Effect of Temperature on the Critical Micelle Concentration and Micellization Thermodynamic of Nonionic Surfactants: Polyoxyethylene Sorbitan Fatty Acid Esters

In this study, non-ionic surfactants, polyoxyethylene sorbitan fatty acid esters (polysorbate) are chosen to examine the temperature effect on the CMC over a wide temperature range. The enthalpy and entropy of micelle formation are evaluated according to the phase separation model. The surface tension of solutions was determined by means of Du Nöuys ring. The CMC values were taken from the sharp breaks in the surface tension vs. logarithms of surfactant concentration plots. As the surfactants’ chain length increases the CMC at a constant temperature decreases, which is directly related to the decrease of hydrophilicity of the molecules. For each surfactant, as the system temperature increases, the CMC initially decreases and then increases, owing to the smaller probability of hydrogen bond formation at higher temperatures. The onset of micellization tends to occur at higher concentrations as the temperature increases. To evaluate the enthalpy of micellization, the CMCs are first correlated by a polynomial equation. It is found that ΔG°m decreases monotonically as the temperature increases over the whole temperature range. Both ΔH°m and ΔS°m appear to be decrease monotonically with an increase in temperature. The compensation temperature was found to be 42 oC by linear regression over the whole temperature range and for all three surfactant systems together

Evaluating the toxicity of permeability enhanchers of polyethylene glycol brij ethers surfactants group on cellular membranes and some of their physicochemical properties

The aim of this study is to evaluate the effect of polyethylene glycol brij ethers surfactants group on red blood cells as a model for biological membranes. Also in this study, physicochemical properties including emulsification index (E24), foam producing activity (Fh) and critical micelle concentration (cmc) were studied. Surfactant solutions were prepared in McIvan’s buffer in specific concentrations. 0.2 ml of red blood cells (RBC) was mixed with 0.2 ml of each surfactant solution. The four surfactant solutions had each been incubated differently at two different temperatures for three different times. Each test was done six times. The results were presented as mean absorbance ± the standard deviation. E24, Fh and cmc were also determined for each surfactant solution. All of the surfactant solutions showed hemolytic activity. In comparison with the four studied surfactants, brij 56 had the highest hemolytic effect and brij 72 the lowest. The values of E24 and Fh had good correlation with hydrophilic-lipophilic balance values. According to the results of this study, brijs should be used at concentrations lower than cmc in formulations. Also, according to the results, the use of brijs with low hemolytic effect such as brij 72, is preferred in pharmaceutical preparations

Isolation, Characterization, and Investigation of Surface and Hemolytic Activities of a Lipopeptide Biosurfactant Produced by Bacillus subtilis ATCC 6633

Bacillus subtilis ATCC 6633 was grown in BHIB medium supplemented with Mn2+ for 96 h at 37oC in a shaker incubator. After removing the microbial biomass, a lipopeptide biosurfactant was extracted from the supernatant. Its structure was established by chemical and spectroscopy methods. The structure was confirmed by physical properties, such as Hydrophile-Lipophile Balance (HLB), surface activity and erythrocyte hemolytic capacity. The critical micelle concentration (cmc) and erythrocyte hemolytic capacity of the biosurfactant were compared to those of surfactants such as SDS, BC (benzalkonium chloride), TTAB (tetradecyltrimethylammonium bromide) and HTAB (hexadecyltrimethylammonium bromide). The maximum hemolytic effect for all surfactants mentioned was observed at concentrations above cmc. The maximum hemolytic effect of synthetic surfactants was more than that of the biosurfactant produced by B. subtilis ATCC 6633. Therefore, biosurfactant would be considered a suitable surface-active agent due to low toxicity to the membran

