Extraction and determination of biologically active components of St. John’s wort and its pharmaceutical preparations

A procedure is developed for the determination of biologically active substances (BAS) of common St. John’s wort (Hypericum perforatum L.) by HPLC using two columns, Luna C18, 100 Å (for the determination of phenolcarboxylic acids and flavonoids), and Onyx Monolithic C18 (for the determination of phloroglucinols and naphthodianthrones), in the gradient elution mode with diode array detection. The detection limits for analytes are 0.05–0.20 μg/mL. To optimize the conditions, we studied the extraction of biologically active substances from St. John’s wort by a water–ethanol solution at different temperatures and pressures and under the effect of microwave radiation and ultrasound. The maximum amounts of substances were extracted in a dynamic mode under heat and pressure. The procedure was applied to the St. John’s wort samples of different brands and some pharmaceutical products based on it. The components of extracts were identified by retention times, UV spectra, and mass spectra. It was shown that the content of biologically active substances in pharmaceutical samples of St. John’s wort depends on the herb habitat. It was shown that hyperforin decomposed in pharmaceutical formulations based on St. John’s wort during storage.     

Synthesis and Solution Properties of Ampholytic Acrylamide Ionomers

The synthesis and semiconcentrated and dilute solution properties of two series of ampholytic acrylamide ionomers, poly(acrylamide MPTMA/AMPS) and poly(acrylamide METMA/MES), are reported as a function of the ionic content and added salt concentration. The viscosity dependence on shear rate was measured with a cone/plate Brookfield viscometer for sermiconcentrated solution and with a Cannon-Ubbelohde four-bulb shear dilution capillary viscometer for dilute solution at 25 ± 0.1°C. The two series of ampholytic acrylamide ionomers showed a characteristic pseudoplastic shear-thinning behavior under both conditions. The semiconcentrated solution viscosity parameters m and n in the power-law model, η = mγ^n-1, were determined and found to be functions of the ionic content. The viscosity at selected shear rates was found to be a complex function of the salt concentration. The intrinsic viscosity [η] was determined and compared with molecular parameters determined by light scattering under identical conditions. The dilute-solution properties of the ampholytic ionomers were found to resemble the properties of neutral polyacrylamide previously reported in the literature.     

Metabolism Studies of Polycyclic Mutagens and Carcinogens Using Liquid Chromatography with Ultraviolet and Electrochemical Detection

Abstract

HPLC ultraviolet (UV) and electrochemical (EC) detectors connected in series were used to classify the metabolites of naphthalene, anthracene, acridine, and phenanthridine into phenolic and nonphenolic categories. This method of classification is based on comparison of the relatively high response of the EC detector to electroactive species such as phenols to the more nonselective response of the UV detector. The method is generally useful for many biologically active substances.     

High resolution capillary gas chromatography and gas chromatography–mass spectrometry of protein and non-protein amino acids,amino alcohols,and hydroxycarboxylic acids as their tert-butyldimethylsilyl derivatives

A simple, single-step derivatization technique is presented for capillary GC-FID and GC-MS separation and identification of common protein and non-protein constituents of natural peptides as their tert-butyldimethylsilyl (TBDMS) derivatives. The tert-butyldimethyl-silylation of more than sixty compounds was accomplished with high yields and a single peak observed for each component. The TBDMS derivatives of both the protein and non-protein substances, moreover, exhibit excellent separation on apolar capillary columns and can be resolved completely using a polydimethylsiloxane or 5 % phenyl polydimethylsiloxane column and, complementarily, a 50 % phenyl polydimethylsiloxane column. Retention data and molar responses of the TBDMS derivatives on the polydimethylsiloxane column are compiled. Direct coupling of the 5 % phenyl polydimethylsiloxane column to an ion trap mass spectrometer enabled fast separation and identification of the investigated components, at nanomole to picomole levels, on the basis of retention and mass spectral data. The general usefulness of the method is demonstrated by research into new biologically active peptides isolated from entomopathogenic fungi.     

Optimization of carvacrol,rosmarinic, oleanolic and ursolic acid extraction from oregano herbs (Origanum onites L., Origanum vulgare spp. hirtum and Origanum vulgare L.)

