P-hydroxy Phenyl Research Articles

The effect of oxygen bleaching on reactivity of syringyl and guaiacyl units of Eucalyptus tereticornis pulps lignin

Dioxin lignin of Eucalyptus tereticornis kraft pulps and its oxygen-treated pulps with kappa number 21.32, 12.84; 13.03, 12.18 were isolated and subjected to alkaline nitrobenzene oxidation studies to determine the structural changes during oxygen bleaching. HPLC quantitatively identified eight compounds during nitrobenzene oxidation of dioxin lignin in alkaline media. Lignin obtained from E. tereticornis has syringyl and guaiacyl units. Residual lignin composition in pulps was studied and found that during oxygen delignification, the syringyl unit was degraded more in comparison to guaiacyl and p-hydroxy phenyl unit, i.e., the molar ratio of syringyl unit is lower than guaiacyl and p-hydroxy phenyl unit. The results are adequately described in the research.

Sensing Behavior of Metal-Free Porphyrin and Zinc Phthalocyanine Thin Film towards Xylene-Styrene and HCl Vapors in Planar Optical Waveguide.

The sensing behavior of a thin film composed of metal-free 5, 10, 15, 20-tetrakis (p-hydroxy phenyl) porphyrin and zinc phthalocyanine complex towards m-xylene, styrene, and HCl vapors in a homemade planar optical waveguide (POWG), was studied at room temperature. The thin film was deposited on the surface of potassium ion-exchanged glass substrate, using vacuum spin-coating method, and a semiconductor laser light (532 nm) as the guiding light. Opto-chemical changes of the film exposing with hydrochloric gas, m-xylene, and styrene vapor, were analyzed firstly with UV-Vis spectroscopy. The fabricated POWG shows good correlation between gas exposure response and absorbance change within the gas concentration range 10–1500 ppm. The limit of detection calculated from the logarithmic calibration curve was proved to be 11.47, 21.08, and 14.07 ppm, for HCl gas, m-xylene, and styrene vapors, respectively. It is interesting to find that the film can be recovered to the initial state with trimethylamine vapors after m-xylene, styrene exposures as well as HCl exposure. The gas-film interaction mechanism was discussed considering protonation and π-π stacking with planar aromatic analyte molecules.

Effect of using regenerated combined FAU and MOR zeolites as catalysts during the pyrolysis of kraft lignin

The SiO2/Al2O3 mole ratio, pore size, and acid sites are the key parameters of zeolite’s activity in lignin pyrolysis. In this study, the comparison of individual Y and M zeolites, the combined ‘Y + M’ sample after regeneration, and their effect on lignin pyrolysis were studied in five cycles (regeneration and reuse). The results were explained using Brunauer, Emmet, and Teller (BET), micropore surface area (MSA), and total acid sites (TAS) analyses. In comparison with the individual Y or M zeolite sample, the consistent higher catalytic activities of the combined ‘Y + M’ sample in repeated cycles were observed. Pyrolysis heavy oils were characterized by nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC). The NMR analyses revealed that with increased zeolite regeneration cycles, p-hydroxy phenyl and methoxyl groups increased. Decreases in guaiacyl phenolic hydroxyl were less for the combined ‘Y + M’ sample than the individual Y and M zeolites. Lower weight average (Mw) of heavy oil for the combined ‘Y + M’ sample indicated the enhanced cleavage of lignin structures in pyrolysis. These results support the higher catalytic activity of regenerated zeolites for the combined ‘Y + M’ sample compared with individual Y and M zeolites due to the improved MSA and TAS.

