Synergistic Effect Of Mixture Research Articles

The synergistic effects of a leaf mixture on decomposition change with a period of terrestrial exposure prior to immersion in a stream.

The effect of mixing litter on decomposition has received considerable attention in terrestrial and aquatic (but rarely in both) ecosystems, with a striking lack of consensus in the obtained results. We studied the decomposition of a mixture of poplar and alder in three terrestrial: aquatic exposures to determine (1) if the effect of mixing litter on mass loss, associated decomposers (fungal biomass, sporulation rates, and richness), and detritivores (abundance, biomass, and richness of invertebrate shredders) differs between the stream (fully aquatic exposure) and when litter is exposed to a period of terrestrial exposure prior to immersion and (2) the effect of the mixture across exposure scenarios. The effect of the mixture was additive on mass loss and synergistic on decomposers and detritivores across exposure scenarios. Within scenarios, mass loss and decomposers showed synergistic effects only in the fully aquatic exposure, detritivores showed synergistic effects only when the period of terrestrial was shorter than the period of aquatic exposure, and when the period of terrestrial was equal to the period of aquatic exposure the effect of the mixture was additive on mass loss, decomposers, and detritivores. The species-specific effects also differed among exposure scenarios. Alder affected poplar only when there was a period of terrestrial exposure, with increased sporulation rates and fungal richness in exposure 25:75, and increased mass loss in exposure 50:50. Poplar affected alder only under fully aquatic exposure, with increased mass loss. In conclusion, the synergistic effects of the mixture changed with a period of terrestrial exposure prior to immersion. These results provide a cross-boundary perspective on the effect of mixing litter, showing a legacy effect of exposure to terrestrial decomposition on the fate of plant litter in aquatic ecosystems and highlighting the importance of also assessing the effect of mixing litter on the associated biota and not only on mass loss.

Biochemical basis of resistance to multiple contaminations in the native and invasive populations of Dreissena polymorpha

The zebra mussel Dreissena polymorpha (Pallas, 1771) is an invasive species and a valuable bioindicator in the inland waters. Nevertheless, the biochemical reasons for the unique competitiveness of zebra mussels are not clear. This study aimed to compare the native and invasive populations of D. polymorpha in their ability to withstand the same multiple environmental challenges (i.e. chemical: microplastics and caffeine; physical: temperatures). The specimens from the invasive population in west Ukraine (Tn) and native population at lower streams of river Dnipro (south Ukraine, Kh) were sampled in the August of 2021 y. Molluscs from both populations were treated simultaneously with microplastics (MP, 1 mg L−1, pore size 2 μm); caffeine (Caf, 20.0 μg L−1) at 18 °C, elevated temperature (25 °C) and MP and Caf combinations at 18 °C and 25 °C for 14 days. Untreated molluscs exposed at 18 °C represented control groups. A set of the 20 markers of oxidative stress, biotransformation, detoxification and apoptosis were assayed in the total soft tissues. From the two controls, Kh-group indicated lower stressful impact. However, both populations increased caspase-3 and GST activities and lysosomal instability in most exposures, and cholinesterase and phenoloxidase activities under the heating and combine exposures, indicating the remarkable properties to respond to new challenges and synergistic effect of mixtures. Inter-population differences were related to the metallothionein, cathepsin D, cytochrome P540 and oxidative stress responses that reflect population-dependent adverse outcome pathways. The discriminant analysis separated two populations with a substantially lesser magnitude of responses in the invasive population as a sign of higher resistance.

Invited Perspective: Challenges in Evaluating the Effect of Per- and Polyfluoroalkyl Substance Mixtures on Polycystic Ovarian Syndrome

Invited Perspective: Challenges in Evaluating the Effect of Per- and Polyfluoroalkyl Substance Mixtures on Polycystic Ovarian Syndrome

Enhancement of polypropylene mechanical behavior by the synergistic effect of mixtures of carbon nanofibers and graphene nanoplatelets modified with cold propylene plasma

