Glossary – phytochemistry (under construction)

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Fagopyrine – a red fluorescent pigment with anthraquinone structure and related to hypericine

Falcarinone – a type of polyacetylene

Febrifugine – a quinazolinone alkaloid

Ferulic acid – a hydroxycinnamic acid; a derivative of the phenylpropanoid cinnamic acid

Flavanones – hydrochalcones; flavonoids isomeric with chalcones, differing from flavones by the absence of the double-bond in the 2,3-position, usually colourless or slightly yellow; examples of flavanones and 3-hydroxyflavanones (dihydroflavonols) are butin, carthamidin and isocarthamidin

Flavanolols – examples of flavanolols are silibinin, silymarin, taxifolin ((+)-dihydroquercetin), pinobanksin

Flavans – 3,4-dihydro-2-phenyl-2H-1-benzopyran; a class of flavonoids

Flavones – flavonoids that lack the 3-hydroxy group of flavonols, derived from flavanones by oxidation, yellow or invisible to the human eye but absorbing in the ultraviolet and visible to bees; flavones are isomeric with isoflavones; examples of flavones and hydroxyflavones (usually as glycosides) are apigenin (5, 7, 4’-trihydroxyflavone), luteolin (5, 7, 3’, 4’-tetrahydroxyflavone), tricin (tricetin 3’, 5’-dimethyl ether = 5, 7, 3’, 5’-pentahydroxyflavone), rpoifolin, nobiletin, tangeretin, flavone, baicalein, chrysin, techtochrysin, diosmetin, diosmin, wogonin; O-glycosidic and C-glycosidic derivatives of flavones (flavone-O- and flavone-C-glycosides) are, e.g., vitexin and orientin

Flavonoids – a C₁₅ skeleton with a chroman ring bearing an aromatic ring in position 2, 3, or 4; there are two benzene rings in the flavonoid nucleus, one derived from condensation of acetate units (three malonyl units), the other from the shikimic acid pathway (cinnamic acid), and these are joined by a C3 structure which may be open or closed; the flavonoid nucleus is usually attached to a sugar, forming a water-soluble glucoside; the major classes are based on the oxidation level of the central ring: anthocyanins, aurones, biflavonoids, C-glycosylflavones, chalcones, coumestans, dihydrochalcones, flavanones, flavones, flavonols, isoflavans, isoflavones, neoflavonoids, phytoalexins, pterocarpans, and rotenoids;O-methylated derivatives are, i.a., tricin (tricetin 3’,5’-dimethyl ether), chrysoeriol (luteolin 3’-methyl ether), and luteolin 5’-methyl ether; examples of 6- and 8-hydroxyflavonoids are quercetagetin (6-hydroxyquercetin) and gossypetin (8-hydroxyquercetin)

Flavonoid sulfates – sulfated flavonoids; flavonoids esterified with sulfate groups, mono- to tetrasulfate esters of common flavones and flavonols or their methyl ethers

Flavonols – 3-hydroxyflavones; flavonoids that differ from flavones in having a 3-hydroxyl substituent; they are yellow co-pigments; examples of flavonols are kaempferol, quercetin, myricetin, rhamnetin, morin, rutin, myricitrin, spirenoside, galangin (3,5,7-trihydroxyflavone), melisymplexin, ternatin, limocitrin, hibiscetin (3,5,7,8,3’,4’,5’-heptahydroxyflavone), robinin, kaempferide, and fisetin; examples of O-methylated flavonols are isorhamnetin (quercetin 3’-methyl ether) and syringetin (myricetin 3’, 5’-dimethyl ether)

Flavonones – dihydroflavones; examples are hesperitin, naringin, naringenin, eriodictyol, hesperidin, pinocembrin, and likvirtin

Flavononols – dihydroflavonols

Fructans – polysaccharides derived from fructose, e.g. inulin

Fructose – a hexose sugar forming a 5-membered ring

Furan – a heterocyclic ring that is the basis of the furanoses and found in limonoids, etc.

Furanocoumarins – a group of complex coumarins in which the coumarin structure is prenylated (i.e., a 5C unit derived from mevalonic acid is attached); this 5C mevalonate-derived unit is usually reduced to two carbons which are part of a furan ring that is attached to a benzene ring; immediate precursors for furanocoumarin synthesis are umbelliferone and isoprene