Displaying publications 21 - 40 of 92 in total

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  1. Salimon J, Abdullah BM, Salih N
    Chem Cent J, 2011;5:67.
    PMID: 22044685 DOI: 10.1186/1752-153X-5-67
    Fatty acids (FAs) are important as raw materials for the biotechnology industry. Existing methods of FAs production are based on chemical methods. In this study potassium hydroxide (KOH)-catalyzed reactions were utilized to hydrolysis Jatropha curcas seed oil.
  2. Rizwan K, Zubair M, Rasool N, Mahmood T, Ayub K, Alitheen NB, et al.
    Chem Cent J, 2018 May 04;12(1):49.
    PMID: 29728881 DOI: 10.1186/s13065-018-0404-7
    Thiophene derivatives have shown versatile pharmacological activities. The Suzuki reaction proved a convenient method for C-C bond formations in organic molecules. In the present research work novel derivatives of 2,5-dibromo-3-methylthiophene (3a-k and 3l-p) has been synthesized, via Suzuki coupling reaction in low to moderate yields. A wide range of functional groups were well tolerated in reaction. Density functional theory investigations on all synthesized derivatives (3a-3p) were performed in order to explore the structural properties. The pharmaceutical potential of synthesized compounds was investigated through various bioassays (antioxidant, antibacterial, antiurease activities). The compounds 3l, 3g, 3j, showed excellent antioxidant activity (86.0, 82.0, 81.3%), respectively by scavenging DPPH. Synthesized compounds showed promising antibacterial activity against tested strains. 3b, 3k, 3a, 3d and 3j showed potential antiurease activity with 67.7, 64.2, 58.8, 54.7 and 52.1% inhibition at 50 µg/ml. Results indicated that synthesized molecules could be a potential source of pharmaceutical agents.
  3. Lee SP, Ramli A
    Chem Cent J, 2013;7(1):149.
    PMID: 24011181 DOI: 10.1186/1752-153X-7-149
    Catalytic deoxygenation is a prominent process for production of renewable fuels from vegetable oil. In this work, deoxygenation of technical grade methyl oleate to diesel fuel aliphatic hydrocarbons (C15 - C18) is evaluated with several parameters including temperature, hydrogen pressure and reaction time in a stirred batch reactor over Pd/SBA-15 catalysts.
  4. Ghasemzadeh A, Karbalaii MT, Jaafar HZE, Rahmat A
    Chem Cent J, 2018 Feb 17;12(1):17.
    PMID: 29455357 DOI: 10.1186/s13065-018-0382-9
    BACKGROUND: In the recent years, the health benefits of the pigmented rice varieties have reported due to the presence of bioactive compounds. In this study, the phytochemical constituents (total phenolic, flavonoid and anthocyanin content) and individual phenolics and flavonoids of the extracts of sixteen genotypes of pigmented rice bran were evaluated using spectrophotometric and ultra-high performance liquid chromatography method. Antioxidative properties of the free and bound fractions were evaluated using nitric oxide and 1,1-diphenyl-2-picrylhydrazyl scavenging assays. Extracts were evaluated for antiproliferative activity against breast cancer cell lines (MCF-7 and MDA-MB-231) using the MTT assay.

    RESULTS: Signifficant diferences were observed in the concentrations of phytochemicals and biological activities among different pigmented rice brans. The highest phytochemical content was observed in black rice bran followed by red and brown rice bran. The concentration of free individual flavonoids and phenolic compounds were significantly higher than those of bound compounds except those of ferulic acid and p-coumaric acid. Highest antioxidant activities were observed in black rice bran, followed by red and brown rice bran extracts. Extracts of black rice bran exhibited potent antiproliferative activity, with half maximal inhibitory concentrations (IC50) of 148.6 and 119.2 mg/mL against MCF-7 and MDA-MB-231 cell lines, respectively, compared to the activity of the extracts of red rice bran (175.0 and 151.0 mg/mL, respectively) and brown rice bran (382.3 and 346.1 mg/mL, respectively).

