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61.
Bioassay‐guided Isolation and Antioxidant Activity of Sulfur‐containing Compounds from Clinacanthus nutans 下载免费PDF全文
Hazrulrizawati Abd Hamid Izzah Hayati Yahya Mashitah M. Yusoff Seema Zareen 《中国化学会会志》2016,63(12):1033-1037
Clinacanthus nutans has been used in traditional herbal medicine for cancer prevention, but the specific bioactive compounds responsible for the observed activities have not been explored. Different polar solvents such as methanol, chloroform, ethyl acetate, and hexane were used for the extraction. The extracts, fractions, and isolated compounds were subjected to DPPH and ferric reducing antioxidant potential (FRAP) assays. Methanol extracts show significant free‐radical scavenging activity of 69.09% in DPPH and 56.49% FRAP. Purification of MeOH extracts afforded the fraction FB28 and two new sulfur‐containing compounds, named clinamide D and E ( 1 , 2 ). Compound ( 1 ) proved to be more active with an IC50 value for DPPH radical scavenging of 118.27 ± 0.01 µg/mL and reduction of Fe3+–TPTZ complex of 386.24 ± 0.02, higher than that of the standard ascorbic acid. Sulfur‐containing compounds isolated from C. nutans is a potential natural antioxidant. 相似文献
62.
K.J. Oyewumi B.J. Falaye C.A. Onate O.J. Oluwadare W.A. Yahya 《Molecular physics》2014,112(1):127-141
With the introduction of a new improved approximation scheme (Pekeris-type approximation) to deal with the centrifugal term, the energy eigenvalues and the wave functions of the Schrödinger equation of the shifted Deng–Fan molecular potential are obtained, via the asymptotic iteration method. Rotational–vibrational energy eigenvalues of some diatomic molecules are presented, these results are in good agreement with other results in the literature. For these selected diatomic molecules, energy eigenvalues obtained are in much better agreement with the results obtained from the rotating Morse potential model for moderate values of rotational and vibrational quantum numbers. Furthermore, thermodynamic properties such as the vibrational mean U, specific heat C, free energy F and entropy S for the pure vibrational state in the classical limit for these energy eigenvalues are studied. 相似文献
63.
Wajid Hussain Muhammad Shahid Iqbal Hui Li Muhammad Sulaman Honglian Guo Chuanbo Li Yahya Sandali Ahmad Irfan Hafiz Saqib Ali 《International journal of quantum chemistry》2024,124(1):e27223
Perylene diimide (PDI) and naphthalene diimides (NDIs) are compounds widely used in supramolecular structures due to their versatile and functional properties. They have high absorptions and photoluminescence capabilities, which make them ideal for electronic transition studies. Reflux method, a widely employed synthetic technique, was utilized to synthesize NDI and PDI derivatives. In this method, the respective amino acids and NTDA (naphthalene-1,4,5,8-tetracarboxylic dianhydride) were combined in acetic acid and the resulting mixture was subjected to reflux. This study centered on a diverse set of NDI and PDI ligands, comprising L-ala-NDI, B-ala-NDI, Gly-NDI, Imi-NDI, Pyr-NDI, L-ala-PDI, B-ala-PDI, Gly-PDI, Imi-PDI, and Pyr-PDI ligands. Crystal structures were obtained for three NDI ligands, while the characterization of all ligands involved several analytical techniques such as NMR, IR, UV, DFT, TD-DFT calculations, and single-crystal x-ray crystallography specifically for the NDI ligands. The investigation focused on studying the electron acceptor/donor behavior of the NDI and PDI ligands, identifying their potential for charge transfer applications. Furthermore, the NLO (nonlinear optical) response of all 10 NDI and PDI ligands was assessed through an analysis involving HOMO-LUMO, TDM, EDDM, NCI, Iso-surface, MEP, natural population, and DOS analysis. This evaluation encompassed the examination of linear polarizability, as well as first and second hyperpolarizability in the context of NLO. The findings of the study revealed that Gly-PDI, Imi-PDI, L-ala-PDI, and B-ala-PDI ligands displayed a higher NLO response compared with the other ligands. These results highlight the potential of these ligands for nonlinear optical applications. The comprehensive characterization and assessment of the NDI and PDI ligands contribute to a deeper understanding of their electron properties, positioning them as promising candidates for charge transfer and nonlinear optical materials. 相似文献
64.
