Chemical and pharmacological aspects of the genus Cecropia

The Cecropia genus consists of about 60 species distributed throughout Latin America, mostly in Brazil. These species are widely used in traditional medicine to treat cough, asthma, bronchitis, high blood pressure, inflammation, heart disease, and as a diuretic. In recent years, there has been an increase in research on Cecropia species, with several phytochemical and pharmacological reports. Concerning its chemical composition, C-glycosylflavonoids and proanthocyanidins have been described as the main constituents of C. glaziovii, C. hololeuca and C. pachystachya, while terpenoids and steroids have been reported in several species, including C. adenopus and C. pachystachya. Among the pharmacological properties described for the genus, the most frequently reported are hypoglycemic activity for C. obtusifolia and C. peltata, and hypotensive and central nervous system activity for C. glaziovii. The present review compiles the information available on this genus because of its ethnopharmacological relevance and the potential therapeutic uses of these species.     

Chemical composition and pharmacological properties of plants of the genusStachys

This review gives information of the distribution of alkaloids, carbohydrates, lipids, essential oils, diterpenoids, iridoids, flavonoids, and pigments in plants of the genusStachys L. (fam. Lamiaceae). It has been shown that the genusStachys is of interest for researchers as a source of biologically active substances of various classes which are responsible for the broad spectrum of pharmaceutical-therapeutic action of plants of this genus and drugs prepared from them. Characteristic for these plants is a low content of saturated fatty acids in the seed lipids and, in the epigeal part, of essential oils, an accumulation of iridoids of the aucubin type, and the fact that all the flavone derivatives present have a large number of substituents in ring A of the flavone nucleus. This indicates the antiquity and phylogenetic primitiveness of theStachys genus. The results of chemical and pharmacological-therapeutic studies of plants of theStachys genus growing on the territory of the former USSR are given. Literature sources up to and including 1991 have been used.     

Chemical and pharmacological aspects of novel hetero MLB complexes derived from NO2 type Schiff base and N2 type 1,10-phenanthroline ligands

A series of hetero ligand MLB complexes (1–5) were synthesised from tridentate NO₂ type Schiff base [H₂L: (E)-2-((2-hydroxy-4-methoxyphenyl)(phenyl)methyleneamino)benzoic acid; derived from 2-hydroxy-4-methoxybenzophenone and 2-aminobenzoic acid] and bidentate N₂ type 1,10-phenanthroline (B: phen) ligands. The structural characterization of the synthesised MLB complexes were carried out via analytical as well as various spectral studies. Additionally, the low molar conductance values (Λ_m = 14–22 Ω⁻¹ cm² mol⁻¹) imply that the complexes (1–5) are non-electrolytes. The obtained results reinforce that stoichiometry of the mononuclear hetero ligand complexes can be represented as [M(II)-Schiff base(L)-phen(B)·H₂O] and both H₂L and (B) ligands can act as tri and bidentates respectively. Moreover, both the ligands bind with metal(II) ions to build a stable six, six, five membered chelate rings with octahedral geometry. The existing solvent water molecule is confirmed from thermal as well as vibrational analysis. Their microcrystalline nature and uniform surface morphology were confirmed by both powder XRD and SEM studies. 3D molecular modeling and analysis of NiLB and CuLB complexes (3 and 4) were also studied. Mn(II), Ni(II) and Cu(II) complexes (1, 3 and 4) strongly interact with DNA through intercalation binding with strong binding constant values. The obtained K_app values were 5.23, 4.98, 6.36, 7.21 and 4.86 × 10⁵ mol⁻¹ for MLB complexes (1–5) respectively and the negative Δ³G values shown that all the complexes are strongly interact with DNA in a spontaneous manner. Further, remarkable biological, antioxidant and DNA activities were remarkably exhibited by MnLB, NiLB and CuLB complexes.     

