BIOSYNTHESIS OF A RETROCHALCONE ECHINATIN: INVOLVEMENT OF O-METHYLTRANSFERASE TO LICODIONE

Article abstract of DOI:10.1016/S0031-9422(00)91021-5

In order to clarify the O-methylation step in the bisynthesis of a retrochalcone, echinatin (4,4'-dihydroxy-2-methoxychalcone), methyl transfer from S-adenosyl-L-methionine (SAM) to licodione (1-(2,4-dihydroxyphenyl)-3-(4-hydroxyphenyl)-1,3-propanedione) in the cell-free extract of the cultured cells of Glycyrrhiza echinata was examined.Time course of methyl transferring activity during culture cycle in 4 strains was correlated to echinatin content.The enzyme catalysing this reaction, licodione O-methyltransferase (LMT), was purified 135-fold.Substrate specificity studies implied that the hydroxy group ortho to the C3 linkage in licodione was methylated in this reaction.O-Methyl-licodiones were synthesized for comparison and the sole product of LMT-catalysed reaction was identified as 2'-O-methyl-licodione.A possible scheme for the last steps of echinatin biosynthesis is proposed. - Key Word Index: Glycyrrhiza echinata; Leguminosae; cell culture; cell free extract; retrochalcone biosynthesis; enzyme; O-methyltransferase; echinatin; licodione; O-methyl-licodiones.