The aim of our study was to increase the extraction efficiency of carvacrol, rosmarinic, oleanolic and ursolic acid from the different species of oregano herbs (Origanum onites L., Origanum vulgare spp. hirtum and Origanum vulgare L.). Various extraction methods (ultrasound-assisted, heat-reflux, continuous stirring, maceration, percolation) and extraction conditions (different solvent, material:solvent ratio, extraction temperature, extraction time) were used, and the active substances were determined by HPLC. The lowest content of carvacrol, rosmarinic, oleanolic and ursolic acid was obtained by percolation. During heat-reflux extraction, the content of active substances depended on the solvent used: ethanol/non-aqueous solvent (glycerol or propylene glycol) mixture was more effective compared with ethanol alone. The results showed that for each species of oregano the most optimal extraction method should be selected to maximize the content of biologically active substances in the extracts.     

Novel amino- and thio(substituted)-1,4-naphthoquinone (NQ) compounds: Synthesis and characterization

Abstract

Synthesis of new 1,4-naphthoquinone derivatives is important in terms of searching new biologically active substances. In particular, compounds with piperazine and thiol moiety in their structure, show a wide range of pharmacological activity such as anti-inflammatory, anticancer, anti-fungal, anti-bacterial, anti-allergic, apoptosis and radical scavenging activities. In this study, new amino- and thio(substituted) naphthoquinone derivatives were synthesized by the reaction of thiols and thioalcohols with four naphthoquinone compounds which were used as starting materials. The new compounds were purified by column chromatography. The structure of the compounds was confirmed by different spectroscopic techniques.     

Fractionation and analysis of Artemisia capillaris Thunb. by affinity chromatography with human serum albumin as stationary phase

A method for the screening and analysis of biologically active compounds in traditional Chinese medicine is proposed. Affinity chromatography using a human serum albumin (HSA) stationary phase was applied to separate and analyze the bioactive compounds from Artemisia capillaris Thunb. Five major peaks and several minor peaks were resolved based on their affinity to HSA, two of them were identified as scoparone (SCO, 6,7-dimethoxycoumarin) and capillarisin (CAP). CAP shows a much higher affinity to HSA than SCO. The effects of acetonitrile concentration, eluent pH, phosphate concentration and temperature on the retention behaviors of several major active components were also investigated, and it was found that hydrophobicity and eluent pH play major roles in changing retention values. The results demonstrate that the affinity chromatography with a HSA stationary phase is an effective way for analyzing and screening biologically active compounds in traditional Chinese medicine.     

Ion-exchange and hydrophobic interactions affecting selectivity for neutral and charged solutes on three structurally similar agglomerated ion-exchange and mixed-mode stationary phases

The nature and extent of mixed-mode retention mechanisms evident for three structurally related, agglomerated, particle-based stationary phases were evaluated. These three agglomerated phases were Thermo Fisher ScientificIon PacAS11-HC – strong anion exchange, Thermo Fisher Scientific IonPac CS10 – strong cation-exchange PS-DVB, and the Thermo Fisher Scientific Acclaim Trinity P1silica-based substrate, which is commercially marketed as a mixed-mode stationary phase. All studied phases can exhibit zwitterionic and hydrophobic properties, which contribute to the retention of charged organic analytes. A systematic approach was devised to investigate the relative ion-exchange capacities and hydrophobicities for each of the three phases, together with the effect of eluent pH upon selectivity, using a specifically selected range of anionic, cationic and neutral aromatic compounds. Investigation of the strong anion-exchange column and the Trinity P1 mixed-mode substrate, in relation to ion-exchange capacity and pH effects, demonstrated similar retention behaviour for both the anionic and ampholytic solutes, as expected from the structurally related phases. Further evaluation revealed that the ion-exchange selectivity of the mixed-mode phase exhibited properties similar to that of the strong anion-exchange column, with secondary cation-exchange selectivity, albeit with medium to high anion-exchange and cation-exchange capacities, allowing selective retention for each of the anionic, cationic and ampholytic solutes. Observed mixed-mode retention upon the examined phases was found to be a sum of anion- and cation-exchange interactions, secondary ion-exchange and hydrophobic interactions, with possible additional hydrogen bonding. Hydrophobic evaluation of the three phases revealed log P values of 0.38–0.48, suggesting low to medium hydrophobicity. These stationary phases were also benchmarked against traditional reversed-phase substrates namely, octadecylsilica YMC-Pac Pro C18 and neutral μPS-DVB resin IonPac NS1-5u, yielding log P values of 0.57 and 0.52, respectively.     

