Page 49 - journal-6-2-S-Full

Ù¯ «“√ “√°“√·æ∑¬å·ºπ‰∑¬·≈–°“√·æ∑¬å∑“߇≈◊Õ° ªï∑’Ë ˆ©∫—∫∑’Ë Ú æƒ…¿“§¡- ‘ßÀ“§¡ (©∫—∫‡ √‘¡) ÚııÒ

OR-8

Production and optimization of hypocholesterolemic substance

biosynthesis by Monascus purpureus in Thai rice

1 1 1 2
Jantana Keereetaweep , Surapol Natakankitkul , Nisit Kittipongpattana , Renu Pinthong
1
Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai, Thailand.
2
Department of Food Science and Technology, Faculty of Agro-Industry, Chiang Mai University, Chiang Mai, Thailand.

Rationale: Red yeast rice, usually obtained by cultivation of Monascus species on the rice grains, has been used
in Asian nations for several hundreds years and there are many reports on the hypocholesterolemic effect of the
active constituent known as monacolin K. In general, monacolin K biosynthesis from Monascus species can be
influenced by various factors, such as Monascus strains, the medium composition especially by the type of carbon
and nitrogen source, which are significant for the development of the fungi. In addition, other components (e.g.,
ammonium chloride, sodium nitrate and monosodium glutamate) and environmental parameters, such as cultivation
method, agitation, temperature and moisture content also affect the production of monacolin K. Since there is no
universal and excellent method for stimulating the formation and isolation of monacolin K by Monascus species
regarding stability, an effective means to increase productivity of monacolin K and quality control are imperative
in order to develop red yeast rice as a drug or food supplement.

Objectives: To investigate the optimal conditions for the production and the analysis of hypocholesterolemic
substance biosynthesized by Monascus purpureus in Thai rice.

Methodology: Monascus purpureus BCC 6131 was grown on potato dextrose agar for 12 days, and subsequently
o
transferred to 50 g Chinart rice, which was previously autoclaved at 121 C for 15 min. The inoculated rice was
o
then incubated at 30 C for 24 days, and red yeast rice sample was collected every 3 days. The methanolic extract
was filtered through a 0.45-µm membrane before injection. The HPLC column of Waters Symmetry C18 (250 mm
x 4.6 mm i.d., 5 µm) was used. The injection volume of 20 µl sample was eluted with acetonitrile/phosphoric
o
buffer pH 2.5 (70:30) at 1.0 ml/min flow rate and column temperature was controlled at 25.0 C. The analysis time
was 15 min. Photo-diode array was set at 237 nm for detection.
Results: The optimized HPLC conditions showed monacolin K was eluted at 8.17 min. The results revealed that
o
2
the solid state cultivation of 1 cm (on PDA) of Monascus purpureus BCC 6131 on Chinart rice at 30 C could
provide monacolin K 109.86 mg/kg. In the contrast, using unpolished rice, monacolin K production was clearly
decreased more than 50%. Interestingly, when the amount of water added to rice substrate was controlled at 37.5%,
the amount of monacolin K was increased to 252.07 mg/kg. Moreover, when increased the amount of inoculum
2
size to 4 cm , the production of monacolin K was increased to 338.86 ± 7.15 mg/kg.
Conclusion: The chromatographic conditions for monacolin K analysis were successfully established, and the
observations from obtained results indicated that monacolin K production is dependent on various factors and that
an optimizing culture conditions, such as temperature and moisture content, is crucially required for high monacolin
K production.