enzimska lipofilizacija vitamina C linolnom kiselinom - određivanje antioksidativnih i difuzionih svojstava L-askorbil-linolata

Lipophilic derivatives of vitamin C are additives with antioxidant properties, attractive for application in food, cosmetics and pharmaceutics. They could be synthesized in lipase-catalyzed processes by using various acyl donors. Hereby, we present application of linoleic acid, which is polyunsaturated fatty acid essential in human nutrition, for esterification of vitamin C catalyzed by immobilized enzyme preparation Novozym® 435 in acetone. Highest specific ester yield, 9.7 mmol/g of immobilized lipase, was accomplished with 0.15 M of vitamin C, 0.6 M of linoleic acid, 3 g/l of enzyme and 0.07% (v/v) of water, at 60°C. NMR analyses of purified product proved that synthesized molecule was identical to 6-O-ascorbyl linoleate. Capacity of ester for scavenging 2,2-diphenyl-1-picrylhydrazyl radicals was two times higher comparing to parent molecule, vitamin C. Its diffusion coefficient, determined using Franz cell and cellulose acetate membrane, was 40% higher than palmitate and 62% higher than oleate. Obtained results showed that L-ascorbyl linoleate could be successfully synthesized in biocatalyzed processes. Furthermore, it was demonstrated that it possess high potential for application in different lipophilic products due to its liposolubility, high antioxidant efficiency and good diffusion properties.Lipofilni derivati vitamina C su aditivi sa antioksidativnim dejstvom pogodni za primenu u prehrambenim, kozmetičkim i farmaceutskim proizvodima. Mogu biti sintetisani u procesima katalizovanim lipazama korišćenjem različitih acil-donora. U ovom radu, opisana je primena linolne kiseline, polinezasićene masne kiseline esencijalne u ljudskoj ishrani, u esterifikaciji vitamina C katalizovanoj imobilisanim enzimskim preparatom Novozym® 435 u acetonu. Najviši specifični prinos estra od 9,7 mmol/g imobilisane lipaze, ostvaren je sa 0,15 M vitamina C, 0,6 M linolne kiseline, 3 g/l enzima i 0,07 zapr. % vode, na 60°C. NMR analize prečišćenog proizvoda dokazale su da je sintetisani molekul identičan 6-O-askorbil-linolatu. Kapacitet estra za vezivanje 2,2- difenil-1-pikrilhidrazil radikala bio je dva puta viši u odnosu na sam vitamin C. Njegov koeficijent difuzije, određen korišćenjem Franz-ove ćelije i celuloza-acetatne membrane, bio je za 40% viši u odnosu na palmitat i za 62% u odnosu na oleat. Ostvareni rezultati pokazali su da L-askorbil-linolat može uspešno biti sintetisan u biokatalizovanom procesu. Pored toga, dokazano je da ovaj estar poseduje značajan potencijal za primenu u različitim lipofilnim proizvodima zbog svoje liposolubilnosti, snažnog antioksidativnog dejstva i pogodnih difuzionih karakteristika

Immobilization of Chaga extract in alginate beads for modified release: simplicity meets efficiency

Chaga (Inonotus obliquus) is a parasitic fungus, which has been used in traditional medicine in Russia and other northern European countries in the treatment of cancer, gastrointestinal andliver diseases. It has been a subject of intensive researchrecently, confirming many of its health-beneficial effects. In order to obtain a product that would allow modified and prolonged release of the Chaga's active metabolites, hot water Chaga extract was immobilized using calcium - alginate. The extract, which was predominantly composed of carbohydrates (57 %), also contained a relatively high amount of antioxidants/phenolic compounds (130 mg gallic acid equivalents per g of dry extract) and exhibited pronounced radical scavenging activity. It showed significant antibacterial activity as well, inhibiting growth of tested bacterial strains at concentrations of 1.25-20 mg/mL. Entrapment efficiency was about 80 %, and the extract-alginate system showed pH-dependant extract release; there was negligible release at pH 1.75 (gastric pH), and the release gradually increased with the increase in pH, reaching similar to 43 % of immobilized extract at pH 8.5 after 90 min. Such a product could be used as a dietary supplement, adjuvant in therapy of gastrointestinal diseases or as a food additive

