The sunscreen compound that absorbs UVB and is derived from cinnamic acid is octinoxate.
Octinoxate is also called octyl methoxycinnamate or ethylhexyl methoxycinnamate. Chemically, it is an ester formed from methoxycinnamic acid and 2-ethylhexanol. Its conjugated molecular structure absorbs ultraviolet radiation, with a peak absorption near 310 nanometres, within the UVB range.
UVB rays are strongly associated with sunburn and contribute to DNA damage in skin. Octinoxate is therefore used in sunscreens, lip balms, and other cosmetic products as an organic, or chemical, UV filter. It is often combined with other filters because no single sunscreen ingredient provides complete protection across the UVA and UVB spectrum.
The name can cause confusion because “octinoxate” is the common sunscreen name, while “octyl methoxycinnamate” describes its chemical identity. Zinc oxide is a mineral filter, not a cinnamic-acid derivative. Oxybenzone and avobenzone are also organic sunscreen filters, but they have different chemical structures and absorption profiles.
Octinoxate has also drawn environmental attention. Hawaii and Palau restricted certain sunscreens containing it, alongside other UV filters, because of concerns about effects on coral-reef ecosystems.