1.
Antioxidant properties of natural polyphenols and their therapeutic potentials for Alzheimer's disease.
Choi, DY, Lee, YJ, Hong, JT, Lee, HJ
Brain research bulletin. 2012;(2-3):144-53
Abstract
Alzheimer's disease (AD) is the most prevalent neurodegenerative disease and most common cause of dementia. However, there is no known way to halt or cure the neurodegenerative disease. Oxidative stress is a cardinal hallmark of the disease and has been considered as therapeutic target for AD treatment. Several factors may contribute to oxidative stress in AD brains. First, mitochondrion is a key player that produces reactive oxygen species (ROS). Mitochondrial dysfunction found in AD patients may exaggerate generation of ROS and oxidative stress. Second, amyloid-beta peptide generates ROS in the presence of metal ions such as Fe(2+) and Cu(2+). Third, activated glial cells in AD brains may produce excessive amount of superoxide and nitric oxide through NADPH oxidase and inducible nitric oxide synthase, respectively. Increased ROS can cause damage to protein, lipid and nucleic acids. Numerous studies demonstrated that natural polyphenolic compounds protect against various neurotoxic insults in vitro and in vivo AD models. In these studies, dietary polyphenolic compounds exhibit neuroprotective effects through scavenging free radicals and increasing antioxidant capacity. Furthermore, they could facilitate the endogenous antioxidant system by stimulating transcription. Some epidemiological and clinical studies highlighted their therapeutic potential for AD treatment. In this review, we will briefly discuss causes of oxidative stress in AD brains, and describe antioxidant neuroprotective effects and therapeutic potential for AD of selected natural polyphenolic compounds.
2.
Effects of medicinal herb tea on the smoking cessation and reducing smoking withdrawal symptoms.
Lee, HJ, Lee, JH
The American journal of Chinese medicine. 2005;(1):127-38
Abstract
Medicinal herbs (21 species) were screened for the antioxidant activity and nicotine degradation activity (NDA) in vitro. Eleven of them with higher antioxidant activity and NDA were selected for preparation of the medicinal herb tea (MHT) and the effects of MHT on smoking cessation and reducing smoking withdrawal symptoms were evaluated in 100 male human smokers. Among these medicinal herbs, Eugenia aromaticum and Astragalus membranaceus Bunge showed the highest antioxidant activity (IC50 of 30.0 microg/mL) and NDA (1.81), respectively. MHT showed relatively high antioxidant activity (IC50 of 50.6 microg/mL) and NDA (1.23). The urinary cotinine level, a metabolite of nicotine, increased in the first 2 weeks and greatly decreased from the 2nd to 4th week in the MHT taking group, which indicates that MHT accelerates the conversion of nicotine into cotinine. Human groups taking MHT for 4 weeks underwent reduced smoking withdrawal symptoms compared to the non-MHT taking subjects, and 38% of subjects taking MHT succeeded in smoking cessation, while only 12% of non-MHT taking subjects succeeded in quitting smoking.
3.
Vitamin C and cancer chemoprevention: reappraisal.
Lee, KW, Lee, HJ, Surh, YJ, Lee, CY
The American journal of clinical nutrition. 2003;(6):1074-8
Abstract
Several studies have reported that even a moderate daily dose of supplementary vitamin C (200 mg) induces the formation of genotoxins from lipid hydroperoxides, thereby resulting in DNA damage and initiation of carcinogenesis. However, other reports questioned the experimental designs used and suggested that the chemopreventive effects of vitamin C may be linked to the inhibition of tumor promotion as well as to the blocking of tumor initiation. In this article, we discuss issues of contention and some controversies related to the potential chemopreventive effects of vitamin C in carcinogenesis.