PQQ

Pyrroloquinoline quinone (PQQ), otherwise known as methoxatin, is an essential, water-soluble, redox-cofactor vitamin which ordinarily does not pass the blood-brain barrier. It has to be bound to glycine to penetrate and effect the brain. It has been shown to be essential for normal growth and development. PQQ is mostly contained in common foods; especially, in natto, tea, papayas, and kiwi fruits, in comparatively in large quantities. A dose of 20 mg per day of PQQ has been shown to be beneficial.