Title : Secondary metabolites from Tectona grandis extracted by extrusion process
Abstract:
Tectona grandis L.F. (teak) is a tree species native to India, Myanmar, Thailand and Laos People’s Democratic Republic1 although it was moved outside of its natural occurrence to several countries in Africa and America during the past century2. Teak is a very recognized timber due to their economic value and remarkable characteristics like strength, ease of working, beauty and decay resistance. This last quality is ascribed to the second metabolites presents in their extractives, such as anthraquinones and naphthoquinones. These chemical compounds exhibit fungicidal and termicidal bioactivity. The conventional extraction methods as soxhlet and maceration as well as the organic solvents are the most used to get the bioactive molecules. Nevertheless, extrusion process can be perform the extraction of secondary metabolites using water as a solvent. This technology has been broadly studied to fractionate and pre-treat lignocellulosic biomass in a continuous way. In the extrusion process, the biomass is mixed, heated and sheared by the action of one or two screws that turn into a confined barrel3. This work is focused on the identification and quantification of chemical compounds from teak sawdust extractives using water at subcritical conditions by extrusion process and the comparison with other extraction methods using common solvents. In addition, the use of raw material coming from a woodworking enterprise located in Mexico intend to valorise wood wastes. The identification of the chemicals compounds was made by the comparison between the authentic ones and the results from the analysis by HPLC-DAD and HPLC-MS. The antioxidant activity was measured by DPPH (α, α-diphenyl-β-picrylhydrazyl) method and the polyphenolic content by Folin-Ciocalteu assay. Besides, the Van Soest and Wine method was conducted to characterise the teak heartwood. According to the results, the aqueous extractives obtained by extrusion contain 2-hydroxy-3-(3-methyl-2-butenyl)-1,4- naphthoquinone (lapachol), anthraquinone-2-carboxylic acid and 2-methyl anthraquinone. These molecules were not identified by the other methods. This approach suggest a promising way to add value to wastes from the timber industry by getting chemical compounds from them. • Kaosa-ard, Apichard, Teak (Tectona grandis Linn. f) its Natural distribution and related factors. Nat. Hist. Bull. Siam. Soc. (1989) 29: 55-74 • Hansen, Ole K. Worldwide translocation of teak—origin of landraces and present genetic base. Tree Genetics & Genomes (2017) 13: 87 • Duque, Aleta et al. Extrusion as a pretreatment for lignocellulosic biomass: Fundamentals and applications. Renewable Energy 114 (2017) 1427-1441
