New bioactive pigments and metabolites variation in a liquid culture domesticated Monascus purpureus

Monascus purpureus is an extensively researched traditional food fungus which is mainly cultured on solid bases such as rice. To explore the potential of liquid fermentation of the fungus, we conducted liquid fermentation domestication through continuous subcultivation in liquid medium. Metabolites comparison between the original and the domesticated strains revealed that liquid culture domestication can greatly increase the production of water soluble pigments through hydroxylation. Three water-soluble hydroxylated pigments were isolated from the fungus. The compound 1 was identified as the known bioactive compound 7-(2-hydroxyethyl)-monascorubramine. The compounds 2 and 3 were identified with HRMS, CD, ECD, 1D and 2D NMR as monascuskaolin C (2) and D (3) respectively. Bioactivity tests showed that 2 and 3, especially 3, strongly reduced the transcription levels of pro-inflammatory cytokines in RAW264.7 cells, and strongly increased 293T cell viability. The increased functional water-soluble pigments and the new bioactive compounds in the domesticated strain suggests that liquid culture domestication can possibly increase the utilization potential of the fungus in health care food and beverage production.