Synergistic interactions mixtures

At present, considerable interest is drawn to the use of natural mixtures of antioxidants isolated from various vegetable materials. Some authors claim that such mixtures manifest stronger antioxidant effects than individual components due to synergistic interactions. It is of course quite possible, but it should be noted that synergistic interactions are not a single mechanism of the interaction between components for example, the simultaneous presence of the antioxidant and prooxidant flavonoids might diminish summary antioxidant effect of the mixture. Furthermore, natural mixtures contain, as a rule, some unknown compounds, which affect the summary effect by unknown manner. 

A possible interaction of many oestrogenic chemicals in the environment with the human oestrogen receptor has received publicity. A warning was actually issued that the synergistic interaction of mixtures of several low-dose environmental chemicals with the hER may have negative consequences on fertility. However, these fears seem to be unfounded.21... 

Paradossi, G., Chiessi, E., Barbiroli, A., and Fessas, D. 2002. Xanthan and glucomannan mixtures Synergistic interactions and gelation. Biomacromolecules 3 498-504. 

Care should be exercised when toxicants affecting more than one organ system are combined that the potentiation or synergistic interactions are considered, because certain substances can cause target organ toxicity at <1% concentration when other ingredients in the mixture are known to potentiate its toxic effect. 

Knowledge on the type of interaction is of profound importance. While the knowledge on synergistic interaction is of paramount public health importance, the knowledge on antagonistic interaction is necessary to reduce the unnecessary utilization of resources for cleanups. Because of the potential unexpected toxicity due to interaction of chemicals, toxicology of mixtures is an active area of scientific investigation. 

Pesticide mixtures have been found to exhibit greater than additive effects when administered together. These enhanced effects may be due to the actions of the pesticides themselves, the presence of so-called inert ingredients in their formulations, synergistic interaction with other environmental pollutants, or combinations of these. 

The basic limitation of the equation for potency-weighted dose additivity used in the HI and TTD approaches is that it does not show the influence of interactions on the overall joint toxicity of mixture. As a result the mixtures risk estimates can be either under- or overpredicted [1,14,20,21], The National Academy of Sciences has proposed the use of additional safety factors if synergistic interactions are of concern [23]. 

LDLDs are mixtures of surfactants. Surfactant mixtures often perform better than the sum of the individual surfactant contributions, or perform synergisti-cally. The origin of this synergistic interaction is head group interactions and is dipolar in nature. The surfactant pairs having the greatest dipolar forces have the... 

Mixtures of two or more different types of surfactants often show a synergistic interaction, i.e., the interfacial properties of the mixture are more pronounced than those of the individual components by themselves. As a result, in many industrial products and processes, mixtures of different types of surfactants, rather than individual materials, are used. A study of the adsorption of the individual surface-active components in the mixture and of the interaction between them affords an understanding of the role of each and makes possible the selection in a rational, systematic manner of components for optimal properties. 

With over 200 hydrocarbons present in JP-8, there is the possibility of toxicokinetics- and toxicodynamics-related antagonistic, additive, and synergistic interactions among various hydrocarbon components. The toxicokinetic parameters of individual chemicals in a complex mixture such as JP-8 are very different from the toxicokinetic profiles of individual chemicals. Chemical-chemical interactions may be related to mutual induction of competing metabolic and elimination pathways or mutual inhibition of absorption, distribution, metabolism, and excretion. Similar CYP450 enzymes and phase II conju-gative metabolic pathways metabolize many alkane hydrocarbons (NRC1996). 

Conflicting information has been pubUshed on the relative extents of extraction of U and UOj " by dioctyl pyrophosphate. The reduction of the feed acid, which is done in the commercial process, may serve mainly to minimize the coextraction of iron(III), which is extracted much more strongly than iron(II). The uranium(IV) complexes extracted by dialkyl pyrophosphate have been reported to be of the type U(R2HP20v)4, 2 and those of uranium(VI) to be of the type U02(R2P207). However, some doubt was subsequently cast on these conclusions when it was found that the dioctyl pyrophosphate used, which had been prepared by the action of octanol upon phosphorus pentoxide, was a complex mixture of products.Indeed, the strong extractive power of this reagent towards uranium(IV) appears to be the result of a fortuitous synergistic interaction between the components of the mixture. ... 

One potential limitation in the use of bioassay-guided fractionation is revealed when a pheromone or other natural product under study is a mixture and the full expression of that mixture s bioactivity requires the simultaneous presence of several or all of its compounds. For example, if more than one fraction has components of the mixture but each fraction contributes a small portion of the mixture s activity, then identification of the bioactive molecules can be difficult. Another example is when there are synergistic interactions among bioactive molecules in different fractions, such that once fractionated, no single fraction has activity. 

Binks BP, Rodrigues JA, Frith WJ (2007) Synergistic interaction in emulsions stabilized by a mixture of sflica nanoparticles and cationic surfactant. Langmuir 23(7) 3626-3636... 

However, in the daily practice of the application of surfactants there is in most cases an interaction of the surfactant mixtures with the extended surfaces of solids. This leads to a decrease in the amount of the most surface-active components in the solution by adsorption at the solid surface. Any synergisms observed in laboratory tests will therefore not occur any more, and a shift of the synergistic effects to higher concentrations will be observed. This changes drastically the proportion of the synergistic-effective mixture. Especially in systems... 

Assessing the effects of pollutants on aquatic ecosystems is complicated by the fact that trace contaminants generally appear as mixtures, often as complex suites of trace metals and organics. This is particularly true for many industrial wastes. Coal-ash effluents may contain significant concentrations of up to 20 or more metals 13, 59). To evaluate the combined toxicity of metal mixtures, more information is required concerning possible antagonistic, additive, or synergistic interactions. 

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