phototoxin

A phototoxin is a substance that can cause skin irritation, redness, or blistering when exposed to sunlight or ultraviolet (UV) light. These compounds are often found in plants, particularly in the essential oils, resins, or other secondary metabolites. Phototoxins can be categorized into two main types: Type I and Type II.

Type I phototoxins are typically aromatic compounds that absorb UV light and form reactive intermediates. These intermediates can then react with cellular components, leading to skin damage. Examples of Type I phototoxins include psoralens found in plants like ferns and some grasses.

Type II phototoxins, on the other hand, are usually porphyrins or porphyrin-like compounds. They require the presence of oxygen and light to generate reactive oxygen species, which can cause oxidative stress and skin irritation. Examples of Type II phototoxins include protoporphyrin IX, a precursor to heme, and certain porphyrins found in some plants.

Phototoxins can cause a range of skin reactions, from mild redness and itching to severe blistering and burns. The severity of the reaction can depend on factors such as the concentration of the phototoxin, the duration of exposure to sunlight, and individual susceptibility.

To avoid phototoxic reactions, it is important to avoid prolonged exposure to sunlight when using products containing phototoxins and to wear protective clothing and sunscreen. Additionally, some plants that contain phototoxins should be avoided in areas where they may be exposed to sunlight, such as in gardens or landscaping.