Search Results

You are looking at 1 - 10 of 4,237 items :

Clear All

Introduction Phenol-formaldehyde (PF) resins are the most commonly used structural adhesives for producing exterior wood composites in the wood industry ( Li et al. 2018 ). However, with the progressively increasing environmental awareness of humans and the shortage of fossil energy, methods for obtaining chemical substitutes for phenol from biomaterials have received increasing attention ( Fan et al. 2011 ; Hemmila et al. 2017 ). In recent years, condensed tannins (CTs), which comprise a group of polyhydroxy flavan-3-ol oligomers (monomer to trimer) and

References Barrett , M.W., Klyne, W., Scopes, P.M., Fletcher, A.C., Porter, L.J., Haslam, E. ( 1979 ) Plant proanthocyanidins. Part 6. Chiroptical studies. Part 95. Circular dichroism of procyanidins. J. Chem. Soc. Perkin Trans. I 2375 –2377. Botha , J.J., Ferreira, D., Roux, D.G. ( 1978 ) Condensed tannins: Direct synthesis, structure, and absolute configuration of four biflavonoids from black wattle bark (‘Mimosa’) extract J. Chem. Soc. Chem. Commun. 700 –702. Botha , J.J., Ferreira, D., Roux, D.G. ( 1981 ) Synthesis of condensed tannins. Part 4. A direct

Effect of Different Condensed Tannins on Trichoplusia ni Performance Azucena G onzá lez-Coloma Instituto de Productos Naturales y Agrobiologia, CSIC, Ave. Astrofisico F. Sänchez 2, 38206 La Laguna, Tenerife, Spain Charles S. W isdom and Philip W. R undel Laboratory of Biomedical and Environmental Sciences, University of California, Los Angeles, California, U.S.A. 90024 Z. Naturforsch. 48c, 722-726 (1993); received July 23/December 8 , 1992 Schinopsis quebracho-color ado, Acacia greggii, Euphorbia micromera, Phoradendron californi- cum, Trichoplusia ni, Condensed

protection is also higher. The wood protection chemicals based on arsenic and chromium are now forbidden because of their ecotoxicity. Thus, the development of environment-friendly wood preservatives is a challenge. Different tree species have a self-protecting antifungal system consisting of specific polyphenolic compounds, flavonoids, lignans, stilbenes, and tannins (Gao et al. 2006; Liimatainen et al. 2011; Smeds et al. 2011). These compounds could also be applied as wood preservatives for indoor constructions and outdoor wood products (e.g., Celimene et al. 1999

Abstract

Colloidal silver nanoparticles were prepared by rapid green synthesis using different tannin sources as reducing agent viz. chestnut (CN), mangrove (MG) and quebracho (QB). The aqueous silver ions when exposed to CN, MG and QB tannins were reduced which resulted in formation of silver nanoparticles. The resultant silver nanoparticles were characterized using UV-Visible, X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), and transmission electron microscopy (TEM) techniques. Furthermore, the possible mechanism of nanoparticles synthesis was also derived using FT-IR analysis. Spectroscopy analysis revealed that the synthesized nanoparticles were within 30 to 75 nm in size, while XRD results showed that nanoparticles formed were crystalline with face centered cubic geometry.

Antifungal Effects of Hydrolysable Tannins and Related Compounds on Dermatophytes, Mould Fungi and Yeasts Klaus Peter Latté and Herbert Kolodziej* Institut für Pharmazie, Pharmazeutische Biologie, Freie Universität Berlin, Königin-Luise-Str. 2+4, D-14195 Berlin, Germany. Fax: + 4 9 -3 0 -8 3 8 -5 3 7 2 9 . E-mail: kolpharm@zedat.fu-berlin.de * Author for correspondence and reprint requests Z. Naturforsch. 55c, 4 6 7 -4 7 2 (2000); received January 28/March 6, 2000 Hydrolysable Tannins, Flavonoids, Antifungal Activity A series of hydrolysable tannins and

Introduction Condensed tannins (CTs) are abundant polyphenols, more precisely polyflavanoids, with varied molecular weights in vascular plants. This substance class is today underutilized despite its traditional utilization in leather industry and high potential for numerous other products (Pizzi 2008). Recently, CTs from pine bark ( Pinus radiata Don. and Pinus pinaster Ait.) have also been applied in the formulation of foams (Lacoste et al. 2013a,b). Limiting factors for their utilization in biomacromolecules are their high reactivity in network

): The effects of tannin-rich plants on parasitic nematodes in ruminants. Trends Parasitol., 22: 253–261. DOI: 10.1016/j.pt.2006.04.004 http://dx.doi.org/10.1016/j.pt.2006.04.004 [17] Huang, C. S. (1985): Formation, anatomy and physiology of giant cells induced by root-knot nematodes. In: Sasser J. N. & Carter C. C. (Eds) An advanced treatise on Meloidogyne, Biology and Control, Vol. I. Raleigh, U.S.A.: North Carolina State University Graphics, pp. 155–164 [18] Hukkeri, V. I., Kalyani, G. A., Hatpaki, B. C., Marvi, V. F. (1993): In vitro antihelmintic activity of

Holzforschung, Vol. 63, pp. 319–326, 2009 • Copyright by Walter de Gruyter • Berlin • New York. DOI 10.1515/HF.2009.043 Article in press - uncorrected proof Amination of pyrogallol nucleus of condensed tannins and related polyphenols by ammonia water treatment Koh Hashida*, Rei Makino and Seiji Ohara Department of Biomass Chemistry, Forestry and Forest Products Research Institute, Tsukuba, Japan *Corresponding author. Wood Extractives Laboratory, Department of Biomass Chemistry, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305

mahogany sapwood and heartwood, including condensed tannins, remain unknown. These polyphenols have been extracted from other plant wood, fruits, seeds and tissues ( Ricci et al. 2017 ) for commercial applications. A recent study showed that the African mahogany bark contained tannin monomers of commercial interest ( Bikoro Bi Athomo et al. 2018 ). Flavonoids and procyanidin oligomers with a large amount of O-glycosylated flavan-3-ol monomers were found. However, condensed tannin content as well as their molecular structure and thermal stability of these African mahogany