Lipstatin is a potent, irreversible inhibitor of pancreatic lipase. It is a natural product that was first isolated from the Actinobacterium Streptomyces toxytricini. Orlistat is a saturated derivative of the natural compound Lipstatin.
Lipstatin, isolated from Streptomyces toxytricini as a potent and selective inhibitor of human pancreatic lipase, is a precursor for tetrahydrolipstatin (also known as orlistat, Xenical, and Alli), the only FDA-approved antiobesity medication for long-term use. Lipstatin features a 2-hexyl-3,5-dihydroxy-7,10-hexadecadienoic-beta-lactone structure with an N-formyl-l-leucine group attached as an ester to the 5-hydroxy group. It has been suggested that the alpha-branched 3,5-dihydroxy fatty acid beta-lactone moiety of lipstatin in S. toxytricini is derived from Claisen condensation between two fatty acid substrates, which are derived from incomplete oxidative degradation of linoleic acid based on feeding experiments. In this study, we identified a six-gene operon (lst) that was essential for the biosynthesis of lipstatin by large-deletion, complementation, and single-gene knockout experiments. lstA, lstB, and lstC, which encode two beta-ketoacyl-acyl carrier protein synthase III homologues and an acyl coenzyme A (acyl-CoA) synthetase homologue, were indicated to be responsible for the generation of the alpha-branched 3,5-dihydroxy fatty acid backbone. Subsequently, the nonribosomal peptide synthetase (NRPS) gene lstE and the putative formyltransferase gene lstF were involved in decoration of the alpha-branched 3,5-dihydroxy fatty acid chain with an N-formylated leucine residue. Finally, the 3beta-hydroxysteroid dehydrogenase-homologous gene lstD might be responsible for the reduction of the beta-keto group of the biosynthetic intermediate, thereby facilitating the formation of the unique beta-lactone ring.
        
Title: Lipstatin, an inhibitor of pancreatic lipase, produced by Streptomyces toxytricini. I. Producing organism, fermentation, isolation and biological activity Weibel EK, Hadvary P, Hochuli E, Kupfer E, Lengsfeld H Ref: J Antibiot (Tokyo), 40:1081, 1987 : PubMed
Lipstatin, a new and very potent inhibitor of pancreatic lipase (the key enzyme of intestinal fat digestion) was isolated from Streptomyces toxytricini. Lipstatin contains a beta-lactone structure that probably accounts for the irreversible lipase inhibition. The IC50 of lipstatin for pancreatic lipase is 0.14 microM. In mice triolein absorption was dose-dependently inhibited by lipstatin, whereas oleic acid was absorbed normally. Other pancreatic enzymes, such as phospholipase A2 and trypsin, were not inhibited even at an inhibitor concentration of 200 microM.