    CONCLUSIONS: Black rice bran contains high levels of phytochemicals, and thus has potent pharmaceutical activity. This highlights opportunities for researcher to breed new genotypes of rice with higher nutritional values, which the food industry can use to develop new products that will compete in expanding functional food markets.

  5. Ghasemzadeh A, Jaafar HZE, Bukhori MFM, Rahmat MH, Rahmat A
    Chem Cent J, 2018 Feb 07;12(1):12.
    PMID: 29417254 DOI: 10.1186/s13065-018-0377-6
    BACKGROUND: Parkia speciosa seeds are a common ingredient in Malay cuisine with traditional interest because of its medicinal importance and content of health-promoting phytochemicals. This study evaluated the phytochemical constituents and biological activities (antioxidant and antibacterial activities) of Parkia speciosa Hassk seeds collected from three different regions of Malaysia (Perak, Negeri Sembilan and Johor). Phytochemical constituents (total flavonoid and total phenolic) were measured using the spectrophotometric method, and individual flavonoids and phenolic acids were identified using ultra-high-performance liquid chromatography. Ferric reducing antioxidant potential (FRAP) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay we used in order to evaluation of antioxidant activities. Disc diffusion method was employed for the evaluation of antibacterial activity of extracts against Gram-positive and Gram-negative bacterial strains.

    RESULTS: The primary screening of phytochemicals showed that P. speciosa seeds contain alkaloids, terpenoids, flavonoids, and phenolics. Samples collected from Perak contained the highest levels of the phytochemical constituents, with highest DPPH and FRAP activity followed by Negeri sembilan and Johor. From the identified compounds, quercetin and gallic acid were identified as the most abundant compounds. Seeds collected from the Perak location exhibited potent antibacterial activity, against both Gram-positive and Gram-negative bacteria strains. Staphylococcus aureus and Bacillus subtilis were recorded as the bacterial strains most sensitive to P. speciosa seed extracts. Correlation analysis showed that flavonoid compounds are responsible for the antioxidant activities of the P. speciosa seeds studied, while antibacterial activity showed a high correlation with the levels of gallic acid.

    CONCLUSIONS: Parkia speciosa seed grown in Perak exhibit the highest concentrations of phytochemicals, as well as the highest biological activity. It may also be recommended for the food industry to use seeds from this area for their products, which are going to compete in the expanding functional food markets.

  6. Yusufzai SK, Osman H, Khan MS, Abd Razik BM, Ezzat MO, Mohamad S, et al.
    Chem Cent J, 2018 Jun 12;12(1):69.
    PMID: 29896651 DOI: 10.1186/s13065-018-0435-0
    A series of novel 4-thiazolidinone inhibitors SKYa-SKYg, containing coumarin as a core structure were synthesized via facile and efficient method. The structures of the synthesized compounds were established by extensive spectroscopic studies (FT IR, 1D NMR, 2D NMR, LC-MS) and elemental analysis. All the synthesized hybrids were further evaluated for their potential as anti-tubercular agents against Mycobacterium tuberculosis H37Rv ATCC 25618, and anti-bacterial agents against Escherichia coli, Enterobacter aerogenes, Salmonella typhi, Streptococcus pneumoniae and Staphylococcus aureus. Interestingly, the hybrids displayed potent bioactivity. However, compounds SKYc, SKYd, and SKYe appeared to be more effective against the tested bacterial strains, among which compound SKYb showed the highest inhibition against all the bacterial strains ranging from 41 to 165 μg/mL, as compared to the standards, streptomycin, kanamycin and vancomycin. Moreover, derivative SKYa was found to be the strongest against M. tuberculosis (83 μg/mL). Additionally, the anti-dengue potential of the coumarin hybrids as two-component NS2B/NS3 DENV flavivirus serine protease inhibitors was calculated using computational molecular docking approach, with reference to the standards 4-hydroxypanduratin, panduratin and ethyl 3-(4-(hydroxymethyl)-2-methoxy-5-nitrophenoxy)propanoate with DS of - 3.379, - 3.189 and - 3.381, respectively. The docking results revealed that the synthesized hybrids exhibited potent anti-dengue activity among which compounds SKYf, SKYd, SKYc and SKYe were found to be the best ones with docking scores of - 4.014, - 3.964, - 3.905 and - 3.889. In summary, we discovered 4-thiazolidinone coumarin derivatives as a new scaffold that may eventually yield useful compounds in the treatment of bacterial and viral infections.
  7. Tahlan S, Ramasamy K, Lim SM, Shah SAA, Mani V, Narasimhan B
    Chem Cent J, 2018 Dec 19;12(1):139.
    PMID: 30569392 DOI: 10.1186/s13065-018-0513-3
    BACKGROUND: The emergence of bacterial resistance is a major public health problem. It is essential to develop and synthesize new therapeutic agents with better activity. The mode of actions of certain newly developed antimicrobial agents, however, exhibited very limited effect in treating life threatening systemic infections. Therefore, the advancement of multi-potent and efficient antimicrobial agents is crucial to overcome the increased multi-drug resistance of bacteria and fungi. Cancer, which remains as one of the primary causes of deaths and is commonly treated by chemotherapeutic agents, is also in need of novel and efficacious agents to treat resistant cases. As such, a sequence of novel substituted benzamides was designed, synthesized and evaluated for their antimicrobial and anticancer activities.

