The purpose of the present study is to survey the extraction conditions and explore the antioxidant potential of the wild herb Cistus incanus, which is non-traditional in Bulgarian ethnomedicine and widespread in the Strandja Mountain. The influence of the extraction time (0–500 min) and solvent composition (0–50% ethanol in water) on the polyphenols, flavonoid yields and on the antioxidant capacity of the extracts of leaves, stalks (wood parts) and bud mixture were studied. The antioxidant capacity (AOC) was evaluated by use of scavenging assays of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. Total polyphenol and flavonoid contents were quantified using UV–vis (ultraviolet-visible) spectrophotometry. The optimal yield of the desired components was obtained with 30% ethanol in water solvent at the 390th min of extraction time. In addition, the influence of seasonality (winter and summer Cistus incanus), and of the different aerial parts—hard-coated seeds, buds, and a mixture of leaves and stalks of the wild plant—on the presence of polyphenols, flavonoids, and AOC were investigated. The present work revealed that the high values of polyphenols, flavonoids and the high AOC occurred not only in the summer leaves, but were also found in the winter leaves, hard-coated seeds, buds, and stalks. Based on the obtained results, the Cistus incanus from Strandja Mountain could be an excellent new source of natural antioxidants in food and for the pharmaceutical industries.
The unsteady mass transfer from a contaminated fluid sphere moving in an unbounded fluid is examined numerically for unsteady-state transfer. The effect of the interface contamination and the flow regime on the concentration profiles, inside and outside a fluid sphere, is investigated for different ranges of Reynolds number (0 \ Re \ 200) and Peclet number (0 \ Pe \ 10 5 ), viscosity ratio between the dispersed phase and the continuous phase (0 \ j \ 10), and the stagnant-cap angle (0 \ h cap \ 180). It was found that the stagnant-cap angle significantly influences the mass transfer from the sphere to a surrounding medium. For all Peclet and Reynolds numbers and j, the contamination reduces the mass transfer flux. The average Sherwood number increases with an increase of stagnant-cap angle and reaches a maximum equal to the average one for a clean fluid sphere at low viscosity ratio and large Peclet numbers. A predictive equation for the Sherwood number is derived from these numerical results.
Because of plants, health benefi ts consumption of herbal infusions as a dietary additive has increased in the last years. The aim of the present study was to establish the individual phenolic profi les using highperformance liquid chromatography with diode-array detection (HPLC-DAD) method of Bulgarian Cistus incanus leaves harvested in summer and winter seasons, Cistus incanus hard-coated seeds, Greek Cistus incanus leaves harvested in summer, Bulgarian Trachystemon orientalis, and Melissa offi cinalis leave and stems extracts prepared as infusions. Cistus incanus L. has played a very interesting role in the historical medicine of the Mediterranean region where is well known. Trachytsemon orientalis L. is wild borage typical for Caucasus nature. Both wild plants are widely distributed in Strandja mountain, Bulgaria and the ethnomedicinal description of them as anti-infl ammatory and antioxidant herbs are missing. The Melissa offi cinalis is wildly used as an aromatic, culinary and medicine remedy and its medicinal properties are well known of Bulgarian folk medicine. In the present study, the newly established HPLC-DAD method developed and validated previously for simultaneous separation of 9 natural substances common in plants -tree major catechins, four major fl avonoids, gallic and vanillic acid was used. The method was successfully applied to the determination of the specifi c bioactive substances in the investigated herbs and especially Cistus incanus species. Analyses under the method applied revealed that in the Bulgarian Cistus incanus summer leaves infusion, the values of (-) -epicatechin (3460.54 ± 1.89 μg/mL) and (-) -epigallocatechin (7369.23 ± 2.56 μg/mL) were found to be signifi cantly higher (p > 0.05) than values of the two catechins found in the other infusions. However, the winter Cistus incanus leaves contains 640.03 ± 1.58 μg/mL (-) -epigallocatechin and 489.98 ± 2.89 μg/mL rutin which are signifi cantly higher concentrations (p > 0.05) almost 2 times more than these present in the Greek Cistus incanus leaves infusion 386.69 ± 3.85 μg/mL and 273.07 ± 0.96 μg/mL, respectively. Nevertheless, the Greek Cistus incanus leaves contains the highest concentration of gallic acid (219.04 ± 1.06 μg/mL, p > 0.05) among all analyzed infusions. The highest polyphenol concentration found in Melissa offi cinalis leaves and stems infusion was (-) -epigallocatechin (188.99 ± 2.08 μg/mL) follow by quercetin, gallic acid, and kaempferol. In Trachystemon orientalis were found only the fl avonoids rutin (56.46 ± 0.31 μg/mL) and myricetin (630.23± 1.63 μg/mL). The investigation has led to a better understanding of the polyphenolic profi les of the analyzed plant infusions, especially the non-traditional for the Bulgaria herbs -Cistus incanus and Trachystemon orientalis and has clearly supported the further utilization of the two species in the Bulgarian traditional medicine. Not least the Cistus incanus leaves harvested in the winter season and Cistus incanus hard-coated seeds could be used as an antioxidant infus...
The antimicrobial activity of nanoparticles (NPs) depends of the surface area in contact with microorganisms. The large surface area of the nanoparticles enhances their interaction with the microbes. In this work, a green, simple, rapid, and efficient ultrasound-assisted reduction method for silver nanoparticles (AgNP) synthesis is presented. For the synthesis, an aqueous solution of silver nitrate, ethanol, and ammonia was used. The adopted method can be easily implemented for any kind of scientific or industrial application due to its cost-effective nature. The effect of sonication time on the nanoparticle formation was investigated. Silver nanoparticles were analyzed through transmission electron microscopy and UV-vis spectroscopy. Antimicrobial additives can be incorporated in mass in different matrixes (polymeric or cellulosic), which is a convenient methodology to achieve antimicrobial activity. In this work, silver nanoparticles were incorporated in cellulose using an ultrasonic bath technique. The most important aspect of cellulose containing silver nanoparticles prepared by this method is its high antimicrobial efficiency. The microbiological study was carried out by a standard agar technique. The analysis showed that cellulose with incorporated silver nanoparticles exhibited strong antimicrobial activity against
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