| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥2,400,000 (Direct Cost: ¥2,400,000)
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| Research Abstract |
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
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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
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