[Screening DPPH radical scavengers from Monascus sp].

Area of Science:

• Microbiology
• Natural Product Chemistry
• Biochemistry

Background:

• Monascus species are utilized in traditional fermented foods like Chinese beni-coji.
• Red yeast rice (hongqu) is known for its diverse microbial communities and potential bioactive compounds.
• Understanding the antioxidant properties of metabolites from Monascus sp. is crucial for food and pharmaceutical applications.

Purpose of the Study:

• To isolate and characterize antioxidant metabolites from a Monascus sp. strain.
• To evaluate the free radical scavenging activity of these isolated compounds.
• To identify potential natural antioxidants from traditional fermented products.

Main Methods:

• Isolation of Monascus sp. from Chinese beni-coji.
• Extraction and fractionation of metabolites using various solvents and chromatographic techniques (silica gel, LH-20, MPLC, HPLC).
• Identification of compounds using Nuclear Magnetic Resonance (NMR) spectroscopy and assessment of antioxidant activity via DPPH assay.

Main Results:

• A Monascus sp. strain was successfully isolated and cultured.
• Ethyl acetate neutral extracts exhibited the highest yield and antioxidant activity.
• Fifteen free radical scavengers were identified, with two analyzed by NMR. Compound C3-1-7 was identified as a potential 3-OH-4-OCH3-benzoic acid derivative.
• The scavenging activity of 40 µmol/L B1-3 was approximately 65%, and C3-1-7 was below 56%, compared to Vitamin C (80.4%) and Vitamin E (78.4%).

Conclusions:

• Monascus sp. from Chinese beni-coji produces effective free radical scavenging metabolites.
• The neutral extract yielded the most potent antioxidants.
• Further investigation into these compounds could lead to the development of new natural antioxidants.