Comparison of qualitative characteristics of propolis extracts using different purification methods

Abstract

Purification of extracts is an essential procedure in order to remove wax and other undesirable ingredients while retaining the polyphenolic fraction which contains most of bioactive components. This study investigates how different purification methods affect the qualitative characteristics of propolis extracts. Five different purification methods were conducted both for ethanolic and methanolic extracts: (a) centrifugation for 30 min at 370 g; (b) centrifugation at −5 °C for 10 min at 1850 g twice with a 15 min interval; (c) centrifugation at 3340 g for 2.5 min twice with a 15 min interval; (d) filtration through a 0.22 μm polyethersulfone membrane; (e) filtration through a 0.45 μm pore size nylon membrane filter using Buchner vacuum system. Methods were evaluated with reference to the post-treatment antioxidant activity (radical scavenging), total phenolic content and total flavonoid content of each extract. Two different methods of centrifugation were found to be the most effective and stable: centrifugation at 3340 g for 2.5 min or for 10 min at 1850 g, at −5 °C.