Natural sunscreens protect the skin from damaging radiation while reducing the risk of allergic reactions. In a recent study, researchers identified a previously unknown compound called β-glucose-bound hydroxy mycosporine-sarcosine. This substance is produced by heat-loving cyanobacteria when they are exposed to UV-A, UV-B, and salty conditions. Unlike other known mycosporine-like amino acids (MAAs), this compound is created through a distinct biosynthesis pathway. The finding offers new possibilities for industrial biotechnology focused on producing natural UV-filtering ingredients.
Cyanobacteria are photosynthetic bacteria that produce oxygen and are known for their ability to survive in harsh environments. To cope with extreme stress, they generate a wide range of chemical compounds. Among these are mycosporine-like amino acids (MAAs), which are small, water-soluble molecules that absorb ultraviolet (UV) radiation. MAAs help protect cells from sun damage and act as antioxidants by neutralizing stress-induced reactive oxygen species (ROS). Although these molecules share a basic structural framework, their variations give rise to different biological activities and functions.
As concerns increase over UV exposure and rising skin cancer rates, scientists are searching for safer compounds that offer effective sun protection. Conventional chemical sunscreens can block UV rays, but they are also linked to allergic reactions and other unwanted side effects. MAAs stand out because they are biocompatible and considered safe for human use. These qualities make them promising candidates for sustainable biotechnology and large-scale production of natural sunscreen alternatives.
In a new study, researchers led by Professor Hakuto Kageyama of Meijo University and Professor Rungaroon Waditee-Sirisattha of Chulalongkorn University identified a novel MAA produced by thermophilic cyanobacteria living in hot springs in Thailand. Beyond identifying a new molecule, the research sheds light on how these organisms adapt to extreme environments. "Understanding stress-responsive biosynthesis in extremophilic cyanobacteria may accelerate industrial biotechnology for natural pigment and antioxidant production," says Prof. Kageyama when describing the motivation behind the work. The study was made available online on December 01, 2025, and later published in Volume 1009 of Science of The Total Environment on December 20, 2025.
A Unique Molecule With Rare Chemical Features
The research team isolated eight strains of heat-tolerant cyanobacteria from the Bo Khlueng hot spring in Ratchaburi Province, Thailand. During laboratory experiments, one strain known as Gloeocapsa species BRSZ produced a previously unknown UV-absorbing compound when exposed to UV-A and UV-B light. The compound, identified as β-glucose-bound hydroxy mycosporine-sarcosine (GlcHMS326), was then examined in detail to understand its structure and function.
GlcHMS326 is notable for undergoing three distinct chemical modifications: glycosylation, hydroxylation, and methylation. These modifications have not been previously reported in MAAs derived from cyanobacteria. Genetic analysis revealed that the cyanobacteria responsible for producing this compound contain a unique set of genes linked to these chemical changes.
Production of GlcHMS326 increases significantly when the cyanobacteria are exposed to UV-A, UV-B, and high salt conditions. Although the organisms originate from hot springs, this specific compound is not triggered by heat stress. The chemical modifications found in GlcHMS326 contribute to its unusual structure and enhanced performance.
Methylation is known to improve the stability, UV absorption, and antioxidant activity of MAA compounds. Glycosylation is believed to further support stability, photoprotection, and antioxidant defense. Compared with more common MAAs, GlcHMS326 demonstrates stronger free-radical scavenging activity, indicating that its modified structure plays a key role in boosting its antioxidant potential.
