溫度對香椿葉片中酚類物質含量之影響

Abstract

香椿(Toona sinensis (A. Juss. ) Roem.)是原產自中國的蔬菜與木材的兼用樹種，嫩葉含有豐富的維生素、鐵、磷、酚類化合物以及植化素(Phyto-chemicals)，全株均可入藥。酚類化合物廣泛存在於植物體中，具有多樣性的生物功能，常被做為醫療及保健食品之用途，並且是植物調適各種環境逆境的產物，因此含量受環境因子影響甚鉅。目前針對香椿對環境反應的栽培研究甚少。為此，本論文分別以30/25℃、25/20℃、20/15℃三種溫度處理香椿實生幼株，觀測並分析溫度對其生長發育、嫩葉(15日齡)、成葉(60日齡)之內容物含量的影響。 為先確定香椿葉片酚類物質之固定與萃取法，比較乾燥方法、萃取液成分與萃取條件對香椿葉片總酚類物質萃取量的影響。以真空冷凍乾燥、甲醇萃取可以獲得最高總酚類物質萃取量。此外不同甲醇濃度(20%、40%、60%、80%、100%)中萃取30 min，結果顯示總酚濃度(y)與甲醇濃度(x)間存在一迴歸關係y=-0.0097(x-69.35)2+38.7，R2=0.9327，P<0.001，顯示在69.35%的甲醇濃度下會有最大的萃取率38.7 mg/g。 盆栽試驗採用三種溫度、三種株高、兩種不同成熟期的葉片之複因子試驗，測定葉片中總酚類物質含量及內容物的含量。 以酒石酸亞鐵法測定香椿15日齡嫩葉與60日齡成葉的總酚類物質含量。結果顯示日夜溫20/15℃處理之植物葉片內總酚類物質含量高於30/25℃及25/20℃。嫩葉總酚類物質含量高於成葉。原始植株高度以植株矮的總酚類物質含量較低。 以高效能液相層析儀(HPLC)分析鑑定香椿日齡15嫩葉與日齡60成葉之生理機能成分，比較嫩葉與成葉間成分的差異，結果顯示嫩葉中生理機能成分，包括沒食子酸(Gallic acid)、沒食子酸甲酯(Methyl gallate)、1,2,3,4,6-O-五沒食子酰葡萄糖(1,2,3,4,6-penta-O-galloyl-β-D-glucose；5GG)、沒食子酸乙酯(Ethyl gallate)皆高於成葉，達極顯著水準；兒茶素(Catechin)反之，而芸香苷(Rutin)在兩者間無顯著差異。日夜溫20/15℃處理之植物葉片生理機能成分以沒食子酸(Gallic acid)、兒茶素(Catechin)、沒食子酸甲酯(Methyl gallate)、芸香苷(Rutin)、1,2,3,4,6-O-五沒食子酰葡萄糖(1,2,3,4,6-penta-O-galloyl-β-D-glucose；5GG)含量顯著高於30/25℃及25/20℃處理，而沒食子酸乙酯(Ethyl gallate)則以20/15℃處理者顯著高於30/25℃處理者，但與25/20℃無顯著差異。原始植株高度以植株矮的六種生理機能成分皆較低，達顯著水準。

Toona sinensis (A. Juss.) Roem. is an original China trees which for vegetable and timber uses. Its leaves are rich in vitamins, iron, phosphorus, phenolic compounds and phytochemicals (Phyto-chemicals) content, and whole plant can be used as medicine. The main phytochemicals of T. sinensis have a lot of biological functions, especially their antioxidant capacity, and succulent shoot often uses as health food. However, less research was done about the factors affected the phytochemicals content of T. sinensis leaves under different environment conditions. Thus, T. sinensis seedling was treated with three different day/night temperatures, which were 30/25℃, 25/20℃and 20/15℃, to observe the effect of temperature to the amount on photochemicals content in different age of leaves. Preliminary experiment was down to determinaled the analysis, and found that vacuum-freeze drying and extracted with 60-80% MeOH for 30 min should be the best analysis condition. Temperzture experiment use a 3 temperatures, 3 plant hights and 2 leaves maturity factorial experiment design, and one-year-old potted seedling plants were used. Lower temperature resulted in higer total phenol content in not only 15-days-old leaves but also 60-days-old leaves. It’s means that leaves under 20/15℃(day/night℃) had significant higher total phenolic compound content than those under 30/25℃ and 25/20℃ condition. Meanwhile, total phanolic content of young leaves is higher than mature leaves, and shorter plants has lower total phenolic content. High Performance Liquid Chromatography (HPLC) was used to analysis and identification components of 15-days-old young leaves and 60-days-old mature leaves of T. sinensis. The results show that the component of young leaves, include gallic acid, methyl gallate, 1,2,3,4,6-penta-O-galloyl-β-D-glucose (5GG), ethyl gallate were significant higher than mature leaves, catechin was on the contrary, while was no significant difference. In 20/15℃ condition, leaves had significant higher all of 6 components. More over, all of six components content of leaves were lower in shorter plants. Latent effect was also found, especially with gallate derivatives.