AbstractIncorporating carbon nanoparticles (CNPs) into polymers can enhance their mechanical behavior; however, enhancement depends strongly on compatibility and homogeneous dispersion. Actual methods to succeed high dispersion and compatibility are complicated, have solvent‐associated problems, and long processing times. The present work proposes the increase of the dispersion and compatibility of CNPs in a polypropylene (PP) matrix to obtain a nanocomposite with high mechanical properties, using simple, fast, and green methodologies: the modification of the CNPs by cold propylene plasma and the synergistic effect resulting from mixtures of carbon nanofibers (CNFs) and graphene nanoplatelets (GNPs) with PP matrix by melt mixing. Mixtures of CNFs and GNPs in 9:1, 8:2, and 7:3 ratios at 1 and 5 wt/wt% with and without surface modification by cold propylene plasma were fabricated. The compatibility and dispersion of the CNPs in the PP matrix were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy, and the results were related to the mechanical properties. The results show that the use of mixtures improved the dispersion in the system and hindered the reagglomeration of CNPs, whereas surface modification with plasma promotes higher compatibility between the phases. The elastic modulus of PP reached an increase of 127.40% using a modified mixture by plasma in a 7:3 ratio (CNF:GNPs) at 5 wt/wt%, while when the CNPs were used individually, the modified CNFs and GNPs at 5 wt/wt%, reached 97.77% and 111.85%, respectively. In addition, a finite element analysis shows that the stresses in nanocomposites fabricated with mixtures of CNPs are supported to a greater extent by GNPs than CNFs due to their morphology with a low number of graphene sheets, which allows them to have greater flexibility.

Comparing the Effects of Encapsulated and Non-Encapsulated Propolis Extracts on Model Lipid Membranes and Lactic Bacteria, with Emphasis on the Synergistic Effects of Its Various Compounds.

Propolis is a resinous compound made by bees with well-known biological activity. However, comparisons between encapsulated and non-encapsulated propolis are lacking. Therefore, the antibacterial activity, effect on the phase transition of lipids, and inhibition of UV-induced lipid oxidation of the two forms of propolis were compared. The results showed that non-encapsulated propolis produces quicker effects, thus being better suited when more immediate effects are required (e.g., antibacterial activity). In order to gain an in-depth introspective on these effects, we further studied the synergistic effect of propolis compounds on the integrity of lipid membranes. The knowledge of component synergism is important for the understanding of effective propolis pathways and for the perspective of modes of action of synergism between different polyphenols in various extracts. Thus, five representative molecules, all previously isolated from propolis (chrysin, quercetin, trans-ferulic acid, caffeic acid, (-)-epigallocatechin-3-gallate) were mixed, and their synergistic effects on lipid bilayers were investigated, mainly using DSC. The results showed that some compounds (quercetin, chrysin) exhibit synergism, whereas others (caffeic acid, t-ferulic acid) do not show any such effects. The results also showed that the synergistic effects of mixtures composed from several different compounds are extremely complex to study, and that their prediction requires further modeling approaches.

Occurrence, distribution, and environmental risk of pharmaceutical residues in Mombasa peri-urban creeks, Kenya

The information on pharmaceutical compounds' distribution and their possible risks in marine ecosystems along the Kenya coast is limited especially in the peri-urban creeks. Hence, this study aimed to determine pharmaceutical residue levels and distribution in selected peri-urban creeks in Mombasa and Gazi bay. The target compounds were analgesic (acetaminophen), antibiotics (trimethoprim and sulfamethoxazole), antiepileptic (carbamazepine), and antiretroviral (nevirapine). Pharmaceutical residues in grab surface seawater in wet and dry seasons ranged from below detection limit (BDL)-1065.6 μg L−1 and BDL-71.3 μg L−1, respectively. The concentration of the pharmaceutical residues was high in Tudor creek in the dry and wet seasons with a mean concentration of 63.3 μg L−1 and 233.1 μg L−1 respectively compared to Makupa creek (dry season, 54.2 μg L−1; wet season 16.2 μg L), and Mtwapa creek (dry season, 43.1 μg L−1; wet season, 15.0 μg L−1). Gazi Bay being used as a control site had a mean concentration of 21.3 μg L−1 and 3.1 μg L−1 during the dry season and wet season respectively. Acetaminophen and nevirapine were the most ubiquitous compounds in seawater since they were found in all seawater samples collected. Risk quotients (RQ) for invertebrates and algae based on the mean concentrations of the analytes were estimated to provide a preliminary environmental risk assessment. The results suggest that the studied acetaminophen, trimethoprim, sulfamethoxazole, and carbamazepine in seawater pose low (0.01 ≤ RQ < 0.1) to medium (0.1 ≤ RQ < 1) ecological risk whereas nevirapine poses medium to high (RQ ≥ 1) ecological risk to the ecosystems of Mombasa periurban creeks and Gazi bay. Further research, however, is encouraged on the distribution of pharmaceuticals in the marine environment and the long-term synergistic effects of mixtures of these compounds on marine biota.