Chemical and pharmacological comparison of modern and traditional dosage forms of Joshanda

Recently, a traditional remedy (Joshanda) has been replaced largely by modern ready-to-use dosage forms, which have not been compared to the original remedy. Therefore, the present study aimed to compare a number of modern dosage forms with traditional remedy. Seven brands, 3 batches each, were compared with a Lab-made formulation with reference to analytical (proximate analyses, spectroscopic and chromatographic metabolomes) and pharmacological profiles (anti-inflammatory and antibacterial activities). Chemical and pharmacological differences were found between Lab-made Joshanda and modern dosage forms. Such variations were also found within the brands and batches of modern formulations (p < 0.05). The Lab-made Joshanda showed significantly higher pharmacological activities as compared to modern brands (p ). The results of the present study indicate that modern dosage forms are unstandardised and less effective than the traditional remedy. Characteristic profiles obtained from Lab-made Joshanda may be used as reference to produce comparable dosage forms.     

Chemical composition and pharmacological properties of plants of the genusStachys

This review gives information of the distribution of alkaloids, carbohydrates, lipids, essential oils, diterpenoids, iridoids, flavonoids, and pigments in plants of the genusStachys L. (fam. Lamiaceae). It has been shown that the genusStachys is of interest for researchers as a source of biologically active substances of various classes which are responsible for the broad spectrum of pharmaceutical-therapeutic action of plants of this genus and drugs prepared from them. Characteristic for these plants is a low content of saturated fatty acids in the seed lipids and, in the epigeal part, of essential oils, an accumulation of iridoids of the aucubin type, and the fact that all the flavone derivatives present have a large number of substituents in ring A of the flavone nucleus. This indicates the antiquity and phylogenetic primitiveness of theStachys genus. The results of chemical and pharmacological-therapeutic studies of plants of theStachys genus growing on the territory of the former USSR are given. Literature sources up to and including 1991 have been used.Division of the Institute of Chemical Physics of the Russian Academy of Sciences, Chernogolovka, fax 2926511 - BOX 18777; and Tashkent State University, fax 462472. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 699–709, November–December, 1994.     

Chemical aspects of amine oxidation by flavoprotein enzymes

The mechanism of amine oxidation by flavoprotein enzymes is critically analysed through analysis of available experimental data. The review assesses available evidence for radical and polar mechanisms, drawing on data from model reactions, kinetic and spectroscopic approaches, structural and mutagenesis studies. The review focused on studies of mammalian monoamine oxidases and the bacterial enzymes trimethylamine dehydrogenase, monomeric sarcosine oxidase and dimethylglycine oxidase.     

Chemical and physical aspects of organic fouling of forward osmosis membranes

The growing attention to forward osmosis (FO) membrane processes from various disciplines raises the demand for systematic research on FO membrane fouling. This study investigates the role of various physical and chemical interactions, such as intermolecular adhesion forces, calcium binding, initial permeate flux, and membrane orientation, in organic fouling of forward osmosis membranes. Alginate, bovine serum albumin (BSA), and Aldrich humic acid (AHA) were chosen as model organic foulants. Atomic force microscopy (AFM) was used to quantify the intermolecular adhesion forces between the foulant and the clean or fouled membrane in order to better understand the fouling mechanisms. A strong correlation between organic fouling and intermolecular adhesion was observed, indicating that foulant–foulant interaction plays an important role in determining the rate and extent of organic fouling. The fouling data showed that FO fouling is governed by the coupled influence of chemical and hydrodynamic interactions. Calcium binding, permeation drag, and hydrodynamic shear force are the major factors governing the development of a fouling layer on the membrane surface. However, the dominating factors controlling membrane fouling vary from foulant to foulant. With stronger intermolecular adhesion forces, hydrodynamic conditions for favorable foulant deposition leading to cake formation are more readily attained. Before a compact cake layer is formed, the fouling rate is affected by both the intermolecular adhesion forces and hydrodynamic conditions. However, once the cake layer forms, all three foulants have very similar flux decline rates, and further changes in hydrodynamic conditions do not influence fouling behavior.     

Chemical aspects of influence of medical drugs on organism functions

Some fundamental problems of pharmacology important for setting investigations dealing with the search for new effective drugs are considered. The ways of introduction of drugs into the body, the types and functions of biological membranes, mediators of central and peripheral nervous systems, various receptor systems, and enzyme inhibitors are discussed.     

