Nitrosative

Nitrosative is an adjective used to describe processes, species, or reactions that involve the nitroso group (–NO) or the introduction of nitroso groups into substrates. In chemistry, nitrosation refers to chemical transformations that add a nitroso group to molecules, producing N-nitroso or O-nitroso derivatives. Nitrosation reactions commonly involve nitrosating agents such as nitrous acid or nitrosyl cations.

In biology and medicine, nitrosative terms relate to reactive nitrogen species (RNS) such as nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (N2O3), and peroxynitrite (ONOO−). Nitrosative modifications include S-nitrosylation of thiols (RS–NO) and various nitrosation events on amines, as well as nitration in certain contexts. S-nitrosylation can serve as a regulatory post-translational modification that modulates protein function and signaling pathways.

Nitrosative stress describes a condition in which excessive RNS overwhelm cellular antioxidant defenses, potentially causing damage to proteins, lipids, and DNA, and contributing to inflammatory or neurodegenerative processes. Peroxynitrite formation from NO and superoxide is a key mechanism linking nitrosative and oxidative stress.

In physiology, nitrosative signaling denotes controlled nitrosylation events that influence processes such as vasodilation, neurotransmission, and immune responses. In environmental and food chemistry, nitrosation reactions can lead to the formation of potentially harmful nitrosamines and related compounds.