722. The chemistry of fungi. Part XXXVII. The structure of rubropunctatin

Abstract

A new pigment, C2IH22O5, rubropunctatin has been isolated from Monascus rubropunctatus SBto. With aqueous ammonia this gives a nitrogen analogue, rubropunctatamine, C,,H2,0,N, which, on reduction with zinc and acetic acid is degraded to an 8-hydroxyisoquinoline derivative, aporubropunctatamine, C,,H2,O2N, and one mol. of carbon dioxide. From degradative studies on the parent compound and these derivatives, aporubropunctatamine is shown to have structure (XII) , whilst structures (XIXa) and (XVIII) are proposed for rubropunctatin and rubropunctatamine respectively.Exhaustive hydrogenation of rubropunctatin gives hexahydroaporubropunctatin, C2oH3003, for which structure (XXIa) is proposed.The probable biogenesis of rubropunctatin is discussed and possible structural implications for the related compound rotiorin are tentatively suggested. DURING an investigation into the metabolic products of the Monascus genus in thisDepartment, a new red pigment, rubropunctatin was isolated from the mycelium of M . rubvopunctatus %to. In a preliminary account of this work2 a close relation was pointed out between the properties of the pigments s~l e r o t i o r i n ,~~~~~,~~~ rotiorin,' monascin,8 monascorubrin? and rubropunctatin.The present paper describes the structural investigations on rubropunctatin which have been carried out during the last five years.Rubropunctatin has the molecular formula, C2lH2205, although the formula, C2,H,0,, Part XXXVI, Dean, Staunton, and Whalley,

Regulation of Growth and Pigmentation of Monascus purpureus by Carbon and Nitrogen Concentrations

“…More red pigments were produced in most media having a final pH above 6 (TABLE I). The orange pigments can be changed to red amine derivatives by reacting with ammonia water (4). Ammonium nitrate at 5 and 10 g/1 may form more ammonium ion or free amino groups intra-or intercellularly which can react with the orange pigments to form red amine derivatives.…”

Synthesis of 7‐acetyloxy‐3,7‐dimethy1‐7,8‐dihydro‐6H‐isochromene‐6,8‐dione and its analogues

“…Monascorubrin 1 [1], rubropunctatin 2 [2], (+)-sclerotiorin 3 [3], (-)-mitorubrin 4 [4] and daldinin A 5 (a mixture of four fatty acid esters) [5] are fungal metabolites produced by fungus such as Monascus purpureus Wentii, M. rubropunctatus Sâto, Penicillium sclerotiorum van Beyma, P. rubrum and Daldinia concentrica, respectively. Those compounds are called azaphilones because of the affinity for ammonia or amine, yielding vinylogous γ-pyridones [6].…”

Pigment Production from Immobilized Monascus sp. Utilizing Polymeric Resin Adsorption

“…The distribution of a substance between the mycelium and the medium has been shown to be related to its solubility (8). Thus, intracellular localization of the pigment is most likely due to its poor solubility in the acidic fermentation broth (3). This fact poses the problem of extracting the pigment from the mycelium in a commercial process.…”