It contains isovaleric acid, salicylic acid, asparagine, sterols, and flavonoids. Phytochemicals include phenolic acids, indole compounds, sterols, and triterpenes. Both oils also contain dense amounts of tocopherols, tocotrienols and plant sterols. The liver preferentially excretes plant sterols over cholesterol. Lanolin Alcohol is composed of Cholesterol, other sterols, and free fatty acids. In 1947, divided lipids into "simple lipids", with greases and waxes (true waxes, sterols, alcohols). Absence of sterols activates SREBP, thereby increasing cholesterol synthesis. The polyene antimycotics bind with sterols in the fungal cell membrane, principally ergosterol. Lanolin is a wax obtained from wool, consisting of esters of sterols. This lipid belongs to a class of molecules called sterols. Adipose and muscle tissue use leucine in the formation of sterols and other compounds. Mammalian and fungal membranes both contain sterols, a primary membrane target for amphotericin B. More than 200 sterols and related compounds have been identified. A variety of synthetic steroids and sterols have also been contrived. Neem oil also contains several sterols, including campesterol, beta-sitosterol, and stigmasterol.