Galangin

The synthesis of flavones has also seen modifications over the years. One of the primary modifications has been substituting the carboxylate salt for other bases. Kohn and Low showed that catalytic amounts of triethylamine allowed for the reaction to be run at 160 Looker and coworkers expanded on the Kohn and Low modification by using amines as the solvent, and thus reduced the reaction temperatures. They typically found that the reaction could be run at the refluxing temperatures of the amine. They showcased this modification by converting oi-methoxyphloroacetophenone (35) to the methyl ether of galangin (36) using a variety of amines in 60-75% yield with benzoic anhydride. 

Pinocembrin, chrysin, galangin, and pinobanksin are main flavonoids in honey and propolis. 

The retention behaviour of flavonoids has also been extensively studied on silica stationary phases using heptane, benzene or dichloromethane as weaker components of the binary mobile phase and ethyl acetate and methyl ethyl ketone as modifier. Flavones (3-hydroxy, 5-hydroxy and 7-hydroxyflavone, tectochrysin, chrysin, apigenin, genkwanin, baicalein), flavonols (galangin, pilloin, kaempferol, rhamnetin, quercetin, robinetin,... 

Cnshnie TP, Hamilton VE, Chapman DG Taylor PW, Lamb AJ. (2007) Aggregation of Staphylococcus aureus following treatment with the antibacterial flavonol glycoside galangin. J Appl Microbiol 103 1562-1567. 

Nothofagus spp. Galangin (flavonol) and the stilbene Deter feeding by leafrollers 371... 

Flavonoids, especially flavones and flavonols, also directly bind to several CYP isoforms (lAl, 1A2, IBl, 3A4) involved in xenobiotics metabolism and inhibit enzyme activity. Structure-activity relationships show rather high isoform selectivities depending on the flavonoid substitution pattern and contrasted inhibition mechanisms. For instance, inhibition by flavonoids of 7-methoxyresorufin O-demethylation in microsomes enriched in CYP lAl and 1A2 reveals that galangin (3,5,7-trihydroxyflavone) is a mixed inhibitor of CYP 1A2 (.ST = 8 nM) and a five times less potent inhibitor of CYP 1A1. By contrast, 7-hydroxy flavone is a competitive inhibitor of CYP lAl (Aii = 15 nM) and a six times less potent inhibitor of CYP 1A2. In addition, fairly selective inhibition of CYP IBl (specifically detected in cancer cells) by some flavonoids has been reported. For example, 5,7-dihydroxy-4 -methoxyflavone inhibits IBl, 1 Al, and 1A2 with IC50 values of 7, 80, and 80 nM, respectively. ... 

Meyer, J.J.M. et al.. Antiviral activity of galangin isolated from the aerial parts of Helichrysum aureonitens, J. Ethnopharmacol., 56, 165, 1997. 

Dimethoxypongapin Dihydroisocycloartomunin 8-(l, l-Dimethylallyl)-galangin 8-(l, 1 -Dimethylallyl)-kaempferol 6,8-Dimethylapigenin Diosmetin... 

Trihydroxyflavone (galangin) 3-Glucoside-8-sulfate Phyllanthus virgatus whole plant Euphorbiaceae 165... 

A2 Acetaminophen, antipyrine, caffeine, clomipramine, phenacetin, tacrine, tamoxifen, theophylline, warfarin Smoking, charcoal-broiled foods, cruciferous vegetables, omeprazole Galangin, furafylline, fluvoxamine... 

Alpinia katsumadai Hayata A. globosum Horan. A. kumatake Mak. Dou Kou Pi Jiang (Greater galangal) (whole plant) Kaempferin, galangin, galangol, cineole, citral, carotene, thiamine, riboflavin.50 Carminative, stomachic, treat malarial disorders, fluxes, and menstruation. 

N.A. Alpinia galanga Miq. Volatile oil, alpha-pinene, cineole, linalool, sesquiterpene lactones, galangol, galangin." A stimulant, carminative, prevents vomiting, antifungal. 

Some improvement in the often moderate yields associated with the Kostanecki-Robinson synthesis has been achieved by substitution of a catalytic amount of triethylamine for the stoichiometric quantity of sodium carboxylate (44CB202). It is also possible to work at somewhat lower temperatures using this technique, an obvious advantage when sensitive groups are present. The modification is particularly attractive in the synthesis of complex hydroxyflavones (77T1405, 1411). A further development, the use of a tertiary amine as a solvent, has been advocated (78JOC2344). For instance, in the synthesis of 5,7-dihydroxy-3-methoxyflavone (galangin 3-methyl ether) (447) from w-methoxyphloracetophenone, the... 

As previously mentioned, certain flavonoids can penetrate into the hydrophobic core of membranes, a feature that mainly relies on their hydrophobic character, which is dictated by flavanoid chemical structure and spatial conformation. When flavonoid hydrophobicity was assessed from the partition coefficient between ra-octanol and an aqueous solution, the following order of hydrophobicity was observed flavone, genistein > eriodictyol, myricetin, quercetin, kaempferol, hesperetin, daidzein > > galangin, morin, flavanone, naringenin, taxifolin (Table 4.1). 

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