A new natural sunscreen: novel compound discovered from thermophilic cyanobacteria

Natural sunscreens shield the skin from harmful radiation, without triggering allergic reactions. In a recently published study, a group of researchers has discovered a novel compound, β-glucose-bound hydroxy mycosporine-sarcosine, which is produced in thermal cyanobacteria under UV-A/UV-B and salt stress. This compound has a unique biosynthesis pathway, which is different from the typical mycosporine-like amino acids (MAAs) biosynthesis mechanism. This discovery aids industrial biotechnology in the production of natural UV-filter compounds.

Cyanobacteria, the oxygen-producing photosynthetic bacteria, survive under extreme conditions. They produce a wide spectrum of primary and secondary metabolites to survive the extreme stressed environmental conditions. Mycosporine-like amino acids (MAAs) are small, water-soluble molecules produced by cyanobacteria that function as ultraviolet (UV)-absorbing compounds. These compounds offer photoprotection and act as antioxidants by scavenging stress-induced reactive oxygen species (ROS). Even though they have a common basic structure, different MAA compounds discovered to date show large structural diversities, which also influence their bioactivity and function.

With a rising risk of harmful UV radiation exposure and skin cancer, researchers are focusing on bioactive compounds with photoprotective abilities. While chemical sunscreens offer the desired protection, they are also associated with allergic reactions and other harmful side effects. MAAs are biocompatible and considered safe for human use, making them immensely important for sustainable biotechnology and large-scale production of natural sunscreen.

In a new study, a team of researchers led by Professor Hakuto Kageyama from Meijo University and Professor Rungaroon Waditee-Sirisattha from Chulalongkorn University has discovered a novel MAA molecule from thermal cyanobacteria inhabiting hot springs in Thailand. The discovery also contributes to understanding the survival strategies of these cyanobacteria, surviving extreme environmental conditions. “Understanding stress-responsive biosynthesis in extremophilic cyanobacteria may accelerate industrial biotechnology for natural pigment and antioxidant production,” mentions Prof. Kageyama, while talking about the motivation behind the study. It was made available online on December 01, 2025, and was published in Volume 1009 of Science of The Total Environment on December 20, 2025.

The team isolated eight thermophilic cyanobacterial strains from the Bo Khlueng hot spring in Ratchaburi Province, Thailand. Under experimental setup, the Gloeocapsa species BRSZ strain produced a novel UV-absorbing compound in response to UV-A and UV-B exposures. This compound, identified as β-glucose-bound hydroxy mycosporine-sarcosine (GlcHMS326), was further analyzed for a detailed understanding of its structure and functional mechanism. This novel compound undergoes triple chemical modifications—glycosylation, hydroxylation, and methylation—which have not been reported in cyanobacteria-derived MAAs before. Genetic analysis showed that these cyanobacteria possess a unique branch of genes that are associated with these modifications.

GlcHMS326 production is strongly induced by UV-A and UV-B irradiation and salt stress. Interestingly, even though the cyanobacteria are obtained from hot water springs, this particular MAA production is not associated with thermal stress. The chemical modifications in GlcHMS326 contribute to its unique structural and functional properties. Methylation can enhance the stability, UV absorption properties, and antioxidant capacity of MAA compounds. Glycosylation of MAAs has been proposed to enhance their stability and support photoprotection and antioxidative defense. This compound shows higher free-radical scavenging property compared to canonical MAAs, suggesting that the derivatized structure of GlcHMS326 contributes to its enhanced antioxidant potential.

The findings of this study contribute to understanding how cyanobacteria living in extreme environments have uniquely evolved metabolic pathways to produce a special natural UV-absorbing substance. This unique MAA plays a pivotal role in abiotic stress tolerance for Gloeocapsa species and likely serves multiple functions in this thermophilic cyanobacteria.

Highlighting the importance of the study, Prof. Waditee-Sirisattha mentions, “Cyanobacteria are deemed unique among the microbial world. Our recent study underscores that extremophilic cyanobacteria are not only ecologically important but also represent a key area of research for multiple disciplines.”

The significance of this compound lies in its diverse functionality and the potential for sustainable, large-scale production using the cyanobacterial “biofactories.” This compound can be utilized as an alternative to certain synthetic UV filters that raise environmental concerns, supporting the development of eco-friendly sunscreens. Its antioxidant activity also hints at its potential applications in anti-aging, skincare, and pharmaceutical formulations.

“This discovery reminds us that nature still holds many chemical surprises. Extremophilic cyanobacteria reveal uncommon molecules that can inspire new directions in basic science and sustainable biotechnology,” concludes Prof. Kageyama.

About Meijo University

Meijo University traces its origin back to the establishment of the Nagoya Science and Technology Course in 1926, giving it a proud history of more than 90 years. As one of the largest universities in the Chubu region, Meijo University is a comprehensive learning institution that supports a wide range of academic fields from the humanities to physical sciences. With a network of more than 200,000 graduates and alumni, it strives to contribute not only to local industries but also to international communities in various fields. Meijo University is also known as the birthplace of the carbon nanotube. To foster the human resources of the next generation, the university continues to tackle ongoing challenges by further enhancing its campus and creating new faculties.

Website: https://www.meijo-u.ac.jp/english/

About Professor Hakuto Kageyama from Meijo University

Dr. Hakuto Kageyama is currently a Professor in the Graduate School of Environmental and Human Sciences, Meijo University, Japan. He earned his PhD in 2006 from the Graduate School of Science, Nagoya University, Japan, where he contributed to the investigation of the circadian clock in cyanobacteria. His research group focuses on compounds derived from cyanobacteria and their biotechnological applications. He has published 70 research articles and has authored and co-authored five books to date. He was awarded the KOSÉ Cosmetology Award by the KOSÉ Cosmetology Research Foundation in 2021.

About Professor Rungaroon Waditee-Sirisattha from Chulalongkorn University

Dr. Rungaroon Waditee-Sirisattha is a Professor in the Department of Microbiology, Faculty of Science, Chulalongkorn University, Thailand. She obtained her Ph.D. degree from Chulalongkorn University in 2001 and was a post-doctoral fellow at Japan Society for the Promotion of Science, JAPAN. Her research interests include understanding the molecular mechanism of extremophiles’ adaptation to extreme environments, the discovery of novel products synthesized by extremophiles, and metabolic engineering and its application for these biocompounds. She has contributed to 100 published research articles to date.

Funding information

This work was supported by the following research grants: Thailand Science research and Innovation fund Chulalongkorn University (FOOD_FF_68_121_2300_022) (to Rungaroon Waditee-Sirisattha), The Singapore Ministry of Education MOE-T2EP30123-0007 (to Rungaroon Waditee-Sirisattha & Stephen B. Pointing), the research grant from Hibi Science Foundation (to Hakuto Kageyama), Japan Society for the Promotion of Science KAKENHI Grants 24K08623 (to Hakuto Kageyama), and Postdoctoral Fellowship, the Second Century Fund (C2F), Chulalongkorn University (to Sasiprapa Samsri).