Two-Phase Flavonoid Formation in Developing Strawberry (Fragaria × ananassa) Fruit

Abstract

Flavonoids are important secondary metabolites in strawberry as they fulfill a wide variety of physiological functions. In addition, they are beneficial for human health. Previous studies have shown for selected enzymes from the flavonoid pathway that flavonoid biosynthesis shows two peaks during fruit development. We provide optimized protocols for the determination of the activities of the key flavonoid enzymes: phenylalanine ammonia lyase, chalcone synthase/chalcone isomerase, flavanone 3-hydroxylase, dihydroflavonol 4-reductase, flavonol synthase, flavonoid 3-O-glucosyltransferase, and flavonoid 7-O-glucosyltransferase. Using these protocols we were able to demonstrate two distinct activity peaks during fruit ripening at early and late developmental stages for all enzymes with the exception of flavonol synthase. The first activity peak corresponds to the formation of flavanols, while the second peak is clearly related to anthocyanin and flavonol accumulation. The results indicate that flavonoid 3-O-glucosyltransferase activity is not essential for redirection from flavanol to anthocyanin formation in strawberry.

A sensitive microextraction by packed sorbent-based methodology combined with ultra-high pressure liquid chromatography as a powerful technique for analysis of biologically active flavonols in wines

“…The formation of flavonols myricetin, quercetin and kaempferol ( Fig. 1) in grapes has been reported to occur through the phenylpropanoid metabolism [1]. Specifically, naringenin is transformed into quercetin and kaempferol by means of the enzyme flavanone 3␤-hydroxylase (FHT), which leads to the production of dihydroflavonols [1][2][3].…”

“…1) in grapes has been reported to occur through the phenylpropanoid metabolism [1]. Specifically, naringenin is transformed into quercetin and kaempferol by means of the enzyme flavanone 3␤-hydroxylase (FHT), which leads to the production of dihydroflavonols [1][2][3]. Regarding myricetin, although it is also produced through the phenylpropanoid metabolism, its synthesis occurs in general terms further in the pathway [4][5][6].…”

Light-Induced Expression of a MYB Gene Regulates Anthocyanin Biosynthesis in Red Apples

“…), Vaccinium sp. such as cranberry (Vaccinium macrocarpon) and bilberry (Vaccinium myrtillus), eggplant (Solanum melongena), and lychee (Litchi chinensis), multiple flavonoid structural genes are coregulated for anthocyanin synthesis or in many of these fruit anthocyanin synthesis is enhanced by sunlight (Tyas et al, 1998;Matsuzoe et al, 1999;Zhou and Singh, 2000;Li et al, 2001;Jaakola et al, 2002;Kim et al, 2003;Kataoka and Beppu, 2004;Steyn et al, 2004;Tsuda et al, 2004;Jia et al, 2005;Lo Piero et al, 2005;Anttonen et al, 2006;Halbwirth et al, 2006). In none of these cases has a MYB or bHLH regulator specific for induction of anthocyanin synthesis in fruit been isolated.…”

Antimicrobial Activity of Thinned Strawberry Fruits at Different Maturation Stages

“…Ferreyra et al (2007) and Montero et al (1996) showed that total phenolic content decreased during strawberry fruit development. Halbwirth et al (2006) reported that the concentration of simple phenolics in strawberry fruits decreased continuously and that flavonol contents increased rapidly during fruit development.…”

“…fruits contain various phenolic compounds (Halbwirth et al, 2006;Kosar et al, 2004). Among these compounds, ellagic acid accounts for 50.9% of the total phenolic compounds in ripe fruits (Häkkinen et al, 1999).…”