Development of a Validated Stability-Indicating LC Assay and Stress Degradation Studies of Linezolid in Tablets

This paper describes the validation of an isocratic LC method for the assay of linezolid in tablets. Validation parameters such as linearity, precision, accuracy, specificity, limit of detection, limit of quantitation and robustness were determined. LC was carried out by reversed phase technique on an RP-18 column with a mobile phase composed of 1% acetic acid:methanol:acetonitrile (50:25:25, v/v/v). Linezolid and your combination drug product were exposed to acid, base, oxidation, dry heat and photolytic stress conditions. A linear response (r > 0.9999) was observed in the range of 8.0–20.0 μg mL⁻¹. The retention time of linezolid was 4.6 min. The method showed good recoveries and intra- and inter-day relative standard deviations were less than 1.0%. The LOD and LOQ were 0.21 and 0.63 μg mL⁻¹, respectively. The developed LC method for determination of related substances and assay determination of linezolid can be used to evaluate the quality of regular production samples. It can also be used to test the stability samples of linezolid.

     

Die Analyse amphoterer Tenside

Zusammenfassung Es wird gezeigt, daß sich auch aus Vielkomponentengemischen mit anderen Tensiden die amphoteren Tenside quantitativ abtrennen lassen, indem man sie in neutraler alkoholischer Lösung an Kationenaustauscherharzen adsorbiert. Auch dünnschicht-chromatographisch lassen sich die amphoteren Tenside nach bereits bekannten Methoden auftrennen. Die quantitative Bestimmung der amphoteren Tenside läßt sich am besten gravimetrisch in saurer Lösung durch Fällung mit Heteropolysäuren durchführen. Die Identifizierung erfolgt durch Aufnahme der IR-Spektren. Die IR-Spektren der Zwitterionenformen und der Hydrochloride werden wiedergegeben und beschrieben.

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Analysis of ampholytic tensides

It is shown that ampholytic detergents can be separated from mixtures with other detergents, anionics or non-ionics, easily and quantitatively by adsorption on cation-exchange resins from neutral alcoholic solution. The separation can also be performed by thin-layer chromatographic techniques. The determination is carried out by precipitation with heteropoly acids in acid solution. The IR-spectra are recorded and discussed.

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Für die sorgfältige Mithilfe bei der Ausführung der experimentellen Arbeiten danke ich Frau Christa Fickel, Frau Marianne Grosse und Fräulein Erika Walldorf.     

Phosphorylated Bromonitroethene in the Reactions with NH- and CH- Acids

Abstract

The interaction between O,O-di(2-dichloroethyl)-2- bromo-2-nitroethenephosphonate and some NH- and CH-acids is discussed.

The highly reactive halonitroethenes attract the attention of scientists so as they are active synthons in the synthesis of various classes of organic compounds. Phosphorylated halonitroethenes can represent particular interest, because of phosphoryl group introduction “a priori” makes the reactivity of such compounds to be higher and allows to synthesize a big number of biologically active compounds. The very first study of interaction between O,O-di(2-chloroethyl)-2-nitroethenephosphonate (1)¹ with some representatives of NH-and CH-acids such as anyline, p-toluydine, dimedone, and malonic ester was conducted by our research group.     

Hybrid macromolecular antioxidants based on hydrophilic polymers and sterically hindered phenols

A novel class of biologically active substances was created. These are hybrid macromolecular antioxidants (HMAO) based on hydrophilic polymers with chemically grafted sterically hindered phenols with different structural parameters. The antiradical activities of HMAO were assessed in reactions with 2,2-diphenyl-1-picrylhydrazyl and the corresponding sodium sulfonate in various solvents. The mechanism that explains the substantially enhanced activities of HMAO in water was proposed. The state of HMAO in solutions was studied by viscosimetry and photon correlation spectroscopy. HMAO were assayed in biological models. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 751–760, April, 2007.     

Retention parameters of some isomeric 2-benzoylbenzoic acids in reversed-phase ion-pair high performance thin-layer and column chromatography

Summary The 2-benzoylbenzoic acid series was investigated by reversed-phase, high-performance, thin-layer and column chromatography using various alkylammonium salts and di(2-ethylhexyl)orthophosphoric acid as polar associating reagents. The effects of the individual substituents on retention were quantified by log k and R_M values. The compounds investigated differing in molecular structure (hydrophilic and hydrophobic substituents) commonly occurring groups in drugs and biologically active substances provide information on molecular interaction in these ion-pair systems. The combined effects on retention of organic modifier and ion-pair reagent concentration were investigated.     

