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A photo-active gellan gum (Gel) derivative was developed by amide bond combination with trans-4-[p-(amino)styryl]pyridine (SP). The SP-Gel was cross-linked by UV curing via the intermolecular 2π + 2π cycloaddition of the inserted SP–CH=CH- moieties. The chemical structure of the obtained photo-crosslinkable biopolymer was investigated before and after the UV curing and the progress of the performed 2π + 2π cycloaddition-based cross-linking was detected via UV–visible light spectra. SP-Gel was evaluated as a polymeric matrix for the immobilization of catalase via entrapment technique. The synthesized biopolymer was mixed with the catalase and molded in the form of membranes that were UV cured to encapsulate the enzyme. The membranes were able to entrap 0.75 mg/cm2 with retained activity reached above 95%. The immobilized catalase displayed higher thermal stability and higher resistance toward the environmental pH disturbances compared to the free enzyme. Also, despite the observed lower catalase-H2O2 affinity upon the entrapment that was indicated from the performed kinetic studies, the reusability and storage stability experiments revealed the economic value of the entire process by preserving around 95% and 83% of the initial catalase activity after the fifth and tenth operation cycles, respectively.

An enantio-selective l -histidine imprinted polymeric resin was fabricated and evaluated for enantiomeric resolution of histidine racemate. The polymerizable chiral salicyloyl- l -histidine amide was first synthesized and anchored onto a polymeric resin network via condensation polymerization with resorcinol and formaldehyde. l -histidine template molecules were then extracted out of the resin texture via alkaline hydrolysis of the amide bond using sodium hydroxide. The synthetic steps were monitored by means of instrumental techniques including elemental analysis; mass spectra along with both Fourier transform infrared and nuclear magnetic resonance spectroscopy. In addition, the surface morphologies of both imprinted and non-imprinted resins were visualized using scanning electron microscope and the images indicated a relatively rougher surface in case of the imprinted resin. Also, the complete extraction of the template l -histidine molecules was assured using energy-dispersive X-ray spectroscopy, which indicated the absence of nitrogen upon alkaline treatment of the synthesized l -histidine containing resin. Selective adsorption experiments indicated that the maximum adsorption was achieved at pH 8 and followed the pseudo-second-order kinetic model with extracted amounts of 165 ± 1 and 90 ± 1 mg/g with respect to l - and D-histidine, respectively. Moreover, Langmuir model displayed the best fit with the experimentally obtained isotherm data and the maximum adsorption capacities were 195 ± 1 and 102 ± 1 mg/g with respect to l - and d - histidine, respectively. The enantiomeric resolution of d / l -histidine racemate was also carried out utilizing a column backed with the imprinted resin and the outlet collected solution displayed an optical activity related to 36% d -histidine enantiomeric excess.

Steroids are components of cell membranes, signaling molecules and are a type of secondary metabolites as a result of their high impact of biological significance. The present review described the literature reports of pentacyclic steroidal pyrimidines as a type of heterocyclic steroids. The main sections included the synthesis of the investigated steroids fused at rings-A or B or D of steroid skeleton, synthesis of binary or linked-type pyrimidines, pyrimidine oxides, macromolecules and mono- or di- or tri-peptides linked-steroidal pyrimidines. Besides, the present research highlighted the biological significance of steroidal pyrimidines, in which the compounds revealed potent anticancer, antioxidant, antibacterial, and anti-Alzheimer agents. In addition, some hetero-steroids were screened for binding DNA assay and gene expression analysis. It was settled that the incorporation of pyrimidine scaffold into steroid basic skeleton is crucial for better biological results.

Benzoxazinone 2 was prepared and reacted with formamide, acetamide, some primary aromatic amines and heterocyclic amines giving the corresponding quinazolone derivatives 3–15 respectively. The reaction of benzoxazinone 2 with hydrazine hydrate and phenyl hydrazine was also studied. Representative compounds of the synthesized products were evaluated as antioxidants and corrosion inhibitors for gasoline engine lubricating oil. The highest antioxidant activities were obtained with compounds 10–15. The optimum concentration recommended for these new additives was found to be 0.1g for 1L of oil for compounds 13–15. In addition, some of the highly effective antioxidant additives, namely 10–15, were thermally analyzed by using thermogravimetric analysis (TGA) and differential thermal gravimetric analysis (DTGA) techniques and the results indicated that compounds are thermally stable and could be used under thermal conditions. Moreover, a comparison of the oxidation stability between the tested oil containing the prepared products and lubricating oil containing commercial additives was also studied.

An enantioselective S-mandelic acid (S-MA) imprinted chitosan (SMIC) was prepared by cross-linking of chitosan using formaldehyde cross-linker, in the presence of S-MA as an imprint template molecule and 0.5% acetic acid solution as a solvent. Non-imprinted cross-linked chitosan (NIC) as control was also prepared by the same procedure in absence of template molecules. The surface morphology of both SMIC and NIC were examined by scanning electron microscope (SEM). SMIC particles were applied to determine the optimum operational condition for S-MA separation from dilute aqueous solution. In adsorption step, optimum pH and retention time were 3.5 and 60 min, while corresponding values in extraction step were 1 and 40 min, respectively. Also, the adsorption isotherms indicated that the maximum adsorption capacities of S- and R-MA on SMIC were 100 ± 0.5 and 64 ± 0.8 mg/g, respectively, while in the case of NIC, both R- and S-MA present the same maximum adsorption.

Oxazolone derivative 2 was utilized as a key intermediate for synthesis of some new oxazolone and imidazolone derivatives. Reaction of oxazolone derivative 2 with diamines under different conditions afforded the corresponding imidazolone derivatives 3–8, respectively. Moreover, oxazolone 2 reacted with some heterocyclic amines in glacial acetic acid giving the corresponding imidazolone derivatives 9–14, respectively. Cyclocondensation of thiosemicarbazide with compound 2 in dry pyridine afforded compound 15. Addition of secondary amines to olefin double bond of compound 2 gave the corresponding addition products 16–19, respectively. Michael addition of compound 2 with some active methylene compounds afforded oxazolone derivatives 20–23, respectively. These prepared products were evaluated as antioxidant and corrosion inhibitors for gasoline lubricating oil and compounds 6a–c, 10 and 15 exhibited the highest antioxidant and anticorrosive activities. The effect of concentration of additives was studied to recommend the optimum concentration to be used. The results showed, for additive 15, 0.1 g for 1 L oil was the more effective concentration. Measurements for thermal analysis and of surface tension of oil after oxidation were also carried out.