Ambrein

Ambrein is a triterpene alcohol that is the chief constituent of ambergris, a secretion from the digestive system of the sperm whale. It has been suggested as the possible active component producing the supposed aphrodisiac effects of ambergris. Although ambrein itself is odorless, it serves as the biological precursor for aromatic derivatives such as ambroxide and is thought to possess fixative properties for other odorants.
It has been shown to act as an analgesic and has been proven to increase sexual behavior in rats, providing some support for its traditional aphrodisiac use.
Apart from its supposed aphrodisiac effects, ambrein has been shown to decrease spontaneous contractions of smooth muscles in rats, guinea pigs, and rabbits. It reduces these contractions by serving as an antagonist and interfering with Ca²⁺ ions from outside the cell.

Discovery

In 1946, Ruzicka and Lardon "established that the fragrance of ambergris is based on the triterpene ambrein".

Ambrein is synthesized from the common triterpenoid precursor squalene. The squalene-hopene cyclase catalyzes the cyclization of squalene into the monocyclic 3-deoxyachilleol A. Tetraprenyl-beta-curcumene synthase converts 3-deoxyachilleol A into the tricyclic ambrein.