Bioactive components of secondary metabolites from Monascus ruber Mr-1

Abstract:

[Background] Monascus is an important food and drug homologous fungus, whose secondary metabolites have many physiological functions. However, the bioactive components in Monascus are rarely reported. It is of great significance to trace the active substances in Monascus fermentation broth for understanding the material basis of Monascus efficacy. [Objective] To study the bioactive components and biological functions of secondary metabolites of Monascus ruber Mr-1. [Methods] The active components were separated and purified by silica gel column and Sephadex LH-20. The structures of the compounds were analyzed by NMR and HR-ESI-MS. The antioxidant, antibacterial and enzyme activities of the identified compounds were determined in vitro. [Results] Four active compounds were isolated from the secondary metabolites of Monascus ruber Mr-1, which were identified as three flavonoids, luteolin (1), hesperetin (2), glycoitin (3), and one terpenoid, ursolic acid (4). Compounds 1, 2 and 4 were isolated from Monascus for the first time. In the antioxidant test, compound 1 had strong scavenging ability to ABTS+, DPPH and OH?, with IC50 of 13.36, 8.74 and 32.75 μg/ml, respectively; in the antibacterial test, compound 4 showed moderate antibacterial activity against Staphylococcus aureus and Listeria monocytogenes, and the diameter of inhibition zone was 13.4 and 11.9 mm, respectively; in the α-glucosidase inhibitory activity test, compound 4 showed a strong inhibitory activity, with IC50 of 21.34 μg/ml. [Conclusion] Monascus ruber Mr-1 is a valuable microbial germplasm resource. Its metabolites contain diverse bioactive components and it has the potential to be developed into functional food materials.

Key words:Monascus, antioxidant, antibacterial, α-glucosidase