ANTIOXIDANT POTENTIAL AND DNA DAMAGE PROTECTING ACTIVITY OF AQUEOUS EXTRACT FROM ARMILLARIA MELLEA

Abstract

ABSTRACT In this study, the antioxidant activities of hot-water extract from cultured mycelia of Armillaria mellea were assessed in different in vitro systems. The extract showed strongly inhibitory effect on microsomal liposome oxidation with an inhibition rate over 85% at 1.0–2.0 mg/mL. The extract was effective in scavenging superoxide radical in a concentration dependent fashion with IC50 value of 1.03 mg/mL whereas that in scavenging abilities of hydroxyl radical was 0.66 mg/mL. 1,1-Diphenyl-2-picrylhydracyl (DPPH) radical scavenging activity of the extract reached more than 77.2% at the concentrations of 4–8 mg/mL. Moreover, phenanthroline-copper complex-mediated chemiluminescent emission of DNA damage was both inhibited and delayed by the extract. The extract at 1.25–5.0 mg/mL also protected supercoiled DNA strand in plasmid pBR322 against scission induced by Fenton-mediated hydroxyl radical. Both mannitol (34.91%, w/w) and polysaccharides (26.94%, w/w) were major naturally occurring components found in the extract to have scavenging activity on hydroxyl radical. In addition, the polysaccharide from the extract displayed both strong scavenging activity on free radical (DPPH and superoxide radicals) and antioxidant effects against microsomal lipid peroxidation, hydroxyl radical-induced supercoiled DNA damage, which suggested that the activity might be derived partly from the polysaccharide of the extract. The results obtained indicated that A. mellea extract may be useful for preventing oxidation and DNA damage in pharmaceutical and food industries. PRACTICAL APPLICATIONS Armillaria mellea, one of the best known traditional Chinese medicine and health edible mushroom, is a symbiotic fungus isolated from the underground tubers of wild orchid Gastrodia elata. It is reported that A. mellea has diverse pharmacological properties, such as anticonvulsant, antibacterial and immunostimulating activities. However, the antioxidant activity has never been studied systematically thus far in A. mellea. From the result of this paper, A. mellea showed the notable free radical-scavenging activities, inhibition of lipid peroxidation and DNA damage protecting activities in vitro. Therefore, A. mellea might be very useful for the development of functional food and raw materials of medicine for antioxidants preventing oxidative stress-related diseases.