Studies on the Constituents of a Relic Plant Trochodendron aralioides and Bitter Principles from Azadirachta indica and Onychium japonicum

• Main Authors: George Chih-Tsong Fong, 馮智聰
• Other Authors: Chiu-Ming Chen
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/36497760390400057507

博士 === 國立清華大學 === 化學系 === 90 === A study on the constituents of Trochodendron aralioides, a relic plant, showed that lupeol (1), erythrodiol 3-palmitate (35), phytosteols (32-34), and nonacosane were isolated from the dried leaves; oleanolic acid (4), lupeol palmitate (37), fatty acid methyl ester, and methyl esters of unsaturated long chain acids (36) were isolated from the fresh fruits of the plant. This is the first discovery that compounds 35 and 37 existed in Trochodendron aralioides. Among the thirteen constituents of neem tree (Azadirachta indica) that were isolated in the laboratory of Prof. Kraus in Hohenheim University, Germany, four weakly active antifeedants toward Mexican beetle Epilachna varivestis, azadirone (39)、azadiradione (40)、epoxy-azadiradione (41), and gedunin (43) were tasteless; two moderate antifeedants 6-deacetylnimbin (45) and nimbolide (46) were weakly bitter; and a very active compound salannin (48) tasted very bitter. It seemed there were some relationships between antifeedant activity and bitterness. For a compound to be bitter, it must consist of a ''bitter unit''- a DH/A pair, and a ''hydrophobic unit''. All bitter principles (45-50) of neem tree possessed ''hydrophobic unit'' but most of them were lack of ''bitter unit''. The bonding ''oxygen bridge'' between C-6 and C-28 may be considered as a limiting case of DH/A pair. Onychiol B (13), a compound with a unique cyathane skeleton of 5-, 6-, 7-membered rings fused in success, and being one of the major bitter principles of Onychium japonicum , was chosen for the study of bitterness-structure relationship. The 7, 14-diol part of onychiol B was supposed to be a DH/A bitter unit that accounted for its bitterness. Transformation of 7,14-diol to 7,14-O-acetals or ketal only weakened the bitterness of onychiol B, suggesting the hydroxy group on C-20 and the unique cyathane skeleton were requied for bitterness.