樹番茄（Tamarillo），Cyphomandra betacea Sendt.，是一種亞熱帶水果，它含有豐富的花青素及類胡蘿蔔素。 我們取樹番茄乙醇萃取物及利用其它溶劑萃取所得之各部抽提物，分析其總多酚含量及探究其生化特性，使我們更容易的了解樹番茄是否能預防氧化壓力並可運用在化妝品中做為美白成分。 釵h證據顯示，低密度脂蛋白（Low-density lipoprotein，LDL）氧化，會引發動脈粥狀硬化的發生。 飲食中攝取適量抗氧化劑，能減少低密度脂蛋白氧化並清除體內自由基。 因此，就能減少罹患動脈粥狀硬化症發生的風險。 酪胺酸酶（Tyrosinase，EC 1.14.18.1）為參與黑色素合成的關鍵酵素，人類膚色的深淺，酪胺酸酶發揮了重要的作用。 若某種化合物對於酪胺酸酶活性能產生抑制作用，則此化合物就能做為有效的美白劑。 樹番茄乙醇粗萃物含有高量的酚類化合物 [ 28.8 ± 0.05 mg catechin equivalents (CE)/g dry weight ]， 並表現出強的DPPH（1,1-diphenyl-2- picrylhydrazyl）自由基清除能力 [ IC50 =189.1 ± 1.3 μg/mL ]。 接著再將乙醇粗萃物先後進行溶劑抽提，分別取得乙酸乙酯層、正丁醇層、水相層。 其中，乙酸乙酯層具有最高的酚含量 [ 61.1 ± 0.06 mg (CE)/g dry weight ]，且DPPH自由基清除能力為 [ IC50 = 89.1 ± 4.2 μg/mL ] 及TEAC [ 56.73 ± 4.5 mg/g ]。 於乙酸乙酯層中樹番茄酚類化合物在相同濃度及作用條件下，表現出比正對照組DL-? tocopherol 相類似的活性及氧化抑制效果，其相關的實驗有：利用Cu2+ 離子誘導低密度脂蛋白氧化，並以硫代巴比妥酸反應物質（Thiobarbituric acid reactive substances , TBARS）分析、延緩共軛雙烯形成（Conjugated diene formation）能力及電泳位移分析（Electrophoretic mobility）等試驗進行評估。 樹番茄甲醇抽提層對於洋菇酪胺酸酶具有強的競爭性抑制作用，而其 [ IC50＝0.246 mg/mL ]。 總而言之，樹番茄可作為供給食物中之抗氧化劑，同時亦能預防動脈粥狀硬化症發生並可做為化妝品中美白劑之應用。 Tamarillo, Cyphomandra betacea Sendt. , is a subtropical fruit containing anthocyanins and carotenoids. To better understand whether tamarillo fruit could prevent oxidative stress and be used as a whitening agent in cosmetics, we analyzed the total phenol contents and investigated the biochemical properties of the ethanol extract and its partitioned fractions on free radical scavenging, anti-LDL oxidation and anti-tyrosinase activities. There is considerable evidence indicated that atherogenesis is initiated and promoted by oxidation of low-density lipoprotein (LDL). Dietary antioxidants might reduce the risk of atherosclerosis by scavenging free radical and reduction of LDL oxidation. Tyrosinase (EC 1.14.18.1) is a key enzyme involved in the synthesis of melanin, which plays a major role in human skin pigmentation. Compounds which inhibit tyrosinase activity could be effective as depigmenting agents. The ethanol extract of tamarillo fruit contained a high content of phenolic compounds [ 28.8 ± 0.05 mg catechin equivalents (CE)/g dry weight ] and showed a strong DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging activity [ IC50 = 189.1 ± 1.3 μg/mL ]. Further solvent partition of the ethanol extract yielded ethyl acetate (EA), n-butanol, and water layers. Among them, EA layer had the highest phenol content [ 61.1 ± 0.06 mg (CE)/g dry weight ], DPPH scavenging potential [ IC50 = 89.1 ± 4.2 μg/mL ] and TEAC [ 56.73 ± 4.5 mg/g ]. Tamarillo phenolics in EA layer also exhibited stronger or compatible inhibitory activity than DL-?tocopherol, at the same working concentration, Copper-induced LDL oxidation was suppressed by the tamarillo phenolics in EA layer more effectively or compatible to DL--tocopherol, as measured by decreased formation of thiobarbituric acid-reactive substances assay（TBARS）, conjugated diene and electrophoretic mobility（REM）. Tyrosinase activity and enzyme kinetics was analyzed by Michaelis-Menten approach. The methanol fraction contained strong competitive inhibitors on mushroom tyrosinase with IC50 0.246 mg/mL. In conclusion, the tamarillo fruit may serve as a dietary antioxidant for prevention atherosclerosis and a whitening agent in cosmetics.
