Antioxidant, antimicrobial, anticancer effects of Korean propolis

Abstract

Propolis is a sticky material made from plant growth point protection secretion and resin which are colledted by bees, then mixed with bee saliva enzyme, it is used to keep bee colony safe by applying inside of bee hive, and it is consisted of about 50% of resin and aromatic, 25% of bee wax, 10% of essential oil, pollen and mineral. In this study, extraction characteristics of propolis by ethanol were confirmed because of its major use as a food, propolis yield and its active ingredient total flavonoid content were better with morer than 70% ethanol concentration. Propolis can be extracted with more than a day extraction time and above 4℃ temperature condition. Propolis samples were collected every two weeks, their amount and ingredient composition changes over time were examined, summer (early June-late August) time collected propolis sample occupied 87% of total 100g colletion. Total flavonoids content (7~8%) and total phenolic content (16~20%) of collected samples were maintained without significant differences. These results confirm the total flavonoid content in propolis samples collected from different regions in Korea, most samples showed 5% or more except Jeju sample (less than 1%). Total phenolic content in propolis was more than 20% with samples from central and southern regions, Jeju smapleis showed about 15%. The content of the amino acids in propolis was examined and various amino acids were observed. Heavy metal content of propolis showed that lead conetent was below the baseline (5ppm), Arsenic and mercury were not detected at all. Minerals (Zn, Cu, Ni) required for the metabolism were contained by a very small amount. Crude lipid contents in propolis of central and southern regions samples showed average 38%, while Jeju sample exhibited 24%. The main substances (Gallic acid, naringenin, quercetin, apigenin, chrysin, galangin) in propolis were confirmed through HPLC analysis of collected propolis samples by comparing with standard product. All Korean propolis samples showed excellent antimicrobial effect against bacteria causing stomach ulcers (Helicobacter pylori), also exhibited excellent antibacterial activities against caries causing bacteria (Streptococcus mutans). The results confirm the proliferative effect on intestinal bacteria (lactic acid) exhibited a high effect when the concentration is low. The antioxidant effect of propolis was confirmed in a number of ways showing the higher the antioxidant effect by rise of propolis concentration, but concentration of 1000㎍ showed rather poor result. In vivo test, glutathione content was increased, lipid peroxidation was decreased, and the increase of propolis concentration exhibited higher effect. The experiment using nude mouse to examine anti-cancer effect of propolis was conducted, propolis ingestion result after tumor induction was determined by monitoring body weight and tumor size change, tumor size showed a tendency to decrease with propolis concentration rise. Antioxidant effect of propolis is common, but propolis has excellent antimicrobial activity against bacteria causing stomach ulcers (Helicobacter pylori). With gastric cancer cell lines, propolis lowered the cell proliferation ratio, also reduced tumor size. Propolis can be developed to health functional food which has stomach protection effect as well as antioxidant effect.