Discovering the anti-hyaluronidase activity of algal extracts

More than 70 % of the Earth's surface is covered by water, and algae are the dominant category of organisms in aquatic environments. Algae are multicellular or single-celled organisms that can be divided into macroalgae and microalgae based on their structure and size. Microalgae belong to the Protista kingdom and are extremely diverse. Their rich biodiversity makes them useful in a wide range of sectors. They have numerous applications in food, cosmetics, pharmaceuticals and the environment. Microalgae can provide various health benefits thanks to the various bioactive molecules present in them and produced at the cellular level. The use of seaweeds as a source of bioactive compounds offers the opportunity to exploit a renewable and under-exploited natural resource. The cosmetics sector is growing rapidly thanks to modern beauty trends that are moving towards a more natural approach. Companies are increasingly focusing on natural bioactive ingredients from environmentally friendly and less toxic sources, including microalgae. In fact, they can offer numerous benefits to cosmetic formulations by acting as the main active ingredients. Their functionality therefore determines their use in anti-ageing, refreshing and regenerating products, emollients and even sunscreens. One key area in which microalgae can play a crucial role is in combating the effects of aging on the skin, particularly by interacting with hyaluronic acid, a key molecule in skin hydration and elasticity. Hyaluronic acid, a natural unbranched polymer, is a widely used ingredient in cosmetics due to its strong moisturising capacity resulting from its hydrophilic nature. The concentration of hyaluronic acid in the body gradually decreases with age, resulting in loss of hydration and skin laxity due to the synthesis of hyaluronidase, a class of homologous enzymes. In fact, hyaluronidases break down HA into smaller fragments, leading to loss of firmness, flexibility and hydration, and consequently to skin ageing. Inhibiting the activity of these enzymes can prevent the rapid degradation of HA, thus preserving its structural integrity. The present study therefore aims to establish the most optimal protocol for the identification of algal extracts capable of inhibiting the enzyme hyaluronidase. Using spectrophotometric analysis, we developed an anti-hyaluronidase assay to evaluate the inhibitory activity of certain seaweeds and microalgae extracts. We tested 9 different seaweeds and microalgae extracts and EGCG as positive control, using different concentrations to determine a dose-response relationship, which is essential to establish the efficacy of the extracts. The anti-hyaluronidase assay performed was based on the hydrolysis of hyaluronic acid, resulting in the release of N-glucosamine. We then used DMAB to form the DMAB-N-glucosamine complex and measured the absorbance at 585 nm. This allowed us to identify the potential inhibitory activity of the extracts, as a decrease in absorbance indicates inhibition of N-glucosamine formation. The project led to the identification of two extracts that showed relevant inhibition rates at the tested concentrations, reaching peaks of up to 94.23 % inhibition. This suggests a potential use of these extracts in anti-aging or cosmetic applications. Further research is needed to enhance the efficacy of these extracts, which could lead to the development of more potent, targeted formulations. This work paves the way for the development of targeted anti-aging cosmetic formulations that harness natural, renewable resources, aligning with current industry trends toward sustainability, while also opening the door to exploring the effects of algal extracts on other skin functions and enzymes relevant to skin health.