Tomatoes naringenin

Chalcones and dihydrochalcones have been reported in a restricted number of foods (Robards and others 1999 Tomas-Barbcran and Clifford 2000). Chalconaringenin occurs in tomato skin, but the acid extraction conditions of the usual polyphenol analyses convert the chalcone to the corresponding flavanone (naringenin) in the tomato. The most common dihydrochalcones found in foods are phloretin glucoside (phloridzin) and phloretin xylogalactoside, which are characteristic of apples (see Table 2.2) and derived products such as apple juice, cider, and pomace (Robards and others 1999 Tomas-Barbcran and Clifford 2000). 

Chalcones are comparatively rare in foods. Naringenin chalcone is present in tomato skin and may be present in juice, paste and ketchup. Acid hydrolysis, commonly applied prior to HPLC, converts the chalcone to the corresponding flavanone (naringenin), which is naturally present only in trace amounts (2-15 mg/kg) in the tomato [23],... 

Krause M, Galensa G. 1992. Determination of naringenin and naringenin-chalcone in tomato skins by reversed phase HPLC after solid phase extraction. Z Lebensmittel... 

Fig. 12 shows a characteristic chromatogram of the phenolic compounds of tomato peel. Especially interesting is the relatively large naringenin chalcone peak. Other peaks are observed in the chromatogram, corresponding to unidentified hydroxycinnamic and benzoic acid derivatives. 

Fig. (12). HPLC chromatogram of tomato peel phenolics (1) chlorogenic acid, (2) quercetin 3-rutinoside, and (3) naringenin chalcone. HPLC conditions RP Cjg column (12 x 0.4 cm particle size S pm). Mobile phase acidified water (5% formic acid) and methanol. Gradient 0 min- 10% B, 30 min- 40% B, 40 min- 80% B. Flow rate 1 mL/min.

Tomato (Petunia) (alfalfa)/ oveiexpiession CaMV35S/ CHSl + CHR Chalcone synthase + chalcone reductase Chalcones -I- deoxychalcones Higher butein, isoliquiritigenin, naringenin, chalcone, and rutin [63]... 

Tomato Grape/ overexpression CaMV35S/ StSy Stilbene synthase Resveratrol High trans-resveratrol (48.48 mg kg FW) and trans-piceid (126.58 mg kg FW)/ decrease in rutin (2-fold) and naringenin (2.4-fold) Seedless fruit [67]... 

Tomato Grape/ overexpression CaMVd35S/ STS Stilbene synthase Resveratrol High stilbenes (resveratrol and piceid), naringenin chalcone, rutin [63]... 

Tomato Tomato/RNAi CaMV35S/ MYB12 MYB12 R2R3-MYB TF mediates the accumulation of flavonoids in tomato peel Lower flavonoid pigment naringenin chalcone Exhibited a y-like phenotype [78]... 

Tomato Tomato/ overexpression CaMV35S/ TAGLl TOMATO AGAMOUS-LIKE 1 MADS-box TF Higher lycopene and naringenin chalcone [81]... 

Feedback inhibition can be limited by optimizing both upstream and downstream enzyme expression such that the inhibitor does not significantly accumulate. In instances where a metabolite inhibits an enzyme in the isoflavonoid pathway, enzyme mutagenesis can alter the structural interaction between the enzyme and its inhibitor to block the inhibition mechanism. Recently, allosteric feedback inhibition of a tomato peel 4CL by naringenin 23, a product several steps downstream, was significantly reduced through directed evolution in E. coli [181]. 

The main flavonoids which had accumulated in tomato fruits were naringenin and rutin (quercetin-3-rutinoside), predominantly detected in the peel [43, 44]. 

Fig. 51.4 Comparison of flavonoid levels in wild type and transgenic skin of fruit at the red stage of ripening. Naringenin levels (X .290 nm) in the wild type and transgenic skin (of almost three) red uits. Outline of llavonols biosynthesis and profiles of accumulation of rutin and kaempferol-rutinoside (X .370 nm) in skin of transgenic tomatoes compared with those of wild type...

Yamamoto T, Yoshimura M, Yamaguchi F, Kouchi T, Tsuji R, Saito M, Obata A, Kikuchi M (2004) Anti-allergic activity of naringenin chalcone from a tomato skin extract. Biosci Biotechnol Biochem 68 1706... 

Targeting F3H appeared less effective. When an RNAi construct for F5H was introduced into tomato, the biosynthesis of flavonoids was reduced beyond this step but not to the extent observed with CHS and FLS. In F3H RNAi fruit peel, rutin levels were decreased to approximately 20% of wild type values (Bovy et al, 2007). This relatively low decrease may have resulted either from just partial downregulation of F3H or because of an intrinsic F3H-like activity of FLS, thereby using naringenin to form flavonols (Lukacin et al, 2003 Martens et al, 2003). Similarly, the simultaneous overexpression of CHS and FLS was sufficient to accumulate flavonols in the fiaiit flesh, despite the very low expression of endogenous CHI and F3H genes in this tissue (Colliver et al, 2002). 

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