Hemoglobin as a peroxidase and drug target for oxidative stress-related diseases

Abstract

Summary paragraphHemoglobin (Hb) is well-known for transporting oxygen in red blood cells within blood vessels1. Although Hb is also present in the brain2, its role remains poorly understood. Here, we show that Hb, found in astrocytes of neurodegenerative animal models and patients, displays significant antioxidant effects through its H2O2-decomposing peroxidase activity, and a small molecule enhancer boosts this activity, reducing aberrant H2O2and mitigating H2O2-induced neurodegeneration. To counteract the harmful effects of aberrant H2O2-production in Alzheimer’s disease (AD), we developed KDS12025, a blood-brain barrier (BBB)-permeable small molecule that effectively enhances the peroxidase activity of Hb by a hundredfold, especially at a low level of Hb. KDS12025 and its analogs achieve this enhancement through its electron-donating amine group. KDS12025 reduces H2O2levels in astrocytes, exhibits neuroprotective effects, and reverses memory impairment in AD models. Gene-silencing of Hbβ abrogates KDS12025’s impact in both culture and animal models of AD. Moreover, KDS12025 prevented the death of dopaminergic neurons in a Parkinson’s disease (PD) model without altering the oxygen-transporting function of Hb. KDS12025 extended survival and improved motor function even in the severe amyotrophic lateral sclerosis (ALS) mouse model. Our findings propose Hb as a new therapeutic target for neurodegenerative diseases, with KDS12025 emerging as a first-in-class drug candidate that enhances Hb’s peroxidase activity to reduce H2O2. Boosting Hb’s peroxidase activity with KDS12025 mitigates oxidative stress and alleviates neurodegeneration in AD, PD, and ALS with broad applicability for numerous oxidative-stress-driven diseases.