Amidepsine B

Structures of amidepsines A, B, C and D, diacylglycerol acyltransferase (DGAT) inhibitors, were determined by spectroscopic studies including various NMR measurements. They were elucidated as 2-hydroxy-4-[[2-hydroxy-4-[(2,4-dimethoxy-6-methylbenzoyl) oxy]6-methylbenzoyl]-oxy]-6-methylbenzoic acid N-alanine amide for amidepsine A, 2-hydroxy-4-[[2-hydroxy-4-[(2-hydroxy-4-methoxy-6-methylbenzoyl) oxy]6-methylbenzoyl]oxy]-6-methylbenzoic acid N-alanine amide for amidepsine B and 2-hydroxy-4-[[2-hydroxy-4-[(2-hydroxy-4-methoxy-6-methylbenzoyl) oxy]6-methylbenzoyl]oxy]-6-methylbenzoic acid N-valine amide for amidepsine C. Amidepsine D was identified with 2,4-di-O-methylgryphoric acid.

Humicola sp. FO-2942, a soil isolate, was found to produce a series of new inhibitors of diacylglycerol acyltransferase (DGAT). Three active compounds, designated amidepsines A, B and C, were isolated from the fermentation broth of the producing strain by solvent extraction, silica gel column chromatography, ODS column chromatography and HPLC. Amidepsines inhibit DGAT activity with IC50 values of 10.2 approximately 51.6 microM in an enzyme assay system using rat liver microsomes. Amidepsines also showed specific inhibition of triacylglycerol formation in intact Raji cells, indicating that they inhibit DGAT activity in living cells.

The total synthesis of (-)-amidepsine B, a potent diacylglycerol acyltransferase inhibitor, has been achieved. This synthetic study resulted in the revision of the previously assigned stereostructure of the natural amidepsine B and determined the absolute configuration.