Products Containing (products + containing)

Distribution by Scientific Domains

Selected Abstracts

Probiotic fermented milks: Present and future

Milk and dairy products have been part of human nutrition since ancient times, constituting an important part of a balanced diet. Fermented dairy products containing living micro-organisms have traditionally been used to restore gut health, being among the pioneers in functional foods. Such utilisation of live micro-organisms forms the basis of the probiotic concept, which constitutes a fast growing market for the development of new products. In this article, we review the current status of fermented milk as a vehicle for delivery of beneficial bacteria and look into future new directions and challenges. [source]

Allergy to peanut oil , clinically relevant?

J Ring
Abstract The increasing prevalence of food allergies (especially allergy to peanuts) has led to a discussion of how safe topical preparations containing peanut oil are with respect to allergy. The major allergens from peanuts are proteins that have been characterized at a molecular level and cloned. Clinical signs of peanut allergy symptoms can be observed on the skin (urticaria), or in the gastrointestinal and/or respiratory tract culminating in cardiovascular symptoms and anaphylactic reactions. In most cases, symptoms are elicited by oral uptake; rarely, a contact urticaria has been described. In vegetable oils, the contents of protein differ depending on the production process: crude oils contain approximately 100 times more proteins than refined oils. This has clear-cut implications for allergic individuals. Quantitative data are available regarding elicitation of symptoms in allergic individuals with a threshold dose of 0.1,1 mg peanut allergen in oral provocation tests. There are anecdotal reports of adverse reactions after topical use of peanut oils. In one epidemiological trial, an association between topical use of skin care products containing peanut oil and the development of peanut allergy was observed; however, the data reflect a retrospective analysis without specifying skin care products containing peanut oil and also without analysing the quantity of topicals used. In contrast, oral tolerance was prevented and allergic sensitization was enhanced in a mouse model using high concentrations of peanut protein. So far, no reliable data are available regarding doses required to induce sensitization against peanut allergen via the epidermal route. A possible induction of sensitization against peanut proteins through contact with the skin via skin care products and the respective protein concentrations is a matter of speculation. Patients with atopic diseases, namely eczema, need appropriate skin care because of the disturbed skin barrier function. The benefit of avoiding damage to skin barrier functions of atopic individuals by the use of peanut protein-containing skin care products seems to outweigh possible risks of sensitization and/or allergy induction against substances contained in those products containing refined peanut oil. [source]

Organometallic chemistry on rhodaheteroborane clusters: reactions with bidentate phosphines and organotransition metal reagents,

Oleg Volkov
Abstract This article reviews our recent work on the reactions of the rhodaheteroboranes [8,8-(PPh3)2 - nido -8,7-RhSB9H10] (1) and [9,9-(PPh3)2 - nido -9,7,8-RhC2B8H11] (2), and their derivatives, with the bidentate phosphines, dppe [(CH2)2(PPh2)2], dppp [(CH2)3(PPh2)2], and dppm [CH2(PPh2)2], and also with organotransition metal reagents. Simple substitution of the two PPh3 ligands by a single bidentate phosphine takes place when a 1 : 1 molar ratio of base (dppe or dppp) to rhodathiaborane (1) is used. However, in the presence of an excess of dppe or dppp, products containing 1 or 2 mol of base are formed. These products include a bidentate ligand on the metal and a monodentate ligand on the cage. The displaced hydrogen atom from the cage has moved to the metal center. These bis(ligand) species are unstable with respect to the loss of dihydrogen, affording closo -11 vertex clusters with a pendent phosphine ligand on the cage. In concentrated solutions, the pendent phosphine attacks another cage to afford linked clusters. Under both sets of conditions, when dppm is used, only one product is observed. This species has two dppm ligands coordinated to the metal: one in a unidentate mode and the other bidentate. A similar product is obtained in the reaction of 2 with dppm, although the arrangement of the ligands on the metal in the product is different. Ligand exchange experiments on the dppm,thiaborane system lead to results that provide keys to the reaction pathways in some of these processes. The bis(dppm) derivatives of 1 and 2 are amenable to further derivatization. A second metal may be added, either as an exo -polyhedral atom in a nido cluster in which the metal is part of a bidentate ligand, in the case of 1 and 2, or in a closo cluster derivative of 1 in which the metal is bonded to a dangling PPh2 moiety. Thus, it was possible to add the metals iridium, rhodium or ruthenium to the cluster, in the case of 1 and ruthenium in the case of 2. However, the reaction of more electrophilic organotransition metal reagents, such as Wilkinson's catalyst, with the dppm derivative of 1 affords species resulting from removal of ligand rather than incorporation of metal, and the products shed light on the rearrangement processes in these systems. Copyright © 2003 John Wiley & Sons, Ltd. [source]