Anti-oxidation properties of 2-substituted furan derivatives: A mechanistic study

2-(p-phenyl substituted styryl)-furans were synthesized and studied the excited state and anti oxidation properties using absorption, fluorescence, density functional theory and DPPH radical scavenging assay. 2-(p-hydroxy phenyl styryl)-furan (6) exhibits good antioxidant properties with IC50 ~ 40 μM as compared to the amine, chloro, cyano methoxy and nitro substituted styryl compounds (1–5, 7–8) (IC50 > 150 μM). It is shown that furans 1–3 with strong electron withdrawing nitro, cyano and chloro substituent do not show antioxidant properties. The O–H bond dissociation energy (BDE) of p-hydroxy substituted furan compound is comparable to the BDE of vitamin E. The antioxidant activity of furan compound is further reduced with increasing the dipolar nature of the molecule. From the thermodynamic parameters and antioxidant properties, it is shown that there is a correlation of antioxidant properties with the ground state dipole moment, X–H bond dissociation energy (X: O; N) and proton affinity (PA). In presence of the furan compound, the quenching of DPPH radical is occurred predominantly through hydrogen atom transfer mechanism.

Antiradical Properties of trans-2-(4-substituted-styryl)-thiophene.

2-substituted thiophene compounds with electron donating and electron withdrawing p-phenyl substitution were synthesized and studied their radical scavenging properties using DPPH assay and DFT method. It is shown that p-hydroxy and p-amino phenyl substituted compound exhibit radical scavenging activity. From DFT and radical scavenging studies, a correlation between IC50 with the bond dissociation enthalpy, proton affinity, ground state dipole moment and optical band gap of compound is found. Compounds 1-3 with electron withdrawing substituent (NO2, CN, Cl) do not show any radical scavenging properties, whereas compounds 6-7 with electron donating substituent (OH, NH2) show antiradical properties. Further, the antiradical activity is reduced drastically by replacing the -OH and -NH2 with methoxy and -N-alkylating group respectively in 6 and 7. The compound with p-hydroxy phenyl substitution, exhibits stronger antiradical activity as compared to the p-amino phenyl substitution due to smaller O-H bond dissociation energy as compared to the N-H bond. From DPPH and DFT studies, it is suggested that the radical scavenging activity in 2-substituted thiophene is occurred through proton transfer mechanism. The other possible SET, SPLET mechanisms are also corroborated. Graphical Abstract Antiradical properties of trans-2-(4-substituted-styryl)-thiophene Anamika Gusain, Naresh Kumar, Jagdeep Kumar, Gunjan Pandey, Prasanta Kumar Hota.

Anti-mycobacterial activity of polyketides from Penicillium sp. endophyte isolated from Garcinia nobilis against Mycobacteriumsmegmatis

Objective/backgroundAccording to estimates by the World Health Organization, there were 9.6 million new tuberculosis (TB) cases in 2014: 5.4 million among men, 3.2 million among women, and 1.0 million among children. There were also 1.5 million TB deaths. Although there are potent anti-TB molecules, the misuse of these drugs in addition to inconsistent or partial treatment have led to the development of multidrug-resistant TB and extensively drug-resistant TB. It is established that plants harbor microorganisms, collectively known as endophytes, which also produce metabolites. Exploring the as-yet untapped natural products from the endophytes increases the chances of finding novel and active compounds. The present study was aimed to investigate the antimycobacterial activity of the crude extract and compounds isolated from Penicillium sp. endophyte associated with Garcinia nobilis against Mycobacterium smegmatis. MethodsLiquid culture obtained from the fermentation of Penicillium sp. was extracted using ethylacetate and the liquid chromatography–mass spectrometry monitored fractionation of crude extracts yielded six compounds. Their structures were elucidated with spectroscopic analyses including two-dimensional nuclear magnetic resonance, high resolution mass spectrometry by dereplication using Antibase, and by comparison to literature data. All compounds and the crude extract from the liquid medium were evaluated for their antimycobacterial activity against M. smegmatis. ResultsIn this study, the activity of penialidins A–C (1–3), citromycetin (4), p-hydroxy phenyl glyoxalaldoxime (5), and Brefeldin A (6) were tested against nonpathogenic M. smegmatis. Penialidin C was the most active compound with a minimum inhibitory concentration of 15.6μg/mL. ConclusionIsolated compounds from Penicillium sp. harbored in G. nobilis exhibited promising antimycobacterial activity against M. smegmatis thus supporting the immensity of the potential of antimycobacterial drug discovery from endophytes from medicinal plants. Penialidin C could further be investigated for antimycobacterial drug development.

