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Assimilation of Cholesterol by Monascus purpureus
Theresa P T Nguyen1, Margaret A Garrahan1, Sabrina A Nance1
1Department of Chemistry & Biochemistry, Loyola University Maryland, Baltimore, MD 21210, USA.
Abstract:
Monascus purpureus, a filamentous fungus known for its fermentation of red yeast rice, produces the metabolite monacolin K used in statin drugs to inhibit cholesterol biosynthesis. In this study, we show that active cultures of M. purpureus CBS 109.07, independent of secondary metabolites, use the mechanism of cholesterol assimilation to lower cholesterol in vitro. We describe collection, extraction, and gas chromatography-flame ionized detection (GC-FID) methods to quantify the levels of cholesterol remaining after incubation of M. purpureus CBS 109.07 with exogenous cholesterol. Our findings demonstrate that active growing M. purpureus CBS 109.07 can assimilate cholesterol, removing 36.38% of cholesterol after 48 h of incubation at 37 °C. The removal of cholesterol by resting or dead M. purpureus CBS 109.07 was not significant, with cholesterol reduction ranging from 2.75-9.27% throughout a 72 h incubation. Cholesterol was also not shown to be catabolized as a carbon source. Resting cultures transferred from buffer to growth media were able to reactivate, and increases in cholesterol assimilation and growth were observed. In growing and resting phases at 24 and 72 h, the production of the mycotoxin citrinin was quantified via high-performance liquid chromatography-ultraviolet (HPLC-UV) and found to be below the limit of detection. The results indicate that M. purpureus CBS 109.07 can reduce cholesterol content in vitro and may have a potential application in probiotics.
Insights
Monascus purpureus fungus actively assimilates cholesterol for growth, lowering levels by over 36% in vitro. This cholesterol assimilation mechanism, independent of secondary metabolites, shows potential for probiotic applications.
Area of Science:
- Microbiology
- Biochemistry
- Mycology
Background:
- Monascus purpureus is known for producing monacolin K, a cholesterol-lowering metabolite.
- Red yeast rice fermentation by M. purpureus is a source of statin drugs.
- The cholesterol assimilation capabilities of M. purpureus were previously uncharacterized.
Purpose of the Study:
- To investigate the cholesterol assimilation mechanism of Monascus purpureus CBS 109.07.
- To quantify cholesterol reduction by active and inactive M. purpureus cultures in vitro.
- To assess the potential of M. purpureus as a cholesterol-lowering probiotic.
Main Methods:
- Incubation of M. purpureus CBS 109.07 with exogenous cholesterol.
- Quantification of remaining cholesterol using gas chromatography-flame ionized detection (GC-FID).
- Assessment of mycotoxin citrinin levels using high-performance liquid chromatography-ultraviolet (HPLC-UV).
Main Results:
- Active M. purpureus CBS 109.07 assimilated 36.38% of cholesterol within 48 hours at 37 °C.
- Resting or dead M. purpureus showed minimal cholesterol reduction (2.75-9.27%) over 72 hours.
- Cholesterol was not metabolized as a carbon source; resting cultures reactivated and assimilated more cholesterol upon transfer to growth media.
- Citrinin levels were below the limit of detection in both growing and resting phases.
Conclusions:
- Active M. purpureus CBS 109.07 utilizes cholesterol assimilation, not secondary metabolites, to reduce cholesterol in vitro.
- The fungus's ability to assimilate cholesterol suggests potential probiotic applications for cholesterol management.
- Further research is warranted to explore the therapeutic potential of M. purpureus in cholesterol reduction.
