Asian Journal of Chemistry

1413-1418

Authors: Anisur R. Molla1, and Pritha Mandal2,*,

Correctly folded proteins play key role in all biological reactions. Folding of protein into its native structure is the most astonishing example of biological self-assembly. Gene mutation, translational or transcriptional error, failure of chaperon mechanism results in misfolded protein structure. Misfolded proteins are responsible for a number of human diseases namely Alzheimer’s disease or Parkinson’s disease. Research for finding therapeutic breakthrough against these ailments has invoked different strategies.

1429-1433

Authors: Shalinder Kaur1, Sangeeta Sharma2,* and Niraj Bala3

In this study, hydroxyapatite (HAP) coating was deposited on substrate of stainless steel alloy by biomimetic deposition and plasma spray technique. The corrosion resistance of plasma sprayed and biomimetic coating was compared with the help of electrochemical corrosion testing with respect to uncoated samples. The surface morphologies of the coatings were studied through scanning electron microscopy and energy-dispersive X-ray spectroscopy techniques. Analysis of the microstructure/ composition and phase formation has also been done before and after corrosion testing respectively. The deposition of hydroxyapatite using both the techniques, i.e. plasma spray technique and biomimetic deposition lead to enhancement in corrosion resistance. From electrochemical corrosion testing, it was confirmed that biomimetic coated hydroxyapatite samples are more corrosion resistant in comparison to as-sprayed plasma spray coated samples and hence found to be better technique as compared to plasma spray technique.

1441-1446

Authors: Tran Dinh Manh1,*, Le Thi Them2,*, Duy Chinh Nguyen3, Hieu Vu-Quang3 and Le Si Ngoc4

The objective of the present study was to optimize flavonoids extraction process from red-top leaves following the Soxhlet method, which is capable of producing the highest flavonoid yield and assess antioxidant and Aspergillus niger antifungal activity of the extract. Besides, this research aims to establish a foundation for the use of these flavonoids instead of synthetic compounds as natural antioxidant for postharvest spoilage management of agricultural products. Optimization of flavonoids extraction process was conducted using response surface methodology with a central composite design. Included extraction factors in RSM are: 70-90 % ethanol solvent concentration; 30-70 v/w solvent/material ratio; 60-80 °C temperature and 30-90 min time. Antioxidant activity of the extract was assessed based on measurements of reducing power and 1.1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activities. Then, Aspergillus niger antifungal activity of the extract was also assessed. The highest flavonoids content was at 6.96 % at following optimal extract conditions: 90 % ethanol concentration; ratio of solvent/material of 70 v/w; extraction temperature and time are 80 °C and 30 min, respectively. Antioxidant and Aspergillus niger antifungal activity of the flavonoids extract were higher than those of ascorbic acid (used as a standard). The highest reducing power was 1.0914 μg/mL obtained at 140 μL of the highest flavonoids contents treatment from extract process (compared with 0.6832 μg/mL ascorbic acid at same conditions) and 76.6 % DPPH activities (ascorbic acid 62.81 %). From this the highest flavonoids contents treatment, at 4.8 % flavonoids extract concentration (MIC = 4.8 %) for Aspegillus niger antifungal activity was 100 % (fungi without development or completely inhibited). Therefore, the flavonoids have been recommended for development of bio-compounds used in postharvest storage and medicine.

1454-1456

Authors: D. Suneetha, P. Shyamala,* and SK. Ameer Khan

A simple and new mixed-micelle cloud point extraction procedure has been developed for the extraction of Meldola′s blue dye. A mixed micelle consists of Triton X-114 and docusate sodium salt at a pH of 4.5 in the presence of Na2SO4. The various parameters show effect on extraction of dye like pH, concentration of Triton X-114, concentration of docusate sodium salt, concentration of Na2SO4, equilibrium temperature and equilibrium time were optimized. Under optimum conditions the linear range of dye Meldola′s blue was found to be 0.0-11.17 μg mL-1. The corresponding detection limit was found to be 0.00311 μg mL-1. The proposed method has been successfully applied to the extraction of Meldola′s blue dye in tap water and sea water. The recoveries were found to be in the range of 85.79-93.13 %.

