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Results for “Polysorbates”

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At least 19 recordsLinked to original sources

PubMed1979

Additivity of action between polysorbate 80 and polymyxin B towards spheroplasts of Pseudomonas aeruginosa NCTC 6750.

When polymyxin B and polysorbate 80 were used together against spheroplasts of Pseudomonas aeruginosa, the activities were found to be additive. These substances have previously been reported to act synergistically against P. aeruginosa, but little or no intrinsic activity towards intact cells has been attributed to polysorbate 80. We suggest that in addition to enhancing polymyxin B penetration to the cytoplasmic membrane, polysorbate 80 may also act as an antimicrobial agent when polymyxin-induced damage to the outer membrane facilitates the surfactant's passage through the cell envelope.

Polyethylene Glycols↗

PubMed1975

Effect of polysorbate 60 on interphase transport of cholesterol.

Interphase cholesterol transport was investigated at 24 +/- 1 degrees in a stirred diffusion cell and in various oil-in-water emulsions. Cholesterol uptake by vegetable oil from a cholesterol-surfactant-rich aqueous phase was extremely slow in the stirred cell; no measurable transport had occurred after 500 hr. Cholesterol transport in oil-in-water emulsions following dilution with a cholesterol-surfactant-rich aqueous phase was much faster due to the greatly increased interfacial area available for mass transfer. Equilibration half-lives, t(50), varied from 2.02 to 28.1 hr. Variations in the t(50) were due to: (a) differences in the mean oil droplet diameter among various emulsions, and (b) differences in cholesterol-polysorbate 60 micelle sizes among various dilution media. When polysorbate 60 was omitted from the dilution medium, transport occurred in a two-stage process. In the first stage, transport was extremely rapid, with the t(50) less than 30 sec; in the second stage, transport was comparable to previous emulsion rates, with the t(50) varying from 7.9 to 8.1 hr. The significance of this two-stage transport to mechanisms of interphase cholesterol transport is briefly discussed.

Cholesterol↗

PubMed1977

Effect of sorbitol on interaction of phenolic preservatives with polysorbate 80.

The effect of sorbital on the binding of several commonly used phenolic preservatives (i.e., p-hydroxybenzoic acid, methylparaben, ethylparaben, and propylparaben) with the nonionic surfactant polysorbate 80 was investigated using an equilibrium dialysis technique. The binding data were expressed in the form of Scatchard plots utilizing a modified form of the Scatchard equation. The data analysis indicated that all four phenolic preservatives were bound to two distinct loci within the polysorbate micelle; one exhibited a high affinity and a low capacity for the preservative molecules, while the other appeared to have a near-zero affinity but an almost infinite binding capacity. The high affinity site was assumed to be located near the junction of the hydrocarbon core with the polyoxyethylene region of the micelle. The interaction of the preservatives with the second class of sites apparently involved a non-specific and nonsaturable partitioning of the preservative molecules into the polyoxyethylene region of the micelle. Sorbitol was ineffective in displacing significant amounts of bound preservative from either binding site, presumably because it was too polar to partition into the micelle sufficiently to displace bound preservative.

Chemical Phenomena↗

PubMed1978

Autoxidation of polysorbates.

Aqueous solutions of polysorbate 20 undergo autoxidation on storage, with the peroxide number increasing and subsequently decreasing again, the acidity increasing continuously, the pH and surface tension falling and tending to level off, and the cloud point dropping sharply until turbidity begins at room temperature. The changes are accelerated by light, elevation of temperature, and a copper sulfate catalyst. At the same time, hydrolysis occurs, liberating lauric acid. Analysis of the alterations in these properties leads to the conclusion that hydrolysis has the major influence near room temperature and that oxyethylene undergoes chain shortening at temperatures above 40 degrees. However, evidence of degradation is detectable even in previously unopened commercial samples of polysorbates 20, 40, and 60, warranting attention to the stability of and standards for these surfactants as compared with the solid alkyl ether type of nonionic surfactant.

Chemical Phenomena↗

PubMed1978

Quantitative determination of polysorbate to in non-standard salad dressings.

Six samples of non-standard salad dressing, containing 0.10 to 0.60% polysorbate 60, were submitted to 6 collaborators. The salad dressing is extracted and the extract is saponified and acidified, and the acids are removed. The aqueous, polyol solution is desalted and the polyoxyethylated polyols are precipitated as a highly insoluble heteropoly acid complex. The polysorbate 60 content is calculated from the weight of the precipitate, using a gravimetric factor. Average recoveries from the collaboration samples ranged from 105 to 130%, with standard deviations from 0.016 to 0.047. The method has been adopted as official first action.

Food Additives↗

PubMed1975

Effect of polysorbate 85 on human skin.

Ten percent polysorbate 85, a nonionic surfactant, was applied on the upper arm of 15 healthy individuals under occlusive dressing daily for 4 days. The other arm was similarly treated with the ointment base (white petrolatum USP) to provide the control area. At the end of treatment, macroscopic observations indicated minor erythema in 11 cases and no visible changes were noted on the surfactant-treated areas of 4 persons or any of the control areas. No definite histologic changes were observed by microscopic evaluations. The results of biochemical assays, however, were more definitive. The content of the epidermal phospholipids was elevated within a range of 5 to 65 percent as a result of the treatment with polysorbate 85 preparation. Radioactive tracer studies indicated higher rates of 32P incorporation into epidermal phospholipids, TCA-soluble, DNA and RNA fractions of the surfactant-treated skin. Results resemble those that were documented in earlier studies with rabbit skin.

Adult↗

PubMed1975

Interaction of substituted benzoic acids with polysorbate 20 micelles.

Equilibrium solubilities of a series of substituted benzoic acids in different concentrations of polysorbate 20 at controlled pH were measured. The maintenance of pH was achieved using a pH-stat assembly. A linear relationship was found between the amount of benzoic acid solubilized and surfactant concentration. As solubilizate polarity increased, the amount solubilized also increased. Solubility data were analyzed, and the interaction between solubilizate molecules and micelles was calculated in terms of partition coefficients of ionized and unionized molecules between aqueous and micellar phases. A linear relationship between pi values (log partition coefficients) of functional groups and aqueous-micellar partition coefficient was found.

Benzoates↗

PubMed1975

In vivo method for monitoring polysorbate 85 effect on epidermal permeability.

An in vivo method of monitoring the rate of water desorption from human forearms, using "dry" nitrogen gas passed over approximately 1 cm-2 of skin was investigated with the aid of a commercial electrolytic moisture analyzer. The assembled apparatus was used to evaluate the differences in water loss rates from treated and untreated (control) forearms following surfactant application. The changes in the differences were also monitored after cessation of treatment, i.e., during the healing process. The apparatus provided an accurate, rapid, and painless method of monitoring relative water loss rates and, as such, could prove a useful tool in routine testing in experimental dermatology and cosmetology. The results confirm the earlier finding from an in vitro method with excised rabbit skin that the tested surfactant increases the permeability of the epidermis.

Adult↗

PubMed1976