Abstract:
Monascus-fermented rice, which is known as red mold rice has been used as Chinese herbal
medicine for treating hyperlipidemia for many years. Monacolin K and citrinin, showing
adipogenesis inhibitory activity, are water-insoluble secondary metabolites of Monascus spp.
However, less attention has been paid regarding water-soluble adipogenesis inhibitors from
Monascus spp. Thus, the current study was conducted to screen Monascus fungi for their watersoluble adipogenesis inhibitors. A total of 25 strains of Monascus fungi were used in screening
for water-soluble adipogenesis inhibitors. Monascus strains were maintained on potato
dextrose agar (PDA) medium at 30 °C for 7 and 10 days, and the spores of these strains were
collected and stored separately at 4 °C until further use. Each strain was cultivated on steamed
rice (RMR) and barley (RMB) separately at 30 °C and 35 °C for 7 and 14 days, and their
respective water extracts were prepared. Cell viability was determined by MTT assay, and the
accumulation of triglycerides in adipocytes was examined by oil red O staining using mouse
3T3-L1 cells. Results of MTT assay confirmed that all tested samples do not affect the viability
of 3T3-L1 cells, and this confirmed that the reduction of lipid accumulation is not due to any
cell death, but due to a secondary metabolite/s produced during the production of RMR or
RMB. Moreover, TLC results revealed that water-soluble fractions of both RMR and RMB are
free from lovastatin and citrinin. According to the obtained results, it can be concluded that the
water extracts of RMR showed a higher adipogenesis inhibitory activity than that of RMB.
Further, since it showed a significantly low lipid accumulation percentage (61.86% ± 3.6) M.
pilosus NBRC4507 grown at 30 °C for 14 days was selected as the best strain and the
cultivation condition respectively, in production of RMR with higher adipogenesis inhibitory
activity.
