Lignins from Agroindustrial by‐Products as Natural Ingredients for Cosmetics: Chemical Structure and In Vitro Sunscreen and Cytotoxic Activities

The growing concern about the environmental impact and human health risk related to
the excessive use of synthetic ingredients in cosmetics and topical formulations calls for the
exploration of safe and sustainable natural alternatives. Lignin‐rich lignocellulosic industrial wastes
such as hazelnut and walnut shells were used as a lignin polymer source. Agro‐derived lignins were
evaluated as a potential natural active ingredient for health care products. Aside from the structural
characteristics of isolated lignins, which were identified by GPC, Py‐GC–MS, and 2D HSQC NMR
techniques, functional properties such as antioxidant power and UV absorption ability were
investigated. The SPF values found for creams containing 5% of hazelnut and walnut lignin content
were 6.9 and 4.5, respectively. Additionally, both lignin types presented appropriate protection
against UVA radiation, highly interesting property to block the full ultraviolet spectrum. The
biological activity of isolated lignins assessed at different concentrations (0.01–1 mg/mL) and
different times (24, 48, and 72 h) on murine fibroblast cell line 3T3 suggested their suitability for
cosmetic applications.