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Abstract

As the main nitrogen source in Malassezia (M.) furfur, tryptophan induces the formation of fluorochromes and pigments, which makes the yeast less sensitive towards UV light. For the investigation of the fluorochromes, M. furfur (CBS1878) was incubated at 32 degrees C for 14 days on a pigment-inducing medium, and the agar extract was purified by column chromatography, preparative TLC and HPLC. The structures of the pure metabolites were determined by mass spectrometry and NMR spectroscopy. A pale yellow compound eluting from the column with 22% acetonitrile was found to exhibit a strong green-yellow fluorescence. The fluorochrome is a new bisindolyl compound (C(20)H(12)N(2)O(3), MW 328.33) named pityrialactone because of its furan-2,3-dione structure. The UV protective properties (lambda(max) 352, 292, 276, 224 nm) of this metabolite were confirmed in a yeast model. As shown by the fluorescence spectrum, pityrialactone appears to be responsible for the green-yellow fluorescence of pityriasis versicolor lesions under Wood light. Pityrialactone is accompanied by the isomeric bisindolylmaleic anhydride (pityriaanhydride), which has not yet been described as a natural product but is a known intermediate in the total synthesis of bisindolylmaleimides.

Pigment Production on L-Tryptophan Medium by Cryptococcus gattii and Cryptococcus neoformans

“…The molecular mass of the three pitriarubin compounds ranged from 524.5 to 526.6. Fluorescent compounds including pityriacitrin and pityrialactone were also produced from tryptophan by Malassezia furfur [49], [50]. These results suggest that the currently described pathways of tryptophan metabolism are incomplete and that there are additional pathways and metabolites that may play important roles in yeast physiology.…”

Malassezin, a Novel Agonist of the Aryl Hydrocarbon Receptor from the Yeast Malassezia furfur, Induces Apoptosis in Primary Human Melanocytes

“…this might contribute to the green fluorescent layer present in the skin affections. [6] Structurally speaking, the orange-to-red bis(indolyl)spiran alkaloids pityriarubin A, B and C resemble bisindolylmaleimides such as arcyriarubin A, a potent but nonspecific inhibitor of protein kinase C. [7] The pityriarubins may act as anti-inflammatory agents, thus explaining the modest levels of inflammation observed in affected skin areas. This thus suggests a role for these compounds in the pathogenesis of pityriasis versicolor.…”

Pityriarubins, Biologically Active Bis(indolyl)spirans from Cultures of the Lipophilic Yeast Malassezia furfur

“…Based on its spectroscopic data and direct comparison with an authentic sample, 1 was identified as 3,4‐bis(indol‐3‐yl)maleic anhydride, an intermediate in the synthesis of arcyriarubin A,6 but previously unknown as a natural product. The unusual bis(indolyl)oxobutenolide structure of 2 was described by us recently 7…”