Isolation and structural characterization of two new metabolites from monascus

Area of Science:

• Natural Product Chemistry
• Mycology
• Food Science

Background:

• Monascus species are known producers of bioactive pigments.
• Red Monascus Pigment, a food additive, contains various fungal metabolites.
• Existing Monascus pigments like monascorubrin and rubropunctatin have a characteristic lactone ring structure.

Purpose of the Study:

• To isolate and characterize novel metabolites from Monascus ruber.
• To investigate the structural differences of new compounds compared to known Monascus pigments.
• To explore the properties of these newly identified metabolites.

Main Methods:

• Isolation using Thin-Layer Chromatography (TLC) and High-Performance Liquid Chromatography (HPLC).
• Structural elucidation via UV, IR, Nuclear Magnetic Resonance (NMR) spectroscopy, and mass spectrometry.
• High-resolution mass spectrometry for determining molecular formulas.

Main Results:

• Two new pale yellow metabolites, monarubrin and rubropunctin, were isolated.
• These compounds share similarities with monascorubrin and rubropunctatin but lack a gamma-lactone ring.
• Molecular formulas C(20)H(26)O(4) and C(22)H(30)O(4) were determined.
• The new metabolites exhibit strong blue fluorescence at 340 nm.

Conclusions:

• Monarubrin and rubropunctin represent novel natural products derived from Monascus ruber.
• The absence of a lactone ring is a key structural distinction from related pigments.
• The fluorescent property of these new compounds warrants further investigation for potential applications.