Diethylhexyl Syringylidenemalonate Bon Antioxydant Anti-âge Diethylhexyl Syringylidenemalonate at a glance An ester that functions as an antioxidant and photostabilizer Stabilizes UV filters, especially avobenzone Can increase critical wavelength (amount of UVA protection) in sunscreen formulas Helps boost SPF of sunscreen formulas Diethylhexyl Syringylidenemalonate description Diethylhexyl syringylidenemalonate (DESM) is an ester that functions as an antioxidant and helps protect cosmetics from chemical or physical deterioration induced by light. This means it is a photostabilizer. In this function, it also stabilizes many UV filters, most notably avobenzone. Research shows diethylhexyl syringylidenemalonate can increase critical wavelength in sunscreens (a measure of protection against UVA rays) and boost SPF in sunscreen formulas. At room temperature it is a viscous yellowish liquid or a low-melting solid. Maximum usage levels for this antioxidant haven’t been established; however, amounts between 0.3–0.5% produce the desired photostabilizing effects in sunscreens.