Chemical constituents of red yeast rice fermented with the fungus Monascus pilosus

A chemical study on the n-BuOH-soluble fraction of the 95% EtOH extract of red yeast rice fermented with the fungus Monascus pilosus (Eurotiaceae) has resulted in the isolation of one new azaphilone derivative, designated as monapilosusazaphilone (1), together with nine known compounds, (+)-5,5'-dimethoxylariciresinol (2), (+)-lariciresinol (3), (+)-5-methoxylariciresinol (4), a mixture of 3 beta-hydroxylstigmast-5-en-7-one (5) and 3 beta-hydroxystigmasta-5,22-dien-7-one (6), 6 beta-hydroxystigmast-4-en-3-one (7), 6 beta-hydroxystigmasta-4,22-dien-3-one (8), N-cis-feruloylmethoxytyramine (9), and scopoletin (10). Their structures were elucidated by 1D and 2D-NMR spectroscopy together with HR-ESI-MS analysis, and comparison of the spectroscopic data with those reported for structurally related compounds.