Chemical and photochemical electron transfer of new helianthrone derivatives: aspects of their photodynamic activity

Helianthrones 2-4 are a new class of synthetic photosensitizers, which have a molecular skeleton related to that of hypericin. We established that irradiation of heliantrones with visible light leads to the formation of semiquinone radicals and reactive oxygen species. The structures of the paramagnetic anion species produced by electron transfer were calculated on the density functional level and investigated by cyclovoltammetry, UV/vis, and EPR/ENDOR spectroscopy. As with hypericin, the pi system of the helianthrones was found to be considerably deviated from planarity, and, upon electron transfer, deprotonation in the bay region occurs. The structure of the semiquinone radicals was found to be identical in THF, DMF, and aqueous buffered solutions regardless of the means by which reduction was achieved. Semiquinone radicals can be formed via self-electron transfer between the excited state and the ground state or via electron transfer from an electron donor to the excited state of helianthrone. Therefore, the presence of an electron donor significantly enhanced the photogeneration of semiquinone and superoxide radical. The kinetic studies showed that no significant photochemical destruction of helianthrones occurred upon irradiation. Generation of superoxide and singlet oxygen upon irradiation of helianthrones was established by spin trapping techniques. This shows that both type I and type II mechanisms are of importance for the photodynamic action of these compounds.     

Antifungal cellulose by capsaicin grafting

Cellulose is one of the most abundant materials in nature. Besides its biological function, cellulose can be extracted from the cell wall and used in several industrial applications. Thus, it can be used in papers, pharmaceuticals, food, cosmetics and innovative materials such as nanocomposites, packaging, coatings and dispersion technology. With the aim of extending cellulose applications and producing so-called “smart” materials, new functionality can be introduced by physical or chemical modifications. Taking into account that capsaicin, the active component of chili peppers, is an excellent antifungal agent, a potential new material could be obtained by chemical reaction between this active compound and cellulose. In this work, capsaicin grafting onto cellulose using polycarboxylic acid as linking agent is proposed. The reaction occurrence was corroborated by Fourier transform infrared spectroscopy and UV–Vis spectrophotometry in reflectance mode. Modified cellulose with <2 wt% of capsaicin shows a strong change in antifungal activity with respect to the unmodified one. This activity was evaluated by the fungal growth inhibition test with two different fungi, Trametes versicolor and Gloeophyllum trabeum. Modified cellulose samples showed a high percentage of fungal growth inhibition, demonstrating the success of the cellulose modification and high antifungal power of the grafting molecule.     

Silicate electrochemical measurements in seawater: Chemical and analytical aspects towards a reagentless sensor

From the study of molybdenum oxidation in aqueous solutions we developed a semi-autonomous method to detect silicate in aqueous samples. Molybdenum oxidation was used to form molybdate in acidic media. The silicomolybdic complex formed with silicate is detectable by amperometry or cyclic voltammetry. The new electrochemical method is in good agreement with the method conventionally used for environmental water silicate analysis. In the second stage, a completely reagentless method was developed using molybdate and proton produced during molybdenum oxidation. Reproducibility tests show a precision of 2.6% for a concentration of 100 μmol L⁻¹. This new method will be very suitable for the development of new autonomous silicate sensors easy to handle and without reagents. In this paper we present the analytical and chemical aspects necessary for a complete documentation of the method before the development of a new reagentless sensor.     

Photochemical and pharmacological aspects of nitric oxide release from some nitrosyl ruthenium complexes entrapped in sol–gel and silicone matrices

The entrapped [Ru(terpy)(L)NO](PF₆)₃, where terpy = 2,2′:6′,2″-terpyridine and L = 2,2′-bipyridine (bpy) and 3,4-diiminebenzoic acid (NH · NHq) complexes into sol–gel processed polysiloxane and silicone matrices, shows NO release characteristics when submitted to light irradiation at 355 and 532 nm, as judged by NO measurement using a NO-sensor electrode. The pharmacological properties of doped matrix showed vasodilator characteristics by visible light irradiation, which is of great interest because the target delivery system can avoid the occurrence of side effects possibly by the aquo ruthenium species. All matrices obtained showed to be amorphous materials. The scanning electron micrographs of the matrices showed irregularly shaped particles, with a broad size of 1000 μm for both matrices and homogeneous distribution.     