    METHODOLOGY: All synthesized compounds were characterized by IR, NMR, Mass and elemental analysis followed by in vitro antimicrobial studies against Gram-positive (Staphylococcus aureus), Gram-negative (Salmonella typhi and Klebsiella pneumoniae) bacterial and fungal (Candida albicans and Aspergillus niger) strains by the tube dilution method. The in vitro anticancer evaluation was carried out against the human colorectal carcinoma cell line (HCT116), using the Sulforhodamine B assay.

    RESULTS, DISCUSSION AND CONCLUSION: Compound W6 (MICsa, st, kp = 5.19 µM) emerged as a significant antibacterial agent against all tested bacterial strains i.e. Gram-positive (S. aureus), Gram-negative (S. typhi, K. pneumoniae) while compound W1 (MICca, an = 5.08 µM) was most potent against fungal strains (A. niger and C. albicans) and comparable to fluconazole (MIC = 8.16 µM). The anticancer screening demonstrated that compound W17 (IC50 = 4.12 µM) was most potent amongst the synthesized  compounds and also more potent than the standard drug 5-FU (IC50 = 7.69 µM).

  8. Yadav S, Lim SM, Ramasamy K, Vasudevan M, Shah SAA, Mathur A, et al.
    Chem Cent J, 2018 May 26;12(1):66.
    PMID: 29804151 DOI: 10.1186/s13065-018-0432-3
    BACKGROUND: The study describes the synthesis, characterization, in vitro antimicrobial and anticancer evaluation of a series of 2-(1-benzoyl-1H-benzo[d]imidazol-2-ylthio)-N-substituted acetamide derivatives. The synthesized derivatives were also assessed for in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv. The compounds found active in in vitro study were assessed for their in vivo antitubercular activity in mice models and for their inhibitory action on vital mycobacterial enzymes viz, isocitrate lyase, pantothenate synthetase and chorismate mutase.

    RESULTS: Compounds 8, 9 and 11 emerged out as excellent antimicrobial agents in antimicrobial assays when compared to standard antibacterial and antifungal drugs. The results of anticancer activity displayed that majority of the derivatives were less cytotoxic than standard drugs (tamoxifen and 5-fluorouracil) towards MCF7 and HCT116 cell lines. However, compound 2 (IC50 = 0.0047 µM/ml) and compound 10 (IC50 = 0.0058 µM/ml) showed highest cytotoxicity against MCF7 and HCT116 cell lines, respectively. The results of in vivo antitubercular activity revealed that a dose of 1.34 mg/kg was found to be safe for the synthesized compounds. The toxic dose of the compounds was 5.67 mg/kg while lethal dose varied from 1.81 to 3.17 mg/kg body weight of the mice. Compound 18 inhibited all the three mycobacterial enzymes to the highest level in comparison to the other synthesized derivatives but showed lesser inhibition as compared to streptomycin sulphate.

