Coral-Inspired Reef-Safe Sunscreen

Oxybenzone and octinoxate — the two most common UV-filter chemicals in conventional sunscreen — are now banned for sale in Hawaii, Palau, and several other jurisdictions after research confirmed they bleach coral reefs, disrupt fish endocrine systems, and persist in marine sediment. The reef-safe sunscreen market has surged in response, but most alternatives replace chemical filters with mineral zinc oxide, which leaves a white cast on darker skin tones and presents its own nanoparticle concerns.

Corals and their symbiotic dinoflagellates have been solving UV protection in saltwater environments for hundreds of millions of years. They synthesise mycosporine-like amino acids — small, water-soluble molecules that absorb strongly in the UVA and UVB ranges through a non-photosensitising mechanism. Unlike chemical UV filters, MAAs do not generate reactive oxygen species upon photon absorption; instead, they dissipate UV energy thermally. They are fully biodegradable and have shown no toxicity to marine invertebrates, fish, or human cells at realistic concentrations.

Soliome is producing MAAs through microbial fermentation, scaling up biosynthetic pathways originally characterised in marine algae. Their lead compound, palythine, is being formulated into commercially viable sunscreen products that provide broad-spectrum UV protection without oxybenzone, octinoxate, or mineral whiteners. Because MAAs are water-soluble, they can also be incorporated into cosmetic carriers that conventional mineral filters cannot enter.

Beyond sunscreen, MAA chemistry represents a broader class of bio-inspired UV-protective additives for coatings, textiles, and optics — applications where synthetic UV absorbers currently create environmental persistence or reactive oxygen species problems. The coral reef, ironically, may supply the chemistry needed to protect swimmers who wish to protect it in return.