AL072 is a potent anti-Legionella antibiotic produced by Streptomyces strain AL91. The compound was isolated from the fermentation broth with 1 volume of isopropyl alcohol, followed by an ethyl acetate extraction and subsequent concentration under reduced pressure. Purification was performed on an octadecyl silica gel column followed by preparative HPLC. AL072 purified as mentioned above showed extremely specific activity only towards Legionella pneumophila. No antibacterial activity against any other bacteria tested was demonstrable. Its molecular weight was determined by FAB-MS (m/z 648) and the compound was identified as a novel 1,3-diacyl glycerol with the molecular formula C41H76O5. One of the two acyl groups is linoleyl and the other is 3,5-dimethyl octadecanoyl.