Novel pyridine-2,4,6-tricarbohydrazide derivatives: Design, synthesis, characterization and in vitro biological evaluation as α- and β-glucosidase inhibitors

A range of novel pyridine 2,4,6-tricarbohydrazide derivatives (4a–4h) were synthesized and its biological inhibition towards α- and β-glucosidases was studied. Most of the compounds demonstrate to be active against α-glucosidase, and quite inactive/completely inactive against β-glucosidase. A number of compounds were found to be more active against α-glucosidase than the reference compound acarbose (IC50 38.25±0.12μM); being compound 4d with the p-hydroxy phenyl motive the most active (IC50 20.24±0.72μM). Molecular modeling studies show the interactions of compound 4d with the active site of target α-glucosidase kinase.

Discrimination of varietal wines according to their volatiles

A method is being proposed in order to discriminate bottled wines of different varieties when no other information is known. The advantages of the method consist in the fact that anyone who wants to certify the variety, which is written on the label or the area of origin, can use such a technique to achieve the conformity. Additionally, the method can be easily applied by laboratories equipped with a GC. The differentiation has been achieved by using only seven of the total extracted volatiles, mainly higher alcohols and higher alcohol esters, namely 3-methyl-1-butanol, 2,3-butanediol, ethyl lactate, 3-methyl-1-butyl acetate, 2-phenylethanol, phenyl ethyl acetate and p-hydroxy phenyl ethanol. These key compounds are not relevant to a single variety. The proposed method does not take into account variables such as the year of vintage and fermentation procedures (agitation, temperature).

Characterization of lignin isolated from some nonwood available in Bangladesh

Lignins isolated from cotton stalks, jute stick and dhaincha by acidolytic dioxane were characterized using alkaline nitrobenzene oxidation, elemental analysis, methoxyl analysis and molecular weight analysis and UV, IR 1H NMR spectroscopy. The C 9 formulas for cotton stalks, jute stick and dhaincha ( Sesbania aculeata) lignin were C 9H 9.36O 4.50(OCH 3) 1.23, C 9H 9.02O 4.57(OCH 3) 1.35 and C 9H 8.88O 4.65(OCH 3) 1.50, respectively. All three lignins were of the guaiacyl–syringyl type. Cotton stalks lignin contained more p-hydroxy phenyl unit than dhaincha and jute stick lignins as observed by alkaline nitrobenzene oxidation products. The β- O-4 units in these nonwood lignins had predominately erythro stereochemistry type.

Synthesis and Antitumor Activity of Some Curcumin Analogs

In this study, four new curcurmin analogs (compounds 1, 2, 17 and 18) were synthesized. 17 [3,5-bis(4-hydroxy-3-methoxy-5-methylcinnamyl)N-methylpiperidone] showed high activity with GI50, TGI, and LC50 MG-MID values of 21.3, 70.7, and 97.7 microM, respectively. 18 [3,5-bis(4-hydroxy-3-methoxy-5-methylcinnamyl)-N-ethylpiperidone] showed the highest activity in this study with GI50, TGI, LC50 MG-MID values of 4.4, 33.8, 89.1 microM, respectively. 18 is even more active than curcumin with GI50, TGI, LC50 MG-MID values of 38.4, 35.6, 66.0 microM; respectively. 8 showed moderate selectivity towards Leukemia cell line-subpanel with a ratio of 5.6 (curcumin ratio: 1.2 for the same subpanel). The in vitro anti-tumor screening reveals that the results go hand in hand with the in vitro free radical scavenging effects. The antioxidant effect of these compounds depends mainly on the stabilization of the formed phenoxy free radical for which the p-hydroxy phenyl moiety is essential. o-substitution by electron-donating groups like the o-methoxy group (and to a even higher degree by the ethoxy group) increases the stability of phenoxy free radical, hence increasing both free scavenging and anti-tumor effects. Increasing the alkyl group chain on the N in the series of substituted N-alkyl piperidones as well as the extension of conjugation, increases the stabilization of phenoxy free radical and thereby the activity towards both free radical scavenging and anti-tumor effects. This may be attributed to an increased positive inductive effect and/or increased lipophilicity of the new compounds, a fact which is proven by the superior activities of compounds 17 and 18.

