Chemically, artemisinin is a sesquiterpene lactone containing an unusual peroxide bridge. It is a sesquiterpene lactone with a chemically rare peroxide bridge linkage. Sirolimus is a natural product and macrocyclic lactone. Emamectin, like other avermectins, is a hydrophobic 16-membered macrocyclic lactone. There are several derivatives of helenaline known within the same sesquiterpene lactone group; pseudoguaianolides. Both molecules include a lactone and a triple-repeating sugar called a glycoside. Chemically, these are polypropionate lactone glycosides. Sclareol is oxidatively degraded to a lactone, which is hydrogenated to the corresponding diol. Cyclopentadecanolide is a natural macrolide lactone and a synthetic musk. It is a macrolide lactone and acts by inhibiting calcineurin. Two molecules of lactic acid can be dehydrated to the lactone lactide. The term is a portmanteau of the words "lactone" + "amide". It is metabolized into the acid form of drospirenone by opening of its lactone ring. In acidic water, a mixture of the lactone and acid forms coexist in an equilibrium. YenS inhibits YenI expression and acylhomoserine lactone production.