Assembly of Asperlicin Peptidyl Alkaloids from Anthranilate and Tryptophan: A Two-Enzyme Pathway Generates Heptacyclic Scaffold Complexity in Asperlicin E
摘要:
Members of the asperlicin family of fungal metabolites produced by Aspergillus alliaceus are known potent CCKA antagonists. Herein, we report the identification of the gene cluster responsible for directing their biosynthesis. We validate and probe the pathway by genetic manipulation, and provide the first biochemical characterization of the oxidative cyclization en route to the heptacyclic asperlicin E by reconstituting the activity of the FAD depend monooxygenase AspB. This report provides the first genetic characterization of a NRPS assembly line that efficiently activates two anthranilate building blocks and illustrates the remarkably efficient biosynthesis of the complex heptacyclic asperlicin E.
Novel indol-3-yl-quinazolino-1,4-benzodiazepin-5,13-diones, which are antagonists of the function of cholecystokinins (CCK), to the preparation of these compounds from compounds prepared by aerobic fermentation of certain Aspergillus alliaceus strains, and to the use of these compounds to antagonize the function of CCK, which antagonism is useful, e.g., for the treatment and prevention of disorders of the gastrointestinal, central nervous and appetite-regulatory systems of mammals, especially of humans.
quinazolinobenzodiazepine alkaloidssclerotigenin (1), (±)-circumdatin F (2), and (±)-asperlicin C (3) via novel microwave-assisted domino reactions were achieved in 55%, 32%, and 20% yields, respectively, from commercially available starting materials. A two-step total synthesis of (±)-benzomalvin A (4) was accomplished with an overall yield of 16%. Additionally, analogues of circumdatin E were synthesized