The World of , - and , -Peptides Comprised of Homologated Proteinogenic Amino Acids and Other Components

Dieter Seebach
The origins of our nearly ten-year research program of chemical and biological investigations into peptides based on homologated proteinogenic amino acids are described. The road from the biopolymer poly[ethyl (R)-3-hydroxybutanoate] to the , -peptides was primarily a step from organic synthesis methodology (the preparation of enantiomerically pure compounds (EPCs)) to supramolecular chemistry (higher-order structures maintained through non-covalent interactions). The performing of biochemical and biological tests on the , - and , -peptides, which differ from natural peptides/proteins by a single or two additional CH2 groups per amino acid, then led into bioorganic chemistry and medicinal chemistry. The individual chapters of this review article begin with descriptions of work on , -amino acids, , -peptides, and polymers (Nylon-3) that dates back to the 1960s, even to the times of Emil Fischer, but did not yield insights into structures or biological properties. The numerous, often highly physiologically active, or even toxic, natural products containing ,- and ,-amino acid moieties are then presented. Chapters on the preparation of homologated amino acids with proteinogenic side chains, their coupling to provide the corresponding peptides, both in solution (including thioligation) and on the solid phase, their isolation by preparative HPLC, and their characterization by mass spectrometry (HR-MS and MS sequencing) follow. After that, their structures, predominantly determined by NMR spectroscopy in methanolic solution, are described: helices, pleated sheets, and turns, together with stack-, crankshaft-, paddlewheel-, and staircase-like patterns. The presence of the additional CC bonds in the backbones of the new peptides did not give rise to a chaotic increase in their secondary structures as many protein specialists might have expected: while there are indeed more structure types than are observed in the , -peptide realm , three different helices (10/12 -, 12 -, and 14 -helix) if we include oligomers of trans -2-aminocyclopentanecarboxylic acid, for example , the structures are already observable with chains made up of only four components, and, having now undergone a learning process, we are able to construct them by design. The structures of the shorter , -peptides can also be reliably determined by molecular-dynamics calculations (in solution; GROMOS program package). Unlike in the case of the natural helices, these compounds' folding into secondary structures is not cooperative. In , - and , -peptides, it is possible to introduce heteroatom substituents (such as halogen or OH) onto the backbones or to incorporate heteroatoms (NH, O) directly into the chain, and, thanks to this, it has been possible to study effects unobservable in the world of the , -peptides. Tests with proteolytic enzymes of all types (from mammals, microorganisms, yeasts) and in vivo examination (mice, rats, insects, plants) showed , - and , -peptides to be completely stable towards proteolysis and, as demonstrated for two , -peptides, extraordinarily stable towards metabolism, even when bearing functionalized side chains (such as those of Thr, Tyr, Trp, Lys, or Arg). The , -peptides so far examined also normally display no or only very weak cytotoxic, antiproliferative, antimicrobial, hemolytic, immunogenic, or inflammatory properties either in cell cultures or in vivo. Even biological degradation by microbial colonies of the types found in sewage-treatment plants or in soil is very slow. That there are indeed interactions of ,- and ,-peptides with biological systems, however, can be seen in the following findings: i) organ-specific distribution takes place after intravenous (i.v.) administration in rats, ii) transport through the intestines of rodents has been observed, iii) , -peptides with positively charged side chains (Arg and Lys) settle on cell surfaces, are able to enter into mammalian cells (fibroplasts, keratinocytes, HeLa cells), and migrate into their cell nuclei (and nucleoli), and iv) in one case, it has already been established that a , -peptide derivative can up- and down-regulate gene expression rates. Besides these less sharply definable interactions, it has also been possible to construct , - and , -peptide agonists of naturally occurring peptide hormones, MHC-binding , -peptides, or amphipathic , -peptide inhibitors of membrane-bound proteins in a controlled fashion. Examples include somatostatin mimics and the suppression of cholesterol transport through the intestinal brush-border membrane (by the SR-BI-protein). The results so far obtained from investigations into peptides made up of homologues of the proteinogenic amino acids also represent a contribution to deepening of our knowledge of the natural peptides/proteins, while potential for biomedicinal application of this new class of substances has also been suggested. [source]