1461-1464

Authors: Yogesh J. Sanghani,*, , Suresh B. Koradiya and Anilkumar S. Patel

A series of novel 4-(4-amino phenyl) morpholine-3-one substituted coumarin derivatives have been prepared by chloramine coupling reaction and were identified. The novel synthetic route involves nucleophilic substitution reaction of 4-chloro-3-nitro-2H-chromene-2-one with 4-(4-amino phenyl)morpholine-3-one. Due to the presence of nitro group in coumarin derivatives make substitution reaction easy and convenient at low temperature. Using DMF as solvent and K2CO3 as base various substituted 4-(4-((3-nitro-2-oxo-2H-chromen-4-yl)amino)phenyl)morpholine-3-one derivatives (YS-1 to YS-10) can be obtain in good yield and high purity. Structural characterization of all synthesized compound was done by NMR, Mass and IR spectra

1470-1472

Authors: Avidha Kulshrestha, , Jaya Pandey,*, and Deepa Panhekar

A condensation reaction of resorcinol, malononitrile and benzaldehyde in presence of sodium carbonate at room temperature on vigorous stirring gives 2-amino-7-hydroxy-4-phenyl-4H-1-benzopyran-3- carbonitrile which on alkylation in presence of dry potassium carbonate in dry acetone at 70-80 ºC with 1,2-chloroethyl pyrrolidine, 1,2-chloroethyl piperidine, 1,2-chloroethyl morpholine gives corresponding novel compounds.

1476-1480

Authors: Bal Krishan Vermani, Vivek Pathania,*, Shashi Kiran Vermani and Shrutila Sharma

Molar conductance values of a large number of copper(I) perchlorate complexes behaving as strong 1:1 electrolytes, have been measured in binary mixtures of dimethylsulfoxide with dimethylacetamide and dimethylformamide at 298 K. The measured conductance data have been analyzed to obtain the limiting molar conductance (Λo) of these electrolytes. The limiting ion conductances (λ±°) for various ions in the binary mixtures of DMSO with DMA and DMF have been calculated by an indirect method using [Bu4N]BPh4 as a reference electrolyte. The actual ionic radii (ri) values for these copper(I) complex ions increase significantly with increase in DMA composition whereas the corresponding ri values for these ions do not show a significant increase with increase in DMF composition that indicates no preferential solvation of copper(I) complex ions for DMF over DMSO, thus showing that DMA solvates the copper(I) complex ions more strongly than DMF.

1489-1494

Authors: Sumeet Kaur Bhatia, Varsha Samdhian and Balbir Kaur*

This article is aimed at the synthesis of new bis-dihydropyrimidines using solid-support. The reactions were carried out using microwave energy. Presented protocol is associated with higher yields of desired products, easier work-up conditions, less reaction times, higher reproducibility and maximum efficiency of method in comparison to conventional heating. The structures of prepared moieties were confirmed by spectroscopic techniques. Further, these bis-heterocycles were also examined for their biological behaviours. Agar well diffusion method was used to carry out in-vitro antimicrobial evaluations. Compound 6j came forward as most active antibacterial and 6b proved itself to be the most potent antifungal agent.

1501-1508

Authors: Surabhi Sagar and Arshi Rastogi*

The adsorption of an acidic dye methyl orange onto the dead blue green algal biomass, Oscillatoria species was investigated in a batch mode with respect to contact time, adsorbent dose, pH and temperature. The functional groups and the surface morphology of Oscillatoria species was analyzed by Fourier transform infrared spectroscopy and scanning electron microscopy. Equilibrium isotherms were analyzed by Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin adsorption models out of which, Langmuir isotherm model was found to be the best fit and exhibited a maximum adsorption capacity of 98.03 mg/g under the optimized conditions. The pseudo-first order, pseudo-second order and intraparticle diffusion models were used to describe the kinetic data and the rate constants at different concentrations were evaluated. Kinetics of adsorption was found to follow the pseudo-second order rate equation. The thermodynamic parameters, such as the changes in enthalpy, entropy and Gibbs free energy showed that the adsorption is endothermic, random and spontaneous at high temperature.The adsorbent could be regenerated using 0.1 mol/L HCl solutions, with upto 75 % recovery. The results indicate that Oscillatoria species could be fruitfully employed as effective biomaterial for the removal of dyes from effluents.