    CONCLUSIONS: A further research on most active synthesized compounds as lead molecules may result in discovery of novel anticancer and antitubercular agents.

  9. Kumar S, Lim SM, Ramasamy K, Mani V, Shah SAA, Narasimhan B
    Chem Cent J, 2018 Jun 25;12(1):73.
    PMID: 29938365 DOI: 10.1186/s13065-018-0440-3
    BACKGROUND: Pyrimidine molecules attracted organic chemists very much due to their biological and chemotherapeutic importance. Their related fused heterocycles are of interest as potential bioactive molecules so, we have designed and prepared a new class of 4,4'-(1,4-phenylene)bis(pyrimidin-2-amine) molecules and screened for their in vitro antibacterial, antifungal and cytotoxicity studies.

    RESULTS: The structures of synthesized bis-pyrimidine molecules were confirmed by physicochemical and spectral means. The synthesized compounds were further evaluated for their in vitro biological potentials i.e. antimicrobial activity using tube dilution method and anticancer activity against human colorectal carcinoma (HCT116) cancer cell line by Sulforhodamine B assay.

    CONCLUSIONS: The biological study demonstrated that compounds s7, s8, s11, s14, s16, s17 and s18 have shown more promising antimicrobial activity with best MIC values than the cefadroxil (antibacterial) and fluconazole (antifungal) and compound s3 found to have better anticancer activity against human colorectal carcinoma (HCT116) cancer cell line.

  10. Kakkar S, Tahlan S, Lim SM, Ramasamy K, Mani V, Shah SAA, et al.
    Chem Cent J, 2018 Aug 12;12(1):92.
    PMID: 30101384 DOI: 10.1186/s13065-018-0459-5
    BACKGROUND: A new series of benzoxazole analogues was synthesized and checked for their in vitro antibacterial, antifungal and anticancer activities.

    RESULTS AND DISCUSSION: The synthesized benzoxazole compounds were confirmed by IR, 1H/13C-NMR, mass and screened for their in vitro antimicrobial activity against Gram-positive bacterium: Bacillus subtilis, four Gram-negative bacteria: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi and two fungal strains: Candida albicans and Aspergillus niger using tube dilution technique and minimum inhibitory concentration (MIC) was noted in µM and compared to ofloxacin and fluconazole. Human colorectal carcinoma (HCT116) cancer cell line was used for the determination of in vitro anticancer activity (IC50 value) by Sulforhodamine B assay using 5-fluorouracil as standard drug.

    CONCLUSION: The performed study indicated that the compounds 1, 10, 13, 16, 19, 20 and 24 had highest antimicrobial activity with MIC values comparable to ofloxacin and fluconazole and compounds 4, 6, 25 and 26 had best anticancer activity in comparison to 5-fluorouracil.

  11. Kashyap S, Kumar S, Ramasamy K, Lim SM, Shah SAA, Om H, et al.
    Chem Cent J, 2018 Nov 20;12(1):117.
    PMID: 30460466 DOI: 10.1186/s13065-018-0487-1
    BACKGROUND: The transition metal complexes formed from Schiff base is regarded as leading molecules in medicinal chemistry. Because of the preparative availability and diversity in the structure of central group, the transition metals are important in coordination chemistry. In the present work, we have designed and prepared Schiff base and its metal complexes (MC1-MC4) and screened them for antimicrobial, anticancer and corrosion inhibitory properties.

    METHODOLOGY: The synthesized metal complexes were characterized by physicochemical and spectral investigation (UV, IR, 1H and 13C-NMR) and were further evaluated for their antimicrobial (tube dilution) and anticancer (SRB assay) activities. In addition, the corrosion inhibition potential was determined by electrochemical impedance spectroscopy (EIS) technique.

    RESULTS AND DISCUSSION: Antimicrobial screening results found complexes (MC1-MC4) to exhibit less antibacterial activity against the tested bacterial species compared to ofloxacin while the complex MC1 exhibited greater antifungal activity than the fluconazole. The anticancer activity results found the synthesized Schiff base and its metal complexes to elicit poor cytotoxic activity than the standard drug (5-fluorouracil) against HCT116 cancer cell line. Metal complex MC2 showed more corrosion inhibition efficiency with high Rct values and low Cdl values.