Studies on bioemulsifier production by Bacillus licheniformis PTCC 1595

Surfactants are amphipathic molecules which reduce surface and interfacial tensions and widely used in pharmaceutical, cosmetic, food and petroleum industries. Biosurfactants are the structurally diverse group of surface-active molecules synthesized by microorganisms. There are several advantages for biosurfactants in contrast with chemical surfactants, such as lower toxicity; higher biodegradability; better environmental compatibility; higher foaming; high selectivity and specific activity at extreme temperatures, pH, and the ability to be synthesized from renewable feed-stock. In the present study, the production of bioemulsifer by Bacillus licheniformis PTCC 1595 was studied. B. licheniformis was grown in the nutrient broth medium and bioemulsifer production was evaluated every 24 h by surface tension and emulsification index (E24). Then B. licheniformis PTCC 1595 was grown in nutrient broth with different conditions in order to get maximum production of bioemulsifer. The best culture medium was found to be nutrient broth medium supplemented with starch, Fe2+, Mn2+ and olive oil. After growing the bacteria, the microbial biomass was removed from the supernatant by acidic precipitation method. Its amphipathic structure was established by biochemical and spectroscopy methods and it was confirmed to be a lipopeptide structure

Formulation of herbal conditioner shampoo by using extract of fenugreek seeds and evaluation of its physicochemical parameters

Nowadays, people are interested in hair preparations and conditioner materials, such as shampoos. Hair tonic and conditioner formulations containing herbal extracts, such as fenugreek, can prevent hair loss and retain hair conditioning. First of all, the proved seeds of fenugreek were extracted with 50% ethanol by maceration method, and then were freeze dried and stored in the fridge. After preparing the formulation, some physicochemical properties such as pH, foam formation, viscosity, conditioning and wettability were evaluated. The pH of the formulated shampoo was determined as 6.6. The results of its rheogram showed good thixotropy property. High foam production and stability were observed; this may be due to the existence of saponin in fenugreek seeds extract. On the basis of wettability and conditioning results, formulated shampoo can represent an attractive and suitable product. The pH of the formulated shampoo was in the standard range of 6 to 8. The formulated shampoo has also shown the better foaming productivity and thixotropic properties which shows its suitable viscosity. The wetting effect of shampoo was taken 5 min which indicates its proper quality in comparison to some other shampoos in the market. Based on the wettability and conditioning data, it can be concluded that the formulated shampoo has a good quality of introducing it to the market

Medicinal plants as surface activity modifiers

Surface active agents have been used in pharmaceutical formulations for different purposes, so the study of the effect of these agent on biological membranes is necessary. The aim of this study is the evaluation of aqueous extract of Tribulus terrestris L., Trigonella foenum-graecum L. and Echium amoenum Fisch, that contain saponins on red blood cells (RBC) as a model of biological membranes. Also some physicochemical properties of the extracts including emulsification index (E24) and foam producing activity (Fh) were investigated. The aqueous extracts were prepared by maceration and then lyophilized. The different concentration of extracts in McIvan’s buffer solution were incubated with RBC in different temperatures (25 and 37°C) for different time periods (15 and 30 min). The absorbance of the samples by UV spectrophotometer determmine the degree of hemolysis. In comparison of three studied extracts, T. terrestris L, have shown the highest hemolytic effect (12.45% in 37°C and 30 min). The values of E24 and Fh showed the extract of T. terrestris L. has the highest emulsification index (24.89%) and the highest foam producing activity (14.42 mm). The extract of H. persicum, with lower hemolytic effect may be preferred in pharmaceutical preparation but if the hemolytic effect was excluded, A. dracunculus is preferred

Study of aqueous extract of three medicinal plants on cell membrane–permeabilizing and their surface properties

The aim of this study was to evaluate the effect of aqueous extract of three medicinal plants, Artemisia dracunculus L, Cuminum cyminum L and Heracleum persicum Desf, which contain saponins on biological membrane. Also in this study, some of their physicochemical properties were studied. At the first step, the aqueous extract of the plants were prepared, using maceration and then the extracts were lyophilized. 0.2 ml of RBC was added to 0.2 ml of different concentrations of each extract in McIvan’s buffer, and then incubated in two different times and temperatures. The absorbance of the samples was determined by UV spectrophotometer. Among the three studied extracts, A. dracunculus L showed the highest hemolytic effect and the Heracleum persicum Desf showed the lowest one. The values of emulsification Index (E24) and foam formation activity (Fh) showed for each extract the properties of surface activity. Regarding the results of this study, when considering the health of consumer, the use of aqueous extract of H. persicum Desf, with low hemolytic effect is preferred in pharmaceutical preparation. But if the hemolytic effect were considered, the use of aqueous extract of A. dracunculus L, with great hemolythc effect in comparison to the two other extract, is preferred

