Lignin for pharmaceutical and biomedical applications: Could this become a reality?

Lignin is an aromatic biopolymer and a primary component of the cell walls in lignocellulosic biomass, where it constitutes between 15 and 40% of its dry mass. This percentage can vary, not only among plant species, but also among different cell types. Currently, the pulping and biorefinery industries worldwide extract large amounts of lignin, which is mostly combusted to generate the power needed to productively transform the lignocellulosic biomass. The specific composition and structure of this technical lignin depends on its botanical origin and on the extraction method applied. In general, however, lignin possesses antioxidant and antimicrobial properties, UV-absorbing capabilities, biocompatibility and low cytotoxicity. Moreover, lignin can increase the mechanical strength of numerous processed biomaterials. Accordingly, lignin is a promising aromatic raw material for the pharmaceutical and biomedical field. This work discusses the recent advances in the valorisation of lignin through the development of drug and gene delivery systems, wound dressings, tissue engineering or sunscreen actives. Finally, a brief overview on the current challenges and opportunities for making lignin-based products for pharmaceutical and medical applications a reality is also discussed.