Assimilation of Cholesterol by Monascus purpureus.

Theresa P T Nguyen,Catherine E Seeger,Margaret A Garrahan,Christian Wong,Sabrina A Nance

doi:10.3390/jof6040352

Theresa P T Nguyen, Catherine E Seeger + Show 3 more

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https://doi.org/10.3390/jof6040352

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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.

Highlights

Monascus purpureus is a filamentous fungus that produces a variety of secondary metabolites, including pigments, lipids, and monacolins
We developed new sample collection methods and used gas chromatography to quantify the levels of cholesterol remaining after incubation with M. purpureus CBS 109.07
After 36 h, M. purpureus removed 18.69 μg/mL or 18.78% of the cholesterol in spent media, which is a significant decrease from the initial concentration (Table 1, Figure 1, p < 0.01)

Summary

Introduction

Monascus purpureus is a filamentous fungus that produces a variety of secondary metabolites, including pigments, lipids, and monacolins. M. purpureus is most widely known for the fermentation of white rice to produce a deep red rice known as angkak or beni koji [1,2,3]. M. purpureus fermented rice is used in food preparation for flavoring, coloring, and preservation, and is consumed in traditional Chinese medicine to improve ailments of circulation and heart health [2,4,5,6,7]. Modern research explored the health claims, and found a plausible cause: M. purpureus can synthesize monacolins, naturally occurring compounds capable of decreasing cholesterol levels by inhibiting HMG-CoA reductase, the rate-limiting step in cholesterol biosynthesis [7,8]. As lyophilized red yeast rice (RYR) supplements emerged as a naturopathic alternative in the U.S, the Food and Drug Administration (FDA) restricted the

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