Shafida Abd Hamid

Biodiesel production via transesterification of palm olein using waste mud crab (Scylla serrata) shell as a heterogeneous catalyst.

A recent rise in crab aquaculture activities has intensified the generation of waste shells. In the present study, the waste shells were utilized as a source of calcium oxide to transesterify palm olein into methyl esters (biodiesel). Characterization results revealed that the main component of the shell is calcium carbonate which transformed into calcium oxide when activated above 700 degrees C for 2 h. Parametric studies have been investigated and optimal conditions were found to be methanol/oil mass ratio, 0.5:1; catalyst amount, 5 wt.%; reaction temperature, 65 degrees C; and a stirring rate of 500 rpm. The waste catalyst performs equally well as laboratory CaO, thus creating another low-cost catalyst source for producing biodiesel. Reusability results confirmed that the prepared catalyst is able to be reemployed up to 11 times. Statistical analysis has been performed using a Central Composite Design to evaluate the contribution and performance of the parameters on biodiesel purity.

Synthesis and mesomorphic properties of 7‐acyloxy‐3‐(4‐acyloxyphenyl)‐4H‐1‐benzopyran‐4‐one

A new homologous series of 7‐acyloxy‐3‐(4‐acyloxyphenyl)‐4H‐1‐benzopyran‐4‐ones was synthesized and characterized by elemental analysis and spectroscopic techniques along with thermal behaviour study using differential scanning calorimetry. Texture observation was performed under the polarizing optical microscope from which the derivatives were found to exhibit different molecular organizations as exemplified by various mesophases. Whilst the compounds containing butanoyloxy and hexanoyloxy groups behave as nematogens, the other compounds with heptanoyloxy and longer side chains show a SmC phase. The octadecanoyloxy derivative was the only member showing a monotropic SmC phase. The difference in phase behaviour is discussed based on the molecular structure and the presence of a lateral dipole which can be associated with the intermolecular interaction within the mesophase.

Possible origin of electronic effects in Rh(I)-catalyzed enantioselective hydrogenation

Reducing the electron density of ligands switches the regioselectivity of Rh(I)-catalyzed hydrometalation. A reversal of the sense of chiral induction was also observed when chiral ligands are electronically tuned in the same manner. The combined data provide an alternative rationale for the electronic effects often observed in asymmetric hydrogenation.

Acid corrosion inhibition of copper by mangrove tannin

Purpose – The purpose of this paper is to evaluate the corrosion inhibition potential of mangrove (Rhizopora apiculata) tannin in hydrochloric acid medium on copper with the view of developing a natural corrosion inhibitor.Design/methodology/approach – The mangrove tannin was extracted from the mangrove bark and its anticorrosion potential was studied by weight loss, electrochemical and scanning electron microscopy (SEM) analysis.Findings – It has been found that the mangrove tannin effectively inhibits the corrosion on copper metal in hydrochloric acid solution. The results of the electrochemical and weight loss methods showed that the inhibition efficiency of mangrove tannin increases with increasing its concentration. Inhibition is achieved through the adsorption of tannin molecules onto the copper surface and the adsorption follows the Langmuir adsorption isotherm model. SEM study also supports the adsorption of the inhibitor molecules onto the copper surface.Originality/value – In this paper, mangrov...

Applications of calixarenes in cancer chemotherapy: facts and perspectives

Research on the therapeutic applications of calixarene derivatives is an emerging area of interest. The anticancer activity of various functionalized calixarenes has been reported by several research groups. Due to their superior geometric shape, calixarenes can accommodate drug molecules by forming inclusion complexes. Controlled release of anticancer drugs by calixarenes might help in targeted chemotherapy. This review summarizes the anticancer potential of the calixarenes and their drug loading properties. The potential use of calixarenes in chemoradiotherapy is also highlighted in brief.

