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

Autor:	Jonathan E. Poulton, Gary W. Kuroki
Rok vydání:	1981
Předmět:	Naringenin biology Acacetin Robinia biology.organism_classification General Biochemistry Genetics and Molecular Biology chemistry.chemical_compound chemistry Biochemistry Callus Apigenin Caffeic acid Quercetin Homogenization (biology)
Zdroj:	Zeitschrift für Naturforschung C. 36:916-920
ISSN:	1865-7125 0939-5075
DOI:	10.1515/znc-1981-11-1202
Popis:	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.
Databáze:	OpenAIRE
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