Identification of new pigments produced by the fermented rice of the fungus Monascus pilosus and their anti-inflammatory activity

Abstract

Red yeast rice was used over than thousands of years, containing abundant secondary metabolites with different bioactivities. Nowadays, the investigation of Monascus spp. was changed from anti-cholesterol monacolin analogues to Monascus pigments. Monascus pilosus BCRC38072 is a citrinin-free red yeast rice from yellow mutant of mycelia, which was already sequenced and assembled. The EtOAc-soluble fraction of the 95 % EtOH extract of this strain has resulted in the isolation of three new azaphilone derivatives with reddish color, named monapilonitrile (1), monapilosine (2) and N-ethanolic monapilosine (3), along with seven known compounds. In addition, we provide complete data of monapilosine (2) and elucidated carefully to revise the structure of rubropunctamine into 2′, which was isolated from Monascus pilosus and elucidated only by UV, IR, and 1D NMR spectrum. The effects of the isolates on the inhibition of NO and production in lipopolysaccharide-activated RAW 264.7 murine macrophages were evaluated. Of the isolates, 1 and 2 exhibited potent anti-NO production activity, with IC50 values of 2.6 ± 0.8 and 12.5 ± 2.2 μM, respectively, compared to that of quercetin, an iNOS inhibitor with an IC50 value of 34.6 ± 1.4 μM. Compound 3 also showed moderate inhibition of NO production, with an IC50 value ranging from 27.5 ± 1.7 μM.