Polyphenols as Neuroprotectants from Taiwanese Botany

• Main Authors: Hsin-Hsueh Lee, 李欣學
• Other Authors: Ling-Ling Yang
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/38795739817481110421

博士 === 臺北醫學大學 === 藥學研究所 === 95 === Neuronal injury occurs via various mechanisms, including the initial ischemic insult which in turn initiates a secondary injury cascade of metabolic and biochemical changes. These changes include production of oxygen free radicals with lipid peroxidation, release of excitatory amino acids such as glutamate, failure of energy metabolism, release of inflammatory mediators, disruption of calcium homeostasis, and potentially other unidentified mechanisms. Natural products have been used as medicinal agents for many years. Through a large number of chemical and pharmacological research works, numerous bioactive compounds have been found from Chinese medicinal plants and some of them have been used clinically. The present study was divided into several parts includes Chinese herbal medicine, the extracts of Taiwan folk medicine plant or Taiwan botany, and their active components. The overall goal in this study is to find out the potential natural resources of polyphenols from traditional Chinese Medicine, folk medical plants, and if they can protect neurotoxicity or excitotoxicity in primary cultured cortical neuron. Our experimental design is that polyphenols, specifically found the flavonoids and the medical plant extracts, and to examine their protective effects on the cortical neurons after exposure to different neurotoxic chemicals. In our results, we found four potential candidates with neuroprotective abilities. Baicalein prevents neurotoxicity induced by both glutamate and glucose deprivation via decreasing intracellular calcium. Tangeretin can against glutamate and glucose deprivation. Tangeretin may protect central neurons by increasing the calcium via a synapse activity-dependent manner and might serve as a GABA mimic modulator to protect neurons against overexcitation-related brain injury and neurodegeneration. In addition, in the crude extract of pre-germinated brown rice (PGBR) with high levels of the nutrient GABA and exert a benefit for the prevention on the neurodegenative diseases. The ethanol extract of PGBR exerted the remarkable neuroprotective against glutamate and arachidonic acid-induced neurotoxicity. The ethanol extract of dried flowers Osmanthus fragrans (OFE) contained a high amount of total flavonoid and polyphenol. The neuroprotective activity of OFE was investigated under different insults (glutamate, arachidonic acid, and 6-hydroxydopamine). This is the first demonstration of the neuroprotective, free radical scavenging and anti-oxidative effects of O. fragrans.