Terephthalylidene dicamphor sulphonic acid

Terephthalylidene Dicamphor Sulfonic Acid is a benzylidene camphor derivative with the chemical formula: C28H34O8S2. Terephthalylidene Dicamphor Sulfonic Acid protects against UV wavelengths in the range between 290 and 400 nanometers with a peak protection at 345 nm. Since the sunscreen does not cover the entire UV spectrum, it is usually combined with other active sunscreens to provide broad spectrum UV protection. Terephthalylidene Dicamphor Sulfonic Acid is a photostable organic UVA absorber that does not degrade significantly under the influence of light. This is in contrast to the widely used UVA absorber avobenzone, which is not photostable per se and requires photostabilizers to prevent significant deterioration of light.

Organic light protection filters are all those UV filters whose effect is not exclusively based on the inorganic, physically active substances titanium dioxide or zinc oxide. Organic, also known as chemical UV filters, are photoactive substances that are able to absorb light quanta in a certain wavelength range (ultraviolet radiation in the range of about 280 to 400 nm = ultraviolet radiation = UVB/UVA spectrum). The absorbed UV is then released as thermal energy without penetrating the skin. In this reversible photoisomerization, the energy of the absorbed photon must correspond to the energy required to lift an electron in the molecule of the filter substance from a lower to a higher orbit. In order to protect over the entire width of the wavelengths relevant to humans from 290 to 400 nm, several chemical filters with different absorption maxima are usually combined. With a suitable combination of organic and physical filters, the content of organic filters can also be reduced with the same UV protection. This is desirable, since especially photounstable organic UV filters can cause phototoxic and photoallergic reactions depending on their concentration in the finished product.

1. Moyal D (2004) Prevention of ultraviolet-induced skin pigmentation. Photodermatol Photoimmunol Photomed 20:243-247.