SAHmap: Synergistic-antagonistic heatmap to evaluate the combined synergistic effect of mixtures of three pesticides on multiple endpoints of Caenorhabditis elegans

The environmental pollution caused by toxic chemicals such as pesticides has become a global problem. The mixture of dichlorvos (DIC), dimethoate (DIM), aldicarb (ALD) poses potential risks to the environment and human health. To fully explore the interaction of complex mixtures on Caenorhabditis elegans behavioral toxicity endpoint. This study created a synergistic-antagonistic heatmap (SAHmap) based on the combination index to systematically describe the toxicological interaction prospect of the mixture system. It was shown that the three pesticides and their binary as well as ternary mixture rays have significant concentration-response relationship on three behavioral endpoints of nematodes, From the perspective of synergistic-antagonistic heatmaps, all the mixture rays in the DIC-DIM mixture system showed strong synergism on the three behavioral and lethal endpoints. In the ternary mixture system, the five mixture rays showed different interaction between the behavioral endpoint and the lethal endpoint, and showed slight synergism to two behavioral endpoints as a whole. The emergence of synergism should arouse our attention to these hazardous chemicals. In addition, the use of SAHmap and the significant linear correlation among three behavioral endpoints further improved the efficiency of the study on the behavioral toxicity of pesticide mixtures to Caenorhabditis elegans.

Benchmark dose in the presence of coexposure to melamine and diethylhexyl phthalate and urinary renal injury markers in pregnant women

Environmental exposures to mixtures of toxic chemicals have potential interaction effects that may lead to hazard index values exceeding one. However, current regulation levels, such as tolerable daily intake (TDI), are mostly based on experimental studies conducted with a single chemical compound. In this study, we assessed the relationships between melamine and di-(2-ethylhexyl) phthalate (DEHP) exposure and their coexposure with the early renal injury markers N-acetyl -D-glucosaminidase (NAG), albumin/creatinine ratio (ACR), and microalbuminuria in 1236 pregnant women. Various generalized linear models with interaction terms and Bayesian kernel machine regression models were used for the (co-)exposure response associations. We derived the benchmark dose (BMD) and the corresponding one-sided 95% confidence bound BMDL based on the estimated (covariate-adjusted) average daily intake of melamine and DEHP metabolites measured in spot urine of the women collected during the third trimester. Given a benchmark response of 0.1, the BMDL level of melamine (DEHP) exposure on NAG (ACR, microalbuminuria) was 2.67 (11.20, 4.45) μg/kg_bw/day, and it decreased to as low as 1.46 (3.83, 2.73) μg/kg_bw/day when considering coexposure to DEHP (melamine) up to the 90th percentile. Both the exposure threshold levels of melamine and DEHP for early renal injuries in pregnant women were several-fold to one order lower than the current recommended TDIs by the WHO and the US FDA and EPA and were even lower considering coexposure. Because of concurrent exposures in real-world environments, more stringent regulation levels are recommended in susceptible populations, such as pregnant women, due to potential synergistic mixture effects.

Cyanoacetylurea as a Thermal Stabilizer for Poly(vinyl chloride)

ABSTRACT Poly(vinyl chloride) (PVC) has been widely used in many fields due to its excellent comprehensive properties, although its thermal stability is poor. In the article, a urea derivative, cyanoacetylurea, is prepared and its structure is characterized by means of FTIR and 1H-NMR. The stabilization effect of cyanoacetylurea on PVC thermal stabilization is evaluated by thermogravimetric analysis (TGA), thermal aging test and Congo red test. Meanwhile, the processability of PVC stabilized by cyanoacetylurea is investigated through dynamic performance test. Compared with calcium stearate (CaSt2) and zinc stearate (ZnSt2), cyanoacetylurea shows higher stabilization effect on PVC thermal stabilization than CaSt2 and ZnSt2. Also, the synergistic effect of mixtures of cyanoacetylurea, CaSt2 and ZnSt2 on PVC thermal stabilization is investigated. At last, the stabilization mechanism is discussed and cyanoacetylurea is able to absorb hydrogen chloride and to add hydrogen chloride on the carbonyl group, as well as postpone “zinc burning.” The results show that cyanoacetylurea presents a good thermal stabilization efficiency and can be a potential organic thermal stabilizer for PVC.

