Pyrroloquinoline quinone (PQQ) is a small molecular molecule that can be found naturally in plants and in the soil. It has been shown to be thermally stable and is a powerful antioxidant. In addition, it has been reported to have potential to reduce oxidative damage, protect against chondrosarcomas, and increase energy levels and mental focus. However, there is still a lack of knowledge on the role of PQQ in humans.
The compound binds to proteins by using carbonyl groups. This binding occurs spontaneously. Once bound, PQQ forms an imidazopyrroloquinoline derivative. These derivatives are capable of readily oxidizing when they are exposed to oxygen. They are also thought to act as prodrugs.
In mice, treatment with PQQ decreased tumor volume and increased expression of a cytokine, Pgc1a. Furthermore, treatment with PQQ improved the apoptosis induced by the apoptotic agent, MEHP. Cleaved caspases 9 and 3 were also reduced.
Moreover, PQQ is also believed to bind to quinoproteins. Quinoproteins are protein molecules that are critical in glycoprotein synthesis. If PQQ is able to bind to quinoproteins, it may affect the quinoproteins’ activity, and thus their contribution to cancer cell apoptosis.
While some studies have suggested that pyrroloquinoline quinone (PQQ) may contribute to the development of cancer, there has not been much evidence of its actual biological activity. Nevertheless, it is a promising agent. Several animal studies have indicated that doses as low as 2 mg are bioactive.
Besides its apoptotic properties, pyrroloquinoline quinone has been reported to exhibit radioprotective effects against hemoglobin. Also, it was found to scavenge reactive oxygen species, and protect the liver mitochondria against oxidative stress.