Simultaneous Optimization of Extraction Yield, Phenolic Compounds and Antioxidant Activity of Moroccan Propolis Extracts: Improvement of Ultrasound-Assisted Technique Using Response Surface Methodology

Abstract

Propolis has given rise to refreshing interest in recent years in the field of conventional medicine. Its extraction represents an important process that requires optimal conditions, which strongly affect the yield of extraction, total polyphenols, flavonoid content, and radical scavenging capacity markers. The objective of the present study was to optimize the ultrasound-assisted extraction conditions of Moroccan propolis. The studied responses were the extraction yield, total polyphenols, flavonoid contents (TPC, TFC), and antioxidant activity of the extract evaluated by DPPH-IC50 and FRAP-EC50 assays. The response surface methodology (RSM) and specifically the Box–Behnken design (BBD) were used, taking into account three variables: sonication time (min), solvent/propolis ratio (mL/g), and ethanol concentration (%). After the realization of experiments and data analysis, optimal response values were 15.39%, 192 mg GAE/g of propolis,45.15 mg QEq/g, 29.8 µg/mL, and 128.3 µmol Fe2+/g for extraction yield, TPC, TFC, DPPH-IC50, and FRAP-EC50, respectively. Besides, optimal ultrasound extraction conditions were 15 min for sonication time, 30 mL/g for solvent/propolis ratio, and 40% for ethanol concentration. All obtained experimental values were in good agreement with the predicted values, suggesting that using an experimental design in the ultrasound-assisted extraction process and optimization was prudently chosen.

Propolis Efficacy: The Quest for Eco-Friendly Solvents

“…Yield comparisons between different works is always uncertain since extraction procedures are usually not performed under the exact same conditions. The extraction yield mainly varies with the technique and solvent used, but also depends on a combination of several other factors such as the ratio between the sample and the solvent, the fragmentation state of the sample and the agitation, temperature and time of extraction [ 14 , 15 , 16 , 17 , 18 ]. Although there is an increase in yield with increasing extraction time, this increase does not imply a significant increase in the phenolic content [ 14 ].…”

Do ultrasonic field effects upon the polyphenolics profile of propolis extracts improve their antioxidant and antimicrobial activity?

“…While most investigations report on results obtained using hydroalcoholic mixtures in the 70–99 % range [2] , [3] , [4] , [22] , [23] , [31] , larger proportions of water were also tested [32] , [33] , demonstrating that water-based solvents tend to extract more phenolic acids than flavonoids. Extraction yield peaks around 40–60 % (v/v) ethanol, when a plateau is reached.…”

“…The study carried out by Aboulghazi et al [33] varied ethanol content (40–80 %), liquid:solid ratio (10:1–30:1, v:w) and time (15 – 45 min) while using a 50 kHz sonic bath at 120 W and 35°C; total phenolics, total flavonoids, antioxidant activity, and extraction yield were the targeted outputs. Simultaneous optimization provided the optimal processing conditions: 15 min, for 30:1 liquid:solid ratio, using 58 % ethanol.…”

Multiobjective response and chemometric approaches to enhance the phytochemicals and biological activities of beetroot leaves: an unexploited organic waste

“…On the other hand, considering the recovery of bioactive compounds' polarity may notably vary with numerous conditions [25], it is complicated to evolve a perfect method for the extraction of all phenolic compounds, and extraction systems can engender inefficient results. In this way, variables like solvent type, solvent-sample ratio, solvent-solvent ratio, extraction time, temperature, and pH can control the efficiency of extraction of total phenolic compounds and consequently the antioxidant/ antimicrobial activities [26,27]. In this respect, the blend of solvents, which can vary from binary, ternary, and even multicomponent mixtures at different polarities, has been recommended for the effective extraction of phytochemicals [28,29].…”