1514-1518

Authors: Santhosh Guduru, V.V.S.R.N. Anji Karun Mutha, B. Vijayabhaskar, Muralidharan Kaliyaperuma, Prabhakar S. Achanta, Sreenivasa Reddy Anugu, Bharath Komandla, Raghu Babu Korupolu, Kishore Babu Bonige and Chidananda Swamy Rumalla,*

Finasteride is a 5-α-reductase inhibitor with a steroidal skeleton and an amide group in its structure. It was subjected to forced degradation to observe its stability under stress conditions according to ICH guidelines. It was found to be stable to base and peroxide. However, in acid medium, three degradation products were observed. All of them were isolated from the reaction mixture by preparative HPLC. Their structures were elucidated by extensive analysis of 1D, 2D NMR spectra and HRMS. To best of our knowledge, none of them have been reported elsewhere.

1527-1531

Authors: Rajesh Kumar Sharma* and V. Ilamathi

Preparation of glasses of xV2O5-(100-x) B2O3 (21 ≤ x ≤ 41) system for x = 21, 31, 41 mol % have been performed using sol-gel process and studied by employing XRD, FT-IR, EPR and UV-visible techniques. The glassy phase was established by powder XRD patterns. Fourier transform infrared red studies of the amorphous samples revealed the appearance of triangular [BO3/2] and tetrahedral [BO4/2] and V = O units. X-band powder EPR studies exhibit partially resolved isotropic lines at 300 K and well resolved hyperfine structure having a 16 line features (8 parallel lines and 8 perpendicular lines) at 77 K. The assignment of EPR parameters, gxx = gyy = g⊥ > gzz = g|| and Azz = A|| > Axx = Ayy = A⊥ is consistent with ground state 2B2 which confirms that the tetravalent vanadium (3d1) exists in the glass matrix as vanadyl ion in tetragonally distorted compressed octahedral symmetry having C4v symmetry. UV-visible absorption spectra of glasses exhibit characteristic two ligand field d-d bands in the tetragonal fields of VO2+ ions. Using EPR parameters and UV-visible data, various molecular orbital bonding parameters were ascertained.

1539-1545

Authors: C. Vanitha, S.V. Satyanarayana and K. Bhaskar Reddy,*

The present work focused on QbD driven approach for the development, optimization of stability indicating method for glecaprevir and pibrentasvir in bulk drug and its degradation products. The chromatographic separation was performed on Hypersil C8 (150 mm × 4.6, 5 μ) with a flow rate of 1 mL/min at 260 nm. The mobile phase employed was sodium phosphate monobasic and monohydric buffer and acetonitrile (65:35) having pH of 4.2 at 30 °C of column temperature. The degradation studies were carried out for glecaprevir and pibrentasvir under the stress condition hydrolysis (acid, base and neutral), oxidation, photolytic and thermal as per ICH guidelines. In alkali degradation chromatogram, more number of degradant peaks was appeared along with the risk factor, selectivity of the method. The selectivity of the method was established by resolving the resolution of degradant peaks and retention time of drugs by the application of design of experiment. The interaction effect of factors of pH mobile phase, column temperature and % mobile phase were studied through response surface method (RSM) and central composite design (CCD). The optimized selective method was established for the detection of glecaprevir and pibrentasvir along with degradant peaks by optimized conditions were proposed by the model. Then the optimized method was validated for the parameters like linearity, accuracy, precision and robustness as per ICH guidelines

1549-1554

Authors: C. Sridevi, S. Sathishkumar, P. Karthikeyan and P. Maheswaran,*

In present work, samarium/europium substituted hydroxyapatite (Sm/Eu-HAP) coating on 316L stainless steel has been carried out by electrodeposition method. The surface characteristics of the developed coating were assessed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), High resolution scanning electron microscopy (HRSEM) and energy dispersive X-ray analysis. The special effects of Sm/Eu-HAP coating on anticorrosion behaviour of 316L stainless steel were also studied using electrochemical analysis in the Ringers solution. The antibacterial activity and in vitro live/dead assay of Sm/Eu-HAP coating were investigated. As a result of these examinations, revealed that Sm/Eu-HAP coating on 316L stainless steel enhanced the corrosion resistance performance and significantly improved the bioactivity. Thus, Sm/Eu-HAP coating can play an important role in biomedical applications.

