In the course of screening for acetylcholinesterase and butyrylcholinesterase inhibitors from natural products by an in vitro Ellman method, the extract of the roots of Vitis amurensis Rupr. (Vitaceae) showed significant cholinesterase inhibitory activity. Employing a bioassay-linked HPLC method, followed by a semi-preparative HPLC method, two compounds of interest were isolated and characterized as vitisin A and heyneanol A. They inhibited effectively both acetylcholinesterase and butyrylcholinesterase in a dose-dependent manner and exhibited higher activity against butyrylcholinesterase compared with that of galantamine, a positive control. Furthermore, the aggregation of beta-amyloid was evaluated in vitro based on a thioflavine T fluorescence assay to expand their activity profile, with the result that both compounds showed the ability to block beta-amyloid aggregation.
Alzheimer's disease (AD), a neurodegenerative disorder of the cortex and hippocampus, is associated with a selective loss of cholinergic neurons and characterized by cognitive and memory deficiencies. The presence of intracellular neurofibrillary tangles and extracellular amyloid deposits in the brain are the hallmarks of AD. The principal component of amyloid deposits found in the plaques is b-amyloid (Ab). 1)The progressive accumulation of Ab peptide is widely believed to initiate the pathogenesis of AD and to trigger a cascade of events such as neurotoxicity, oxidative injury, and inflammatory response that contribute to the progression of AD. 2)There is mounting evidence that oxidative stress plays a primary role in the pathogenesis of AD. Ab facilitates the generation of free radicals causing the peroxidation of membrane lipids, and the increased production of reactive oxygen species (ROS) results in cellular damage.3) Moreover, several studies have suggested that oxidative stress precedes Ab deposition. 4,5) This vicious cycle between Ab deposition and free radical generation eventually leads to neuronal damage, cognitive dysfunction, and various behavioral and psychological symptoms in AD patients. 6) Therefore, considerable efforts have been made to search for the antioxidants that reduce Ab-induced oxidative stress in AD. Among them, much attention has been drawn to polyphenols that are natural substances obtained from plants, fruits, and vegetables.Vitis amurensis RUPR. (Vitaceae), a wild-growing grape, is widely distributed in Japan, China and Korea. Its fruits have been used as the raw materials for juice and wine in Korea, and its roots have been used as traditional medicine for the treatment of cancer and various pains. In recent studies, it has been reported that the roots of V. amurensis possess antiinflammatory and anti-tumor activity and contain structurally diverse resveratrol oligomers. 7,8) Resveratrol (trans-3,5,4Ј-trihydroxystilbene), a naturally occurring polyphenol mainly found in grapes and red wine, has been spotlighted as potential therapeutic agents for several pathological disease. Many studies demonstrated that resveratrol prevents the cognitive deficits as well as the oxidative stress in the treatment of neurodegenerative diseases such as AD.9,10) This representative nonflavonoid polyphenol has been purported to provide many beneficial effects, mainly attributable to its powerful antioxidant capability and its neuroprotective action is also principally related to this property.11,12) However, the neuroprotective effect of resveratrol oligomers has not been studied yet in spite of their diverse biological activities including antioxidative and anti-inflammatory activities.7,13) In a preliminary study (unpublished data), we found that the extract of the roots of V. amurensis protected rat pheochromocytoma (PC12) cells against Ab-induced cytotoxicity. On the basis of these facts, it is expected that the resveratrol oligomers from V. amurensis may have potential as novel therapeutic a...
The hydroxyl radical (*OH) scavenging and ferrous ion chelating activities of four isoquinoline alkaloids isolated from Coptis chinensis Franch were studied for the identification of their structural characteristics to scavenge *OH. The *OH was generated via Fe(II)-catalazed Fenton reaction in this study and the reliable measurement of *OH scavenging activities of isoquinoline alkaloids were achieved using electron spin resonance (ESR) spectrometry method. At the 1 mM concentration, berberrubine (85%) showed the strongest *OH scavenging activity and the next were in the decreasing order of coptisine (79%), berberine (23%), and palmatine (22%). The ferrous ion chelating effects of the alkaloids showed similar pattern with their *OH scavenging effects. These results suggest that *OH scavenging effects of the alkaloids were closely related to their ferrous ion chelating activities. In addition, metal chelating functional groups such as hydroxy group at C-9 and methylenedioxy group at C-9 and C-10 were thought to contribute to the *OH scavenging activities of the isoquinoline alkaloids.
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