- Melanogenesis inhibitory activity of a 7-O-9'-linked neolignan from Alpinia galanga fruit
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An aqueous acetone extract from the fruit of Alpinia galanga (Zingiberaceae) demonstrated inhibitory effects on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells (IC50= 7.3 μg/mL). Through bioassay-guided separation of the extract, a new 7-O-9'-linked neolignan, named galanganol D diacetate (1), was isolated along with 16 known compounds including 14 phenylpropanoids (2–15). The structure of 1, including its absolute stereochemistry in the C-7 position, was elucidated by means of extensive NMR analysis and total synthesis. Among the isolates, 1 (IC50= 2.5 μM), 1'S-1'-acetoxychavicol acetate (2, 5.0 μM), and 1'S-1'-acetoxyeugenol acetate (3, 5.6 μM) exhibited a relatively potent inhibitory effect without notable cytotoxicity at effective concentrations. The following structural requirements were suggested to enhance the inhibitory activity of phenylpropanoids on melanogenesis: (i) compounds with 4-acetoxy group exhibit higher activity than those with 4-hydroxy group; (ii) 3-methoxy group dose not affect the activity; (iii) acetylation of the 1'-hydroxy moiety enhances the activity; and (iv) phenylpropanoid dimers with the 7-O-9'-linked neolignan skeleton exhibited higher activity than those with the corresponding monomer. Their respective enantiomers [1' (IC50= 1.9 μM) and 2' (4.5 μM)] and racemic mixtures [(±)-1 (2.2 μM) and (±)-2 (4.4 μM)] were found to exhibit melanogenesis inhibitory activities equivalent to those of the naturally occurring optical active compounds (1 and 2). Furthermore, the active compounds 1–3 inhibited tyrosinase, tyrosine-related protein (TRP)-1, and TRP-2 mRNA expressions, which could be the mechanism of melanogenesis inhibitory activity.
- Manse, Yoshiaki,Ninomiya, Kiyofumi,Nishi, Ryosuke,Kamei, Iyori,Katsuyama, Yushi,Imagawa, Takahito,Chaipech, Saowanee,Muraoka, Osamu,Morikawa, Toshio
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p. 6215 - 6224
(2016/12/06)
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- Identification of dihydrogalangal acetate in galangal [Alpinia galangal (L.) Swartz] extracts
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Dihydrogalangal acetate has been discovered for the first time in galangal roots [Alpinia galangal (L.) Swartz]. The compound has a taste sensation similar to galangal acetatesthe pungent principle of galangalsbut it is more stable in food and beverage applications. Therefore, dihydrogalangal acetate provides many advantages as a flavor ingredient for alcohol enhancement and taste modification. Dihydrogalangal acetate is present in approximately 0.0005% of fresh roots and in about 0.004% of dried roots. (S)-Dihydrogalangal acetate is found as the main optical isomer in galangal roots (98%), while its minor (R)-isomer is less abundant (2%). Enantiomers of galangal acetate and dihydrogalangal acetate were separated and evaluated by sensory analysis. (R)-Galangal acetate has a very faint woody and sweet aroma, and (R)-dihydrogalangal acetate is almost odorless, while (S)-galangal acetate has strong and (S)-dihydrogalangal acetate has weak pungent and woody notes. Although the aroma characters of these optical isomers are different, taste sensations were found to have no significant differences among galangal acetate, dihydrogalangal acetate, and their optical isomers.
- Yang, Xiaogen,Rohr, Martin,Jordan, Jason
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experimental part
p. 3286 - 3290
(2010/06/14)
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- Structure-activity relationships of 1′S-1′-acetoxychavicol acetate for inhibitory effect on NO production in lipopolysaccharide-activated mouse peritoneal macrophages
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1′S-1′-Acetoxychavicol acetate from the rhizomes of Alpinia galanga inhibited nitric oxide (NO) production in lipopolysaccharide-activated mouse peritoneal macrophages with an IC50 value of 2.3 μM. To clarify the structure-activity relationship of 1′S-1′- acetoxychavicol acetate, various natural and synthetic phenylpropanoids and synthetic phenylbutanoids were examined, and the following structural requirements were clarified. (1) The para or ortho substitution of the acetoxyl and 1-acetoxypropenyl groups at the benzene ring was essential. (2) The S configuration of the 1′-acetoxyl group was preferable. (3) The presence of the 3-methoxyl group and disappearance of the 2′-3′ double bond by hydrogenation reduced the activity. (4) The substitution of acetyl groups with propionyl or methyl groups reduced the activity. (5) Lengthening of the carbon chain between the 1′- and 2′-positions reduced the activity.
- Matsuda, Hisashi,Ando, Shin,Morikawa, Toshio,Kataoka, Shinya,Yoshikawa, Masayuki
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p. 1949 - 1953
(2007/10/03)
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