Total Phenolic Content and Antimicrobial Activity of Different Lithuanian Propolis Solutions

Abstract

The manufacture of ethanol-free propolis solutions offers a broader application. A few trials with Lithuanian propolis have been conducted. The aims of the study are to manufacture propolis water and water-free solutions and evaluate the quality and antimicrobial activity of these solutions. The studied solutions containing 2.5%, 5%, and 10% propolis are prepared. As solvents, purified water, 70% v/v ethanol, 96.3% v/v ethanol, propylene glycol, and their systems were used. Determination of total levels of phenolic compounds (FAE mg/g) is based on colour oxidation-reduction reaction using Folin-Ciocalteu reagent under alkaline conditions and performed at 765 nm wavelength using UV spectrophotometer. The highest content of phenolic compounds was determined in solutions containing 10% propolis extracts, and the lowest amounts in 2.5% propolis extracts. The water extracted the lowest amount of phenolic compounds from crude propolis, ethanol extracted the highest amount, and propylene glycol ranked the middle position. It is determined that technological parameters (stirring, temperature) contribute to content of phenolic compounds. During microbiological study, MICs were determined. The studies showed that water extracted propolis solutions and solvents mixture did not inhibit the growth of the studied microorganisms, and propolis solutions in propylene glycol were found to have antimicrobial activity.

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“…The mixture was kept at room temperature for 60 min, then the absorbance at 765 nm was measured (Ramanauskienė et al . ). Gallic acid was served as standard and results were expressed as mg of gallic acid equivalent (GAE)/g d.m.…”

Novel Formulation Based on Chitosan-Arabic Gum Nanoparticles Entrapping Propolis Extract Production, physico-chemical and structural characterization

“…Particularly, Romanian propolis possessed high amounts of biologically active compounds such as phenolic acids, flavonoids (flavonols, flavanones, flavanols), aminoacids and minerals [12,13]. So, the composition of propolis varies according to the species of bee, geographic origin, month of collection, as well as to the solvent used in extraction process -higher content of active substances was obtained when ethanol was used [14]. On the other hand, the administration of phenolic compounds requires the formulation of a protecting system, able to maintain the structural integrity of the polyphenol until the consumption or the administration towards a physiological target.…”

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“…Ethanol has been proposed as a good solvent for polyphenol extraction and is known as safe for human consumption. Similarly, Ramanauskiene et al [29] studied quality and antimicrobial activity of Lithuanian propolis prepared by different solutions (2.5%, 5%, and 10% propolis) and solvents (purified water, 70% v/v ethanol, 96.3% v/v ethanol, propylene glycol). They found the highest content of phenolic compounds in increased propolis solutions and propolis extracts, whilst the water extracted had the lowest amount of phenolic compounds from crude propolis.…”