Quantitative structure-agonist activity relationship of capsaicin analogues

Summary The MULTIple Computer Automated Structure Evaluation (MULTICASE) methodology has been used to study the quantitative structure-agonist activity relationship of a series of capsaicin agonists. A number of substructures and physicochemical properties of capsaicin analogues were identified as being responsible for high agonist potency. The optimal log P value for the agonist potency as estimated from QSAR analysis is 5.12. It was also found that a cluster of inactive molecules in the database have lipophilicity values below 2.94. Molecular modeling was employed to elucidate the detailed structural features of the pharmacophore of capsaicin analogues. Systematic conformational analysishas shown that the activity of capsaicin analogues strongly depends upon their ability to reach the required conformational profile. Based upon these observations, a three-dimensional pharmacophore model for the capsaicin-receptor interactions is proposed.     

Gas chromatographic analysis of capsaicin in Gochujang

A sensitive, precise, and specific gas chromatographic (GC) method was developed for the analysis of capsaicin in Gochujang and validated by comparing with a column high-performance liquid chromatographic (HPLC) method (AOAC 995.03). The method validation parameters yielded good results, including linearity, precision, accuracy, and recovery. The GC separation was performed on a (5% phenyl)-methylpolysiloxane column [length 30 m, internal diameter (id) 250 microm, film thickness 0.25 microm] followed by flame ionization detection. The conditions of temperature programming were initially 220 degrees C for 1 min, ramp at 5 degrees C/min to 270 degrees C, and hold for 10 min. The recovery of capsaicin in Gochujang was more than 92%, and the detection limit and lower determination limit of the GC analysis were 1.0 and 5.0 microg/g, respectively. The calibration graph for capsaicin was linear from 1 to 250 microg/mL for GC and 0.5 to 50 microg/mL for HPLC. The interday and intraday precisions (relative standard deviations) were <4.02%.     

Chemical aspects of penicillin allergy. The direct formation of penicilloyl determinants in penicillin

The aminolysis of two penicillin-like compounds which cannot form penicillenic acid has been studied:

• 1 6-Aminopenicillanic acid (which is highly immunogenic) reacts directly with ε-amino groups at pH 7,4 under CO₂-free conditions; the possible role of its polymerisation in this reaction remains to be studied.
• 2 6-Dinitrophenylamino-penicillanic acid reacts with εamino groups at pH 7,4 as fast as benzylpenicillin and other penicillins. Its immunogenicity in the rabbit is similar to that of benzylpenicillin.

     

Chemical aspects of the radiation stability of macrocyclic extractants designed for 90Sr separation

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Functionalization of poly(ethylene terephthalate) in the melt state: Chemical and rheological aspects

This article deals with a new way of improving the melt viscosity of linear poly(ethylene terephthalate) (PET) chains through the reaction of the PET end groups (alcohol and acid) with new chain extenders, 3‐(triethoxysilyl)propylsuccinic anhydride (ASSI) and 3‐glycidoxypropyltrimethoxysilane, during the melt processing of PET. The reactions, investigated with model compounds monomethylterephthalate and triethylene glycol monomethylether for PET? COOH and ? OH end groups, respectively, by multinuclear NMR spectroscopy (¹H, ¹³C, and ²⁹Si), provided evidence of well‐known acid–epoxide and alcohol–anhydride reactions, respectively. In addition, numerous other species appeared because of the presence of alkoxysilane groups, such as alcohol–alkoxysilane exchange reactions, acyloxysilane formation, and hydrolysis–condensation reactions of alkoxysilane. All these reactions led to the formation of branched chains when transposed to PET melt modification. A size exclusion chromatography analysis and the rheological behavior confirmed the presence of branched structures embedded in shorter linear PET chains. The rheological behavior of this blend was drastically modified in comparison with that of neat PET; consequently, there was an important increase in the zero‐shear viscosity, with a maximum concentration of branched structures of about 17 vol % obtained with an ASSI/PET molar ratio of 4. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2207–2223, 2005