Naturally Occurring Perylenequinones

Determination of a transcriptional regulator-like gene involved in biosynthesis of elsinochrome phytotoxin by the citrus scab fungus, Elsinoë fawcettii

“…Agar plugs bearing fungal mycelium were cut with a 6 mm sterilized cork borer, and soaked in 5 M KOH in the dark for at least 12 h. The A 480 of the soaking solution was measured using a model Genesys 5 spectrophotometer (Spectronic Instruments). Since elsinochromes and cercosporin have a similar structure and molecular mass (Weiss et al, 1987), elsinochromes were quantified using a molar absorption coefficient of 23 300 l mol 21 cm 21 (Jenns et al, 1989) and expressed as nmoles per plug. For TLC analysis, elsinochromes were extracted twice from dried agar medium with fungal mycelia in acetone for 16 h, condensed and separated on a TLC plate coated with 60 F254 fluorescent silica gel (5620 cm, Selecto Scientific) as previously described (Liao & Chung, 2008a, b).…”

“…Many Elsinoë species produce red or orange pigments, collectively termed elsinochromes, in culture (Weiss et al, 1987). Elsinochromes consist of at least four interconvertible tautomers (A, B, C and D) that have a core phenolic quinone to which various side chains are attached, and they have remarkable structural similarity to many perylenequinone phytotoxins, such as cercosporin, stemphyltoxin, hypomycin, hypocrellin and phleichrome of fungal origin (Weiss et al, 1987;Daub et al, 2005).…”

“…Elsinochromes consist of at least four interconvertible tautomers (A, B, C and D) that have a core phenolic quinone to which various side chains are attached, and they have remarkable structural similarity to many perylenequinone phytotoxins, such as cercosporin, stemphyltoxin, hypomycin, hypocrellin and phleichrome of fungal origin (Weiss et al, 1987;Daub et al, 2005). Elsinochrome A is readily converted to elsinochrome B or elsinochrome C in the presence of chromium trioxide (Lousberg et al, 1969); elsinochrome D, containing a methylenedioxy ring, is derived from elsinochrome C (Shirasugi & Misaki, 1992).…”

Enhancement of a pentacyclic tyrosine kinase inhibitor production in Cladosporium cf. cladosporioides by Cladosporol

“…An intramolecular phenol oxidation results in the formation of polyaromatic metabolites. One of the simplest natural compounds, the 4,9−dihydroxyperylene−3,10−quinone, shows a coupling between C1 and C5′ (for enumeration, see skeleton of 3 Scheme 1), and is considered the parent compound of several bioactive-extended quinone pigments, like cercosporins, phleichromes, elsinochromes, calphostins, and cladochromes (Weiss et al 1987;Arnone et al 1989). The biological activity of the aforementioned compounds is mainly due to their photodynamic properties, which in the cladochromes and calphostins have been also related to their capability to inhibit the protein kinase C isoenzyme family (Tamaoki and Nakano 1990).…”

Cellular toxicity of elsinochrome phytotoxins produced by the pathogenic fungus, Elsinoë fawcettii causing citrus scab

“…Many of the perylenequinone pigments produced by fungi have been shown to be toxic to mice, bacteria, and many fungi, to be cytotoxic to animal tumors, to be potent antiviral agents, and to inactivate protein kinase C (Tamaoki & Nakano, 1990;Hudson & Towers, 1991;Diwu, 1995;Hudson et al ., 1997). (a) Structure of elsinochromes with various side-groups (R) (redrawn based on the work of Weiss et al, 1987 Except for cercosporin produced by many members of the fungal genus Cercospora (Callahan et al ., 1999;Choquer et al ., 2005Choquer et al ., , 2007Chen et al ., 2007;Dekkers et al ., 2007), none of the perylenequinones of fungal origin have been demonstrated to act as a crucial factor in plant diseases caused by the producing pathogen.…”