Showing papers on "Acacetin published in 1981"

Mutagenicities of 61 flavonoids and 11 related compounds

Abstract: The mutagenicities of 61 flavonoids (naturally occurring flavonoid aglycones and flavonal glycosides and synthetic flavonoids) and those of 11 compounds structurally related to flavonoids were tested with Salmonella typhimurium strains TA100 and TA98. Among the 22 flavone derivatives tested, only wogonin was strongly mutagenic, while five derivatives, apigenin triacetate, acacetin, chrysoeriol, pedalitin, and pedalitin tetraacetate, were only weakly mutagenic. Two bisflavonyl derivatives, neither of which has a 3-hydroxyl group, were not mutagenic. Of the 16 flavonol derivatives tested, all except 3-hydroxyflavone and the tetra- and penta-methyl ethers of quercetin were mutagenic. Of the five flavanone derivatives tested, only 7,4-dihydroxyflavanone was mutagenic, showing weak activity. Of the four flavanonol derivatives tested, hydrorobinetin and taxifolin were weakly mutagenic. Of the six isoflavone derivatives tested, tectorigenin was weakly mutagenic. Of the 11 compounds in the miscellaneous group structurally related to flavonoids, only iso-liquiritigenin was mutagenic, showing weak activity. For the emergence of strong mutagenicity, the double bond between positions 2 and 3 and the hydroxyl group at position 3 are required, except in wogonin, which does not have a hydroxyl group at position 3 but is strongly mutagenic to TA100. The 3-O-acetyl ester of flavonol, quercetin, was mutagenic with S9 mix, but 3-O-methyl ethers were not. Six flavonol glycosides, three quercetin glycosides and three kaempferol glycosides were mutagenic after preincubation with “hesperidinase,” a crude extract of Aspergillus niger. Of 66 flavonoid agylcones and compounds structurally related to flavonoids, quercetin was the strongest mutagen. The carcinogenicity of this compound should be clarified because it is ubiquitously found in vegetables.

Flavonoids from the flowers of Clerodendron infortunatum.

Abstract: Apigenin, acacetin and a new flavone glycoside, characterised as the methyl ester of acacetin-7-0-glucuronide have been isolated from the flowers of Clerodendron infortunatum.

The Para-O-Methylation of Apigenin to Acacetin by Cell-Free Extracts of Robinia pseudoacacia L.

Abstract: Crude extracts from young Robinia pseudoacacia seedlings, shoots, and callus tissue catalyze the para-O-methylation of apigenin to acacetin using S-adenosyl-ʟ-methionine as methyl donor. Optimum activity was exhibited at pH 9.0, and Mg²⁺ was not required for maximum activity. EDTA (10 mᴍ) did not affect the reaction rate, but 47% inhibition was observed with SAH (100 μᴍ). β-Mercaptoethanol (5 mᴍ) was required in the homogenization medium for optimum O-methyltransferase activity. Apigenin (Kₘ, 50 μᴍ) was the best substrate, but significant activity was shown towards caffeic acid, 5-hydroxyferulic acid, naringenin, and quercetin. Paracoumaric, ferulic, and sinapic acids were not methylated. The Kₘ for S-adenosyl-ʟ-methionine was 31 μᴍ. Our demonstration of a para-O-methyltransferase activity methylating apigenin, but not para-coumaric acid, strongly supports the conclusion that the B-ring methylation pattern of acacetin is determined at the C₁₅-level in Robinia pseudoacacia.