrophoresis method. Cu(II) complexes have been found to promote DNA cleavage in presence of biological reductant such as ascorbate and oxidant like hydrogen peroxide.
Condensation of 2-amino-3-hydroxypyridine with thenoyl chloride in 1-methyl-2-pyrrolidon afforded 2-(2-thienyl)oxazolo4,5-
b
pyridine. Reactivity of the latter towards electrophilic substitution ...(nitration, bromination, formylation, acylation) was studied. It is shown that the reaction occurred exclusively at the position
5
of the thiophene ring. Nucleophilic substitution of pyridine ring was performed. Quaternization of 2-(2-thienyl)oxazolo4,5-
b
pyridine with methyl iodide in benzene was carried out. Chichibabin amination with an excess of sodium amide in xylene failed.
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