Yahya ZAMANI Mehdi BAKAVOLI Mohamad RAHIMIZADEH Ali MOHAJERI Seyed Mohamad SEYEDI 《催化学报》2012,(7):1119-1124
Effect of promoters such as Barium and Lanthanum has been investigated on the conventional nanostructured iron catalyst in Fischer-Tropsch synthesis (FTS). The nanosized iron-based catalysts were prepared by a microemulsion method with the general formulation of 100Fe/4Cu, 100Fe/4Cu/2La, 100Fe/4Cu/ 1La/1Ba, and 100Fe/4Cu/2Ba. The phase, structure, and morphology of the catalysts were characterized by X-ray diffraction, N2 adsorption, transmission electron microscopy, temperature-programmed desorption of CO2, and temperature- programmed reduction. The results indicated that the addition of promoters could improve the activity of Fe catalysts for FTS and WGS (water-gas shift reaction) and lower the gas fraction at the outlet. In addition, both Ba- and La-promoted Fe catalysts exhibit the highest activity due to the synergetic effect. 相似文献
65.
Ternary tellurite glasses with the chemical formula 80TeO2–(2 ? x)ZnO–xFe2O3 (x = 0–15 mol%) have been prepared by the melt-quenching method. Elastic and structural properties of the glasses were investigated by measuring both longitudinal and shear velocities using the pulse-echo overlap method at 5 MHz and Fourier transform infrared (FTIR) spectroscopy, respectively. Both longitudinal and shear velocity showed a large increase of 3.40% and 4.68%, respectively, at x = 5 mol% before a smaller increase for x > 5 mol%. Interestingly, longitudinal modulus (L), shear modulus (G), bulk modulus (K) and Young's modulus (E) recorded similar trends with increase in Fe2O3. The initial large increases in shear and longitudinal velocity and related elastic moduli observed at x = 5 mol% are suggested to be due to structural modification which enhances rigidity of the glass network. FTIR analysis showed increase in bridging oxygen (BO) as indicated by the relative intensity of the TeO4 assigned peaks and increase in intensity of the FeO6 assigned peak (~ 451 cm? 1) which indicates that Fe acts as a modifier in the glass network. The increase in rigidity of the glass system is suggested to be due to the increase of BO together with the formation of strong covalent FeO bond. Quantitative analysis based on the bulk compression and ring deformation models showed that the kbc/kexp value decreased gradually from 2.41 (x = 0 mol%) to 2.02 (x = 15 mol%) which infers that the glass system became a relatively more open 3D network as Fe2O3 was increased. 相似文献
66.
Rahim Hekmatshoar Issa Yavari Yahya S. Beheshtiha Majid M. Heravi 《Monatshefte für Chemie / Chemical Monthly》2001,132(6):689-691
Summary. In the presence of metallic zinc, aldehydes and ketones experience reductive coupling in tetrahydrofuran-saturated aqueous
ammonium chloride (5:3) to afford the corresponding pinacols in moderate to high yields.
Received October 23, 2000. Accepted (revised) December 12, 2000 相似文献
67.
With collaborative purchasing programmes where one of the aims is to develop suppliers, vendor rating is important not only in supplier selection and in deciding how to allocate business but also to determine where scarce development effort is best applied. This paper describes a case study into vendor rating for a government sponsored Entrepreneur Development programme in Malaysia. The paper reviews current methods for vendor rating and finds them wanting. It illustrates a new approach based on the use of Saaty's Analytic Hierarchy process method, which was developed to assist in multi-criteria decision problems. The new method overcomes the difficulties associated with the categorical and simple linear weighted average criteria ranking methods. It provides a more systematic way of deriving the weights to be used and for scoring the performance of vendors. 相似文献
68.