Tyrosine and Phenylalanine Catabolism by Lactobacillus Cheese Flavor Adjuncts

Bacterial metabolism of Tyr and Phe has been associated with the formation of aromatic compounds that impart barny-utensil and floral off-flavors in cheese. In an effort to identify possible mechanisms for the origin of these compounds in Cheddar cheese, we investigated Tyr and Phe catabolism by Lactobacillus casei and Lactobacillus helveticus cheese flavor adjuncts under simulated Cheddar cheese-ripening (pH 5.2, 4% NaCl, 15°C, no sugar) conditions. Enzyme assays of cell-free extracts indicated that L. casei strains catabolize Tyr and Phe by successive, constitutively expressed transamination and dehydrogenation reactions. Similar results were obtained with L. helveticus strains, except that the dehydrogenase enzymes were induced during incubation under cheese-ripening conditions. Micellar electrokinetic capillary chromatography of supernatants from L. casei and L. helveticus strains incubated under simulated cheese-ripening conditions confirmed that Tyr and Phe transamination and dehydrogenation pathways were active in both species and also showed these reactions were reversible. Major products of Tyr catabolism were p-hydroxy phenyl lactic acid and p-hydroxy phenyl acetic acid, while Phe degradation gave rise to phenyl lactic acid, phenyl acetic acid, and benzoic acid. However, some of these products were likely formed by nonenzymatic processes, since spontaneous chemical degradation of the Tyr intermediate p-hydroxy phenyl pyruvic acid produced p-hydroxy phenyl acetic acid, p-hydroxy phenyl propionic acid, and p-hydroxy benzaldehyde, while chemical degradation of the Phe intermediate phenyl pyruvic acid gave rise to phenyl acetic acid, benzoic acid, phenethanol, phenyl propionic acid, and benzaldehyde.

Benzodiazepine Compounds as Inhibitors of the Src Protein Tyrosine Kinase: Screening of a Combinatorial Library of 1,4-Benzodiazepines

We screened 1680 spatially separated compounds of a diverse combinatorial library of 1,4-benzodiazepines for their ability to inhibit the kinase activity of protein tyrosine kinases Src, Yes, Abl, Lck, Csk, and fibroblast growth factor receptor. This screening yielded novel ligands for the protein tyrosine kinase Src. In the 1,4-benzodiazepine-2-one scaffold, the preferred substituent at position R1 was 4-hydroxyphenylmethyl or a 3-indolemethyl derived from a tyrosine or tyrptophan used in building the benzodiazepine, while the substituent at R2, introduced by alkylating agents, was preferably aromatic in nature. The preferred ring structure introduced on the bicyclic ring of the scaffold by acid chlorides was a p-hydroxy phenyl group. The lead compound, designated as N-l-Yaa, has a l-4-hydroxyphenylmethyl ring at R1 and a biphenylmethyl substituent at R2. The compound has an IC50 of 73 μM against Src, 2- to 6-fold lower than against other protein tyrosine kinases and >10-fold lower than against other nucleotide-utilizing enzymes. The mechanism of binding of N-l-Yaa to Src is mixed against the peptidic substrate with a Ki of 35 μM and noncompetitive against ATP-Mg with a Ki of 17 μM. Multiple inhibition analysis of the lead compound in the presence of other competitive inhibitors demonstrated that the binding of the lead compound is nonexclusive to the other competitive inhibitor. The inhibitor was found to be nontoxic to the AFB-13-human fibroblasts cells and inhibited the colony formation of HT-29 colon adenocarcinoma cells that are dependent on Src activity.