    CONCLUSION: From the results, we can conclude that complexes MC1 and MC2 may be used as potent antimicrobial and anticorrosion agents, respectively.

  12. Kakkar S, Kumar S, Lim SM, Ramasamy K, Mani V, Shah SAA, et al.
    Chem Cent J, 2018 Dec 04;12(1):130.
    PMID: 30515643 DOI: 10.1186/s13065-018-0499-x
    BACKGROUND: In view of wide range of biological activities of oxazole, a new series of oxazole analogues was synthesized and its chemical structures were confirmed by spectral data (Proton/Carbon-NMR, IR, MS etc.). The synthesized oxazole derivatives were screened for their antimicrobial and antiproliferative activities.

    RESULTS AND DISCUSSION: The antimicrobial activity was performed against selected fungal and bacterial strains using tube dilution method. The antiproliferative potential was evaluated against human colorectal carcinoma (HCT116) and oestrogen- positive human breast carcinoma (MCF7) cancer cell lines using Sulforhodamine B assay and, results were compared to standard drugs, 5-fluorouracil and tamoxifen, respectively.

    CONCLUSION: The performed antimicrobial activity indicated that compounds 3, 5, 6, 8 and 14 showed promising activity against selected microbial species. Antiproliferative screening found compound 14 to be the most potent compound against HCT116 (IC50 = 71.8 µM), whereas Compound 6 was the most potent against MCF7 (IC50 = 74.1 µM). Further, the molecular docking study has been carried to find out the interaction between active oxazole compounds with CDK8 (HCT116) and ER-α (MCF7) proteins indicated that compound 14 and 6 showed good dock score with better potency within the ATP binding pocket and may be used as a lead for rational drug designing of the anticancer molecule.

  13. Kumar S, Lim SM, Ramasamy K, Vasudevan M, Shah SAA, Selvaraj M, et al.
    Chem Cent J, 2017 Sep 18;11(1):89.
    PMID: 29086867 DOI: 10.1186/s13065-017-0322-0
    BACKGROUND: Heterocyclic pyrimidine nucleus, which is an essential base component of the genetic material of deoxyribonucleic acid, demonstrated various biological activities. A series of bis-pyrimidine Schiff bases were synthesized and screened for its antimicrobial and anticancer potentials. The molecular docking study was carried to find the interaction between active molecules with receptor.

    RESULTS: The structures of synthesized bis-pyrimidine Schiff bases were confirmed by spectral studies. The synthesized bis-pyrimidine derivatives were evaluated for their antimicrobial activity (MIC = µmol/mL) against selected Gram positive; Gram negative bacterial and fungal strains by tube dilution method. The anticancer activity (IC50 = µmol/mL) of the synthesized compounds was determined against human colorectal carcinoma (HCT116) cancer cell line by Sulforhodamine B (SRB) assay. Molecular docking studies provided information regarding the binding mode of active bis-pyrimidine Schiff bases with the cyclin-dependent kinase 8 (CDK8) receptor.

    CONCLUSIONS: The antimicrobial screening results indicated that compounds, q1 (MICbs = 0.83 µmol/mL), q16 (MICan = 1.54 µmol/mL and MICec = 0.77 µmol/mL), q1 and q19 (MICca = 0.41 µmol/mL) and q20 (MIC = 0.36 µmol/mL) are the most active ones. Compounds q1 (IC50 = 0.18 µmol/mL) have emerged as potent anticancer molecule against human colorectal carcinoma cancer cell line than the reference drug, 5-fluorouracil. Molecular docking studies indicated that compound q1 (the most active molecule) has the maximum hydrogen bond interaction (four) and π-π stacking (three) network among the bis-pyrimidine Schiff bases. Graphical abstract Graphical illustration of predicted binding mode of bis-pyrimidine Schiff bases in the active site of CDK8. a. Compound 1 (magenta color), b. Compound 5 (green color), c. Compound 8 (red color), d. Compound 13 (split pea color).

