SEOUL, July 02 (AJP) -Researchers at the Korea Advanced Institute of Science and Technology have developed a drug that activates only inside diseased brain tissue, using a toxic molecule long blamed for worsening Alzheimer's disease as the trigger that switches the treatment on.
The molecule is hydrogen peroxide, a reactive form of oxygen that damages cells and builds up at abnormally high levels in the brains of Alzheimer's patients. Scientists have traditionally viewed it purely as a threat to be cleared out. The team behind this study flipped that logic, engineering a drug that stays dormant in healthy tissue and only turns active when it encounters the excess hydrogen peroxide found in a diseased brain. In animal testing, mice treated with the compound showed measurable improvements in memory and navigation, offering an early signal for a new approach to dementia treatment.
Korea Advanced Institute of Science and Technology (KAIST) said in a statement on Thursday that the work was led by chemistry professor Lim Mi-hee and carried out jointly with professor Kim Min-geun from Chonnam National University, along with Lee Cheol-ho and Kim Kyung-sim from the Korea Research Institute of Bioscience and Biotechnology (KRIBB), and Lee Young-ho of the Korea Basic Science Institute (KBSI).
The drug belongs to a class called prodrugs, compounds with no therapeutic effect on their own that convert into an active medicine only under specific conditions inside the body. In this case, that condition is direct contact with elevated hydrogen peroxide, effectively turning a marker of disease into the key that unlocks treatment. The result is a compound designed to act like a targeted switch, largely inert in healthy brain tissue and activated only where the disease is already underway.
The researchers created two prodrug candidates, named BE-1 and BE-2. In tests, both showed little to no reaction in healthy brain conditions. When exposed to the elevated hydrogen peroxide levels typical of a brain affected by dementia, they converted into active compounds called AP-1 and AP-2. That conversion did two things at once. It reduced hydrogen peroxide and related reactive oxygen molecules, and it interfered with amyloid beta, a protein that accumulates in the brain and damages neurons, from clumping into the large, toxic aggregates considered a central driver of Alzheimer's disease. Using advanced analytical techniques, the team confirmed that the activated compounds altered the structural shape of amyloid beta in a way that blocked it from growing into these larger, more damaging clusters.
The team then tested the approach in a mouse model of Alzheimer's disease. The drug crossed the blood-brain barrier, the protective membrane that controls which substances from the bloodstream are allowed to reach the brain, and converted into its active form once inside. Mice given the drug over an extended period showed reduced oxidative stress in the hippocampus, the brain region responsible for memory, along with lower buildup of amyloid beta. The animals also performed better on behavioral tests measuring their ability to recognize new objects and find their way through mazes, both standard measures of cognitive function in mouse studies.
Most existing Alzheimer's drugs are built to target a single protein. The researchers said their approach is different because it uses the diseased environment itself, rather than one specific molecular target, to determine where and when the drug activates. That design, they said, could increase treatment effectiveness while reducing side effects, since the compound remains inactive in healthy tissue. The team also pointed to potential applications beyond Alzheimer's disease, including Parkinson's disease and other neurodegenerative conditions that involve similar patterns of oxidative stress.
Lim Mi-hee, the KAIST chemistry professor who led the research, said in a statement translated from Korean that the significance of the work lies in using hydrogen peroxide, previously treated only as a substance to eliminate, as the signal that activates the drug. She said the technology, which activates medicine only in diseased tissue, is expected to serve as a new platform for treating complex diseases such as Alzheimer's disease more safely and effectively.
KAIST doctoral students Lee Ji-min and Hong Eun-seo, both from the university's chemistry department, served as co-first authors of the study. The findings were published online on May 31, 2026, in the journal Small, which ranks in the top 10 percent of chemistry publications by impact factor, under the title "A Prodrug Approach for Activity-Based Chemical Modulation toward Multiple Pathological Targets in Alzheimer's Disease."
Reference Information
Journal/Source: Small (Impact Factor 12.1, top 10% in chemistry)
Title: A Prodrug Approach for Activity-Based Chemical Modulation toward Multiple Pathological Targets in Alzheimer's Disease
Link/DOI:10.1002/smll.74013
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