Synergistic effects of microbial polysaccharide mixing with polymer and nonionic surfactant on rheological behavior and enhanced oil recovery

A novel sphingan WL was mixed with an anionic polyacrylamide (APAM) and a nonionic surfactant (Brij 35). The viscosity and rheological properties of the two mixtures were systematically investigated. An obvious increase in viscosity was observed for the mixed solution containing WL and APAM in a ratio of 9:1. The two inflection points on the surface tension curve indicated intermolecular interactions between WL and Brij 35. The combination of WL and the APAM or WL and Brij 35 resulted in the formation of networks in the solution through electrostatic interactions and hydrogen bonding interactions. Moreover, the rheological properties of WL-APAM were observed to be maintained under high temperature and high salinity conditions, and the WL-Brij 35 could tolerate high temperature, too. The mixtures of WL–APAM and WL–Brij 35 with only 0.035 wt% WL could enhance the oil displacement efficiencies by 21.31% and 22.17%, respectively. Therefore, the synergistic effects between exopolysaccharides and polymers/surfactants were demonstrated to improve oil recovery. • WL-APAM mixture has a positive synergistic effect on solution viscosity. • Interaction between WL and Brij 35 was proved through surface tension measurement. • Intermolecular interactions improved the solution's salt and temperature tolerance. • The synergistic effect of mixtures improved their oil displacement ability in EOR.

Enhancement of a foaming formulation with a zwitterionic surfactant for gas mobility control in harsh reservoir conditions

This work presents the design of a robust foam formulation that tolerates harsh reservoir conditions (high salinity, high divalent ion concentration, high temperature, light oil, and hydrocarbon injection gas) in a sandstone reservoir. For this, we selected anionic Alpha Olefin Sulfonate (AOS) surfactants and studied their synergistic effects in mixtures with zwitterionic betaines to enhance foam performance. The laboratory workflow used to define the best formulation followed a de-risking approach in three consecutive phases. First, (phase 1) the main surfactant (AOS) was selected among a series of commercial candidates in static conditions. Then, (phase 2) the betaine booster to be combined with the previously selected AOS was chosen and their ratio optimized in static conditions. Subsequently, (phase 3) the surfactant/booster ratio was optimized under dynamic conditions in a porous medium in the absence and the presence of oil. As a result of this study, a mixture of an AOS C14–C16 and cocamidopropyl hydroxysultaine (CAPHS) was selected as the one having the best performance. The designed formulation was proven to be robust in a wide range of conditions. It generated a strong and stable foam at reservoir conditions, overcoming variations in salinity and foam quality, and tolerated the presence of oil.

Correlated Ni, Cu, and Zn Sensitivities of 8 Freshwater Algal Species and Consequences for Low-Level Metal Mixture Effects.

Predicting metal sensitivities and metal mixture interactions for species within each trophic level is essential to understand the effects of metals at the ecosystem level. The present study was set up to explore the correlations of metal sensitivities among species and if these sensitivities or metal mixture interactions are related to growth or morphological traits. The toxicity of Ni, Cu, and Zn on algal growth was tested for 8 freshwater algal species when dosed singly and in combinations in phosphorus-limiting static systems. The metal sensitivities on specific growth rate (10% effect concentrations expressed as free ion activities) varied 2 to 3 orders of magnitude among species depending on metal. These sensitivities were unrelated (p > 0.05) to their specific growth rate (0.7-1.8 d-1 ) or cell volume (100 -103 m3 cell-1 ). Species-specific differences in one or more toxicokinetic and/or toxicodynamic (TKTD) processes are likely at the basis of this variation. The log-transformed metal sensitivities positively correlated (p < 0.1) among the species in all 3 binary combinations (Ni-Cu, Ni-Zn, and Cu-Zn), suggesting that species have correlated TKTD rates for these metals. Furthermore, they would also predict stronger effects of metal mixtures on algal community biodiversity than what would be expected without a positive correlation. Low-level metal mixture effects varied similarly, largely among species and mixture interactions that were highly variable: ranging from synergistic to antagonistic relative to independent action during exponential growth, whereas mixture interactions at 10% effect shifted toward additivity/synergism relative to concentration addition at carrying capacity. Some evidence was found for stronger synergistic mixture effects in smaller species. Overall, the present study highlights the importance of incorporating more species in sensitivity distributions and accounting for mixture toxicity in risk assessment. Environ Toxicol Chem 2021;40:2015-2025. © 2021 SETAC.

