The effect of extraction conditions on the chemical profile of obtained raw poplar propolis extract

Abstract

Various conditions of extraction were applied to obtain active extracts of raw poplar-type propolis. The extraction efficiency of traditional maceration was evaluated in terms of used solvent: ethanol (70 and 96% v/v), acetone (pure and 70%), propylene glycol, glycerol (50%), water and water with extraction modifiers: PEG 400 and lecithin. For obtained extracts, the total amounts of extracted phenolics and flavonoids as well as antioxidant activity were compared. For the most active extracts, the profile of volatile organic compounds with the use of GC × GC–MS and selected polyphenols content by HPLC–DAD was compared. To increase the activity of water propolis, extract ultrasound and microwave-assisted extraction were applied and obtained water extracts were compared regarding the main polyphenolic compounds content quantified by HPLC method. The recovery of 70% ethanolic extraction and the effect of the extension of extraction time were also examined by the HPTLC method. Based on conducted analyses, 70% ethanolic extract was found as the most aromatic and bioactive, followed by pure acetone and polypropylene glycol extracts. Compared to the classic maceration, water extraction assisted by microwaves and ultrasounds did not provide a higher extraction yield. In the case of 70% ethanolic extraction, the 5-day duration is recommended which allows to recovery of close to 80% of bioactive components of raw propolis.