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Antioxidative effects of flavonoids in propolis

Flavonoids belong to the recently popular phytochemicals ; they are ubiquitous in plant kingdom and cannot be synthesised by humans. Biochemical effects of flavonoids in living systems can be divided into four categories - (a) binding affinity to biological polymers, (b) binding of heavy metal ions, (c) catalysis of electron transport and (d) ability to scavenge free radicals. Antioxidant potential is one of the earliest functions discussed for this group of compounds and preferred interpretation of that effect lies in the radical-scavenging properties. One of the most concentrated sources of flavonoids available is propolis - resinous material collected by honeybees. The aim of our study was to investigate whether or not daily intake of propolis has influence on antioxidant defence enzymes (such as superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT)) in human subjects. Analysis of SOD and GPx activity was performed using RANSOD and RANSEL antioxidant kits (Randox Laboratories Ltd., Crumlin, United Kingdom), while the catalase activity was measured according to the method of Aebi (Methods Enzymol. 105, 1984). Fourty healthy male and female volunteers aged between 20 and 30 years were included in our study and were divided into two groups (study and control group). Inclusion and exclusion criteria were developed to mimic the average population ; ingestion of any dietary supplements and medications was forbidden and the intake of flavonoid rich diet was limited. During the study, blood samples were taken four times - two times in the period of 14 days before propolis supplementation (to establish the baseline status of antioxidant enzymes of all volunteers) and two times during propolis therapy. Propolis supplementation for study group began after their baseline blood samples were taken and lasted for 30 days. Propolis product used was EPID BUSTINE (powdered propolis extract soluble in water ; Specchiasol, Bussolengo - Verona, Italy). Volunteers received 1 dose three times per day during the given period (one dose contains 16, 25 mg of flavonoids ; daily intake was 48, 75 mg) and the blood samples were taken 2 times, every 14 days. It is expected that elevation of daily intake of flavonoids is associated with the reduction of the expression of antioxidative defence enzymes. The statistical significance of the results is discussed.

antioxidative effect; flavonoids; propolis

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