Poloxamine/D-α-Tocopheryl polyethylene glycol succinate (TPGS) mixed micelles and gels: Morphology, loading capacity and skin drug permeability

The combination of polymeric surfactants with different features into mixed micelles give access to properties that may be superior to the single-component micelles. In this work, we investigated synergistic effects in mixtures of D-α-Tocopheryl polyethylene glycol succinate (TPGS) with poloxamines (also known as Tetronic), pH-responsive and thermogelling polyethylene oxide (PEO)-polypropylene oxide (PPO) 4-arm block copolymers. We examined the morphology of the self-assembled micelles of TPGS with Tetronic 1107 (T1107) and 908 (T908) in the presence of naproxen (NA), used as a model drug, and assessed the capacity of the single and mixed micelles to trap the guest, using a combination of small-angle neutron scattering (SANS) and NMR spectroscopy (1D, 2D-NOESY and diffusion NMR), over a range of compositions and temperatures, in the dilute regime and gel state. NA did not interact with T1107 or T908 in their unimer form, but it was incorporated into the hydrophobic core of the micelles above the critical micellar temperature (CMT). In contrast, TPGS dissolved NA at any temperature, mainly in the tocopherol core, with some partitioning in the PEG-shell. The micellar structure was not altered by the presence of NA, except for an expansion of the core size, a result of the preferential accumulation of NA in that compartment. The solubility of the drug in single component micelles increased markedly with temperature, while mixed micelles produced an intermediate enhancement of the solubility between that of TPGS and the poloxamines, which increased at higher TPGS/poloxamine ratios. Micellar hydrogels formed by the packing of the polymeric mixed micelles in a BCC macrolattice, whose structure was not altered by the presence of the drug (at least at 0.2 wt%). The applicability of the drug-loaded gels for topical formulations was explored by transdermal diffusion testing using a synthetic model of skin, showing that the diffusion of NA across the membrane was enhanced by incorporating small amounts of TPGS to the hydrogel, especially with the more hydrophilic T908.

New Conceptual Toxicokinetic Model to Assess Synergistic Mixture Effects between the Aromatic Hydrocarbon β-Naphthoflavone and the Azole Nocodazole on the CYP1A Biomarker in a Fish Cell Line.

Toxicokinetic interactions with catabolic cytochrome P450 (CYP) enzymes can inhibit chemical elimination pathways and cause synergistic mixture effects. We have created a mathematical bottom-up model for a synergistic mixture effect where we fit a multidimensional function to a given data set using an auxiliary nonadditive approach. The toxicokinetic model is based on the data from a previous study on a fish cell line, where the CYP1A enzyme activity was measured over time after exposure to various combinations of the aromatic hydrocarbon β-naphthoflavone and the azole nocodazole. To describe the toxicokinetic mechanism in this pathway and how that affects the CYP1A biomarker, the model uses ordinary differential equations. Local sensitivity and identifiability analyses revealed that all the 10 parameters estimated in the model were identified uniquely while fitting the model to the data for measuring the CYP1A enzyme activity. The model has a good prediction power and is a promising tool to test the synergistic toxicokinetic interactions between different chemicals.