1558-1564

Authors: Aisha M. Turkustani *, Nehad M. Gumgumji and Abdulrahman S. Al Hajar

Corrosion is one of the serious problems in industry, specially acidic corrosion which is caused by acidic solutions which are widely used in acid cleaning, acid pickling and acid descaling. Mild steel (MS) is widely used in the the industrial field is vulnerable to be corroded by the acidic solution. In the industrial media, corrosion processes are responsible for the loss of metals. There are various methods to mitigation the degradation or destruction of metal surface. Using inhibitors is one of the most potent methods in control of corrosion is due to its low cost and eases of application and practice. As the concern is focused on the safety of any industrial process in health and environment, the use of organic plants as corrosion inhibitors is in the forefront in the current trend of corrosion inhibition studies. In the last decades the need of novel corrosion inhibitor compounds has become more and more stringent. In this study, the efficiency of the bark of Olea europaea subsp. Cuspidata as corrosion inhibitor for mild steel in 1.0 M sulphuric acid was studied by electrochemical measurements [potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS)]. The results showed that Olea europaea subsp. Cuspidate wood tar oil acts as a potent corrosion inhibitor and the performance of the inhibitor varied with concentrations for mild steel in 1.0 M H2SO4 + 10 % EtOH. The maximum inhibition (%) was 94.97 %, the results were supported by different techniques used. Electrochemical analysis indicated that Olea europaea subsp. Cuspidata wood oil tar extract acts as mixed mainly cathodic inhibitor. Also, surface analysis the scanning electron microscope (SEM) was carried out to determine the corrosion inhibition property of Olea europaea subsp. Cuspidata wood tar oil in (1.0 M H2SO4 + 10 % EtOH) solution. The adsorption of the wood tar extract on mild steel surface followed Langmuir isotherm.

1569-1573

Authors: S. Mahdjar*, , H. Dendougui and M. Hadjadj

Anvillea garcinii subsp. radiata (Coss. & Dur.) are an endemic species of Sahara region especially in Morocco and Algeria. This plant is widely used in traditional medicine. The extraction of phenolic compounds from A. radiata flowers is carried out using solvents of different polarity (chloroform, ethyl acetate, butanol). The yields of extraction from the flowers were 19.34, 0.278, 0.149, 1.750 and 3.308 % for the crude, chloroform, ethyl acetate, butanol and aqueous extracts, respectively. The amount of total phenolics, flavonoids, tannins and in vitro antioxidant and antibacterial properties of extracts of A. radiata flowers. The antioxidant activities were evaluated by measuring the ability of the extracts to scavenge the DPPH, ferric reducing power FRAP and phosphomolybdenum assay. The maximum extractable total phenolics and flavonoids were recorded in ethyl acetate fraction, while the tannins were present in chloroform fraction. Among the five extracts of A. radiata flowers, the maximum DPPH free radical scavenging activity was shown in ethyl acetate and butanol fractions (IC50 = 0.20 ± 0.001 and 0.31 ± 0.004 mg/mL, respectively). The highest activity of FRAP assay and phosphomolybdenum reduction was observed in butanol fraction (358.58 ± 12.55 and 95.09 ± 0.67 mM, respectively). The results were compared with natural and synthetic antioxidants. In antibacterial properties, the chloroform extract has the highest activity. These results implied that these plant extracts may possess health promoting effects and might be potential sources of potent natural antioxidant and antimicrobial.