  14. Kumar S, Lim SM, Ramasamy K, Vasudevan M, Shah SAA, Narasimhan B
    Chem Cent J, 2017 Aug 08;11(1):80.
    PMID: 29086907 DOI: 10.1186/s13065-017-0312-2
    BACKGROUND: In the past few years, increased resistance of microorganisms towards antimicrobial agents become a serious health problem, so there is a need for the discovery of new antimicrobial agents. On the other hand, bis-pyrimidines possess various types of biological activity. In view of this, in the present study we have designed and synthesized a new series of bis-pyrimidine acetamides by Claisen-Schmidt condensation and screened for its in vitro antimicrobial and anticancer activities.

    RESULTS: The synthesized bis-pyrimidine acetamide derivatives were confirmed by IR, (1)H/(13)C-NMR, Mass spectral studies as well C, H, N analyses. The synthesized compounds were evaluated for their in vitro antimicrobial potential against Gram positive (Staphylococcus aureus and Bacillus subtilis); Gram negative (Escherichia coli, Pseudomonas aeruginosa and Salmonella enterica) bacterial and fungal (Candida albicans and Aspergillus niger) strains by tube dilution technique and the minimum inhibitory concentration (MIC) recorded in µmol/mL was comparable to reference drugs, cefadroxil (antibacterial) and fluconazole (antifungal). The in vitro anticancer activity (IC50 value) determined against human colorectal carcinoma (HCT116) cancer cell line by Sulforhodamine B (SRB) technique and 5-fluorouracil used as reference drug.

    CONCLUSIONS: The biological study demonstrated that compounds 3, 13, 16, 17 and 18 were found to be most active antimicrobial agents with best MIC values than the cefadroxil (antibacterial) and fluconazole (antifungal) and compounds 12, 16 and 18 found to have better anticancer activity against human colorectal carcinoma (HCT116) cancer cell line with best IC50 value than the 5-fluorouracil (anticancer). Graphical abstract SAR of bis-pyrimidine acetamides.

  15. Abdollahi Y, Zakaria A, Aziz RS, Tamili SN, Matori KA, Shahrani NM, et al.
    Chem Cent J, 2013;7:137.
    PMID: 23938168 DOI: 10.1186/1752-153X-7-137
    In fabrication of ZnO-based low voltage varistor, Bi2O3 and TiO2 have been used as former and grain growth enhancer factors respectively. Therefore, the molar ratio of the factors is quit important in the fabrication. In this paper, modeling and optimization of Bi2O3 and TiO2 was carried out by response surface methodology to achieve maximized electrical properties. The fabrication was planned by central composite design using two variables and one response. To obtain actual responses, the design was performed in laboratory by the conventional methods of ceramics fabrication. The actual responses were fitted into a valid second order algebraic polynomial equation. Then the quadratic model was suggested by response surface methodology. The model was validated by analysis of variance which provided several evidences such as high F-value (153.6), very low P-value (<0.0001), adjusted R-squared (0.985) and predicted R-squared (0.947). Moreover, the lack of fit was not significant which means the model was significant.
  16. Azahar NF, Gani SSA, Mohd Mokhtar NF
    Chem Cent J, 2017 Oct 02;11(1):96.
    PMID: 29086882 DOI: 10.1186/s13065-017-0324-y
    This study focused on maximizing the extraction yield of total phenolics and flavonoids from Curcuma Zedoaria leaves as a function of time (80-120 min), temperature (60-80 °C) and ethanol concentration (70-90 v/v%). The data were subjected to response surface methodology (RSM) and the results showed that the polynomial equations for all models were significant, did not show lack of fit, and presented adjusted determination coefficients (R(2)) above 99%, proving their suitability for prediction purposes. Using desirability function, the optimum operating conditions to attain a higher extraction of phenolics and flavonoids was found to be 75 °C, 92 min of extraction time and 90:10 of ethanol concentration ratios. Under these optimal conditions, the experimental values for total phenolics and flavonoids of Curcuma zedoaria leaves were 125.75 ± 0.17 mg of gallic acid equivalents and 6.12 ± 0.23 mg quercetin/g of extract, which closely agreed with the predicted values. Besides, in this study, the leaves from Curcuma zedoaria could be considered to have the strong antioxidative ability and can be used in various cosmeceuticals or medicinal applications.
  17. Jamil DM, Al-Okbi AK, Al-Baghdadi SB, Al-Amiery AA, Kadhim A, Gaaz TS, et al.
    Chem Cent J, 2018 Feb 05;12(1):7.
    PMID: 29404816 DOI: 10.1186/s13065-018-0376-7
    BACKGROUND: Relatively inexpensive, stable Schiff bases, namely 3-((4-hydroxybenzylidene)amino)-2-methylquinazolin-4(3H)-one (BZ3) and 3-((4-(dimethylamino)benzylidene)amino)-2-methylquinazolin-4(3H)-one (BZ4), were employed as highly efficient inhibitors of mild steel corrosion by corrosive acid.

