Aqueous Extract from Taiwanese Agrocybe cylindracea strain B Protects DNA against •OH- mediated Strand Breaks
LIEN-HUI WANG 1, SHUN-JEN TSAI 2 AND SHWU-YUANN LIN 3*
1. Department of Food Science and Technology, Chung Hwa College of Medical Technology, 89 Wunhua 1st St., Rende Township, Tainan County 717, Taiwan, R.O.C.
2. Department of Food Science, National Chung Hsing University, 250 Guoguang Rd., South District, Taichung City 402, Taiwan, R.O.C.
3. Department of Food and Nutrition, Chung Hwa College of Medical Technology, 89 Wunhua 1st St., Rende Township, Tainan County 717, Taiwan, R.O.C.
(Received: August 20, 2003: Accepted: July 8, 2004)
ABSTRACT
Water extract from Agrocybe cylindracea strain B (ACE), an edible mushroom produced in Taiwan, has previously been studied for its antioxidative activities. ACE is an efficient antioxidant in vitro. Since oxidative alterations of DNA can be linked to the development of cancer, we decided to study whether ACE protects DNA against oxidative stress. We report here that pUC18 plasmid DNA and HepG2 cells' DNA are damaged by • OH radicals generated from Cu (II) plus H2O2. The DNA damage was quantified by determining the diminution of supercoiled DNA forms and the DNA migration after oxidative attack using agarose gel electrophoresis. The IC50 values of ACE were 69.7 μg/mL and 91.6 μg/mL for cupric-mediated • OH formation by determining the diminution of supercoiled DNA forms and Comet assay, respectively. The antioxidant capacity of ACE was significantly higher than that of Lentinus edodes extract (LEE) and the two known scavengers of hydroxyl radical, mannitol and thiourea. ACE and LEE could also inhibit the oxidative degradation of 2'-deoxyribose caused by • OH radicals generated from metal ions plus H2O2. The malondialdehyde (MDA) inhibition effect of active fractional protein from ACE was better than that of LEE. The major protein components of ACE were different from LEE.
Key words: Agrocybe cylindracea, DNA damage, hydroxyl radical, antioxidative activity