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

本研究旨在通过不同的方法评价几种可食用植物成分的体外自由基清除能力，并阐明这些抗氧化剂的化学结构和活性关系。首先，从巴布亚肉豆蔻和豆蔻（Myristica argentea）中分离得到10个亲脂性化合物，并通过NMR和MS对其结构进行了鉴定，鉴定出6个二甲基丁烷木脂素和4个四氢呋喃木脂素。通过三种不同的清除DPPH自由基和O2-自由基的方法以及ORAC（氧自由基吸收能力）来测定这些分离的木脂素的自由基清除活性。DPPH自由基清除和ORAC方法测定的活性似乎依赖于苯环上羟基的数量。然而，含有亚甲基苯的木脂素对DPPH自由基的清除能力往往高于含有氧和苯基碳的木脂素，而ORAC往往较低。另一方面，木脂素的化学结构与其清除O2-自由基的活性之间没有明确的关系。其次，从salam （Syzygium polyanthum）叶中分离得到5个亲水性化合物，鉴定为2个杨梅苷类化合物和3个鞣花单宁类化合物。用上述三种不同的方法测定了这五种化合物与先前从乙酸乙酯可溶性部分分离得到的单宁和黄酮类化合物的自由基清除活性。DPPH自由基清除活性与苯环上羟基的数量有关。相反，比较具有相同邻三羟基苯基（o-THP）基团数量的五种鞣花单宁清除O2-自由基的活性表明，分子中六羟基二酚（HHDP）基团数量越多，其清除O2-自由基的活性越强。另一方面，分子中含有3个以上o-THP基团的单宁的ORAC不受没食子酰和HHDP基团数量的影响。因此，通过三种不同的方法获得的自由基清除能力不一定相同，因此，需要不止一种方法来评估抗氧化剂。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