Biflavones of Dacrydium sensu lato

A survey of the biflavonyls in the leaves and branchlets of all three sections of the genus Dacrydium s.l. revealed a complex mixture of amentoflavone and its partial methyl ethers and hinokiflavone in most species. A group of three species in section C, however, were characterised by cupressuflavone derivatives as the major biflavone constituents. The results are used to discuss proposals for revised generic boundaries.     

Biflavones of the subfamily cupressoideae,cupressaceae

Thirty species, representing all eight genera of the subfamily Cupressoideae, were examined for biflavonoid content of the leafy twigs. The major biflavonoid constituents are based on amentoflavone, cupressuflavone and hinokiflavone. The affinities suggested by biflavonyl distribution do not correlate with the currently recognized tribal groupings. There is evidence of closer links between northern and southern hemisphere genera than would be expected on the basis of the presently recognized subfamilies.     

Biflavones from the leaves of Araucaria excelsa

Eight biflavones have been isolated from the leaf extracts of Araucaria excelsa. 7″-O-Methylamento-flavone, 7,7″-di-O-methylamentoflavone, 4′ or 4″', 7-di-O-methylcupressuflavone, 7,7″,4″'-tri-O-methyl agathisflavone and 7,4′,7″-tri-O-methylamentoflavone are new compounds and are being reported for the first time. The others are 7,7″-di-O-methylagathisflavone,7,4′,7″,4″'-tetra-O-methylamentoflavone and 7,4′,7″,4″'-tetra-O-methyl-cupressuflavone. Mass and NMR spectral studies are used for structural elucidation. In addition, the presence of several other biflavones has been indicated by TLC examination of methylated products.     

Biflavones of Dioon

Seven biflavones, amentoflavone, bilobetin, sequoiaflavone, ginkgetin, sciadopitysin, 7,4′,7′,4?-tetra-O-methylamentoflavone, and diooflavone (amentoflavone hexamethyl ether), were identified from extracts of the cycad genus Dioon. The biflavones were identified by direct comparison with authentic samples using m.m.p., co-chromatography in 3 solvents, and NMR studies of the acetates. This is the first time amentoflavone hexamethyl ether has been identified as a natural product. After surveying numerous species of the Cycadales, no evidence could be obtained for the occurrence of biflavone glycosides or of biflavones based upon any other nucleus than apigenin.     

银杏外种皮的双黄酮成分

从银杏外种皮的乙酸乙酯提取中分离得到６个化合物,其中５个经物理常数及光谱分析鉴定为金松双黄酮、银杏素、奶杏素、１－５’－甲氧基白果素及白果素。这些化合物均首次从银杏外种皮分离。     

Biflavonyls and the affinities of Blepharocarya

An analysis of fruit and/or leaf biflavonyls from the genus Blepharocarya and representatives of Burseraceae, Simaroubaceae, Meliaceae and Anacardiaceae strongly supports a close affinity of the genus with the Anacardiaceae, and in particular with the tribe Rhoeae.     

八种苏铁植物叶轴的比较解剖研究

对苏铁科和泽米铁科8种苏铁植物,即台湾苏铁(Cycas taiwaniana)、海南苏铁(C·hainanensis)、元江苏铁(C·parvulus)、单羽苏铁(C·simplicipinna)、滇南苏铁(C·diannanensis)、越南篦齿苏铁(C·elon-gata)、长刺大泽米铁(Macrozamia longispina)、双子铁(Dioon edule)的叶轴横切面结构进行了比较研究,以期为苏铁植物的系统演化和分类进一步提供解剖学依据,并探讨其解剖结构与生态的适应机制。结果表明,较原始的苏铁科和较进化的泽米铁科叶轴的横切面结构无论在表皮、机械组织、基本组织和维管组织,还是在后含物方面都存在着明显的不同;泽米铁科的大泽米铁属与双子铁属差异也较大;苏铁科科内的6个种则相似性稍大,表明它们是亲缘关系较密切的类群,但每个种都有各自的结构特点。越南篦齿苏铁的维管束排列方式和数目的增加方式与泽米铁科两个种的相似,因此推断它处于较进化的地位。研究还发现苏铁科种类的叶轴的近轴面均像叶片那样具有栅栏组织状同化组织存在。苏铁类植物叶轴具有旱生植物的解剖结构特征:角质层较厚、表皮细胞壁厚、机械组织发达、晶体较多、分泌道和维管束数目较多等结构特征。这些对研究苏铁纲各科及种类之间的进化与亲缘关系提供了佐证,同时揭示了苏铁纲这类古老的植物类群其多个属的种类能够经历如此漫长的地质年代而幸存下来,是由于其在长期演化过程中均形成了这些独特的结构特征,因而具备了相对应的生理功能,能够在恶劣的自然环境下,具备耐干旱、贫瘠、高温及耐盐碱等逆境的结果。     

Diterpenes from the seed of Sciadopitys verticillata

Thirteen new labdane-type diterpenes have been isolated from the seeds of Sciadopitys verticillata together with six known ones, sciadin, sciadinone, dimethyl sciadinonate, lambertianic acid and its methyl ester and trans-communic acid. Their structures have been determined by chemical and spectral methods.     

Biflavones of the subfamily callitroideae,cupressaceae

Twenty species, including representatives of all 11 genera of the Callitroideae, were examined for biflavonoid content of the leafy twigs. The major biflavonoids are based on amentoflavone, cupressuflavone and hinokiflavone. Their uneven distribution amongst the genera allows the distinction of five groups. These do not correlate strongly with currently recognized tribal groupings. The affinities of these genera are discussed.     

Amentoflavones from Callitris species

The biflavonoid patterns of the leaves of five species of Callitris are characterized as amentoflavone based derivatives only. This contrasts markedly with the diversity of biflavones reported for northern genera of the Cupressaceae.     

Terpenoids from the seed of chamaecyparis pisifera: the structures of six diterpenoids

Six new diterpenes, 12-hydroxy-20-nor-abieta-1(10),2,8,11,13-pentaene, pisiferanol (10S,12-dihydroxy-9(10 → 20)-abeo-abieta-8,11,13-triene), pisiferadinol (20S-hydroxypisiferanol), 12-deoxypisiferanol, 1β-hydroxyisopisiferin (1R,12-dihydroxy-9(10 → 2O)abeo-abieta-8,10(20),11,13-tetraene), and the dimethylamine salt of O-methylpisiferic acid were isolated from the seed of Chamaecyparis pisifera. The structures of these diterpenes were established by spectral and chemical methods. In addition, 15 mono-, four sesqui- and nine diterpenes were identified.