Production, bleaching, and characterization of pulp from Stipa tenacissima

Alfa grass pulping was successfully performed in hydro-organic acid medium under mild conditions (107°C, atmospheric pressure, cooking time: 3 h). Use of an acetic acid/formic acid/water mixture as pulping liquor was perfectly suitable for selective isolation of pulp, lignin, and hemicelluloses. The unbleached pulp obtained in good yield was first delignified by peroxyacids in organic acid medium and then bleached with hydrogen peroxide in a basic medium to give pulp offering good physico-chemical and mechanical characteristics.     

In Vitro and In Silico Study of Analogs of Plant Product Plastoquinone to Be Effective in Colorectal Cancer Treatment

Plants have paved the way for the attainment of molecules with a wide-range of biological activities. However, plant products occasionally show low biological activities and/or poor pharmacokinetic properties. In that case, development of their derivatives as drugs from the plant world has been actively performed. As plant products, plastoquinones (PQs) have been of high importance in anticancer drug design and discovery; we have previously evaluated and reported the potential cytotoxic effects of a series of PQ analogs. Among these analogs, PQ2, PQ3 and PQ10 were selected for National Cancer Institute (NCI) for in vitro screening of anticancer activity against a wide range of cancer cell lines. The apparent superior anticancer potency of PQ2 on the HCT-116 colorectal cancer cell line than that of PQ3 and PQ10 compared to other tested cell lines has encouraged us to perform further mechanistic studies to enlighten the mode of anti-colorectal cancer action of PQ2. For this purpose, its apoptotic effects on the HCT-116 cell line, DNA binding capacity and several crucial pharmacokinetic properties were investigated. Initially, MTT assay was conducted for PQ2 at different concentrations against HCT-116 cells. Results indicated that PQ2 exhibited significant cytotoxicity in HCT-116 cells with an IC₅₀ value of 4.97 ± 1.93 μM compared to cisplatin (IC₅₀ = 26.65 ± 7.85 μM). Moreover, apoptotic effects of PQ2 on HCT-116 cells were investigated by the annexin V/ethidium homodimer III staining method and PQ2 significantly induced apoptosis in HCT-116 cells compared to cisplatin. Based on the potent DNA cleavage capacity of PQ2, molecular docking studies were conducted in the minor groove of the double helix of DNA and PQ2 presented a key hydrogen bonding through its methoxy moiety. Overall, both in vitro and in silico studies indicated that effective, orally bioavailable drug-like PQ2 attracted attention for colorectal cancer treatment. The most important point to emerge from this study is that appropriate derivatization of a plant product leads to unique biologically active compounds.     

Structural properties of new spiro-1,3-propanediaminocyclotriphosphazene derivatives

New 1,3-propanediaminocyclotriphosphazene derivatives (7-17) were synthesized from the reactions of spiro-1,3-propanediaminocyclotriphosphazene, N₃P₃Cl₄[NH(CH₂)₃NH] (1) with the cyclopropanemethylamine (2), cyclohexylamine (3), pyrrolidine (4) cyclohexanol (5), cyclopropylmethanol (6). The structures of the novel compounds (7-17) were characterized by elemental analysis, mass spectrometry, ¹H and ³¹P NMR spectroscopy. The molecular structures of 8, 12 and 13 were determined by X-ray crystallography. The structures of all these three compounds are in the monoclinic crystal system; compounds 8 and 12 have the P21/c space group while compound 13 has the P21/n space group. The ring conformation of the cyclotriphosphazene and other external rings were investigated based on the X-ray crystal structures.     

Fluorescent sensing platform for low-cost detection of Cu2+ by coumarin derivative: DFT calculation and practical application in herbal and black tea samples

A fluorogenic probe based on a coumarin-derivative for Cu²⁺ sensing in CH₃CN/H₂O media (v/v, 95/5, 5.0 μM) was developed and applied in real samples. 3-(4-chlorophenyl)-6,7-dihydroxy-coumarin (MCPC) probe was obtained by synthetic methodologies and identified by spectral techniques. The probe MCPC showed remarkable changes with a “turn-off” fluorogenic sensing approach for the monitoring of Cu²⁺ at 456 nm under an excitation wavelength of 366 nm. The response time of the probe MCPC was founded as only 1 min. The detection limit of the probe MCPC was recorded to be 1.47 nM. The binding constant and possible stoichiometric ratio (1:1) values were determined by Benesi-Hildebrand and Job’s plot systems, respectively. The mechanism of the probe MCPC with Cu²⁺ was further confirmed by ESI-MS and FT-IR analyses, as well as supported by theoretical calculations. Furthermore, the probe MCPC was successfully employed for the practical applications to sense Cu²⁺ in different herbal and black tea samples. The proposed sensing method was also verified by ICP-OES method.     

