Isolation, structural elucidation and synthesis of a novel antioxidative pseudo-di-peptide, hanasanagin, and its biogenetic precursor from the Isaria japonica mushroom.

Abstract The entomogenous ‘Hanasanagitake’ mushroom, Isaria japonica , is used as a folk medicine and as a traditional health food choice in Japan. A search for naturally occurring antioxidative compounds from the mushroom led to the isolation of a novel pseudo-di-peptide, named Hanasanagin, and a possible biogenetic precursor. The structures of the pseudo-di-peptides were determined as ( R )-3,4-diguanidinobutanoyl-( S )-DOPA and ( R )-3,4-diguanidinobutanoyl-( S )-tyrosine by spectral analysis, chemical synthesis and enzymatic conversion.