title: Artepillin C, a major ingredient of Brazilian propolis, induces a pungent taste by activating TRPA1 channels.
abstract: Brazilian green propolis is a popular health supplement because of its various biological properties. The ethanol extract of Brazilian green propolis (EEBP) is characteristic for its herb-like smell and unique pungent taste. However, the ingredients responsible for its pungency have not yet been identified. This study provides the first evidence that artepillin C is the main pungent ingredient in EEBP and that it potently activates human transient receptor potential ankyrin 1 (TRPA1) channels. EEBP was fractionated using column chromatography with a step gradient elution of an ethanol-water solution, and the fractions having the pungent taste were determined by sensory tests. HPLC analysis revealed that the pungent fraction was composed primarily of artepillin C, a prenylated derivative of cinnamic acid. Artepillin C was also identified as the pungent compound of EEBP by organoleptic examiners. Furthermore, the effects of artepillin C and other cinnamic acids found in EEBP on TRPA1 channels were examined by calcium imaging and plate reader-based assays in human TRPA1-expressing cells to investigate the molecular mechanisms underlying their pungent tastes. Artepillin C and baccharin activated the TRPA1 channel strongly, whereas drupanin caused a slight activation and p-coumaric acid showed no activation. Because the EC(50) values of artepillin C, baccharin, and allyl isothiocyanate were 1.8 µM, 15.5 µM, and 6.2 µM, respectively, artepillin C was more potent than the typical TRPA1 agonist allyl isothiocyanate. These findings strongly indicate that artepillin C is the main pungent ingredient in EEBP and stimulates a pungent taste by activating TRPA1 channels.
authors.affiliation: Nagaragawa Research Center, API Co., Ltd., Nagara, Gifu, Japan.
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Hata
authors.forename: Shigemi
authors.initials: S
authors.lastname: Tazawa
authors.forename: Shozo
authors.initials: S
authors.lastname: Ohta
authors.forename: Mee-Ra
authors.initials: MR
authors.lastname: Rhyu
authors.forename: Takumi
authors.initials: T
authors.lastname: Misaka
authors.forename: Kenji
authors.initials: K
authors.lastname: Ichihara
mesh_terms: D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D002460:Cell Line; D002626:Chemistry, Pharmaceutical / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002934:Cinnamates / Q000494:pharmacology; D003373:Coumaric Acids / Q000032:analysis; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D015195:Drug Design; D006801:Humans; D017879:Isothiocyanates / Q000737:chemistry; D008956:Models, Chemical; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010666:Phenylpropionates / Q000032:analysis* / Q000737:chemistry; D010936:Plant Extracts / Q000494:pharmacology; D011422:Propionates; D011429:Propolis / Q000378:metabolism; D000074025:TRPA1 Cation Channel; D013649:Taste; D014162:Transfection; D050051:Transient Receptor Potential Channels / Q000378:metabolism*; D014255:Trichothecenes / Q000737:chemistry
chemical_list: D015220:Calcium Channels; D002934:Cinnamates; D003373:Coumaric Acids; D017879:Isothiocyanates; D009419:Nerve Tissue Proteins; D010666:Phenylpropionates; D010936:Plant Extracts; D011422:Propionates; D000074025:TRPA1 Cation Channel; C473350:TRPA1 protein, human; D050051:Transient Receptor Potential Channels; D014255:Trichothecenes; C029010:cinnamic acid; C102259:artepillin C; D011429:Propolis; C004471:allyl isothiocyanate; C012764:baccharin; C495469:p-coumaric acid; D002118:Calcium