    FINDINGS: The inhibition efficiencies were estimated based on weight loss method. Moreover, scanning electron microscopy was used to investigate the inhibition mechanism. The synthesized Schiff bases were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy and micro-elemental analysis. The inhibition efficiency depends on three factors: the amount of nitrogen in the inhibitor, the inhibitor concentration and the inhibitor molecular weight.

    CONCLUSIONS: Inhibition efficiencies of 96 and 92% were achieved with BZ4 and BZ3, respectively, at the maximum tested concentration. Density functional theory calculations of BZ3 and BZ4 were performed to compare the effects of hydroxyl and N,N-dimethylamino substituents on the inhibition efficiency, providing insight for designing new molecular structures that exhibit enhanced inhibition efficiencies.

  18. Al-Azawi KF, Al-Baghdadi SB, Mohamed AZ, Al-Amiery AA, Abed TK, Mohammed SA, et al.
    Chem Cent J, 2016;10:23.
    PMID: 27134648 DOI: 10.1186/s13065-016-0170-3
    BACKGROUND: The acid corrosion inhibition process of mild steel in 1 M HCl by 4-[(2-amino-1, 3, 4-thiadiazol-5-yl)methoxy]coumarin (ATC), has been investigated using weight loss technique and scanning electron microscopy (SEM). ATC was synthesized, and its chemical structure was elucidated and confirmed using spectroscopic techniques (infrared and nuclear magnetic resonance spectroscopy).

    FINDINGS: The results indicated that inhibition efficiencies were enhanced with an increase in concentration of inhibitor and decreased with a rise in temperature. The adsorption equilibrium constant (K) and standard free energy of adsorption (ΔGads) were calculated. Quantum chemical parameters such as highest occupied molecular orbital energy, lowest unoccupied molecular orbital energy (EHOMO and ELUMO, respectively) and dipole moment (μ) were calculated and discussed. The results showed that the corrosion inhibition efficiency increased with an increase in both the EHOMO and μ values but with a decrease in the ELUMO value.

    CONCLUSIONS: Our research show that the synthesized macromolecule represents an excellent inhibitor for materials in acidic solutions. The efficiency of this macromolecule had maximum inhibition efficiency up to 96 % at 0.5 mM and diminishes with a higher temperature degree, which is revealing of chemical adsorption. An inhibitor molecule were absorbed by metal surface and follow Langmuir isotherms low and establishes an efficient macromolecule inhibitor having excellent inhibitive properties due to entity of S (sulfur) atom, N (nitrogen) atom and O (oxygen) atom.

  19. Ahmad M, Yamin BM, Mat Lazim A
    Chem Cent J, 2013;7:85.
    PMID: 23680098 DOI: 10.1186/1752-153X-7-85
    α-Mangostin was extracted with methanol from the rind of mangosteen fruit and purified by using silica gel column chromatography technique. The compound is characterised using infrared, (13)C and (1)H NMR as well as UV-vis spectroscopy. The α-mangostin dispersion in colloidal systems was studied by incorporating it with an ionic microgel, poly (N-Isopropylacrylamide)-co-2VP at different pH.
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