Protection against solar ultraviolet (UV) radiation is critical to minimize the biological damage to the skin. Irradiation causes short-term damage like sunburns and long-term issues of skin cancers and accelerating skin aging.

Inorganic UV-blocking ingredients like titanium dioxide (TiO2) and zinc oxide (ZnO) reflect UV rays while organic synthetic UV-blocking ingredients like avobenzone and octyl methoxycinnamate absorb UV light. Inorganic UV blockers are preferred over organic ones because of concerns around skin irritation, photostability, and environmental impact. Many natural polyphenol extracts have been investigated as alternative UV blockers but most have small molecules with low purity, poor photostability, and are only partial spectrum sun blockers.

Lignin is a naturally abundant biopolymer often produced as a waste byproduct from industrial and agricultural processing. This powerful material can absorb a broad spectrum of UV light (both UVA and UVB, 250–400 nm). With its sun-blocking attributes, there is a great amount of interest in exploring its applications in cosmetics, packaging and transparent films, and microorganism protection.

But the complex structure, polydispersity in molecular weight, brownish colour, and impurities provide challenges for manufacturing an ideal bio-based UV blocker. Intermediate steps of lignin modification, purification, and/or fractionation to improve UV blocking performance and application are required. Exciting new developments lately have been paving the way towards lignin's real potential as a market cosmetic sunscreen ingredient.

A 2015 study by Qian et al. showed that when industrial lignin was blended with a pure cream and a commercial sunscreen, the lignin significantly boosted SPF performance. Interestingly, further increasing lignin quantity did not improve sunscreen effect. When lignin-modified sunscreens were exposed to UV radiation for 2 hours, UVA and UVB absorbance increased several times. This unexpected improvement in sunscreen performance under UV radiation is not entirely clear. Researchers believe it may be a synergistic effect between lignin and other sunscreen actives.

Molecular engineering for improved performance (Guo et al., 2024)

Guo et al. created a green strategy to molecularly engineer lignin into a better cosmetic sunscreen ingredient. The process transformed lignin into a lignin-3-(2-hydroxyphenyl)propionate ester derivative through a transesterification reaction between 3,4-dihydrocoumarin and the aliphatic hydroxyls in lignin under organocatalysis. After the process, the result had better dispersion, antioxidant activity, and good biocompatibility. A successful protocol was created that is simple, safe, and non-toxic.

Why Particle Size Matters (Liang et al., 2024)

Another 2024 study looked at various lignin oligomers from several lignocellulosic biomasses. The UV-blocking capabilities for the lignin nanoparticles (LNPs) performed much better than lignin oligomers because of the structure. Higher SPF values were also found when sunscreens had a combination of large and small LNPs than sunscreens with little size variation. The uneven sizes allowed some particles to fill gaps, creating a more compact UV-blocking shield.

Fixing SPF and Color at the Same Time (Li et al., 2025)

Li et al. addressed two major drawbacks of lignin in sunscreens, low SPF and dark coloration. Researchers attached methylene bis-benzotriazolyl tetramethylbutylphenol (MBTT) to alkali lignin (AL) to make a new polymer, AL-g-MBTT. This turned the molecules into tiny spheres, some with and some without titanium dioxide (TiO2).

Experimental data found dramatic improvements:

The sunscreens retained its sun protection effectiveness and colour even after 3 hours of UV exposure and demonstrated excellent biocompatibility with human keratinocytes.

Brightening Without Losing UV Protection (Utami et al., 2025)

A novel two-step approach was created to brighten the ingredient while maintaining its high UV absorption property. Previous methods were developed, however, they decreased ability to absorb UV. The innovative method works by first fractionation followed by bleaching. Organosolv lignin was fractionated with methanol and then bleached with NaOCl under mild conditions. The resulting lignin-based cream enhanced the SPF value, while also being highly homogeneous, stable, and more biocompatible.

Indeed, lignin is a truly natural sun-blocker. However, there is still a lot of work to be done before it's in the hands of consumers. Particularly around scaling, regulation, and long-term testing — but the progress so far is exciting. Consumers who want eco-friendly, sustainable, and safe skincare have a lot to look forward to!

Sadeghifar, H., & Ragauskas, A. (2020). Lignin as a UV Light Blocker-A Review. Polymers, 12(5), 1134. doi:10.3390/polym12051134

Qian, Y., Qiu, X., & Zhu, S. (2015). Lignin: a nature-inspired sun blocker for broad-spectrum sunscreens. Green Chemistry: An International Journal and Green Chemistry Resource: GC, 17(1), 320–324. doi:10.1039/c4gc01333f

Guo, Y., Liu, P., Deng, L., Lui, C., North, M., Hu, G., … Xie, H. (2024). Molecularly engineered lignin to polyphenol via organocatalysis as an active sunscreen ingredient. Journal of Bioresources and Bioproducts, 9(2), 197–210. doi:10.1016/j.jobab.2024.03.003

Liang, T., Ma, Y., Jiang, Z., Remón, J., Zhou, Y., & Shi, B. (2024). New insights into greener skin healthcare protection: Lignin nanoparticles as additives to develop natural-based sunscreens with high UV protection. Carbon Resources Conversion, 7(4), 100227. doi:10.1016/j.crcon.2024.100227

Li, Y., Hu, D., Tang, Z., Zhou, X., Zhang, J., Song, X., … Zhang, Z. (2025). Synthesis of lignin terpolymer submicron sphere for sunscreen application. Industrial Crops and Products, 224(120309), 120309. doi:10.1016/j.indcrop.2024.120309

Utami, R., Lee, D., Lee, E.-C., Bhang, S. H., Won, K., & Lee, E. Y. (2025). Light-colored lignin with high UV absorption for sunscreens by fractionation and bleaching. Environmental Technology & Innovation, 40(104602), 104602. doi:10.1016/j.eti.2025.104602