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Lignins and lignans as natural polyphenols exhibit a rather broad variety of common physico-chemical features that can be of interest with respect to their use in the pharmaceutical sector. While polyphenol types have antioxidant, antiinflammatory, antibacterial and eventually antiviral activities in common, structural features beyond the polyphenol aspect differ enormously: isolated lignins are oligomers and/or polymers of monolignol C9-building blocks, while lignans are based on dimers thereof. The structural differences caused lignin to be exploited in the pharmaceutical sector mainly as material for the generation of matrices and carrier for drug delivery, while lignans are tested for the suitability as APIs. The chapter gives an overview of this situation, including the biological backgrounds of the two interesting natural polyphenols, isolation and methods for their characterisation.

Salicylate and benzoate sunscreen agents have been encapsulated by the green, fast and robust ultrasound technique in tannin microcapsules (TMCs). The generated TMCs, obtained without use of cross linking agents, were fully characterised, including encapsulation efficiencies with respect to the encapsulated actives. Release kinetics of TMCs have been studied mimicking skin conditions. Body cream base samples containing specific concentrations of microcapsules filled with sunscreen actives were prepared and showed synergistic effects in terms of UV-protection abilities generated by the interplay between sunscreen actives and natural tannin polyphenols. The synergistic effect exerted by the tannin and the controlled active release allows to reduce the amount of synthetic sunscreens needed, and does thus contribute to the development of more sustainable and environmentally benign UV-protection systems.

Nature offers a diverse set of renewable biopolymers, among them the variety of natural polyphenols, whose structural diversity provides opportunities for further manipulation like the generation of chemicals and novel functional materials. These land‑based renewable biomaterials exhibit also a wide range of heterogeneous intrinsic reactivities and activities that render them ideal starting oligomeric and polymeric materials for the generation of multifunctional supramolecular structures as well as the development of high value-added materials. Lignins in particular display a variety of common physico‑chemical features that can be of enormous interest with respect to their eventual use in the pharmaceutical area. These natural polyphenols possess some interesting pharmaceutical properties such as antioxidant, anti‑inflammatory, antibacterial and eventually antiviral activities. In addition, based on their chemical features, i.e., oligomers and/or polymers of monolignol C9-building blocks. lignins can be exploited in the pharmaceutical sector mainly as material for generation of matrices and carriers for drug delivery. The present work attempts a review of the state of the art in lignin use in pharmaceutical applications. Keywords biopolymers, lignins, microcapsules, nanoparticles, renewable resources

Novel valorization routes for tannins were opened by the development of a simple, straightforward, robust, and flexible approach to the selective functionalization of condensed and hydrolyzable tannins. Irrespective of the different degrees of polymerization, different commercial tannins were efficiently functionalized by the generation of an ether linkage bound to a short linker carrying the desired functional group. Functionalizations could be realized at varying degrees of technical loadings, i.e., amounts of introduced tannin-alien functionalities per number of phenolic hydroxyl groups. The same strategy was found suitable for the synthesis of polyethylene glycol-functionalized tannin copolymers. Condensed tannins functionalized with carboxylic acid moieties could be converted into a tannin–oligopeptide hybrid., Commercially available condensed and hydrolyzable tannins were functionalized with different functional groups at different concentrations.

Microcapsules of sulfited Acacia mearnsii tannin (AmST-MCs) were generated for the first time via the sonochemical method. Their stability profile was assessed and set in the general context of tannin microcapsules (TMCs) generated under the same experimental conditions. The analytical data gathered in this work indicate an excellent stability of TMCs over time as well as under high temperature and pressure, which is a major milestone toward the meaningful applications of TMCs in industrial, pharmaceutical, and biomedical applications in which sterilization of TMCs might be a prerequisite. Active release is shown to be efficiently triggered by varying pH and/or salinity, with different profiles for TMCs from sulfited and nonsulfited species. Surfactants also affect the stability of TMCs significantly, with effects eventually amplifiable by pH and the inherent kosmotropic and chaotropic characteristics of salt components in solutions.

Stimuli-responsive behavior of lignin microcapsules (LMCs) has been investigated along with the detailed characterization of their stability profiles. The disassembly of LMCs was found to be salt species-dependent, indicating the specific relevance of inherent kosmotropic and chaotropic characteristics. For the first time, a connection between the Hofmeister series and the stability profile of lignin microscale materials is established. LMCs showed excellent stability in water and under high temperature and pressure (autoclaving conditions). Active release is efficiently triggered by pH changes and balancing chaotropic and kosmotropic effects via salinity tuning.