EFFECT OF GALACTO-OLIGOSACCHARIDES ON STAPHYLOCOCCUS EPIDERMIDIS GROWTH AND EXAMINATION OF THEIR DIFFUSION FROM COSMETIC FORMULATIONS

According to the current definition, a prebiotic is described as “a substrate that is selectively utilized by host microorganisms conferring a health benefit”. Originally, the concept of prebiotics was defined for the gut microbiota. However, it can be also applied to modulate the composition of other microbiological populations, for example, skin microbiota. In recent years, scientific interest in the composition and function of the dermal microbiota has been growing, as it has been established that certain skin diseases are associated with dysbiosis of the skin microbiota. Consequently, for the cosmetics industry, it is of utmost importance to develop products that have a prebiotic effect and thus can provide a balanced composition of the skin microbiota. In this paper, an assessment of the galacto-oligosaccharides (GOS) prebiotic activity was performed by following the effect of the addition of these oligosaccharides on the growth of Staphylococcus epidermidis, a member of the permanent skin microbiota. Simultaneously, changes in nutrient medium composition during the fermentation were monitored using high-performance liquid chromatography. In the end, bearing in mind the future implementation of GOS in cosmetic formulations, the possibility of controlled release was determined using the Franz cell diffusion study. The obtained results showed that GOS has a stimulating effect on the growth of S. epidermidis since it has been noticed that the number of vegetative cells increases with increasing concentration of GOS up to the concentration of 5 % (w/v). Based on the change in the composition of soluble sugars in nutrient media enriched with oligosaccharides, it was confirmed that the bacteria S. epidermidis can utilize GOS. Finally, the effective diffusion coefficients of GOS, that have been incorporated into two different cosmetic formulations for previously defined optimal concentration (5 % w/v), were determined. Namely, the best results were obtained for formulation with Heliogel as a gelling agent - the effective diffusion coefficients of GOS trisaccharides (GOS3) and GOS tetrasaccharides (GOS4) were 1.904·10-6 cm2/s and 4.696·10-9 cm2/s, respectively. On the other hand, the effective diffusion coefficient of GOS3 in hydrogel Aristoflex AVC was 5.148·10-8 cm2/s, while the diffusion coefficient of GOS4 could not be determined, due to the low diffused concentrations. This indicates that GOS3 diffuse significantly faster than GOS4 and the rate and mechanism of transport of these molecules are highly dependent upon the type and characteristics of the formulation

Freeze versus Spray Drying for Dry Wild Thyme (Thymus serpyllum L.) Extract Formulations: The Impact of Gelatin as a Coating Material

Freeze drying was compared with spray drying regarding feasibility to process wild thyme drug in order to obtain dry formulations at laboratory scale starting from liquid extracts produced by different extraction methods: maceration, heat-, ultrasound-, and microwave-assisted extractions. Higher powder yield (based on the dry weight prior to extraction) was achieved by freeze than spray drying and lower loss of total polyphenol content (TPC) and total flavonoid content (TFC) due to the drying process. Gelatin as a coating agent (5% w/w) provided better TPC recovery by 70% in case of lyophilization and higher powder yield in case of spray drying by diminishing material deposition on the wall of the drying chamber. The resulting gelatin-free and gelatin-containing powders carried polyphenols in amount ~190 and 53-75 mg gallic acid equivalents GAE/g of powder, respectively. Microwave-assisted extract formulation distinguished from others by higher content of polyphenols, proteins and sugars, higher bulk density and lower solubility. The type of the drying process affected mainly position of the gelatin-derived -OH and amide bands in FTIR spectra. Spray dried formulations compared to freeze dried expressed higher thermal stability as confirmed by differential scanning calorimetry analysis and higher diffusion coefficient; the last feature can be associated with the lower specific surface area of irregularly shaped freeze-dried particles (151-223 µm) compared to small microspheres (~8 µm) in spray-dried powder.Preprint: [10.20944/preprints202105.0358.v1

Hydrogels based on poly(methacrylic acid) for controlled release of anti-inflammatory drugs

