Kahweol
Kahweol is a diterpenoid molecule found in the beans of Coffea arabica and is structurally related to cafestol. It was named after the Arabic قهوة meaning "coffee".
Kahweol belongs to a group of organic compounds known as naphthofurans, containing both naphthalene and furan moieties. It is a colourless crystal at room temperature that oxidises readily and yellows within hours.
History
Kahweol was first isolated and identified as a constituent of coffee bean oil in 1932. The compound was isolated as its free "unsaponifiable" alcohol form. The solvent used greatly influences the crystal form, with acetone producing "large colorless trigonal or pentagonal dense plates," methanol producing "massive colorless quadratic plates," and ether producing "very long, snow-white silky needles."While the presence of esters of cafestol were apparent since the 1960s, it was not until 1982 that kahweol was isolated as an ester of its own. Following the development of liquid chromatography-mass spectrometry in the late 20th century, kahweol was isolated in other esteric forms, namely stearate, linoleate, and oleate, with minor amounts of arachidate and behenate.