Putative structure and characteristics of a red water-soluble pigment secreted byPenicillium marneffei

Abstract

The dimorphic fungus, Penicillium marneffei, produces and secretes a brick red pigment, during growth at temperatures below 30 degrees C. It generally diffuses into commonly used media like Sabouraud dextrose agar and malt extract agar. The pigment was purified by reverse-phase liquid chromatography and subjected to structural determination by elemental and spectral analysis using atomic absorption (AAS), ultra violet and visible (UV-VIS), fluorescence, infra red (IR), nuclear magnetic resonance (NMR) and tandem mass spectrometry (MS-MS). The pigment showed a buffering ability in aqueous solutions, maintaining an alkaline pH of 8.0. It behaved as a colorimetric pH indicator over a wide acidic and alkaline pH range, with discoloration occurring ostensibly through hydrolysis of key chemical groups at extremely acidic pH ( approximately 2.0). The pigment was found to have some structural resemblance with the copper-colored pigment (herquinone) produced by Penicillium herquei as both pigments contain the phenalene carbon framework. The notable differences between herquinone and the pigment produced by P. marneffei are (i) the latter's apparent dimerization through a sulphur-sulphur (disulfide) bond and (ii) the presence of 1,1,3,3-tetramethyl-2,3-dihydropyrrole moiety in the latter instead of 2,3,3-trimethyl-2,3-dihydrofuran moiety found in the former. The delineation of the structure of the pigment produced by Penicillium marneffei may help in understanding certain aspects of the biology of this pathogenic fungus.

The biosynthetic pathway for a thousand-year-old natural food colorant and citrinin in Penicillium marneffei

“…This is in line with experiments that showed that amino acids can be conjugated to monascorubrin and rubropunctatin under specific conditions without enzymatic catalysis 20 . The conclusions drawn on the identity of the red pigment in the present study is in contrast to that of a previous article by Bhardwaj et al , which claimed that the red pigment of P. marneffei structually resembled herquinone and appeared as a dimer through disulfide bond 21 . In the present study, such a compound was not observed in wild type P. marneffei and the knockdown mutants.…”

Fungal Pigments and Their Prospects in Different Industries

“…Studies report the production of a herqueinone-like pigment from Talaromyces marneffei (formerly known as Penicillium marneffei), Monascus-like azaphilone pigments (N-glutarylmonascorubramine and N-glutarylrubropunctamine) from Talaromyces purpureogenus (formerly known as Penicillium purpureogenum), industrially important red pigments (mitorubrin, monascorubrin, PP-R, glauconic acid, purpuride, and ZG-1494α) from Talaromyces atroroseus, trihydroxyanthraquinones (emodin, erythroglaucin, and catenarin) from Talaromyces stipitatus, and a xanthone dimer (talaroxanthone) from Talaromyces sp. (Figure 3b) [100,101,103,107,109]. An uncharacterized red pigment was discovered from Talaromyces siamensis under submerged fermentation [71].…”

Extraction and optimisation of red pigment production as secondary metabolites from Talaromyces verruculosus and its potential use in textile industries

“…Extracted pigment samples were purified and run in Ultimate TM 3000 HPLC, following the method mentioned in a similar research article (Bhardwaj et al 2007). As Liquid chromatography-mass spectrometry (LC-MS) method is required to have an idea about the chemical structure and MS attachment was not available; the obtained LC curve was compared with some similar coloured natural pigment HPLC analysis.…”