Natural sunscreens protect the skin from harmful radiation and at the same time reduce the risk of allergic reactions. In a recent study, researchers have identified a previously unknown compound called β-glucose-linked hydroxy-mycosporin-sarcosine. This substance is produced by thermophilic cyanobacteria when exposed to UV-A, UV-B radiation and salty conditions. In contrast to other known mycosporine-like amino acids (MAAs), this compound is produced by a special biosynthetic pathway. This discovery opens up new possibilities for industrial biotechnology focused on the production of natural UV-filtering ingredients.
Growing Interest in Safe UV Protection
Cyanobacteria are photosynthetic bacteria that produce oxygen and are known for their ability to survive in harsh environments. To cope with extreme stresses, they produce a variety of chemical compounds. These include mycosporine-like amino acids (MAAs), small, water-soluble molecules that absorb ultraviolet (UV) radiation. MAAs protect cells from sun damage and act as antioxidants by neutralizing stress-induced reactive oxygen species (ROS). Although these molecules have a common basic structure, their variations lead to different biological activities and functions.
With increasing concerns about UV radiation and rising skin cancer rates, scientists are looking for safer compounds that provide effective sun protection. Conventional chemical sunscreens can block UV rays, but are also associated with allergic reactions and other undesirable side effects. MAAs are characterized by the fact that they are biocompatible and considered safe for human use. These properties make them promising candidates for sustainable biotechnology and the large-scale production of natural sunscreen alternatives.
Discovery in the Hot Springs of Thailand
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 could accelerate industrial biotechnology for the production of natural pigments and antioxidants,” Prof. Kageyama explains the motivation behind the work. The study was published online and later published in volume 1009 of Science of The Total Environment.
A Unique Molecule with Rare Chemical Properties
The research team isolated eight strains of heat-tolerant cyanobacteria from the Bo Khlueng hot spring in Ratchaburi province, Thailand. During laboratory experiments, a strain called 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-linked hydroxy-mycosporin-sarcosine (GlcHMS326), was subsequently studied in detail to understand its structure and function.
GlcHMS326 is characterized by three distinct chemical modifications: Glycosylation, hydroxylation and methylation. These modifications have not yet been described in MAAs from cyanobacteria. Genetic analyses revealed that the cyanobacteria responsible for the production of this compound contain a unique set of genes associated with these chemical modifications.
The 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 thought to further support stability, photoprotection and antioxidant defense. Compared to more common MAAs, GlcHMS326 exhibits stronger free radical scavenging activity, suggesting that its modified structure plays a key role in enhancing its antioxidant potential.
Potential for Eco-Friendly Sunscreens and Beyond
The study offers new insights into how cyanobacteria have evolved specialized metabolic pathways in extreme environments to produce effective natural UV-protective compounds. This unique MAA appears to play an important role in helping Gloeocapsa species tolerate environmental stress and likely fulfills multiple functions within these thermophilic cyanobacteria. The current study emphasizes that extremophilic cyanobacteria are not only ecologically important, but also represent an important area of research for several disciplines.
The newly identified compound is characterized by its versatility and its potential for sustainable, large-scale production using cyanobacteria as “biofactories”. It could serve as an alternative to certain synthetic UV filters that raise environmental concerns and thus contribute to the development of more environmentally friendly sunscreens. Its antioxidant properties also make it a potential candidate for anti-ageing products, skincare formulations and pharmaceuticals. “This discovery reminds us that nature still has many chemical surprises in store. Extremophilic cyanobacteria reveal unusual molecules that can inspire new directions in basic research and sustainable biotechnology,” summarizes Prof. Kageyama.