Synthesis,Spectral Characterization,and In Vitro Biological Evaluation of Some Novel Isoquinolinone‐based Heterocycles as Potential Antitumor Agents

A series of new N‐substituted isoquinolin‐1,3‐dione derivatives were prepared, starting from reaction of (Z)‐4‐((E)‐3‐phenylallylidene)isochromane‐1,3‐dione 4 with different nitrogen nucleophiles. The assigned structures of the prepared compounds were elucidated by spectral methods (IR, ¹H NMR, ¹³C NMR, and mass spectroscopy). Some of the newly prepared compounds were tested in vitro against a panel of three human tumor cell lines, namely, hepatocellular carcinoma (liver) HepG2, colon cancer HCT‐116, and mammary gland breast MCF‐7. Also, they were tested as antioxidants. Some of the tested compounds showed very strong cytotoxic activity with respect to the standard.     

The relation between GTi-spaces and fuzzy proximity spaces, G-compact spaces, fuzzy uniform spaces

In this paper, we study the relation between the fuzzy separation axioms, which had been introduced by the authors in 2001, and the fuzzy proximity defined by Katsaras in 1980. We study also the relation between our fuzzy separation axioms and the G-compactness defined by Gähler in 1995. Moreover, we show here the relation between these fuzzy separation axioms and the fuzzy uniform structures introduced and studied by Gähler and the first author in 1998.     

Studies on 3,3′-dichloro-, 4,4′-dichloro- and 5,5′-dichloro,2-2′-dimethyldithizone and their reactions with metal ions

Three new derivatives of dithizone are reported, with their electronic and i.r. spectra, acidity constants and partition coefficients between 0.5 M sodium perchlorate and chloroform or carbon tetrachloride. The extraction equilibria with Cd, Co(II), Hg(II), Ni, Pb, Tl(I), Zn and Bi and the spectrophotometric characteristics of the extractable metal chelates are described. Complete extraction of these complexes requires higher pH than that needed with dithizone itself. The 4,4′-dichloroisomer is more efficient than the 3,3′ and 5,5′-isomers, or dithizone itself, for the separation of cadmium from zinc or cobalt from nickel.     

Approximation of functions of two variables by certain linear positive operators

We introduce certain linear positive operators and study some approximation properties of these operators in the space of functions, continuous on a compact set, of two variables. We also find the order of this approximation by using modulus of continuity. Moreover we define an rth order generalization of these operators and observe its approximation properties. Furthermore, we study the convergence of the linear positive operators in a weighted space of functions of two variables and find the rate of this convergence using weighted modulus of continuity.     

Synthesis,characterization, and optimum reaction conditions of oligo‐2‐[(pyridine‐2‐yl‐methylene) amino] phenol

The reaction conditions of the oxidative polycondensation of 2‐[(pyridine‐2‐yl‐methylene) amino] phenol (2‐PMAP) with air O₂, H₂O₂, and NaOCl were studied in an aqueous alkaline medium between 60 and 90 °C. Oligo‐2‐[(pyridine‐2‐yl‐methylene) amino] phenol (O‐2‐PMAP) was characterized with ¹H NMR, Fourier transform infrared, ultraviolet–visible, size exclusion chromatography (SEC), and elemental analysis techniques. Moreover, solubility testing of the oligomer was performed in polar and nonpolar organic solvents. With the NaOCl, H₂O₂, and air O₂ oxidants, the conversions of 2‐PMAP into O‐2‐PMAP were 98, 87, and 62%, respectively, in an aqueous alkaline medium. According to SEC, the number‐average molecular weight, weight‐average molecular weight, and polydispersity index of O‐2‐PMAP were 2262 g mol^?1, 2809 g mol^?1, and 1.24 with NaOCl, 3045 g mol^?1, 3861 g mol^?1, and 1.27 with air O₂, and 1427 g mol^?1, 1648 g mol^?1, and 1.16 with air H₂O₂, respectively. Also, thermogravimetric analysis showed that O‐2‐PMAP was stable against thermooxidative decomposition. The weight loss of O‐2‐PMAP was 96.68% at 900 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2717–2724, 2004