Diseases such as Alzheimer’s, Parkinson’s, and Huntington’s slowly damage the brain by destroying neurons, the cells that carry messages through the nervous system. As these cells are lost, people can experience memory problems, cognitive decline, and movement difficulties that often become severe enough to require constant care.
Current medicines can ease some symptoms, and recent Alzheimer’s therapies such as lecanemab and donanemab can slow decline in certain people with early disease, but they do not restore lost memories or rebuild damaged brain tissue. That is why researchers are pursuing another ambitious idea: helping the brain replace neurons that have been lost.
A Vitamin Better Known for Blood and Bones
Vitamin K is best known for its role in blood clotting and bone health. In recent years, however, scientists have also linked it to brain protection and neuronal differentiation, the process by which immature neural cells become functioning neurons.
One form of vitamin K, menaquinone 4 (MK-4), is naturally active in the body. Even so, its effects may not be strong enough on their own for future use in regenerative medicine aimed at neurodegenerative disease.
In work published online in ACS Chemical Neuroscience on July 03, 2025, researchers from Shibaura Institute of Technology in Japan created vitamin K analogues designed to be more active in the nervous system. The study was led by Associate Professor Yoshihisa Hirota and Professor Yoshitomo Suhara of the Department of Bioscience and Engineering.
Dr. Hirota explains, “The newly synthesized vitamin K analogues demonstrated approximately threefold greater potency in inducing the differentiation of neural progenitor cells into neurons compared to natural vitamin K. Since neuronal loss is a hallmark of neurodegenerative diseases such as Alzheimer’s disease, these analogues may serve as regenerative agents that help replenish lost neurons and restore brain function.”
Building a Stronger Brain Active Compound
To make vitamin K more potent, the team synthesized 12 hybrid vitamin K homologs. Some were linked to retinoic acid, an active metabolite of vitamin A that is known to promote neuronal differentiation. Others included a carboxylic acid moiety or a methyl ester side chain. The researchers then compared how strongly these compounds encouraged neural progenitor cells to become neurons.
Vitamin K and retinoic acid influence gene activity through different receptors. Vitamin K acts through the steroid and xenobiotic receptor (SXR), while retinoic acid acts through the retinoic acid receptor (RAR). When the team tested the compounds in mouse neural progenitor cells, the hybrid molecules preserved the biological activity of both vitamin K and retinoic acid.
The researchers also measured microtubule associated protein 2 (Map2), a marker associated with neuronal growth. One compound stood out. It combined the retinoic acid structure with a methyl ester side chain and showed threefold higher neuronal differentiation activity than the control, along with significantly stronger activity than natural vitamin K compounds. The researchers referred to it as Novel vitamin K analog (Novel VK).
A Surprising Signal in the Brain
The team then investigated how vitamin K might be producing these neuroprotective effects. They compared gene expression in neural stem cells treated with MK-4, which promotes neuronal differentiation, with cells treated using a compound that suppresses the process.
The analysis pointed to metabotropic glutamate receptors (mGluRs), which appeared to help drive vitamin K induced neuronal differentiation through downstream epigenetic and transcriptional regulation. The effect of MK-4 was specifically tied to mGluR1.
That connection is important because mGluR1 has already been linked to synaptic transmission, the communication between neurons. Mice lacking mGluR1 show motor and synaptic problems, features that overlap with the kinds of dysfunction seen in neurodegenerative diseases.
Crossing Into the Brain
To explore whether the vitamin K compound could interact with mGluR1, the researchers used structural simulations and molecular docking studies. Their results suggested that Novel VK had stronger binding affinity for mGluR1 than MK-4.
They also tested how well Novel VK entered cells and converted into bioactive MK-4. Inside cells, MK-4 levels rose in a concentration dependent way. Novel VK also converted into MK-4 more easily than natural vitamin K.
Mouse experiments added another key finding. Novel VK showed a stable pharmacokinetic profile, crossed the blood brain barrier, and produced higher MK-4 concentrations in the brain than the control.
Why the Finding Matters
The work highlights a possible route toward therapies that do more than manage symptoms. By pushing neural progenitor cells toward becoming neurons, vitamin K based compounds could one day contribute to strategies aimed at slowing, delaying, or potentially reversing parts of neurodegeneration.
That remains a long term goal. The findings are based on cell studies and mouse experiments, not human trials. No vitamin K derived drug has yet been shown to repair the brains of people with Alzheimer’s, Parkinson’s, or Huntington’s disease. Still, the results give researchers a clearer target, especially the mGluR1 pathway, for developing future brain repair therapies.
The broader Alzheimer’s field is already moving beyond purely symptom based treatment. FDA approved anti amyloid therapies now target disease biology in early Alzheimer’s, though they are not cures and do not restore lost memory or cognitive function. A regenerative approach, if eventually proven safe and effective, would aim at a different challenge: replacing or restoring damaged neural cells.
Dr. Hirota says, “Our research offers a potentially groundbreaking approach to treating neurodegenerative diseases. A vitamin K-derived drug that slows the progression of Alzheimer’s disease or improves its symptoms could not only improve the quality of life for patients and their families but also significantly reduce the growing societal burden of healthcare expenditures and long-term caregiving.”
The hope is that this line of research will eventually move from promising laboratory results toward clinically meaningful treatments for people living with neurological disease.
About Associate Professor Yoshihisa Hirota from SIT, Japan
Dr. Yoshihisa Hirota is an Associate Professor at the Shibaura Institute of Technology in the Department of Bioscience and Engineering, College of Systems Engineering and Science. He has also worked internationally as a Visiting Scholar at the University of Cincinnati.
His research centers on Medicinal Science and Nutritional Biochemistry, with a special focus on how fat soluble vitamins and nucleic acids function in biological systems. Dr. Hirota has published 56 papers, and his work connects molecular biology with nutrition in pursuit of better health care solutions and longer healthy life expectancy.
About Professor Yoshitomo Suhara from SIT, Japan
Dr. Yoshitomo Suhara is a Professor at the Shibaura Institute of Technology in the Department of Bioscience and Engineering, College of Systems Engineering and Science.
His work focuses on medicinal chemistry and drug discovery, especially the creation of bioactive small molecules derived from fat soluble vitamins such as vitamins D and K. He has authored more than 100 peer reviewed publications and several patent applications. His multidisciplinary projects include neurogenic compounds that promote neuronal differentiation, antiviral agents, and novel anti cancer molecules.
Funding Information
This study was partly supported by a fund for the Mishima Kaiun Memorial Foundation and the Suzuken Memorial Foundation, KOSÉ Cosmetology Research Foundation, Koyanagi Foundation, Research Grants from the Toyo Institute of Food Technology, the Science Research Promotion Fund and the Takahashi Industrial and Economic Research Foundation.
Additional support came from a Fund for the Promotion of Joint International Research (Fostering Joint International Research (A)) [grant number 18KK0455] and a Grant in Aid for Scientific Research (C) [grant numbers 20K05754 and 18K11056, 21K11709, and 24K14656], Grant in Aid for Early Career Scientists [grant number 23K14091] from the Japan Society for the Promotion of Science (JSPS).