UV-filters in cosmetic products

The first SPF Boosters were developed for film formation and stabilising UV filters, thereby increasing SPF efficacy¹⁵. Current trends favour SPF boosters from natural sources¹⁶ such as grape seed extract, jasmine, hibiscus, desert rose, propolis, aloe vera, yellow milfoil, and vetty fruit^{6, 17}. However, the production of bio-based SPF boosters often necessitates extensive cultivation and energy-intensive extraction methods, adversely affecting sustainability and cost-effectiveness¹⁸. For a bio-based cosmetic ingredient to be genuinely sustainable, it should be abundantly available and exhibit properties highly relevant to the cosmetics sector.

Derived from the Latin term “lignum” meaning “wood,” Lignin is a highly diverse polyphenol20 and a key structural component of terrestrial plants and algae. Lignin, the second most prevalent renewable biopolymer, is found in wood and woody plants and makes up 18 – 35% of plant biomass²⁰. Lignin functions as a UV shield, a free radical scavenger, and reinforces secondary cell walls in plants. With the rising demand for bio-based ingredients and the strategic importance of bio-based industries, new-generation biorefineries are becoming operational globally²³. Unlike in traditional pulp mills, they do not burn lignin for energy but use modern processes that yield lignin in a near-native form without sulfur contamination, strong odors, or dark colors^{18, 21, 22}. These new extraction methods also preserve lignin’s inherent functions, such as UV protection and antioxidative potential important for high-value applications¹⁹.
However, even with advanced extraction techniques, raw or bulk Lignin is not suitable for use in cosmetic formulations²⁴ because it is often characterised by particle sizes exceeding 10 µm, irregular shapes, wide molecular weight distribution, and heterogeneous moleular structure^{25, 26}. Therefore, refining bulk Lignin is essential for its application in cosmetics.
Unlocking the Power of Lignin for Cosmetic Applications To optimise the utility and effectiveness of regular lignin particles, they can be transformed into Colloidal Lignin Particles (CLPs), characterised by uniform, spherical shapes, a narrow molecular weight range, and particle sizes less than 1 µm. These modifications enhance processability, dispersibility, performance, and uniformity, rendering them suitable for cosmetic formulations. Scanning electronmicroscopy (SEM) images of bulk Lignin and CLPs demonstrate this transformation^{27, 28} (Figure 1).
strate this transformation27, 28 (Figure 1). Comparative studies of emulsions using bulk Lignin and CLPs reveal that CLPs stabilise oil-in-water (o/w) emulsions, creating an evenly distributed particle network (Figure 1) compared to bulk Lign.

CLPs exhibit several advantageous properties for cosmetic applications, particularly in sun protection.
• Their small size and uniform distribution in sunscreen films enable enhanced reflection and scattering of sunlight29.
• Their predominantly hydrophilic surface properties (Figure 2) stabilise o/w emulsions by aligning at the oil-water interface, forming a robust droplet network.
• This leads to improved and uniform distribution of UV filters, thereby increasing their efficacy (Figure 2).
• Furthermore, their potent antioxidative properties stabilise UV filters and mitigate skin damage from UV exposure³⁰.

A comparative analysis between typical bulk lignin and CLPs manufactured by Lignovations was conducted. Lignovations used a patented physical process to create CLPs with diameters ranging from 100-200 nm featuring high efficacy and enhanced dispersibility delivered in a stable water suspension (Figure 1).

To validate the SPF boosting potential of CLPs, an empirical methodology was adopted to determine the optimal formulation route for integrating aqueous CLPs into oil-in-water (o/w) cosmetic products.
Maintaining a stable colloidal system is crucial for ensuring uniform distribution of active particles. Precise particle sizing and purification in the production process result in stable aqueous suspensions of CLPs. Initial assessments evaluated the compatibility of these suspensions with common sunscreen ingredients, identifying the viscosity and conductivity of the aqueous phase as critical performance parameters. Favorable conditions include low viscosity and minimal salt concentration for incorporating CLPs.
Utilising this knowledge, sunscreen formulations were developed incorporating a variety of inorganic and organic UV filters in the oil phase and CLPs in the aqueous phase. Optical microscopy, centrifugal testing, and in-vitro SPF assessments (based on DIN EN ISO24443) were conducted to evaluate the formulations.
It was observed that formulations containing CLPs had smaller oil droplets compared to control formulations without CLPs. Long-term stability and resistance to phase separation and creaming were confirmed through centrifugal (3000 g/20 min/25 °C) and thermal (40 °C over 6 months)stability tests. This stability is attributed to the robust droplet network established and maintained by the CLPs (Figure 2).

