phototoxins

Phototoxins are substances that become toxic when exposed to light. This toxicity can manifest in various ways, often involving cellular damage or disruption of biological processes. The interaction between the phototoxin, light, and biological tissue is the key mechanism.

When a phototoxin absorbs light energy, it can transition to an excited state. This excited state can then lead to several damaging reactions. One common pathway involves the transfer of this energy to molecular oxygen, generating reactive oxygen species (ROS) such as singlet oxygen. ROS are highly reactive molecules that can damage DNA, proteins, and cell membranes, leading to cell death or dysfunction. Alternatively, the excited phototoxin can directly interact with cellular components, causing damage through oxidation or other chemical reactions.

Phototoxins have applications in medicine, particularly in photodynamic therapy (PDT). In PDT, a photosensitizing drug (a type of phototoxin) is administered to a patient and preferentially accumulates in target tissues, such as tumors. When light of a specific wavelength is applied to the area, the photosensitizer is activated, producing ROS that destroy the targeted cells.

However, phototoxins can also be harmful. Exposure to certain chemicals found in plants or produced by microorganisms, which can act as phototoxins, can cause phototoxic reactions in humans and animals. These reactions can range from mild skin irritation and rash to severe blistering and burns, especially after exposure to sunlight. Some medications can also cause photosensitivity, increasing the risk of phototoxic reactions when the individual is exposed to UV radiation. Understanding the properties and mechanisms of phototoxins is crucial for both therapeutic applications and for preventing adverse effects.