Terpendoles, Novel ACAT Inhibitors Produced by Albophoma yamanashiensis. II. Structure Elucidation of Terpendoles A, B, C and D.

Structures of terpendoles A, B, C and D, novel acyl-CoA: cholesterol acyltransferase (ACAT) inhibitors, were determined by spectroscopic studies.All terpendoles consist of diterpene and indole moieties in common.Terpendoles A, C and D possess an additional isoprenyl unit via oxygen atom(s) of their diterpene moieties.Therelative stereochemistries of terpendoles C and D were confirmed by NOEexperiments and X-ray crystallographic analysis.Terpendoles produced by Albophomayamanashiensis showed potent inhibitory activity against acyl-CoA:cholesterol acyltransferase (ACAT).Two known related compounds, paspaline1} and emindole SB2'3), were also isolated from the culture broth of the producer.The fermentation, isolation, and biological properties of terpendoles have been described in the preceeding paper4).Wewill report herein the structure elucidation ofterpendoles A, B, C and D. Results Physico-chemical Properties of TerpendolesA,B,CandD Physico-chemical properties of terpendoles A, B, C and D are summarized in Table 1.The molecular formulas were determined to be C32H41NO6 for A, 5 C27H35NO3 for B, C32H41NO5 for C and C32H43NO4for D by high resolution electron impact mass spectra (HREI-MS)and fast atom bombardment mass spectra (FAB-MS).Terpendoles showed the same absorption