Pharmaceutical applications of lignin-derived chemicals and lignin-based materials: linking lignin source and processing with clinical indication

Abstract

Lignocellulosic biomass is one of the most abundant bioresources on Earth. Over recent decades, various valorisation techniques have been developed to produce value-added products from the cellulosic and hemicellulosic fractions of this biomass. Lignin is the third major component accounting for 10–30% (w/w). However, it currently remains a largely unused fraction due to its recalcitrance and complex structure. The increase in the global demand for lignocellulosic biomass, for energy and chemical production, is increasing the amount of waste lignin available. Approaches to date for valorizing this renewable but heterogeneous chemical resource have mainly focused on production of materials and fine chemicals. Greater value could be gained by developing higher value pharmaceutical applications which would help to improve integrated biorefinery economics. In this review, different lignin extraction methods, such as organosolv and ionic liquid, and the properties and potential of the extracted chemical building blocks are first summarized with respect to pharmaceutical use. The review then discusses the many recent advances made regarding the medical or therapeutic potential of lignin-derived materials such as antimicrobial, antiviral, and antitumor compounds and in controlled drug delivery. The aim is to draw out the link between the source and the processing of the biomass and potential clinical applications. We then highlight four key areas for future research if therapeutic applications of lignin-derived products are to become commercially viable. These relate to the availability and processing of lignocellulosic biomass, technologies for the purification of specific compounds, enhancements in process yield, and progression to human clinical trials.

From waste to resource: advancements in sustainable lignin modification

“…Then, the pressure is released rapidly and the steam present in the biomass expands, causing fibers to break down. 13 This process is considered to be one of the most efficient and cost-effective, although it is important to note that it is often used as pretreatment of lignocellulosic biomass before other processes are applied, 26 and there is a large heterogeneity of the lignin obtained. 13 Hydrolysis lignin, on the other hand, is usually a by-product of bio-ethanol production from cellulose hydrolysis.…”

Designing Lignin-Based Biomaterials as Carriers of Bioactive Molecules

“…Lignin is an aromatic polymer with abundant phenolic and aliphatic hydroxyl groups, and it has many chemically reactive sites (such as the C3 and C5 positions of the aromatic ring of lignin), which enable it to form multifunctional hydrogels [4,51]. Typically, all types of lignin have been utilized to fabricate lignin-based hydrogels [51][52][53][54]. In general, lignin has been combined with other polymers via crosslinking copolymerization, crosslinking monomers with grafted lignin, or interpenetrating lignin into a polymer network to produce lignin-based hydrogels.…”

“…In general, lignin has been combined with other polymers via crosslinking copolymerization, crosslinking monomers with grafted lignin, or interpenetrating lignin into a polymer network to produce lignin-based hydrogels. It has also been demonstrated that lignin can be copolymerized with crosslinking agents to directly prepare lignin-based hydrogels [53][54][55]. Recently, Evstigneev [56] also disclosed a patent describing a method to produce a pure lignin hydrogel without adding any copolymer.…”

Integral Valorization of Posidonia oceanica Balls: An Abundant and Potential Biomass

“…Lignin, due to its properties, has a wide range of applications, ranging from precursor of several high added-value chemical products, to its use in the production of bio-materials or even biofuels [ 23 , 24 ]. Hemicelluloses, among other possible applications, can be used to obtain different oligosaccharides with diverse applications [ 25 ].…”