Despite the fact that Thymus serpyllum is well-known medicinal plant and its chemical profile and biological activity have been investigated, there is no detailed study regarding the influence of different techniques and conditions on the extraction of polyphenolic compounds from Serpylli herba. The aim of this study was optimization of the extraction parameters that improves the efficiency of polyphenols extraction from T. serpyllum: particle size, solid-to-solvent ratio, solvent type and extraction time, by using maceration, heat-and ultrasound-assisted extraction (HAE and UAE). The extraction efficiency was expressed via total polyphenol content (TPC) and total flavonoid content (TFC). The statistical analysis (one-way ANOVA and full factorial design) has revealed that the optimal conditions for achieving the best polyphenols yield were particle size of 0.3 mm, 1:30 solid-to-solvent ratio and 50% ethanol, as environmentally friendly extraction medium, while extraction time has not shown statistically significant influence on polyphenols concentration, in all procedures. Under these conditions, the measured TPC was 26.6 mg GAE/L in maceration, 29.8 mg GAE/L in HAE and 32.7 mg GAE/L in UAE, which was in agreement with the predicted values, while TFC was 14.3 mg CE/L, 12.4 mg CE/L and 16.7 mg CE/L for maceration, HAE and UAE, respectively. According to total polyphenols yield, the efficiency of the extraction methods for all variables was ranked by significance in the following order: UAE > HAE > maceration, whereas total flavonoids yield was the highest in UAE, although there was no statistically significant difference between maceration and HAE. According to our results, UAE could be selected as the most successful and suitable technique for extraction of bioactive polyphenolic compounds from Serpylli herba. Using LC/MS and HPLC analysis, 9 polyphenolic compounds were identified and quantified: 6,8-Di-C-glucosylapigenin, chlorogenic acid, 6-hydroxyluteolin 7-O-glucoside, caffeic acid, luteolin 7-O-glucuronide, apigenin glucuronide, salvianolic acid K isomer, rosmarinic acid and salvianolic acid I. This study was an initial step in production of polyphenols-rich wild thyme extracts aimed to be used for formulation of foodstuffs and medicines.

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Properties and biocompatibility of a series of thermoplastic poly(urethane-siloxane)s (TPUSs) based on α,ω-dihydroxy ethoxy propyl poly(dimethylsiloxane) (PDMS) for potential biomedical application were studied. Thin films of TPUSs with a different PDMS soft segment content were characterized by (1) H NMR, quantitative (13) C NMR, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), contact angle, and water absorption measurements. Different techniques (FTIR, AFM, and DMA) showed that decrease of PDMS content promotes microphase separation in TPUSs. Samples with a higher PDMS content have more hydrophobic surface and better waterproof performances, but lower degree of crystallinity. Biocompatibility of TPUSs was examined after attachment of endothelial cells to the untreated copolymer surface or surface pretreated with multicomponent protein mixture, and by using competitive protein adsorption assay. TPUSs did not exhibit any cytotoxicity toward endothelial cells, as measured by lactate dehydrogenase and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assays. The untreated and proteins preadsorbed TPUS samples favored endothelial cells adhesion and growth, indicating good biocompatibility. All TPUSs adsorbed more albumin than fibrinogen in competitive protein adsorption experiment, which is feature regarded as beneficial for biocompatibility. The results indicate that TPUSs have good surface, thermo-mechanical, and biocompatible properties, which can be tailored for biomedical application requirements by adequate selection of the soft/hard segments ratio of the copolymers.