cytotoxins

Cytotoxins are substances that damage or kill cells. They may be produced by bacteria, plants, and animals, or synthesized for research or therapeutic purposes. In biology, the term typically refers to agents that exert cytotoxic effects on cells, rather than toxins that primarily affect nerves or the heart, though some agents have multiple targets.

Mechanisms of action vary. Cytotoxins can disrupt cell membranes by forming pores or degrading lipids, or they can enzymatically modify intracellular targets to halt essential processes. Examples include inhibitors of protein synthesis such as ricin, which inactivates ribosomes, and diphtheria toxin, which blocks elongation factor-2. Other cytotoxins damage DNA, impair mitochondria, or trigger programmed cell death (apoptosis) or uncontrolled cell death (necrosis). The effects may be broad or selective for certain cell types.

Prominent examples include ricin from castor beans and diphtheria toxin from Corynebacterium diphtheriae. Bacterial toxins such as streptolysin O and Staphylococcus aureus alpha-toxin are also described as cytotoxins due to their ability to kill or lyse cells. Some venom components, particularly certain cardiotoxins, exert cytotoxic effects by disrupting cellular membranes. In medicine and research, cytotoxicity is exploited in chemotherapy and in engineered immunotoxins that target specific cells, while safety and specificity are key considerations in clinical use.

Assessment of cytotoxicity is a standard part of toxicology and pharmacology, used to evaluate potential hazards of chemicals and the safety and efficacy of therapeutic agents.