{{Chembox | ImageFile =Variegatic acid.svg | ImageSize = 200px | ImageAlt = | ImageFile1 = | ImageSize1 = 300 | ImageAlt1 = Space-filling model | Name=Variegatic acid | PIN=(''E'')-(3,4-Dihydroxyphenyl)[4-(3,4-dihydroxyphenyl)-3-hydroxy-5-oxofuran-2(5''H'')-ylidene]acetic acid | OtherNames=3,3′,4,4′-Tetrahydroxy pulvinic acid |Section1={{Chembox Identifiers | CASNo= 20988-30-1 | CASNo_Ref = {{Cascite|correct|CAS}} | CASNo1_Ref = {{cascite|correct|CAS}} | CASNo1 = 15404-65-6 | CASNo1_Comment = (non-specific) | UNII_Ref = {{fdacite|correct|FDA}} | UNII = C7PLL5BF8H | ChemSpiderID = 74025443 | PubChem=101967051 | InChI =1S/C18H12O9/c19-9-3-1-7(5-11(9)21)13-15(23)16(27-18(13)26)14(17(24)25)8-2-4-10(20)12(22)6-8/h1-6,19-23H,(H,24,25)/b16-14+ | InChIKey =MRRYHTCWZKZVIH-JQIJEIRASA-N | SMILES =O=C(C(C1=CC(O)=C(O)C=C1)=C/2O)OC2=C(C(O)=O)/C3=CC(O)=C(O)C=C3 }} |Section2={{Chembox Properties | C=18 | H=12 | O=9 | MolarMass= | Appearance= | Density= | MeltingPt= | BoilingPt= | Solubility= }} |Section3={{Chembox Hazards | MainHazards= | FlashPt= | AutoignitionPt = }} }}
'''Variegatic acid''' (3,3',4,4'-tetrahydroxypulvinic acid) is an orange pigment found in some mushrooms. It is responsible for the bluing reaction seen in many bolete mushrooms when they are injured. When mushroom tissue containing variegatic acid is exposed to air, the chemical is enzymatically oxidized to blue-colored quinone methide anions<ref name="Velíšek 2011"/> It is derived from xerocomic acid, which is preceded by atromentic acid and atromentin, but the full biosynthetic pathway is unknown. In its oxidized form (due to the production of a second lactone ring) is variegatorubin, similar to xerocomorubin.
It was first isolated from ''Suillus variegatus''.<ref name="Edwards 1967"/> It has strong antioxidant properties,<ref name="Kasuga 1995"/><ref name="Vidovic 2010"/> and a nonspecific inhibitory effect on cytochrome P450 enzymes.<ref name="Huang 2009"/> A total synthesis was reported in 2001 that uses a Suzuki cross coupling reaction.<ref name="Ahmed 2005"/> It was found antibiotically inactive against an array of bacteria and fungi using the disk diffusion assay at 50 μg.<ref name="Tauber"/> However, at similar concentrations it was found to inhibit swarming and (probably consequently) biofilm formation of Bacillus subtilis. In vitro data supports that this pigment is an Fe<sup>3+-</sup>reducant in Fenton chemistry during the initial attack of dead plant matter as part of the brown-rot saprobic lifestyle.<ref name="Eastwood"/>
==Derivatives== Variegatic acid methyl ester, 3-''O''-methylvariegatic acid methyl ester, and 3,3',4,4'-tetra-''O''-methylvariegatic acid methyl ester are red-orange pigments found in ''Boletales''.<ref name="Gruber"/><ref name="Gill"/> <gallery> Variegatic acid methyl ester.svg|Variegatic acid methyl ester 3-O-methyl variegatic acid methyl ester.svg|3-''O''-Methylvariegatic acid methyl ester 3,3',4,4'-Tetra-O-methyl variegatic acid methyl ester.svg|3,3',4,4'-Tetra-''O''-methyl variegatic acid methyl ester </gallery>