Morphology, gelation and cytotoxicity evaluation of D-α-Tocopheryl polyethylene glycol succinate (TPGS) – Tetronic mixed micelles

HypothesisThe combination of polymeric surfactants into mixed micelles is expected to improve properties relevant to their use in drug delivery, such as micellar size, gelation, and toxicity. We investigated synergistic effects in mixtures of D-α-Tocopheryl polyethylene glycol succinate (TPGS), an FDA-approved PEGylated derivative of vitamin E, and Tetronic surfactants, pH-responsive and thermogelling polyethylene oxide (PEO)-polypropylene oxide (PPO) 4-arm block copolymers. We hypothesized that mixed micelles would form under specific conditions and provide a handle to tune formulation characteristics. ExperimentsWe examined the morphology of the self-assembled structures in mixtures of TPGS with two Tetronic: T1107 and T908, using a combination of dynamic light scattering (DLS), small-angle neutron scattering (SANS), NMR spectroscopy (NOESY and diffusion NMR) and oscillatory rheology, over a range of compositions, temperatures and pH. Cell viability was assessed in NIH/3T3 fibroblasts. FindingsThe combination of TPGS with either of the two Tetronic produces spherical core-shell micelles that comprise both surfactants in their structure (mixed micelles). T1107 unimers incorporate into TPGS aggregates below the critical micelle temperature of the poloxamine, while mixed micelles only form under limited conditions with T908. At high concentration/temperature, small proportions of TPGS extend the gel phase, more markedly with T1107, with similar elastic moduli (30–50 kPa) and a BCC crystalline structure. Cell viability of NIH/3T3 fibroblasts grown in the hydrogels increases significantly when the poloxamine gels are doped with TPGS, making the combination of poloxamines and TPGS a promising platform for drug delivery.

Liquid-liquid extraction of cobalt(II) and zinc(II) from aqueous solutions using novel ionic liquids as an extractants

Abstract Extraction efficiencies of Co(II) and Zn(II) from aqueous phase with new ionic liquids (ILs) in comparison with already studied in literature ILs, but without addition of acids and at low temperatures are presented. Thus the new, environmental-friendly method of extraction of metal ions is proposed. A novel ammonium ILs, benzyldimethyloctadecylammonium bis(2,4,4-trimethylpentyl)phosphinate [NBz,1,1,18][BTMPP], didecyldimethylammonium saccharinate, [N10,10,1,1][SACH] and didecyldimethylammonium acesulfamate, [N10,10,1,1][ACE] were synthesized and used between others for this extraction. The solvent extraction behavior was compared to well known in this process ILs: methyltrioctylammonium chloride ([N8,8,8,1][Cl]), Aliquat 336, trihexyltetradecylphosphonium chloride, ([P6,6,6,14][Cl]), Cyphos IL 101 and trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate, ([P6,6,6,14][BTMPP]). Extraction was provided with pure ILs and with addition of complexion agents, such as: 18-crown-6, 24-crown-8, alkanes C24H50, C27H56, Triton TM X-100 and L-histidine. It was shown that quick and efficient extraction, where >90% of Co(II) and Zn(II) may be obtained using pure IL, or with additives, using synergistic effects of mixture of two ILs, or using ILs in Aqueous Biphasic Systems (ABS) method with NaCl at low temperature T = 303 K. The tributyltetradecylphosphonium chloride, [P4,4,4,14][Cl], tetraoctylphosphonium bromide, [P8,8,8,8][Br], and benzalkonium chloride [NBz,1,1,R][Cl] (R = C12H25–60%; C14H29–40%) were used in ABS experiment. The extraction behavior was carried out also using Deep Eutectic Solvents, DES non miscible with water, which presented lower efficiency. The extraction process confirmed the large efficiency and distribution ratio using [P6,6,6,14][BTMPP] with addition of 18-Crown-6 at pH = 7 for Co(II), as well as using Cyphos IL 101 ([P6,6,6,14][Cl]) with addition of 18-crown-6, or Triton TM X-100, or L-histidine at pH 1 (no addition of acid) for Zn(II). The same results for Zn(II) were obtained with ABS method with {[P4,4,4,14][Cl] + NaCl + Zn (II)}. However, the best results were obtained with trihexyltetradecylphosphonium thiocyanate, [P6,6,6,14][SCN] for both metal ions.