1581-1584

Authors: Sadaf Zaidi* and Mridula Saxena

A novel, solvent free and high yielding method was accomplished for one-pot synthesis of dithiocarbazates by the reaction of various alkyl halides (primary, secondary and tertiary) with variety of substituted hydrazines using Triton-B (benzyl-trimethylammonium hydroxide) and carbon di sulphide. This new method of synthesizing dithiocarbazates involves mild conditions, simple procedures and high yields of the products as compared to previously used methods

1591-1594

Authors: K. Ravi Kumar, SK. Ameer Khan and P. Shyamala*

A new cloud point extraction (CPE) procedure with spectrophotometry for the pre-concentration and determination of iron(II) has been developed. In this method, Fe2+ was complexed with 1,10-phenanthroline at a pH of 4.2. Fe2+-1,10-phenanthroline complex was then extracted into mixed micelles of Triton X–114 (TX–114) and docusate sodium salt (DOSS). Various parameters such as pH, concentration of 1,10-phenanthroline, concentrations of the surfactants (TX–114 and DOSS), concentration of salt (Na2SO4), equilibration temperature and equilibration time were optimized. Under optimum conditions the linear range of Fe2+ was found to be 0.14-2.23 μg mL–1. The corresponding detection limit was found to be 5.1 ng mL–1. The proposed method has been successfully applied to the determination of Fe2+ in tap water and sea water samples. The recoveries were found to be in the range of 80-95 % and the effect of sodium nitroprusside on the recovery was studied.

1599-1602

Authors: R. Tiwari , S.S. Mal*, and S. Dutta*,

In present work, Keggin-type commercial heteropoly acids have been employed as efficient solid acid catalysts in the acetalization of biomass-derived furfural with ethylene glycol. The reaction was optimized on parameters such as the type and loading of catalyst, duration of reaction and the relative ratio of reagents. The reaction was scaled up and the cyclic acetal 2-(furan-2-yl)-1,3-dioxolane was isolated in 92 % yield within 4 h using only 2 wt % of phosphotungstic acid in refluxing benzene

1609-1616

Authors: Aziza Mnasri1, A. Chakchouk-Mtibaa2, Abdullah Sulaiman Al-Ayed3, Mosbah Jemmali3, L. Mellouli2, Hallouma Bilel1,4 and Naceur Hamdi1,3,*

A simple, green, efficient and economical procedure for the synthesis of, 2-amino-6-(4-hydroxy-2- oxo-chromen-3-yl)-4-(aryl) nicotine nitrile (4a-g) by two routes carried in same conditions, have been reported. The new compounds 4a-g were characterized by 1H NMR, 13C NMR, FT-IR and elemental analysis. The synthesized compounds were screened for their antibacterial activities against Gram-positive bacterial strains (Micrococcus luteus LB14110, Staphylococcus aureus ATCC 6538, Listeria monocytogenes ATCC 19117), Gram-negative bacteria (Escherichia coli, Salmonella typhimurium ATCC 14028 and Pseudomonas aeruginosa). The coumarin derivative 4a and 3-acetyl- 4-hydroxycouamrin (1) were the most active against two bacteria Staphylococcus aureus ATCC 6538 and Candida albicans respectively. The best minimum inhibitory concentration values were obtained for the compound 4a against Candida albicans (0.0195 g/cm3). In addition, compounds 4a-g were investigated for their antioxidant activities by DPPH (2,2-diphenyl-1-picrylhydrazyl) in which most of them displayed significant antioxidant activities.

1626-1628

Authors: Consolacion Y. Ragasa *, Maria Carmen S. Tan, Virgilio C. Linis and Chien-Chang Shen

Chemical investigation of dichloromethane extract of moss Macromitrium orthostichum Nees ex Schwägr. has led to the isolation of zeorin (1), atranorin (2) and a mixture of β-sitosterol (3) and stigmasterol (4) in about 1:1 ratio. The structure of compound 1 was elucidated by extensive 1D and 2D NMR spectroscopy, while compounds 2-4 were identified by comparison of their NMR data with literature data.

1636-1638

Authors: Neha Singh* and Richa Khare*

A facile and novel method to synthesize isothiocyanides from cyclic and acyclic amines and carbon disulphide in DMSO with Triton-B as catalyst in non-aqueous medium is being reported. The method is less tedious and offers excellent yields. The structures have been elucidated by 1H NMR, 13C NMR and mass spectroscopy