Quantitative analysis and stability test of the orange pigments from the Monascus Kaoliang KB9-fermented Rice

Name: Pacharaphan Songjanthuek

LCSH: Kasetsart University -- Theses. M.S. (Chemistry) 2021

Classification :.LCCS: QK623.M63

LCSH: Kasetsart University. -- Department of Chemistry -- Theses

LCSH: Monascus

LCSH: Pigments

LCSH: Bioactive compounds

LCSH: Biosynthesis

Abstract: Two orange pigments, rubropunctatin (1) and monascorubrin (2), as well as two yellow pigments, monascin (3) and ankaflavin (4), were isolated from rice fermented with Monascus kaoliang KB9 (MKR), also known as red yeast rice. This is the first time that rubropunctatin and monascorubrin were first isolated and identified from M. kaoliang KB9. Both orange pigments have a wide range of biological activities especially anticancer activity and appeared to be the major constituents of this fermented rice. Quantitative analysis and stability tests of both orange pigments, therefore, are important for developing this red yeast rice as a highquality food supplement. In this work, quantitative analysis of both orange pigments was performed by using quantitative 1H NMR (qHNMR) method due to its fast sample preparation and data acquisition. Stability of the dichloromethane crude extract (CE), MKR powder (RP) and encapsulated form of the MKR crude extract using spray dry technique (SPD) were also tested and the result showed that the amounts of orange pigments quantified by qHNMR technique did not alter significantly during 0-50 days at 30 °C. However, only qHNMR technique could not be used to quantifying each orange pigment, as the 1H NMR signals of both orange pigments were mostly identical. 13C NMR experiments were then utilized in this study to quantify the amounts each orange pigment in the dichloromethane crude extract from M. kaoliang KB9-fermented rice. The amounts of orange pigments, rubropunctatin and monascorubrin, obtained by combination of qHNMR and 13C NMR techniques were 0.2069 ± 0.0130 and 0.3656 ± 0.0167 mg/mg of the crude extract, respectively. These values were similar to those obtained by HPLC, 0.2340 ± 0.0015 mg/mg of crude extract for rubropunctatin and 0.4049 ± 0.0029 mg/mg of crude extract for monascorubrin. The crude extracts of M. kaoliang KB9-fermented rice were also initially screened for their HMG-CoA reductase and acetylcholinesterase inhibitory activities by using colorimetric method. Unfortunately, the UV-Vis absorption measured in the assays were interfered by the high absorption of orange pigments in the crude extracts therefore the results obtained were not valid. Nevertheless, our findings in this work provide information on stability and chemical constituents of the M. kaoliang KB9-fermented rice for future product development. The combination of qHNMR and 13C NMR experiments could also provide an alternative method for quantifying a mixture of bioactive compounds when their 1H NMR signals are indistinguishable.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Pakorn Wattana-Amorn

Role: Thesis Advisor

Name: Wanchai Pluempanupat

Role: Thesis CO-Advisor

Name: Tharinee Saleepochn

Role: Thesis CO-Advisor

Created: 2021

Modified: 2025-07-17

Issued: 2025-07-17

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2564/pacharaphan-son-all.pdf

CallNumber: QK623.M63 .P33

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Chemistry

Grantor: Kasetsart University

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