Modulation of antioxidant, chelating and antimicrobial activity of poplar chemo-type propolis by extraction procures

Abstract

This investigation was aimed to prepare solid propolis extracts by lyophilisation and to evaluate the efficiency of different extraction procedures (maceration/ultrasound extraction) and different types of extraction media used on extraction of phenolic compounds (TP), flavonoids (TF) and phenolic acids (TPA) from the raw poplar type propolis. Obtained lyophilised extracts were evaluated in terms of extraction yield, antioxidant potential and antimicrobial activity against selected bacterial/fungal stains. Those parameters varied significantly as a function of extraction parameters applied. In this regard, 80% ethanol was found to be the preferred extraction medium, allowing efficient extraction of TP and TF with high extraction yields. The resulting extracts were notable radical scavengers showing high antibacterial efficiency against Streptococcus mutans but were less efficient against Pseudomonas aeruginosa. Also, moderate antifungal activity against Candida albicans was observed. On the contrary, extracts prepared by aqueous extraction showed poor antimicrobial activity against tested stains but were active Fe2+ chelators. Ultrasound extraction showed comparable efficiency as maceration in extraction of bioactive compounds from the raw propolis, but offered additional advantages by ensuring the efficient extraction of phenolic compounds from propolis at rather low temperature (4 °C vs. 25/50 °C for maceration) in a short time (30 min vs. 24 h for maceration).