tailieunhanh - BIOLOGICALLY ACTIVE NATURAL PRODUCTS: AGROCHEMICALS - CHAPTER 6

Triterpenoids và các hợp chất có khả năng đăng nhập khác từ rơm lúa mì: Phân lập, nhận dạng và tổng hợp Rơm bao gồm các phân số trên mặt đất (thường được cắt ở độ cao khoảng 20 cm) của cây ngũ cốc sau khi loại bỏ các Tùy thuộc vào hệ thống thu hoạch, một phần của rơm cắt trái trong lĩnh vực này cùng với các gốc rạ. Chiều dài và đường kính ống hút khác nhau rất nhiều, do đó, năng suất sinh khối trong và giữa các loài | 6__ Triterpenoids and Other Potentially Active Compounds from Wheat Straw Isolation Identification and Synthesis Elvira Maria M. S. M. Gaspar H. J. Chaves das Neves and M. Manuela A. Pereira CONTENTS Introduction Active Extracts from Wheat Straw Phenolic Compounds Fatty Acid Derivatives Triterpenoids HPLC-MS of Ketosteroids Synthesis Conclusions References Introduction Straw consists of the above-ground fractions normally cut at a height of around 20 cm of cereal plants after removal of the Depending on the harvesting system part of the cut straw is left in the field together with the stubble. The straw length and diameter vary greatly and consequently also the biomass yield both within and between species. The biomass production and its chemical composition are important parameters since straw and other fibrous by-products from cereals that are available in the world amount to approximately 3 trillion tonnes per Part of the straw is utilized for feed 3 paper 4 and fuel 5 but a major part of the straw is discarded as a waste product. In some regions of the world straw is used in mulch-tillage in no-till cropping systems 6 7 a common agricultural practice credited with a number of ecological advantages such as reduction of soil compaction good erosion control better water retention and conservation of organic matter. In many instances inhibitory effects on germination and growth of other plant species were observed. The direct or indirect harmful or beneficial effects of plants on other plants of the same or of different species by means of chemicals released from living or decaying plant material has been broadly defined as The presence of chemical signals in ecosystems has been attributed to numerous types of secondary metabolites9 which are able to 1999 by CRC Press LLC induce physiological and morphological changes in plants .