<Emphasis Type="Italic">N</Emphasis>-(silylmethyl)amines, -amides,and -amino acids: biological activity and prospects in drug synthesis

The data on biological activity of the compounds with the geminal fragment N-C-Si are systematized. The examples of using N-(silylmethyl)amines and related compounds in syntheses of biologically active substances, including natural compounds, are considered.     

Functional proteomics: application of mass spectrometry to the study of enzymology in complex mixtures

This review covers recent developments in mass spectrometry-based applications dealing with functional proteomics with special emphasis on enzymology. The introduction of mass spectrometry into this research field has led to an enormous increase in knowledge in recent years. A major challenge is the identification of “biologically active substances” in complex mixtures. These biologically active substances are, on the one hand, potential regulators of enzymes. Elucidation of function and identity of those regulators may be accomplished by different strategies, which are discussed in this review. The most promising approach thereby seems to be the one-step procedure, because it enables identification of the functionality and identity of biologically active substances in parallel and thus avoids misinterpretation. On the other hand, besides the detection of regulators, the identification of endogenous substrates for known enzymes is an emerging research field, but in this case studies are quite rare. Moreover, the term biologically active substances may also encompass proteins with diverse biological functions. Elucidation of the functionality of those—so far unknown—proteins in complex mixtures is another branch of functional proteomics and those investigations will also be discussed in this review.     

Simultaneous Determination of Phenolic Compounds in Red Wines by HPLC‐UV

Abstract

Ten samples of commercially Italian red wines were analyzed in order to determine the phenolic content. Variations in wine types are largely due to differences in concentration and composition of these compounds. Polyphenolic compounds are a large and complex group of substances which constitute one of the most important quality parameters of wine. These constituents of red wine contribute to organoleptic characteristics and to antioxidant and anti‐inflammatory properties. Moderate wine consumption is associated with several beneficial physiological effects, which include anticancer activities, inhibition of platelet aggregation, and inhibition of LDL oxidation which constitutes the initial stage of the pathogenesis of arteriosclerosis.

For the analysis, reversed‐phase high performance liquid chromatography (HPLC) method coupled with UV‐Vis detection was used. The method uses a gradient elution to identify nine biologically active phenolic constituents: catechin; epicatechin; trans‐ and cis‐resveratrol; gallic, chlorogenic and caffeic acid; rutin and quercetin in red wine samples. The samples are injected directly without any pretreatment. The method is simple, fast, not expensive and shows good linearity for all constituents, and the detection limits ranged from 0.3–1.6 µg/ml for trans‐resveratrol and gallic acid, respectively. Moreover, the samples were analyzed in different times for estimation of stability of these compounds.     

Synthesis and Physicochemical Properties of Heterocyclic Compounds Based on 5,7-Diimino-2,5,6,7-tetrahydro-1H-cyclopenta[cd]phenalene

N,N'-Bis(7-amino-2,5-dihydro-1H-cyclopenta[cd]phenalen-5-ylidene)-substituted derivatives of 2,5-diamino-1,3,4-thiadiazole, 2,6-diaminopyridine, and 3,5-diamino-1-phenyl-1,2,4-triazole were synthesized. The products are soluble in water, and they attract interest as potential biologically active substances.     

Synthesis of low-molecular-weight <Emphasis Type="Italic">N</Emphasis>-(2-hydroxypropyl)methacrylamide sulfonated copolymers as carriers of biologically active substances

New water-soluble copolymers of N-(2-hydroxypropyl)methacrylamide with 2-acrylamido-2-methylpropanesulfonic acid as carriers of cationic biologically active substances were synthesized. The physicochemical properties of the copolymers were studied.     

Synthesis and antimicrobial activity of o- and p-hydroxybenzoic acid thiosemicarbazides

The ortho- and para-hydroxybenzoic acid thiosemicarbazide derivatives which are potentially biologically active substances were obtained by the reaction of the corresponding hydrazides with various isothiocyanates. Their structures were determined using IR, ¹H NMR spectroscopy, and mass spectrometry. Pronounced antimicrobial activity of synthesized derivatives was revealed.