Flavonoid aglycones from leaf resins of two species of Heterotheca (compositae)

Twenty-nine flavonoid aglycones have been identified from two populations each of Heterotheca grandiflora and H. psammophila. Considerable qualitative variation was found between populations of the same species. Overall, H. grandiflora is more complex in its flavonoid profile, accumulating a total of 24 compounds based on eight skeletal types, compared with 13 compounds based on four skeletal types in H. psammophila.     

The occurrence of aurentiacin and flavokawin B on Pityrogramma triangularis var. pallida and Didymocarpus species

The two chalcones, aurentiacin and flavokawin B, were isolated from the frond exudate of Pityrogramma triangularis var. pallida. In addition, flavokawin B was obtained from the leaf exudate of Didymocarpus corchorifolia.     

高效液相色谱法分析测定越桔果渣中的黄酮甙元

采用高效液相色谱法对越桔果渣中黄酮甙元进行定性和定量分析.用甲醇和水（60：40）以0.8 mL/min流速进行洗脱,368 nm波长检测越桔果渣水解液中黄酮类成分并测定其含量.结果：越桔果渣中黄酮甙元主要有杨梅素和槲皮素,其含量分别为：0.0206%和0.0686%.该方法测定样品简单易行,分离效果佳,灵敏度高,重现性好,结果准确可靠.     

Flavonoid aglycones in the resin of Hazardia squarrosa var. Grindelioides

Thirty three flavonoid aglycones have been identified from the external stem and leaf resin of Hazardia squarrosa var. grindelioides by TLC co-chromatography with authentic samples. The occurrence of compounds with oxygenation at C-6 and C-5′, which are also found in the genus Haplopappus, supports the previously believed close relationship between these two genera.     

Triangularin,a new chalcone from Pityrogramma triangularis

2′,6′-Dihydroxy-4′-methoxy-3′-methylchalcone has been isolated from the exudate farina of the ceroptin chemotype of Pityrogramma triangularis. The analogous flavanone was also detected as a minor component in the extract.     

蕨菜黄酮苷元的组成及含量测定研究

以80%乙醇浸提经乙醚脱脂预处理的干蕨菜粉,减压回收乙醇得浓缩液.浓缩液以8%硫酸沸水浴水解3 h后,加入20%NaOH中和至弱酸性,过滤,滤渣以三氯甲烷索氏提取获总蕨菜黄酮苷元.TLC法检测总黄酮苷元的组成,HPLC法测定其主要苷元的含量.结果表明,通过酸水解获得总蕨菜黄酮苷元,其主要成分为山奈酚,含量约占蕨菜干重的1.9%.     

木蝴蝶化学成分研究

本文对木蝴蝶Oroxylum indicum(L.)Vent.种子的化学成分进行了研究,以85%乙醇加热回流提取木蝴蝶成熟种子,提取物经柱层析和重结晶手段分离,最终得到10个化合物,根据波谱学手段和理化性质,鉴定其结构分别为木蝴蝶苷B(1),木蝴蝶苷A(2),白杨黄素(3),白杨黄素-7-O-双葡萄糖苷(4),白杨黄素-7-O-β-吡喃半乳糖醛酸苷(5),芹菜素(6),羽扇豆醇(7),2α,3β-二羟基羽扇豆醇(8),豆甾醇(9),油酸(10),其中,化合物6～9为首次从木蝴蝶属植物中分得。     

HPLC analysis of leaf surface flavonoids for the preliminary classification of birch species

Flavonoid aglycones found on the surfaces of birch (Betula spp.) leaves may constitute up to 10% of the dry weight of the leaf. A facile extraction and HPLC procedure has been developed that can be used for the preliminary classification of birch species according to the patterns of their leaf surface flavonoids. The procedure involves no complex sample preparation steps, and is able to provide HPLC chromatograms from fresh leaves in less than 30 min. If necessary, leaves do not even need to be removed from the tree. Since the genus Betula is taxonomically complex and separation of different birch species can be problematic, the developed method was applied to 15 Betula species and four sub-species of Betula pendula Seven of the studied species were classified as B. pubescens and eight as B. pendula-type birches. The remaining four species did not belong to either of these two classes on account of their unique pattern of external flavonoids. The difference between the leaf surface flavonoid composition of B. pubescens and B. pendula type birch species was unambiguously clear, and the developed method could reliably distinguish between the two species. Whilst leaf surface flavonoids can be valuable chemotaxonomic markers, they classify birch species differently from morphological markers. Birch species with diploid chromosome sets did not contain any of the flavanones that were present in the leaves of other species. The close relationship between the occurrence of some flavonoid aglycones and the ploidy level of Betula species suggests that these chemotaxonomic markers may be useful both in taxonomic and phylogenetic analyses.     

Flavonoidmuster im knospenexkret der betulaceen

In the Betulaceae, buds of the genus Alnus, Betula (Betuleae) and Ostrya (Coryleae) excrete a lipophilic “coat” consisting of terpenoids and flavonoid aglycones. The variation of the substitution pattern of these latter compounds has been investigated in relation to taxonomy. Characteristic compounds which occur are the methyl ethers of 6-hydroxykaempferol, ermanin (kaempferol-3,4′-Me), acacetin and pectolinarigenin. Other methyl derivatives of kaempferol, quercetin, apigenin and naringenin also occur more or less frequently. Evidence is given for the species-specifity of the flavonoid pattern in many of these exudates.     

The occurrence of flavanones in the farinose exudate of the fern Onychium siliculosum

The yellow farina on fertile pinnules of Onychium siliculosum is composed of 2′,6′-dihydroxy-4′-methoxychalcone and 2′,6′-dihydroxy-4,5′-di     

Flavonoid patterns in the farina of goldenback and silverback ferns

Most species of the fern genus Pityrogramma show a farinose indument caused by a deposit of exuded flavonoid aglycones. Some 220 samples, comprising 14 species, have been studied for the chemical composition of their farinas. Flavones, flavonols and C-methylated flavonoid are rarely found. The presence of certain chalcones and dihydrochalcones, however, appears to be to some extent characteristic for the genus. In some cases the farina flavonoid pattern is species-specific; in one species also variety-specific patterns and even chemotypes are observed. In general, the flavonoid chemistry in Pityrogramma parallels frond morphology to a great extent. This supports the concept that around a core of generalized species a few variant species exist which are best treated as belonging to Pityrogramma.