New Review: PQQ’s Neuroprotective Effects — From Mitochondrial Repair to Treating Cerebral Folate Deficiency

With the acceleration of global population aging, the incidence of neurodegenerative diseases and neurodevelopmental disorders continues to rise. Central nervous system (CNS) disorders such as Alzheimer’s disease, Parkinson’s disease, and cerebral folate deficiency place a heavy burden on patients, families, and society. Recently, a research team from the University of Toronto’s Faculty of Pharmacy published a comprehensive review in the Journal of Nutritional Biochemistry, systematically elucidating the protective effects and molecular mechanisms of pyrroloquinoline quinone (PQQ) in CNS disorders. The study found that PQQ exhibits significant neuroprotective effects in various models of neurological diseases through a triple mechanism: enhancing mitochondrial function, inhibiting inflammatory responses, and combating oxidative stress. Notably, it offers a novel therapeutic approach for cerebral folate deficiency, a challenging pediatric neurological condition.

Research Background: New Hope for Neuroprotection

PQQ is a naturally occurring quinone cofactor found in soil and food, initially identified as an essential coenzyme for bacterial dehydrogenases. Recent studies have revealed that PQQ also plays important physiological roles in mammals. Animal studies indicate that dietary PQQ insufficiency leads to growth retardation and impaired reproductive function. More importantly, PQQ has been shown to possess significant neurotrophic and neuroprotective effects. It can improve mitochondrial function, inhibit inflammatory responses, and reduce oxidative stress by activating various signaling pathways, positioning it as a promising candidate compound for treating multiple neurological disorders.

Core Mechanisms: A Triple Protective Action

1. Enhancing Mitochondrial Function – Activating Energy Metabolism

Mitochondria are the “powerhouses” of cells, and their dysfunction is closely linked to various neurodegenerative diseases. The research reveals that PQQ promotes mitochondrial biogenesis by activating the PGC-1α signaling pathway. The specific mechanism involves PQQ acting as a cofactor for lactate dehydrogenase, catalyzing the conversion of NADH to NAD⁺, thereby increasing NAD⁺ levels. This activates NAD⁺-dependent SIRT1 and SIRT3. SIRT1/3 activate PGC-1α through deacetylation, which then cooperates with transcription factors like NRF-1 to promote mitochondrial DNA replication and the expression of respiratory chain enzymes, ultimately increasing ATP production and restoring neuronal energy balance.

In models of Parkinson’s disease, PQQ reversed rotenone-induced mitochondrial dysfunction, restored mitochondrial DNA content, and protected dopaminergic neurons. In Alzheimer’s disease models, PQQ improved mitochondrial membrane potential, increased ATP levels, and alleviated cognitive dysfunction. PQQ’s role in enhancing mitochondrial function via the PGC-1α/NRF-1 pathway lays a theoretical foundation for its application in various neurological diseases.

2. Anti-inflammatory Effects – Inhibiting Microglial Activation

Neuroinflammation is a common pathological feature of many CNS disorders. Studies show that PQQ can significantly inhibit microglial activation and reduce the production of pro-inflammatory cytokines. Its mechanism involves inhibiting the NF-κB signaling pathway, decreasing the release of inflammatory mediators such as TNF-α, IL-1β, and IL-6. In LPS-induced neuroinflammation models, PQQ treatment reduced microglial activation and improved neurological function. Its anti-inflammatory effects and promotion of functional recovery have also been demonstrated in models of spinal cord injury and traumatic brain injury.

3. Antioxidant Effects – Activating Endogenous Defense Systems

Oxidative stress is a key mechanism of neuronal damage. PQQ’s antioxidant action has a dual nature: on one hand, PQQ itself acts as a free radical scavenger, directly neutralizing reactive oxygen and nitrogen species; on the other hand, PQQ can activate the Nrf2 signaling pathway, upregulating the expression of antioxidant enzymes (such as heme oxygenase-1, superoxide dismutase, and catalase) and enhancing the cell’s endogenous antioxidant defense capabilities. In glutamate-induced neurotoxicity models, PQQ treatment significantly reduced reactive oxygen species levels, protecting nerve cells from damage.

Clinical Evidence: Improvement in Cognitive Function

Clinical research on PQQ, though still in early stages, has shown promising results. In a randomized, double-blind, controlled trial involving healthy elderly individuals aged 50-70, supplementation with PQQ (21.5 mg/day) for 12 consecutive weeks significantly improved immediate memory. Another study showed that BioPQQ (PQQ disodium salt) supplementation improved language function in patients with mild dementia. More recent research found that 12 weeks of PQQ supplementation at 20 mg/day not only benefited the elderly but also improved cognitive function in healthy young adults aged 20-40. These clinical findings align with the mechanistic studies—PQQ enhances neuronal energy metabolism efficiency by improving blood flow and oxygen metabolism in the prefrontal cortex.

Special Application: Therapeutic Potential for Cerebral Folate Deficiency

Cerebral folate deficiency is a rare pediatric neurological disorder caused by low folate levels in the cerebrospinal fluid, leading to severe neurological symptoms such as developmental delay, epilepsy, and movement disorders. Existing high-dose folate supplementation often fails to effectively elevate cerebrospinal fluid folate levels. The review highlights PQQ’s therapeutic potential for this specific condition.

The research team discovered that PQQ can upregulate the expression of reduced folate carriers in the blood-brain barrier and brain parenchyma via the PGC-1α/NRF-1 pathway, promoting the transport of folate into the CNS. In cellular and animal models of folate deficiency, PQQ treatment was able to reverse neuroinflammation, oxidative stress, and mitochondrial dysfunction, offering a novel strategy for treating cerebral folate deficiency. This finding is significant because it targets the underlying defect in folate transport rather than merely addressing symptoms.

Future Outlook: From Bench to Bedside

PQQ’s multi-target mechanism of action positions it as a standout molecule in the field of neuroprotection. From mitochondrial repair to inflammation suppression, from antioxidant defense to regulating folate transport, PQQ forms a synergistic neuroprotective network by activating key signaling pathways such as PGC-1α, inhibiting NF-κB, and inducing Nrf2. However, current clinical studies have limitations, including small sample sizes, short intervention periods, and a lack of data from patient populations. Future larger-scale, rigorously designed clinical trials are needed to determine the optimal dosage, safety, and long-term efficacy of PQQ in different neurological diseases.

Conclusion

This review from the University of Toronto systematically synthesizes the scientific evidence for PQQ’s protective role in the CNS, revealing its triple mechanism of action in enhancing mitochondrial function, inhibiting neuroinflammation, and reducing oxidative stress. Of particular note is PQQ’s therapeutic potential in cerebral folate deficiency, a challenging pediatric disease, offering a new direction for clinical translation.

Nugene Pharma, based in Shandong, China, is deeply engaged in the field of functional ingredients. Its VigouFull® PQQ product employs a strict quality control system to ensure high purity and high bioavailability. Serving as a bridge between scientific exploration and industrial translation, VigouFull® PQQ is committed to providing high-quality raw material support for neurological health.