4-hydroxynonenal (4-HNE)

4-hydroxynonenal (4-HNE) is a highly reactive alpha,beta-unsaturated aldehyde generated during the lipid peroxidation of omega-6 polyunsaturated fatty acids, such as linoleic and arachidonic acids [1, 3]. It is widely recognized as a key biomarker and "toxic second messenger" of oxidative stress, capable of diffusing from its site of origin to form covalent adducts with proteins, DNA, and lipids via Michael addition or Schiff base formation [2, 8]. These modifications often lead to protein dysfunction, enzyme inactivation, and the triggering of pro-inflammatory and apoptotic pathways [1, 7]. 4-HNE is implicated in the pathogenesis of numerous chronic conditions, including neurodegenerative diseases like Alzheimer's and Parkinson's, cardiovascular disorders, type 2 diabetes, and various cancers [4, 13, 16]. Therapeutically, 4-HNE is targeted through direct scavenging by molecules like carnosine or hydralazine, or by enhancing its metabolic detoxification using activators of aldehyde dehydrogenase 2 (ALDH2), such as Alda-1 [10, 15]. While high concentrations are cytotoxic, low physiological levels of 4-HNE play a role in adaptive signaling, such as the activation of the Nrf2 antioxidant response pathway [8, 14].

Other names

4-hydroxy-2-nonenalHNE4-hydroxy-trans-2-nonenaltrans-4-hydroxy-2-nonenal4-hydroxynon-2-enal

Direct scavenging and neutralization of the reactive aldehyde, activation of metabolic detoxification enzymes such as aldehyde dehydrogenase 2 (ALDH2) and glutathione S-transferase (GST), and reduction of precursor lipid peroxidation through antioxidant activity [1, 10, 13, 17].