A Novel Nitrogen-containing Glyceride from Fungal Saprobe Tubeufia rubra Reverses MDR of Tumor Cell Lines to Doxorubicin

Abstract

A chemical investigation of secondary metabolites from the saprobic fungus Tubeufia rubra led to isolation of a novel nitrogen-containing glyceride, Rubracin A (1), and a novel eight-membered cyclic ether carboxylate methyl ester, Rubracin H (2). Together with six known compounds (3-8). The chemical structure of these new compounds were elucidated by 1D and 2D NMR and HR-ESI-MS techniques. Although, there are no observed cytotoxic effects of compound 1 against MCF-7/Dox A549/Dox, and K562/Dox cells at oncentrations below 25 g/mL, usage of compound 1 and doxorubicin revealed the MDR reversal via decreased IC50 values than that of sole doxorubicin application in the cell lines. A preliminary Western Blot assay indicated that the MDR reversal of compound 1 was due to suppression of P-glycoprotein (P-gp) expression.