Bioactive molecules in wood extractives: Methods of extraction and separation, a review

Bioactive molecules are those capable of interacting with living organisms, causing changes in them. Wood extractives contain important amounts of these molecules, and some of them have good antioxidant and antimicrobial activity, which favors their use as preservatives. Several different extraction methods are employed to obtain the extractives, some of which have been used for a long time. However, these conventional methods have significant disadvantages, being the most important ones high solvent, energy, and time consumption. To overcome these drawbacks, new extraction techniques are being developed whose aim is also the optimization of the process. Separation techniques such as chromatography and molecular distillation allow extractives purification and the acquisition of the desired molecules. This review aims to provide an overview of the extraction and purification methods used for wood bioactive molecules. To this end, issues such as raw material, solvent type, solid/liquid ratio (SLR), temperature, pressure, and extraction time are discussed. The application of extractives as preservatives for low durability woods is also analyzed. The study concludes that the quality and quantity of bioactive molecules, besides depending on the raw material, are determined by the employed methods and solvents to obtain these molecules. Therefore, the choice of method and solvent is of fundamental importance to achieve the desired results.