Screening Three Strains of Pseudomonas aeruginosa: Prediction of Biosurfactant-Producer Strain

Problem statement: The chemical surfactants have some disadvantages; especially, toxicity and no biodegradability. Approach: Biosurfactants were the structurally diverse group of surface-active molecules synthesize by micro-organisms. The microbial surfactants were interesting, because of the biodegradable and have many applications in industry, agriculture, medicine. Results: In the present study, the production of biosurfactant by three strains of Pseudomonas aeruginosa (PTCC 1074, 1310 and 1430) was investigated. The hemolytic and foam forming activity of different strains were studied and consequently, P. aeruginosa PTCC 1074 was selected as the suitable strain. P. aeruginosa PTCC 1074 was grown in the nutrient broth medium and biosurfactant production was evaluated every 24 h by emulsification index and surface tension for the best of production time. After that, in order to get maximum production of biosurfactant, the selected strain was grown with different additives in nutrient broth and the best culture medium was found. The biosurfactant was isolated from the supernatant and its amphipathic structure was confirmed by chemical methods. Conclusion: Biosurfactant produced by Pseudomonas aeruginosa PTCC 1074 would be considered as a suitable surfactant in industries due to its low toxicity

ANTIMICROBIAL ACTIVITY OF BACILLUS SP. STRAIN FAS1 ISOLATED FROM SOIL

During screening for antibiotic producing microorganisms from environmental soil samples, the supernatant of a bacterial isolate was found to have antibacterial and antifungal activity on the standard indicator species. The standard cylinder-plate method was used to determine the inhibitory effect of the crude supernatant of each isolate on 6 bacterial and 3 fungal standard strains by measuring the diameter of inhibition zone. The highest inhibition zone on Aspergillus niger belonged to culture broth of isolate FAS1 by 25 mm, and this isolate was the most efficient microorganism to inhibit standard bacterial and fungal species. Based on morphological and biochemical properties as well as 16S rDNA gene analysis, the selected isolate (isolate FAS1) belonged to Bacillus genus. Investigation on the ability of different culture media for antibiotic production led to select Luria-Bertani media for further studies. Treatment of the culture broth of the isolate FAS1 using typical protease didn’t decrease the antimicrobial activity of the supernatant. After extracting of culture broth of the selected isolate by ethyl acetate as an organic solvent, the inhibitory effect was mainly increased. More investigation was done by bioautography method where the ethyl acetate fraction of the broth culture was separated on TLC by chloroform:methanol, 60:40 as mobile phase and Rf were calculated for inhibition spots

Antimutagenic activity of major fractions of Zataria multiflora Boiss by Ames method

Zataria activity and richness of flavonoids. Antimutagenicity effect of total extract of the plant has been reported previously. multiflora is a medicinal plant that has been interested in antimutagenicity effect because of its high antioxidant Aerial parts of Z. multiflora were extracted by petroleum ether, chloroform and 80% methanol by liquid‑liquid extraction method consequently. The fractions were concentrated in vacuum and dried at 40°C in oven. The genotype of two standard strains of Salmonella typhimurium (TA98, TA100) was confirmed by the evaluation of two important factors of histidine requirement and the presence of R factor. The minimum inhibition concentration (MIC) of the fractions against these two strains was determined by agar dilution method. From each fraction, various concentrations less than MIC were studied for anti‑mutagenic test. The sample along with bacterial strain and mutagen agent were incubated at 37°C for 48 h. The number of revertant colonies was counted and compared with control plates. Our results showed that all fractions especially petroleum ether and chloroform ones maintain the number of colonies in the standard range in control plates and prevent from the growth of many strains of bacteria and increase of revertant colonies enhancement in a concentration‑dependent manner. This effect was prominent against TA100 starin. Methanolic fraction exhibited anti‑mutagen activity just in the highest used concentration in the presence of TA98