高速逆流色谱对大黄蒽醌类成分的分离研究

利用高速逆流色谱对大黄中的5个蒽醌活性成分进行了分离,当两相溶剂系统的组成是石油醚∶乙酸乙酯∶甲醇∶水=8∶2∶8∶1时,分离出大黄素;当两相溶剂比为3∶4∶3∶2时,分离出大黄酸和芦荟大黄素;当溶剂比为12∶2∶12∶1时,分离出大黄酚和大黄素甲醚;经高压液相色谱检测大黄素、大黄酸和芦荟大黄素、大黄酚和大黄素甲醚的含量分别为98.81%9、9.15%、98.51%9、8.89%和98.16%。     

Knipholone: a unique anthraquinone derivative from Kniphofia foliosa

The roots of Kniphofia foliosa afforded, in addition to chrysophanol, a novel anthraquinone named knipholone, whose structure was determined by spectroscopic methods as well as by degradation to known compounds     

Three hydroxy ellagic acid methyl ethers,chrysophanol and scopoletin from Shorea worthingtonii and Vatica obscura

Extraction of the bark and timber of Shorea worthingtonii and Vatica obscura gave three new natural products: hexamethylcoruleoellagic acid, pentamethylflavellagic acid, tetramethylflavellagic acid, together with tetramethylellagic acid, scopoletin and chrysophanol. The above are reported for the first time in the family. Several triterpenes, already described from this family, were also isolated.     

Polyketides in insects: ecological role of these widespread chemicals and evolutionary aspects of their biogenesis

Polyketides are known to be used by insects for pheromone communication and defence against enemies. Although in microorganisms (fungi, bacteria) and plants polyketide biogenesis is known to be catalysed by polyketide synthases (PKS), no insect PKS involved in biosynthesis of pheromones or defensive compounds have yet been found. Polyketides detected in insects may also be biosynthesized by endosymbionts. From a chemical perspective, polyketide biogenesis involves the formation of a polyketide chain using carboxylic acids as precursors. Fatty acid biosynthesis also requires carboxylic acids as precursors, but utilizes fatty acid synthases (FAS) to catalyse this process. In the present review, studies of the biosynthesis of insect polyketides applying labelled carboxylic acids as precursors are outlined to exemplify chemical approaches used to elucidate insect polyketide formation. However, since compounds biosynthesised by FAS may use the same precursors, it still remains unclear whether the structures that are formed from e.g. acetate chains (acetogenins) or propanoate chains (propanogenins) are PKS or FAS products. A critical comparison of PKS and FAS architectures and activities supports the hypothesis of a common evolutionary origin of these enzyme complexes and highlights why PKS can catalyse the biosynthesis of much more complex products than can FAS. Finally, we summarise knowledge which might assist researchers in designing approaches for the detection of insect PKS genes.