Raman spectroscopic study of space structure of membrane proteins and membrane lipids in photodamaged human erythrocyte sensitized by hypocrellin B

Laser Raman spectroscopy was used to investigate the photodamage characteristics of human erythrocyte membranes sensitized by hypocrellin B (HB) at the molecular level. It brought to light that the essence of the changes of erythrocyte membranes' functions caused by membrane protein cross-linking and membrane lipid peroxidation, including increase of fluidity and ion permeability of membranes, etc., was that the orderly structure of erythrocyte membranes had been damaged by the active oxygen ((1)O(2), O(2)(-) and, OH) generated by HB, including the decrease of alpha-helix, beta-sheet and the increase of random coil in the main-chain of membrane proteins, the decrease of mercapto groups, indole rings, p-hydroxy phenyl rings, monosubstituted phenyl rings, etc. in the side-chain, and the changes of the conformations of membrane lipids as well. With the increase of the irradiation time, the trans conformation of membrane lipids increased first, then decreased. On the contrary, the gauche conformation decreased first, then increased. In addition, the decrease of the intensities of the lines assigned to bending vibration of the conformation-insensitive CH(2) and CH(3) of membrane proteins and lipids suggested that break of their chains had occurred.

Simultaneuous Determination of Enalpril Maleate and Hydrochlorothiazide in Tablets by Reversed Phase HPLC

A new simple, precise, rapid and selective RP-HPLC method has been developed for the simultaneous determination of Enalpril maleate and Hydrochlorothiazide from formulations, using 0.025M orthophosphoric acid [(adjusted to pH 3.0 with triethyl amine (TEA)]: Acetonitrile (84 16 V/V), as a mobile phase at a flow rate of 1.0 ml/min and μ Bondapak C18 column (10 micron, 30cm × 3.9 mm) as a stationary phase. Detection was carried out using a UV detector at 226 nm. p-hydroxy phenyl acetamide (PHPA) was used as an internal standard. Linearity range and percentage recoveries for Enalpril maleate and Hydrochlorothiazide were 40–200 μg/ml and 50–500 μg/ml, 99.74 and 99.69 respectively. Minimum detection limit obtained was 0.8 μg/ml and 0.4 μg/ml for Enalpril maleate and Hydrochlorothiazide respectively.

Determination of the acid dissociation constants of N-carboxymethyl-N-(p-hydroxy phenyl carbamoylmethyl)-2,3-dihydroxy-5-carbomethoxy benzylamine and the stability constants of its metal complexes

The acid dissociation constants of N-carboxymethyl-N-(p-hydroxy phenyl carbamoyl-methyl)-2,3-dihydroxy-5-carbomethoxy benzylamine (CHDCB) and the stability constants of its 1:1 complexes with alkaline earth, Cd(II), Co(II), Ni(II), Cu(II), Zn(II), Fe(III), Th(IV) and U(VI) ions have been determined at 25.0 ± 0.1 °C and at an ionic strength of 0.1 (KNO3) by pH titration method. The probable coordination sites have also been discussed.

Monoclonal antibody NMS-1 increases N-formyl chemotactic peptide-mediated oxidative burst generation in human neutrophils.

Murine monoclonal antibody (mAb) NMS-1 was generated which binds to the surface of living human neutrophils. The antigens on neutrophil plasma membranes recognized by mAb NMS-1 were solubilized in Nonidet P-40 and immunopurified on matrix-bound mAb NMS-1. mAb NMS-1 binds to four periodate-sensitive structures of 70,000, 95,000, 140,000, and 170,000 Da on the plasma membrane surface of human neutrophils as was shown by Western blot analysis. Binding of mAb NMS-1 to human neutrophils induced a rapid transient rise in cytosolic free calcium (Quin 2 fluorescence) but no detectable generation of reactive oxygen metabolites. The oxidative burst of N-formyl peptide-treated neutrophils, however, increased in the presence of mAb NMS-1. The kinetics of N-formyl peptide (N-formyl-norleucyl-leucyl-phenylalanyl-norleucyl-tryrosyl-lysine; FNLPNTL)-mediated hydrogen peroxide formation (p-hydroxy phenyl acetate oxidation) in the presence of mAb NMS-1 was analyzed quantitatively. 1) When neutrophils were incubated with mAb NMS-1 before FNLPNTL addition, an increase in rate, magnitude, and duration of hydrogen peroxide formation was observed compared with controls which received no mAb NMS-1 treatment. After termination of the initial linear phase of response, a second transient linear phase of hydrogen peroxide formation was induced. This second phase of activation was not observed in neutrophils which received no mAb NMS-1 treatment. The onset of the response and latency before attainment of the initial linear rate of hydrogen peroxide formation was not changed by mAb NMS-1 pretreatment. 2) When neutrophils were stimulated with FNLPNTL, the addition of mAb NMS-1--after termination of the FNLPNTL-induced response--without delay induced a second transient burst of hydrogen peroxide formation. Persistent activation of hydrogen peroxide formation by mAb NMS-1 in FNLPNTL-stimulated neutrophils was not observed.

