Systematic evaluation of radical scavenging active compounds in some edible plants using some different methods

本研究旨在用不同的方法评价几种食用植物成分的体外清除自由基活性，并阐明这些抗氧化剂的化学结构和活性关系。首先，从肉豆蔻和豆蔻(Myristica Argentea)中分离得到10个脂类化合物，并通过核磁共振和质谱分析鉴定了它们的结构，测定了6个二甲基丁烷木脂素和4个四氢呋喃木脂素。用三种不同的方法测定了木脂素对DPPH自由基和O2-自由基的清除能力，以及氧自由基吸收能力(ORAC)。用DPPH自由基清除法和ORAC法测定的活性似乎都依赖于苯环上的羟基数目。然而，与含氧…的木脂素相比，含有苯亚甲基的木脂素对DPPH自由基的清除能力更强活性更高的苄基碳，而倾向于表现出较低的ORAC。另一方面，木脂素类化合物的化学结构与其对O2-的清除活性之间没有明显的相关性。其次，从柳叶(Syzygium Polyanthum)中分离得到5个亲水性化合物，分别鉴定为2个杨梅素糖苷和3个鞣皮单宁。用上述三种不同的方法测定了这五个化合物以及从乙酸乙酯可溶物中分离得到的一些单宁和黄酮类化合物的自由基清除活性。DPPH自由基的清除活性依赖于苯环上的羟基数目。相反，比较了具有相同邻三羟基苯基(o-THP)基数的五种鞣胶对O2-的清除活性，发现分子中六羟基二苯基(HHDP)的数目越多，清除活性越强。另一方面，分子中含有三个以上邻THP基团的单宁的ORAC不受没食子酰基和HHDP基团数目的影响，因此，三种不同方法获得的清除自由基的能力并不一定相同，因此需要多种方法来评价抗氧化剂。较少

This study was aimed to evaluate in vitro radical scavenging activity of some edible plant constituents using some different methods and elucidate chemical structure and activity relationship of these antioxidants.Firstly, ten lipophilic compounds were isolated from Papuan nutmeg and mace (Myristica argentea) and their structures were elucidated on the basis of spectroscopic evidences of NMR and MS, resulting in determination of six dimethylbutane lignans and four tetrahydrofuran lignans. Radical scavenging activities of these isolated lignans were measured by three different methods, evaluation of scavenging effects on DPPH radical and O2- radical, and evaluation of ORAC (Oxygen Radical Absorbance Capacity). The activities measured by both DPPH radical scavenging and ORAC methods seemed to be dependent on the number of hydroxyl groups on the benzene ring. However, lignans having benzyl methylene tended to show a higher scavenging ability against DPPH radical than lignans having oxygen … More ated benzylic carbon, while tended to show a lower ORAC. On the other hand, no clear relationship was observed between the chemical structure of lignans and their scavenging activity against O2- radical.Secondarily, five hydrophilic compounds were isolated from salam leaves (Syzygium polyanthum) and they were identified as two myricetin glycosides and three ellagitannins. The radical scavenging activities of these five compounds together with some tannins and flavonoids which had been previously isolated from the ethyl acetate soluble fraction were measured using three different method mentioned above. The DPPH radical scavenging activity was dependent on the number of hydroxyl groups on the benzene ring. On the contrary, comparing the O2- radical scavenging activity in five ellagitannins having the same number of ortho-trihydroxyphenyl (o-THP) groups indicated that the more the number of hexahydroxydiphenoyl (HHDP) groups were in the molecule, the more the activity was. On the other hand, ORAC of tannins having more than three o-THP groups in the molecule was not influenced by the number of galloyl and HHDP groups.Consequently, the radical scavenging abilities obtained by three different methods were not necessarily the same, therefore, more than one method are required to evaluate antioxidants. Less