Secondary Metabolites Isolated From the Fungus Monascus Kaoliang-Fermented Rice

Abstract

A chemical study of the EtOAc-soluble ethanolic extract of Monascus kaoliang BCRC 31506 (Eurotiaceae) fermented rice led to the isolation of a new furan-3-one derivative along with 9 known compounds, monascin (2), ankaflavin (3), N-trans-feruloyltyramine (4), vanillic acid (5), 4-acetonyl-3,5-dimethoxy-p-quinol (6), (+)-β-eudesmol (7), trans-phytol (8), aesculetin dimethyl ether (9) and (-)-matairesinol (10). Structure 1 is proposed for monascuskaoliaone on the basis of spectroscopic evidence (NMR, UV, IR, and HRMS). None of the compounds exhibited significant scavenging activity toward DPPH radical in bioautography or spectroscopic assays.

Phylogenetic and chemical diversity of fungal endophytes isolated fromSilybum marianum(L) Gaertn. (milk thistle)

“…The 1 H NMR spectrum exhibited signals for an olefinic proton, an isolated pair of mutually coupled methylene units, two methyl groups (singlet and triplet), and a cluster of aliphatic protons (Figure S4). A similar set of signals were also observed for a known natural product, monascuskaoliaone ( 5 ; molecular formula C 17 H 30 O 3 ) that was also encountered during the course of our studies (Cheng et al 2010). A comparison with the available literature data for 5 suggested an identical five-membered furan-derived ring system and a similar side chain at C-5 in the new metabolite 4 .…”

“…& Schwein.) DitmarG340LeafVerrucarin A,Verrucarin J,Verrucarin L acetate, andMyrochromanolNMR, UV, and MS(Tamm et al 1972; Namikoshi et al 2000; Liu et al 2006) Chaetomidium arxii BennyG341LeafDihydro-5-(hydroxyphenylmethyl)-2(3H)-furanoneNMR, UV, and MS(Hargreaves et al 2002a) Daldinia loculata (Lév) Sacc.G343 1,8-dimethoxynaphthaleneNMR, UV, and MS(Yang et al 2008) Fusarium sp.G344G345LeafLeafBeauvericinNMR, UV, and MS (Zhan et al 2007) Microascus nidicola (Microascales)G377LeafMonascuskaoliaone,Nigragillin,Asperazine,Fonsecin,Fonsecin B, Epi -pestalamide A (6)Campyrone A,Campyrone C,Carbonarone A, andMonascuskaoliaone B (4)NMR, UV, and MS(Caesar et al 1969; Isogai et al 1975; Varoglu et al 1997; Zhang et al 2007; Ding et al 2008; Cheng et al 2010; Shaaban et al 2012; Mouafo Talontsi et al 2013) Alternaria sp.G378LeafAlternariol,9-O-methylalternariol, andAltenueneNMR, UV, and MS(Koch et al 2005; Altemöller et al 2006; de Souza et al 2013) Biscogniauxia mediterranea (De Not.) KuntzeG410Leaf(3R)-5-methylmellein,(3R,4R)- cis -4-hydroxy-5-methylmellein,Acuminatopyrone,Chlamydospordiol,Chlamydosporol (major:minor mixture of diastereomers), andCyclo-[L-Phe-L-Leu-L-Leu-L-Leu-L-Ile],Biscognin A (1)Biscognin B (3)NMR, UV, optical rotation, and MS(Okuno et al 1986; Solfrizzo et al 1994; Visconti et al 1994; Li et al 2004) Biscogniauxia atropunctata (Schwein.)…”

“…Due to extensive overlap in the 1 H NMR signals for the aliphatic chain of 4 , the only useful Δ δ S-R value (+0.12) for H 3 -17 was employed for the above assignment (Figure S5). Monascuskaoliaone ( 5 ) was isolated originally from Monascus kaoliang as a racemic mixture (Cheng et al 2010). However, optically active samples for 4 and 5 were obtained from the extract of Microascus nidicola (G377).…”

Side-chain Modifications of Highly Functionalized 3(2H)-Furanones

“…As a prominent structural feature, 3(2 H )-furanone seems to be relevant in many classes of biologically active natural products, such as the examples collected in Figure 1 [ 1 , 2 , 3 , 4 ]. Sesquiterpene lactones encompass a large class of natural products showing a large diversity of molecular structures and a variety of biological activities.…”

Deep eutectic solvents as sustainable media for multicomponent sulfonylation: an efficient strategy to synthesize (hetero)aryl sulfones

“…[30][31][32][33][34][35][36] DABCO•(SO 2 ) 2 (DABSO) is often used as a convenient sulfur dioxide surrogate to access a wide range of sulfonyl-containing products (Scheme 1a). [37][38][39] Inorganic sulfur dioxide surrogates such as K 2 S 2 O 5 and Na 2 S 2 O 5 have also been used (Scheme 1a). [40][41][42][43][44][45][46][47][48][49] Although significant progress has been made in sulfone synthesis, some problems still need to be solved, such as the use of specialized and expensive ligands, transition-metal catalysts with high loadings, volatile and harmful solvents, stoichiometric phasetransfer additives and air-sensitive reagents, which are contrary to the concepts of green chemistry.…”