Hemalatha Murugaiah Chow Lun Teh Kai Chew Loh Ahmad Ramli Mohamad Yahya Nur Asshifa Md Noh Noor Hana Hanif Abu Bakar Daruliza Kernain Rokiah Hashim Yazmin Bustami 《Molecules (Basel, Switzerland)》2021,26(21)
Here, we report the extracellular biosynthesis of silver nanoparticles (AgNPs) and determination of their antibacterial and anticancer properties. We also explore the efficacy of bioAgNPs incorporated in cellulose nanocrystals (CNCs) and alginate (Alg) for the formation of an antibacterial hydrogel film. Streptomyces sp. PBD-311B was used for the biosynthesis of AgNPs. The synthesized bioAgNPs were characterized using UV-Vis spectroscopy, TEM, XRD, and FTIR analysis. Then, the bioAgNPs’ antibacterial and anticancer properties were determined using TEMA and cytotoxicity analysis. To form the antibacterial hydrogel film, bioAgNPs were mixed with a CNC and Alg solution and further characterized using FTIR analysis and a disc diffusion test. The average size of the synthesized bioAgNPs is around 69 ± 2 nm with a spherical shape. XRD analysis confirmed the formation of silver nanocrystals. FTIR analysis showed the presence of protein capping at the bioAgNP surface and could be attributed to the extracellular protein binding to bioAgNPs. The MIC value of bioAgNPs against P. aeruginosa USM-AR2 and MRSA was 6.25 mg/mL and 3.13 mg/mL, respectively. In addition, the bioAgNPs displayed cytotoxicity effects against cancer cells (DBTRG-0.5MG and MCF-7) and showed minimal effects against normal cells (SVG-p12 and MCF-10A), conferring selective toxicity. Interestingly, the bioAgNPs still exhibited inhibition activity when incorporated into CNC/Alg, which implies that the hydrogel film has antibacterial properties. It was also found that bioAgNP-CNC/Alg displayed a minimal or slow release of bioAgNPs owing to the intermolecular interaction and the hydrogel’s properties. Overall, bioAgNP-CNC/Alg is a promising antibacterial hydrogel film that showed inhibition against the pathogenic bacteria P. aeruginosa and MRSA and its application can be further evaluated for the inhibition of cancer cells. It showed benefits for surgical resection of a tumor to avoid post-operative wound infection and tumor recurrence at the surgical site. 相似文献
69.
Increasing production of cocoa (Theobroma cacao L.) leads to a higher environmental burden due to its solid waste generation. Cocoa pod husk, one of the major solid wastes of cocoa production, contains rich bioactive compounds unveiling its valorization potential. With that in mind, our research aimed to explore the biological and antioxidant activities of aqueous extracts from cocoa pod husks. In this present work, cocoa pod husk was extracted using water and subsequentially partitioned using n-hexane, ethyl acetate, and methanol. The antimicrobial investigation revealed that the ethyl acetate solubles were active against the Staphylococcus aureus, Escherichia coli, and Candida albicans, where at a 20% w/v concentration, the inhibition diameters were 6.62 ± 0.10, 6.52 ± 0.02, and 11.72 ± 0.36 mm, respectively. The extracts were found non-toxic proven by brine shrimp lethality tests against Artemia salina with LC50 scores ranging from 74.1 to 19,054.6 μg/mL. The total phenolic content and total flavonoid content were obtained in the range of 47.44 to 570.44 mg/g GAE and 1.96 to 4.34 mg/g QE, respectively. Antioxidant activities of the obtained extracts were revealed by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assay with EC50 reached as low as 9.61 μg/mL by the ethyl acetate soluble. Phytochemical screening based on gas chromatography—mass spectroscopy analysis on the sample with the highest antioxidant activities revealed the dominant presence of three phytosterols, namely gamma-sitosterol, stigmasterol, and campesterol. 相似文献
70.
Gholami Aysan Ajabshirchi Yahya Ranjbar Seyed Faramarz 《Journal of Thermal Analysis and Calorimetry》2019,138(2):1395-1403
Journal of Thermal Analysis and Calorimetry - In this study, thermo-economic optimization of single-pass SAHs (solar air heaters) with obstacles of arcuate shape has been carried out. The research... 相似文献