甘草與茶多酚併用之輻射保護功能評估
徐雪瑩
慈濟大學
輻射因其物理特性，除了在生物體內產生大量自由基外，也會直接造成細胞結構包括DNA的破壞，最終在器官系統內出現包括骨髓與腸胃系統病變等嚴重症狀，甚而導致死亡。輻射與生活息息相關，然而核能意外頻傳，也造成民眾的恐慌。研發不具毒性的輻射保護劑，保護個體在意外發生且無法避免的情況下，免於受到輻射的嚴重傷害，被認為是除了在醫療上以高能量游離輻射進行腫瘤治療所衍生正常組織的保護外，現有以輻射進行軍事防禦、核能工業發展以及核爆意外或太空旅行時極為重要的議題。如同過去已經研究的多種合成性化合物，近年許多天然物也被用以進行抗輻射功能的研究。甘草素又名甘草酸，是甘草所含三萜苷的主要活性成分，具有包括抗發炎、抗過敏、抗病毒等藥理活性，也被報告藉由其高度的抗氧化活性，具有輻射保護之功能。茶多酚是茶的主要組成，其中所含成分種類多元，具有多項生化及藥理功能；茶多酚中又以酯化型兒茶素(EGCG)含量最多、生物活性最高且化學保護性最強，EGCG也因其結構特性而被報告具有輻射保護的能力。
甘草與茶多酚都曾各別被報告在合併其他化合物的處理下，具有明顯的藥理加成活性，然而甘草合併茶多酚處理的藥理研究報告卻極為有限。為了研發具有高度保護功能且不具明顯生物毒性的輻射保護配方，本研究以降低濃度的甘草酸及兒茶素合併，分析對輻射照射之免疫細胞及小鼠骨髓組織的影響及其作用機制，以評估利用甘草與茶多酚之生物活性，合併兩者以發展輻射保護劑之可行性。
關鍵字：甘草酸、兒茶素、輻射保護
Evaluation of radioprotection by combination of glycyrrhiza and tea polyphenols
Hsu HY
Due to physical actions, radiation induced oxidative damage as well as DNA damage in cellular structures result in deleterious effects in various tissues derived from bone marrow failure, gastro intestinal tract problems, ultimately lead to death. Protection of biological systems from radiation is of paramount importance during accidental and unavoidable exposures to radiation and development of novel and effective approaches to combat radiation damages using non-toxic radioprotectors is of considerable interest for defense, nuclear industries, radiation accidents, space travels,etc., besides the protection of normal tissues during radiotherapy of tumors. Recent years, many natural as well as synthetic compounds have been investigated for their efficacy to protect against irradiation damage.
Glyzyrrhizic acid, a major bioactive triterpene glycoside of glyzyrrhiza, has many attributed pharmacological effects which anti-inflammatory, anti-allergic and antiviral activities are included, and is reported to possess radioprotective properties through its strong anti-oxidative activity. Tea polyphenols, the main components of the tea, exert a wide range of biochemical and pharmacological effects, most of which are considered to be due to the presence of a wide range of phytochemicals. EGCG is the most chemopreventive constituent and had been reported to exert radioprotective properties by its structural characteristics.
The synergistic effects of glyzyrrhizic acid and tea polyphenols have been reported by combination with other bioactive compounds, respectively. To investigate the efficacy of glyzyrrhizic acid combined with EGCG as an agent to protect biological systems from radiation-induced damages, the present project aimed to evaluate the radioprotective effect of glyzyrrhizic acid and EGCG against irradiation-induced damage in cells and mice, and elucidate the underlying mechanisms.
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