Synthesis, thermal stabilities, and anisotropic properties of some new isoflavone‐based esters 7‐decanoyloxy‐3‐(4′‐substitutedphenyl)‐4H‐1‐benzopyran‐4‐ones

A series of new isoflavonic esters 7‐decanoyloxy‐3‐(4′‐substitutedphenyl)‐4H‐1‐benzopyran‐4‐ones containing a heterocycle in their central core with one flexible alkyl chain and various substituents, R (where R = F, Cl, Br, CH3, OCH3, or H) at 4′‐position at one end, have successfully been synthesised, isolated, and characterised. The physical properties of title compounds were studied using spectroscopic techniques (Fourier transform infrared, 1H and 13C nuclear magnetic resonance). The liquid crystalline properties and the textures of these compounds along with their thermal stabilities were investigated via polarising optical microscopy and differential scanning calorimetry. All the compounds except the member without the substituent were enantiotropic mesogens exhibiting smectic A and/or nematic phases. The layer periodicities in relation to different phases were substantiated by X‐ray diffraction wherein the molecules within the SmA phase were found to be intercalated. The structural changes that resulted in a variation of transition temperature as well as the electronic polarisability of the respective compounds are also discussed.

Human topoisomerase II alpha as a prognostic biomarker in cancer chemotherapy

Topoisomerases are nuclear enzymes that regulate topology of DNA by facilitating the temporary cleavage and ligation cycle of DNA. Among all forms of topoisomerases, TOP-IIA is extensively associated with cell proliferation and therefore is an important therapeutic target in diseases that involved cellular proliferation such as cancers. Nearly half of present-day antitumor regimens contain at least one prescription that act as a topoisomerase inhibitor. Generally, tumor cells show divergent expression of TOP-IIA compared to normal cells. The remarkable expression of TOP-IIA in various carcinomas provides a significant biomarker toward understanding the nature of malignancy. TOP-IIA expression and amplification studies help in diagnosing cancer and to observe the disease progression, overall survival (OS) of patients, and response to therapy. This review highlights the research output and analysis in exploring the standing of TOP-IIA in various carcinomas. As some reports show contradiction within the same field of interest, the outline of that may help to induce researchers for further investigation and clarification. To the best of our knowledge, this is the first overview briefly summarizing the prognostic feature of TOP-IIA in various types of cancer.

Microwave-assisted synthesis of sec/tert-butyl 2-arylbenzimidazoles and their unexpected antiproliferative activity towards ER negative breast cancer cells

A new series of N-sec/tert-butyl 2-arylbenzimidazole derivatives was synthesised in 85–96% yields within 2–3.5 min by condensing ethyl 3-amino-4-butylamino benzoate with various substituted metabisulfite adducts of benzaldehyde under focused microwave irradiation. The benzimidazole analogues were characterised using 1H NMR, 13C NMR, high resolution MS and melting points. Evaluation of antiproliferative activity of the benzimidazole analogues against MCF-7 and MDA-MB-231 revealed several compounds with unexpected selective inhibitions of MDA-MB-231 in micromolar range. All analogues were found inactive towards MCF-7. The most potent inhibition against MDA-MB-231 human breast cancer cell line came from the unsubstituted 2-phenylbenzimidazole 10a.

2-Amino-N-(2-hydr-oxy-3-methoxy-benzyl-idene)aniline.

The reaction of o-vanillin 1 with o-phenylenediamine 2PD, in dichloromethane at low conditions produced novel amino benzeneamine: 2-amino-N-(2-hydroxy-3-methoxybenzylidene) aniline 2. Intermediate 2 is isolated and obtained as single crystals and the structure was determined and studied by x-ray crystallography. The complete assignments of 2 were made using FTIR, HRMS, 1D and 2D NMR including APT, COSY, HMQC and HMBC in CDCl3 and will be discussed.

Ethyl 1-tert-butyl-2-(4-methoxy-phen-yl)-1H-benzimidazole-5-carboxyl-ate.

In the title molecule, C21H24N2O3, the imidazole ring is essentially planar, with a maxium deviation of 0.015 (1) Å. The dihedral angle between the benzene and imidazole rings is 65.47 (6)°. The crystal packing is stabilized by weak intermolecular C—H⋯O and C—H⋯N hydrogen bonds, forming zigzag chains along the c axis. The crystal structure is further stabilized by C—H⋯π interactions.