The in-vitro evaluations of sunscreens indicated promising SPF enhancement capabilities of CLPs for both organic and mineral filters. Subsequently, four sunscreen formulations with 2 – 3 wt% CLPs underwent in-vivo SPF testing to measure real-life SPF enhancement. These tests, conducted according to DIN EN ISO 24444 at an external institute, revealed SPF boosts up to 50% or 11 SPF points compared to control sunscreens (Figure 3).

The collaboration of Lignovations GmbH and Vienna University of Technology (TU Wien) has showcased a groundbreaking innovation in the field of sun protection with the application of CLPs as SPF boosters in cosmetic products. As the cosmetic industry faces challenges related to the environmental impact, health concerns, and supply shortages associated with conventional UV filters, exploring sustainable alternatives is critical.
Lignin, derived from forestry and wood processing waste, emerges as a promising solution due to its abundance and the utilisation of green chemistry techniques. The transformation of Lignin into CLPs overcomes inherent hurdles, such as heterogeneity, making it a viable option for cosmetic applications.
he demonstrated increase in SPF efficacy of CLPs, achieving a 50% or 11-point SPF boost, highlights their potential to improve both the effectiveness and sustainability of sun protection products. The successful demonstration of CLPs as SPF boosters not only marks a significant advancement in cosmetic technology but also aligns with the growing demand for sustainable and eco-friendly beauty solutions.
Based on the research, Lignovations has developed a commercial CLP dispersion marketed as LignoGuard. This multifunctional cosmetic ingredient is made from upcycled biomass and has received COSMOS and NaTrue approval. Samples are available from Lignovations, including sample formulations and best practices using CLPs in cosmetic products as well as extensive technical and regulatory documentation.

