A superpower molecule that does it all: protects against UV degradation, stabilises your formulations from oxidation and even helps prevent the effects of air pollution on skin. Add it as a habit and avoid future headaches imo.
 
The active molecule here is Diethylhexyl Syringylidenemalonate, which is a very bulky molcule with powerful singlet oxygen quenching abilities. Also contains Caprylic/Capric Triglyceride as a rheology modifier and solvent.
 
Unlike BHT and some Avobenzones, which have encountered various safety controversies, DESM has a completely clean record (both for your cosmetic assessor and the increasingly ingredients-conscious consumers inspecting the backs of your packages).
 
Usage is about 0.2-0.5% in fine fragrances (that's % of the final product, rather than your formula)