P57 is an oxypregnane steroidal glycoside isolated from the African cactiform Hoodia gordonii. P57 is thought to be the main active constituent from this plant that may be responsible for the possible appetite suppressant activity of Hoodia extracts.
In a rat study at Brown Medical School, intracerebroventricular injections of the purified P57 demonstrated that the compound has a likely central nervous system (CNS) mechanism of action. The studies demonstrated that the compound increases the content of ATP by 50-150% in hypothalamic neurons. In addition, third ventricle administration of P57 reduced subsequent 24-hour food intake by 40-60%.