SYNERGISTIC EFFECT OF BINARY QUERCETIN–MONOSACCHARIDE MIXTURES IN THE RE-ACTION WITH FREE RADICALS

The presence of a synergistic effect of binary mixtures of quercetin–monosaccharide in the model reaction with the 2,2'-diphenyl-1-picrylhydrazyl radical in deoxygenated ethanol was established. It was shown that the studied carbohydrates related to the tetrose, pentose and hexose groups exhibit a synergistic effect to some extent enhancing the anti-radical effect of quercetin. The synergistic effect of the mixture is determined by the number of hydroxyl substituents and by the presence of aldehyde or ketone groups in carbohydrate molecules. The synergistic compositions of quercetin with glucose and galactose in the ratio of 60:40% showed the highest antiradical activity. The maximum synergistic effect of the mixture is 75%. It is achieved due to the fact that, firstly, when dissolved in water, quercetin transforms into a tautomeric diketo form where hydrogen bonds form between its carbonyl groups and hydroxy groups of the monosaccharide, promoting the formation of molecular complexes, improving solubility of flavonoid in water and the manifestation of a synergistic effect in a mixture with carbohydrate. Secondly, reducing carbohydrates are able to restore oxidized forms of quercetin, which is confirmed by the great synergistic effect of aldose in comparison with ketoses, regardless of the number of hydroxy groups in the molecule. The synergistic effect of the quercetin–monosaccharide compositions, established in a model reaction with a hydrazyl radical, was compared to that in the autoxidation process of cottonseed oil. In the reaction with the peroxy radicals of cottonseed oil, the synergistic effect of the quercetin monosaccharide compositions increases up to 300% only for sugars capable of reducing quercetin radicals and reacting with air oxygen, reducing the steady-state concentration of peroxy radicals in the system.

Synergistic effect of mixture of two proline-rich-protein salivary families (aPRP and bPRP) on the interaction with wine flavanols

In this study, we have evaluated by HPLC-DAD, DLS and MALDI-TOF a synergic effect of the coexistence of two salivary-PRP fractions (basic-PRPs and acidic PRPs) on the interaction with flavanols. Results obtained showed noticeable enhancement of the interaction between (epi)catechin and PRPs when both types of proteins are blended. Up to 30 soluble aggregates have been tentatively identified with molecular weight from 4680 to 35,851. (epi)Catechins seem to bind preferentially bPRPs than aPRPs, although the medium size aggregates flavanol-bPRPs formed could favour the interaction with aPRPs giving rise to soluble mixed aggregates.

Synergistic Effects in Mixtures of Surface-Active Substances in the Course of Mechanical Treatment of Metals

The influence of separate surface-active substances (surfactants) and their mixtures on the surface tension of neutral aqueous salt solutions and on the microhardness of a steel is studied. To determine the dependence of these factors on the ratio of the molar concentrations of mixtures of components, we use the method of isomolar series. It is shown that the compositions of surfactants with different polarities of functional groups are characterized by the phenomenon of synergy with well-pronounced extremum at a certain ratio of the concentrations of components. Its location on the liquid-air and fluid-metal interfaces has a symbatic character, which can be explained by the mutual attraction of functional groups on different interfaces.

Synergistic effect of co-exposure to cadmium (II) and 4-n-nonylphenol on growth inhibition and oxidative stress of Chlorella sorokiniana

Toxicological effect of freshwater algae co-exposure to Cd and 4-n-nonylphenol (4-n-NP) was seldom reported. In the present study, Chlorella sorokiniana was selected for testing the single and combined effect of Cd and 4-n-NP by detecting the growth inhibition and oxidative stress after exposure for 48 h, 72 h, and 96 h. The combined effects were evaluated by using toxic units (TU) method and concentration addition（CA）model. The synergistic effect of mixture on algal growth inhibition was both observed at 48 h and 72 h, and the additive effect was observed at 96 h. In addition, the significant alterations of superoxide, thiobarbituric acid reactive substances and antioxidant defenses (superoxide dismutase, catalase, glutathione) have been detected. It could be observed that the mixture predominantly lead to synergistic effects in superoxide induction, and the antagonistic effects in the GSH induction. A similar trend between the superoxide induction and growth inhibition were observed, which may indicate that the oxidative effects of Chlorella sorokiniana contributed to the growth inhibition after exposure to Cd and 4-n-NP. These findings may have important implications in the risk assessments of heavy metals and endocrine disruptors in the aquatic environment.