Herbicide activity of extracts from Ailanthus altissima (Simaroubaceae).

The purpose of the present study was to isolate and characterize ailanthone-rich materials from the bark of the deciduous tree Ailanthus altissima (Mill.) Swingle and to assess their herbicide activity on selected herbaceous species. Ailanthone-rich fractions were obtained from A. altissima bark by extraction with dichloromethane and ethyl acetate and subsequent purification of these crude extracts, and of the remaining water mixture after solvent extraction, by means of gel permeation chromatography. A number of fractions were isolated and characterized for ailanthone content. A dichloromethane fraction was shown to contain 92% w/w of ailanthone, as demonstrated by HPLC and NMR analysis. A significant pre-emergence herbicide activity was found for most of the extracts which was directly correlated to ailanthone concentration. A remarkable combined pre- and post-emergence herbicide activity was found for a specific fraction. These results indicate that the bark of A. altissima may represent an interesting source for the production of natural herbicides for use in agriculture.

Hyaluronan: from biomimetic to industrial business strategy.

Hyaluronan (hyaluronic acid) is a naturally occurring polysaccharide of a linear repeating disaccharide unit consisting of beta-(1-->4)-linked D-glucopyranuronic acid and beta-(1-->3)-linked 2-acetamido-2-deoxy-D-glucopyranose, which is present in extracellular matrices, the synovial fluid of joints, and scaffolding that comprises cartilage. In its mechanism of synthesis, its size, and its physico-chemical properties, hyaluronan is unique amongst other glycosaminoglycans. The network-forming, viscoelastic and its charge characteristics are important to many biochemical properties of living tissues. It is an important pericellular and cell surface constituent; its interaction with other macromolecules such as proteins, participates in regulating cell behavior during numerous morphogenic, restorative, and pathological processes in the body. The knowledge of HA in diseases such as various forms of cancers, arthritis and osteoporosis has led to new impetus in research and development in the preparation of biomaterials for surgical implants and drug conjugates for targeted delivery. A concise and focused review on hyaluronan is timely. This review will cover the following important aspects of hyaluronan: (i) biological functions and synthesis in nature; (ii) current industrial production and potential biosynthetic processes of hyaluronan; (iii) chemical modifications of hyaluronan leading to products of commercial significance; and (iv) and the global market position and manufacturers of hyaluronan.