(2S)-2-amino-3-[[(2R)-2-butanoyloxy-3-propanoyloxypropoxy]-hydroxyphosphoryl]oxypropanoic acid
Phosphatidyl serine (PS) is a phospholipid nutrient found in fish, green leafy vegetables, soybeans and rice, and is essential for the normal functioning of neuronal cell membranes and activates Protein kinase C (PKC) which has been shown to be involved in memory function. In apoptosis, phosphatidyl serine is transferred to the outer leaflet of the plasma membrane. This is part of the process by which the cell is targeted for phagocytosis. PS has been shown to slow cognitive decline in animal models. PS has been investigated in a small number of double-blind placebo trials and has been shown to increase memory performance in the elderly. Because of the potentail cognitive benefits of phosphatidylserine, the substance is sold as a dietary supplement to people who believe they can benefit from an increased intake.  The dietary supplement was originally processed from bovine sources however Prion disease scares in the 1990s outlawed this process, and a soy-based alternative was adopted.