Types of sesquiterpenes from Artemisia douglasiana

Artemisia douglasiana afforded, in addition to known compounds, two new C₁₄-acetylenes, five longipinene derivatives, three nerolidol derivatives, a lactone and a ketone with a new carbon skeleton and lavendulol-2-methylbutyrate. The structures were elucidated by spectroscopic methods and some chemical transformations. The configurations of several oxo longipinene-7, 9-di- and 7, 8, 9-triesters isolated previously were corrected. The biogenesis of the new lactones is discussed briefly.     

海南木莲叶挥发油化学成分研究

目的：分析海南木莲叶的挥发油成分。方法：采用水蒸气法提取挥发油,气相色谱-质谱-计算机联用技术分析。结果：共鉴定出49种化合物,占挥发油总量的99．99％,其中主要成分是橙花叔醇（16．44％）;3,7-二甲基-2,6-辛二烯-1-醇（5.27％）;3,7-二甲基1,6-辛二烯-3-醇（5．12％）;α-丁香烯（4．97％）和丁香烯（4．48％）。     

Oxygenated nerolidol derivatives from Artemisia alba

From the aerial parts of Artemisia alba of Calabrian origin, five oxygenated nerolidol derivatives were isolated, two of them bearing hydroperoxyl groups. Structures were elucidated by spectral data and chemical reactions. Acetylation of the major hydroperoxyl constituent afforded a tris-nor aldehydic derivative as a result of loss of acetone from an unstable intermediate perester. An internally consistent set of ¹³C NMR assignments for the natural products and some derivatives is presented.     

高等植物的次级代谢—C11和C16萜烯同系物和间接自我保护

［２Ｈ５］－橙花叔醇,［２Ｈ５］－咙牛儿基沉香醇和糖甙酶等为底物,对５０多种单子叶和双子叶植物进行培养实验,证明许多高等植物尤其是大多数农作物在被害虫侵袭时,叶片中所含橙花叔醇糖甙被水解产生游离醇,又在细胞内的氧化裂解酶的作用下产生次级代谢,表现为其次级代谢物将大大增多,其中萜类以及Ｃ１１、Ｃ１６萜烯同系物的含量增加更加显著。许多试验表明,植物以此引诱害虫天敌,实现自我保护。     

Neue sesquiterpenlactone und nerolidol-derivate aus Ursinia-arten

The aerial parts of U. anethoides afforded, in addition to new nerolidol derivatives, a new germacranolide. The structure could only be elucidated by formation of the corresponding pyrazoline derivative and by comparison of the ¹H NMR data with those of similar pyrazolines. The aerial parts of U. alpina also contain a new nerolidol derivative and, in addition to the known 9β-hydroxycostunolide, a new eudesmanolide. The roots of all species contain furanosesquiterpenes, which are also present in related genera.     

Allenic germacranolides,bourbonene derived lactones and other constituents from Vernonia species

An investigation of seven Vernonia species, mainly from northern Brazil, afforded in addition to known compounds three new unusual sesquiterpene lactones with an allenic group. Intensive NMR studies fully established the structures. Furthermore, two lactones derived from bourbonene, two new glaucolides, a new furansesquiterpene, a nerolidol derivative and two other sesquiterpenes derived from eudesmane were isolated. The biogenetic relationships of the sesquiterpene lactones present in Veronia species as well as the chemotaxonomic aspects are discussed.     

Nocturnal emission and post-pollination change of floral scent in the leafflower tree,Glochidion rubrum,exclusively pollinated by seed-parasitic leafflower moths

Many insect-pollinated plants use floral scent signals to attract and guide the effective pollinators, and temporal patterns of their floral scent emission may be tuned to respond to the pollinator's activity and pollination status. In the intimate nursery pollination mutualism between monoecious Glochidion trees (Phyllanthaceae) and Epicephala moths (Gracillariidae), floral scent signals mediate species-specific interactions and influence the moth's efficient pollen-collecting and pollen-depositing behaviors on male and female flowers, respectively. We tested the hypotheses that both sexes of flowers of Epicephala-pollinated Glochidion rubrum exhibit a diel pattern of scent emission matching the activity period of the nocturnally active pollinator, and that female flowers change the chemical signal after pollination to reduce further visits and oviposition by the pollinator. We investigated the diel change of floral scent emissions during two consecutive days and the influence of pollination on the floral scent by conducting hand-pollinations in the field. The total scent emission of male and female flowers was higher at night than in the day, which would be expected from the nocturnal visitations of Epicephala moths. Some compounds exhibited a clear nocturnal emission rhythm. Hand-pollination experiments revealed that emission of two compounds, nerolidol and eugenol, drastically decreased in pollinated flowers, suggesting that these compounds may function as key attractants for the pollinator; however, the total scent emission of the female flower was not influenced by hand-pollination. The pattern of the floral scent emission of G. rubrum may be optimized to attract nocturnal pollinators and reduce oviposition.     

Heliangolides and other constituents from Bejaranoa semistriata

The investigation of Bejaranoa semistriata, a new genus in the tribe Eupatorieae, afforded in addition to known compounds a new furanoheliangolide, two epimeric 1-keto-heliangolides, two germacranolides, two nerolidol derivatives and a geranylnerol derivative. The structures were elucidated by spectroscopic methods and a few chemical transformations.     

Heliangolides,and nerolidol and p-hydroxyacetophenone derivatives from Calea species

A new Calea species afforded a heliangolide, closely related to niveusin C, while from Calea teucrifolia two new nerolidol derivatives and eight p-hydroxyacetophenone derivatives were isolated. The structures were elucidated by spectroscopic methods and a few chemical transformations. The spectral data of 8β-angeloylatripliciolide, the main constituent of C. teucrifolia, are also included. The chemotaxonomic situation is discussed briefly.     

Isocedrene derivatives and other sesquiterpenes from moscharia pinnatifida

From the aerial parts of Moscharia pinnatifida nine further α-isocedrene, two guaiane, three cyperene and two nerolidol derivatives were isolated. The structures were elucidated by high field NMR studies. Chemotaxonomic aspects are discussed.