==See also== * Pulvinic acid * Pulvinone * Vulpinic acid
==References== {{Reflist|refs=
<ref name="Ahmed 2005">{{cite journal |vauthors=Ahmed Z, Langer P |title=Synthesis of natural pulvinic acids based on a '[3+2] cyclization-Suzuki cross-coupling' strategy |journal=Tetrahedron |year=2005 |volume=61 |issue=8 |pages=2055–63 |doi=10.1016/j.tet.2004.12.048}}</ref>
<ref name="Edwards 1967">{{cite journal |vauthors=Edwards RL, Elsworthy GC |title=Variegatic acid, a new tetronic acid responsible for the blueing reaction in the fungus ''Suillus (Boletus) variegatus'' (Swartz ex Fr.) |journal=Chemical Communications |year=1967 |issue=8 |pages=373b–374 |doi=10.1039/C1967000373B}}</ref>
<ref name="Huang 2009">{{cite journal |vauthors=Huang YT, Onose J, Abe N, Yoshikawa K |title=''In vitro'' inhibitory effects of pulvinic acid derivatives isolated from Chinese edible mushrooms, ''Boletus calopus'' and ''Suillus bovinus'', on cytochrome P450 activity |journal=Bioscience, Biotechnology, and Biochemistry |year=2009 |volume=73 |issue=4 |pages=855–60 |pmid=19352038 |doi=10.1271/bbb.80759|s2cid=39654350 |doi-access=free }} {{open access}}</ref>
<ref name="Kasuga 1995">{{cite journal |vauthors=Kasuga A, Aoyagi Y, Sugahara T |title=Antioxidant activity of fungus ''Suillus bovinus'' (L: Fr.) O. Kuntze |journal=Journal of Food Science |year=1995 |volume=60 |issue=5 |pages=1113–85 |doi=10.1111/j.1365-2621.1995.tb06304.x}}</ref>
<ref name="Velíšek 2011">{{cite journal |vauthors=Velíšek J, Cejpek K |title=Pigments of higher fungi: A review |journal= Czech Journal of Food Sciences|year=2011 |volume=29 |issue=2 |pages=87–102 |url=http://www.agriculturejournals.cz/publicFiles/37205.pdf |doi=10.17221/524/2010-CJFS |doi-access=free }}</ref>
<ref name="Vidovic 2010">{{cite journal |vauthors=Vidovic SS, Mujic IO, Zekovic ZP, Lepojevic ZD, Tumbas VT, Mujic AI |title=Antioxidant properties of selected ''Boletus'' mushrooms |journal=Food Biophysics |year=2010 |volume=5 |issue=1 |pages=49–58 |doi=10.1007/s11483-009-9143-6|s2cid=84061662 }}</ref>
<ref name="Tauber">Tauber, J. P., Schroeckh, V., Shelest, E., Brakhage, A. A. and Hoffmeister, D. (2016), Bacteria induce pigment formation in the basidiomycete Serpula lacrymans. Environ Microbiol, 18: 5218–5227. doi:10.1111/1462-2920.13558</ref>
<ref name="Eastwood">Eastwood et al. (2011) The Plant Cell Wall- Decomposing Machinery Underlies the Functional Diversity of Forest Fungi. Science.</ref> <ref name="Gill">Gill, M., and Steglich, W. (1987) Pigments of fungi (Macromycetes). Prog Chem Org Nat Prod 51: 1–317.</ref> <ref name="Gruber">{{cite web |last1=Gruber |first1=Gertraud |title=Isolierung und Strukturaufklärung von chemotaxonomisch relevanten Sekundärmetaboliten aus höheren Pilzen, insbesondere aus der Ordnung der Boletales |url=https://edoc.ub.uni-muenchen.de/783/1/Gruber_Gertraud.pdf |website=edoc.ub.uni-muenchen.de |access-date=2023-08-10 |language=de |date=2002}}</ref> }}
Category:Fungal pigments Category:Polyphenols Category:Furanones Category:Catechols Category:Carboxylic acids