References:  
1 Jesus, A., Sousa, E., Cruz, M.T., Cidade, H., Lobo, J.M.S., Almeida, I.F.: UV Filters: Challenges and Prospects. Pharmaceuticals (Basel, Switzerland) 15(3) (2022). doi: 10.3390/ph15030263
2 John D’Orazio, Stuart Jarrett, Alexandra Amaro-Ortiz and Timothy Scott: UV Radiation and the Skin
3. Tian, X.Q., Chen, T.C., Matsuoka, L.Y., Wortsman, J., Holick, M.F.: Kinetic and thermodynamic studies of the conversion of previtamin D3 to vitamin D3 in human skin. Journal of Biological Chemistry 268(20), 14888–14892 (1993). doi: 10.1016/S0021-9258(18)82416-4
4 Yangmyung, M., Jinah, Y.: History of sunscreen: An updated view. Journal of cosmetic dermatology(20(4)), 1044–1049 (2021)
5 Sabzevari, N., Qiblawi, S., Norton, S.A., Fivenson, D.: Sunscreens: UV filters to protect us: Part 1: Changing regulations and choices for optimal sun protection. International journal of women’s dermatology 7(1), 28–44 (2021). doi: 10.1016/j.ijwd.2020.05.017
6 Shaath, N.: Sunscreens Regulations and Commercial Development. Third Edition. Taylor & Francis Group (2005)
7 Downs, C.A., Kramarsky-Winter, E., Segal, R., Fauth, J., Knutson, S., Bronstein, O., Ciner, F.R., Jeger, R., Lichtenfeld, Y., Woodley, C.M., Pennington, P., Cadenas, K., Kushmaro, A., Loya, Y.: Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone (Benzophenone-3), on Coral Planulae and Cultured Primary Cells and Its Environmental Contamination in Hawaii and the U.S. Virgin Islands. Archives of environmental contamination and toxicology 70(2), 265–288 (2016). doi: 10.1007/s00244-015-0227-7
8 Brown, J.: Sunscreen: What science says about ingredient safety (2019)
9 Rehfeld, A., Egeberg, D.L., Almstrup, K., Petersen, J.H., Dissing, S., Skakkebaek, N.E.: EDC IMPACT: Chemical UV filters can affect human sperm function in a progesterone-like manner. Endocrine Connections(7), 16–25 (2018)
10 Japhet Cheuk-Fung Law, Yanran Huang, Chi-Hang Chow, Tsz-Ki Lam, Kelvin Sze-Yin Leung: Comparative physicochemical properties and toxicity of organic UV filters and their photocatalytic transformation products
11 Huang, Y., Law, J.C.-F., Lam, T.-K., Leung, K.S.-Y.: Risks of organic UV filters: a review of environmental and human health concern studies. The Science of the total environment 755(Pt 1), 142486 (2021). doi:10.1016/j.scitotenv.2020.142486
12 Downs, C.A., DiNardo, J.C., Stien, D., Rodrigues, A.M.S., Lebaron, P.: Benzophenone Accumulates over Time from the Degradation of Octocrylene in Commercial Sunscreen Products. Chemical research in toxicology 34(4), 1046–1054 (2021). doi: 10.1021/acs.chemrestox.0c00461
13 U.S. Food and Drug Administration: FDA advances new proposed regulation to make sure that sunscreens are safe and effective (2019)
14 Khan, G.B., Akhtar, N., Khan, M.F., Ullah, Z., Tabassum, S., Tedesse, Z.: Toxicological impact of Zinc Nano Particles on tilapia fish (Oreochromis mossambicus). Saudi journal of biological sciences 29(2), 1221–1226 (2022). doi: 10.1016/j.sjbs.2021.09.044
15 Shaath, N.A.: SPF Boosters Photostability of Ultraviolet Filters (2007)
16 Li, L., Chong, L., Huang, T., Ma, Y., Li, Y., Ding, H.: Natural products and extracts from plants as natural UV filters for sunscreens: A review. Animal Models and Experimental Medicine(6), 183–195 (2023)
17 Yarovaya, L., Khunkitti, W.: Effect of grape seed extract as a sunscreen booster. Songklanakarin Journal of Science & Technology(41(3)), 708–715 (2019)
18 Serna-Loaiza, Miltner, Friedl: A Review on the Feedstocks for the Sustainable Production of Bioactive Compounds in Biorefineries. Sustainability 11(23), 6765 (2019). doi: 10.3390/su11236765
19 Chauhan, P.S., Agrawal, R., Satlewal, A., Kumar, R., Gupta, R.P., Ramakumar, S.S.V.: Next generation applications of lignin derived commodity products, their life cycle, techno-economics and societal analysis. International journal of biological macromolecules 197, 179–200 (2022). doi: 10.1016/j.ijbiomac.2021.12.146
20 Puglia, D., Santulli, C., Sarasini, F.: Micro and Nano Lignin in Aqueous Dispersions and Polymers. Elsevier 12(6) (2020). doi: 10.3390/ polym12061364
21 Ragauskas, A.J., Beckham, G.T., Biddy, M.J., Chandra, R., Chen, F., Davis, M.F., Davison, B.H., Dixon, R.A., Gilna, P., Keller, M., Langan, P., Naskar, A.K., Saddler, J.N., Tschaplinski, T.J., Tuskan, G.A., Wyman, C.E.: Lignin valorization: improving lignin processing in the biorefinery. Science (New York, N.Y.) 344(6185), 1246843 (2014). doi: 10.1126/ science.1246843
22 Brienza, F., Cannella, D., Montesdeoca, D., Cybulska, I., Debecker, D.P.: A guide to lignin valorization in biorefineries: traditional, recent, and forthcoming approaches to convert raw lignocellulose into valuable materials and chemicals. RSC Sustain. (2023). doi: 10.1039/ D3SU00140G
23 Annevelink, B., Garcia Chavez, L., van REe, R., Vural Gursel, I.: Global biorefinery status report 2022. IEA Bioenergy: Task 42 Biorefining in a circular economy (2022)
24 Tomasich, J., Beisl, S., Harasek, M.: Production and Characterisation of Pickering Emulsions Stabilised by Colloidal Lignin Particles Produced from Various Bulk Lignins. Sustainability 15(4), 3693 (2023). doi: 10.3390/su15043693
25 Stefan Beisl: From Complexity to Consistency: Overcoming Heterogeneity for Industrial Applications (2023)
26 Beisl, S., Friedl, A., Miltner, A.: Lignin from Micro- to Nanosize: Applications. International journal of molecular sciences 18(11) (2017). doi: 10.3390/ijms18112367
27 Beisl, S., Miltner, A., Friedl, A.: Lignin from Micro- to Nanosize: Production Methods. International journal of molecular sciences 18(6) (2017). doi: 10.3390/ijms18061244
28 Österberg, M., Sipponen, M.H., Mattos, B.D., Rojas, O.J.: Spherical lignin particles: a review on their sustainability and applications. Green Chem. 22(9), 2712–2733 (2020). doi: 10.1039/D0GC00096E
29 Darmawan, M.A., Ramadhani, N.H., Hubeis, N.A., Ramadhan, M.Y.A., Sahlan, M., Abd-Aziz, S., Gozan, M.: Natural sunscreen formulation with a high sun protection factor (SPF) from tengkawang butter and lignin. Industrial Crops and Products 177, 114466 (2022). doi: 10.1016/j. indcrop.2021.114466
30 Lu, X., Gu, X., Shi, Y.: A review on lignin antioxidants: Their sources, isolations, antioxidant activities and various applications. International journal of biological macromolecules 210, 716–741 (2022). doi: 10.1016/j.ijbiomac.2022.04.228