Everyday struggle of humanity with novel diseases and present once, urge researchers to find novel and improve existing therapies to enhance their efficiency and safety. One of the promising approaches to overcome these challenges is controlled release of drugs. Biomaterials based on poly(methacrylic acid) (PMAA) are excellent drug delivery systems because they can control release rate and released amount of drug. Also, due to their pH sensitivity the PMAA hydrogels can release drug at the site of action. Namely, these nontoxic and biocompatible hydrogels swell in the environment with pH value higher than pKa of PMAA (4.6) and release encapsulated drug during the process. In present study, PMAA hydrogels are synthetized under ambient conditions by simple, cost effective and eco-friendly synthesis. Novel initiation system based on hydrogen peroxide, potato peel peroxidase and vitamin C (VC) is used for the first time for free radical polymerization of PMAA hydrogel. In accordance with the principles of circular economy, peroxidase was isolated from potato peel waste by water extraction for 12 h at 4 ℃. Four PMAA hydrogels were prepared by using potato peel peroxidase with various enzyme activity (0.4; 0.8; 1.2 and 1.8 IU), whereas the amounts of H2O2 (30 mL) and VC (10 mg) have been kept constant. The composition of the PMAA hydrogels was confirmed by FTIR analysis, whereas their porous structure was revealed by SEM. The swelling of the PMAA hydrogels was monitored in two media: 0.1M HCl (as simulation of human stomach) and phosphate buffer with pH 7.4 (as simulation of human intestines). In order to encapsulate anti-inflammatory drug – dexamethasone into the PMAA hydrogels, the hydrogels were immersed into the dexamethasone aqueous solution (5 mg/ml) and left to swell to the equilibrium, after which they were dried at room temperature. Dexamethasone release from the PMAA hydrogels was monitored in the same environments as was the PMAA swelling. The results showed that around seven times higher amount of dexamethasone was released in the medium with pH 7.4 than in the medium with pH 1. Present study has showed that the PMAA hydrogels, prepared through green and eco-friendly method, have huge potential for encapsulation and controlled release of anti-inflammatory drugs and therefore, for the treatment of rheumatoid arthritis

Freeze vs. Spray Drying for Dry Wild Thyme (Thymus serpyllum L.) Extract Formulations: The Impact of Gelatin as a Coating Material

Freeze drying was compared with spray drying regarding feasibility to process wild thyme drugs in order to obtain dry formulations at laboratory scale starting from liquid extracts produced by different extraction methods: maceration and heat-, ultrasound-, and microwave-assisted extractions. Higher total powder yield (based on the dry weight prior to extraction) was achieved by freeze than spray drying and lower loss of total polyphenol content (TPC) and total flavonoid content (TFC) due to the drying process. Gelatin as a coating agent (5% w/w) provided better TPC recovery by 70% in case of lyophilization and higher total powder yield in case of spray drying by diminishing material deposition on the wall of the drying chamber. The resulting gelatin-free and gelatin-containing powders carried polyphenols in amount ~190 and 53-75 mg gallic acid equivalents GAE/g of powder, respectively. Microwave-assisted extract formulation was distinguished from the others by a higher content of polyphenols, proteins and sugars, higher bulk density and lower solubility. The type of the drying process mainly affected the position of the gelatin-derived -OH and amide bands in FTIR spectra. Spray-dried formulations compared to freeze-dried expressed higher thermal stability as confirmed by differential scanning calorimetry analysis and a higher diffusion coefficient; the last feature can be associated with the lower specific surface area of irregularly shaped freeze-dried particles (151-223 µm) compared to small microspheres (~8 µm) in spray-dried powder

Gas-solid and gas-liquid mass transfer: Effect of turbulent Schmidt number

The scope of this paper is to explain effect of eddy viscosity and turbulent Schmidt number on mass transfer rate. New, theoretically based correlation for gas-liquid mass transfer coefficients are proposed.Cilj rada je bio da se objasni uticaj turbulentnog viskoziteta i turbulentnog Schmidt-ovog broja ne prenos mase. Predložene su nove korelacije za određivanje koeficijenta prelaza mase u sistemima gas-tečno. Prednost ovih korelacija je njihova teorijska zasnovanost

The flow of Newtonian and drag-reducing fluids around sphere

The flow around a sphere placed coaxially in a cylindrical tube, the separation of the boundary layer and the wake shedding phenomena are investigated. The results of the simultaneous determination of the drag coefficients and local mass transfer rates present a completely new picture of the flow around a sphere in the critical range in both: polymer drag reducing solutions and pure water