Algae or cyanobacteria, in a pond. Image by Tim Sandle.
Microbiologists from Meijo University, studying cyanobacteria from hot springs in Thailand, have discovered a new natural ultraviolet light (UV)-blocking compound with impressive antioxidant power. The compound acts in a way similar to conventional sunscreens – but with a difference.
Unlike conventional sunscreens, the compound is biocompatible and potentially safer for both people and the environment. The molecule is produced only under UV and salt stress and uses a unique biosynthetic pathway never seen before. This could help drive a new generation of eco-friendly sunscreens and skincare products.
The compound is β-glucose-bound hydroxy mycosporine-sarcosine. This is a substance produced naturally by heat-loving cyanobacteria when they are exposed to UV-A, UV-B, and salty conditions.
Mycosporine-like amino acids (MAAs) are small secondary metabolites produced by organisms that live in environments with high volumes of sunlight, usually marine environments.
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
Cyanobacteria use photosynthetic pigments such as various forms of chlorophyll, carotenoids and phycobilins to convert the photonic energy in sunlight to chemical energy.
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.
New study
In a new study, researchers 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.
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 also known to improve the stability, UV absorption, and antioxidant activity of MAA compounds. Glycosylation is believed to further support stability, photoprotection, and antioxidant defence. 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.
This unique MAA appears to play an important role in helping Gloeocapsa species tolerate environmental stress and likely serves several functions within these thermophilic cyanobacteria.
Significance of the finding
The new compound could serve as an alternative to certain synthetic UV filters that raise environmental concerns, helping advance the development of more eco-friendly sunscreens. Its antioxidant properties also suggest possible uses in anti-ageing products, skincare formulations, and pharmaceuticals.
Research publication
The research appears in the journal Science of The Total Environment, the paper is titled “Discovery of a novel natural sunscreen from thermophilic cyanobacteria with a potentially unique biosynthetic pathway and its transcriptional response to environmental stresses.”