Degradation of epoxy polymers: Part 4—Thermal degradation of bisphenol-A diglycidyl ether cured with ethylene diamine

The principal characteristics and products of thermal degradation of a commercial epoxy resin prepared by reaction of 2,2-bis-(4′-hydroxyl phenyl)propane (bisphenol-A) with 1-chloro-2,3-epoxy propane (epichlorhydrin) and cross-linked (cured) with ethylene diamine have been studied. The principal products are small amounts of hydrogen and methane, ethane, propene, ammonia, methylamine with a trace of trimethylamine, water, phenol, cresols, 4-isopropyl phenol, 4-isopropenyl phenol, bisphenol-A, 2-(benzo-fur-5-yl)-2-( p-hydroxy phenyl)propane and 2-(benzo-pyran-6-yl)-2-( p-hydroxy phenyl)propane. These products appear from about 300°C and mechanisms for their formation are proposed.

Rapid detection and presumptive identification of Clostridium difficile by p-cresol production on a selective medium.

A modification of a selective medium for Clostridium difficile is described. The ability of Cl difficile to produce p-cresol from p-hydroxy phenyl acetic acid provides a means for the rapid, sensitive detection and presumptive identification of this species in faecal cultures.

Untersuchung von Kobalt(II)-Komplexen mit N-Arylthioharnstoffen

The complexes of cobalt(II) chloride with o, m, p-tolyl thiourea (I–III); m, p-nitrophenyl thiourea (IV, V); o, m, p-hydroxy phenyl thiourea (VI–VIII); m, p-bromophenyl thiourea (IX, X); p-iodophenyl thiourea (XI) and o-bromo-p-methyl phenyl thiourea (XII) have been synthesised. The elemental analysis reveals that ligands (I–V) form bis and the rest forms tris complexes with cobalt(II). Infrared and farinfrared spectral measurements prove that sulphur is taking part in co-ordination. All complexes are nonelectrolytes in acetone as revealed by conductivity measurements. The data obtained from magnetic susceptibility measurements, electronic spectra in solution are consistant with a practically tetrahedral symmetry.

Low molecular weight organic acids as inhibitors of kinin-forming activity of a rodent tumor acid protease and human plasma kallikrein

Low molecular weight organic acids were studied in vitro against the kinin-forming activity of human plasma kallikrein and an acid protease isolated from the rodent Murphy Sturm lymphosarcoma. Acids studied included β-phenyl-1-lactic, phenyl pyruvic, α-ketoglutaric, hydrocinnamic, α-keto isocaproic, phenyl acetic, 3-indole acetic, 3-indole proprionic, and ϱ-hydroxy phenyl pyruvic. The acids, studied in concentrations ranging from 1×10 −1M to 15×10 −4M were incubated for 60 minutes at 37° with human plasma kallikrein plus human kininogen substrate (in 0.4M tris buffer, pH 7.8) and with the tumor acid protease plus tumor kininogen (in 1.0M acetic acid, pH 4.0). Kinin formed was measured at pH 7.8 by bioassay on the perfused isolated rat uterus. Based on estimates of inhibitory dose 50 (ID 50), phenyl lactic, phenyl pyruvic, p-hydroxy phenyl pyruvic and α-keto isocaproic acids were most effective at concentrations 7.5×10 −3M against the tumor acid protease. Acids most effective against human plasma kallikrein in concentrations ranging from 5.0×10 −3M to 18.5×10 −3M included 3-indole proprionic, p-hydroxy phenyl pyruvic and phenyl pyruvic.