HPLC identification of flavonol-glycosides in maize endosperm

--Elizabeth E. 0. Caldwell and Peter A. Peterson

High performance liquid chromatography was used to analyze the flavonol-glycoside content of pooled aleurone and starchy endosperm. Tissue was collected from mature, fully-colored, red, C-(lineC) sh Bz wx kernels.

Individual kernels were prepared for analysis as follows:

1. pericarp and embryo tissues removed

2. remaining endosperm (including aleurone) ground to a slurry with water

3. supernatant lyophilized

4. pigments redissolved in methanol

Flavonol-glycosides were separated using a C18 reverse phase column (Lichrosorb 1ORP18, 25 x 0.5cm) and detected at 340nm. The aqueous eluent (Eluent 1) was 1% triethylamine in water, adjusted to pH 3.0 with phosphoric acid. The second eluent was acetonitrile. The following gradient was a modification of one published by Asen and Griesbach (J. Amer. Soc. Hort. Sci. 108:845-850, 1983):
Time Eluent 1 Eluent 2
0 to 20 min 100% to 80% 0% to 20%
21 to 40 min 80% 20%

Individual flavonol-glycosides were identified by comparing the unknown retention times with results from extracts of lyophilized Blue Magic petunia petals. The Blue Magic standard was provided by Dr. Robert Griesbach along with the identification of its flavonol-glycoside content.

By comparing the maize and Blue Magic extracts, six flavonol-glycosides were identified in the C-(lineC) sh Bz wx mature endosperm tissue. These include: quercetin-3-glucoside, quercetin-3,7-diglucoside, quercetin-7-glucoside, quercetin-3-sophoroside, quercetin-3-sophoroside-7-glucoside, and quercetin-3-(caffeoylsophoroside)-7-glucoside. Of these, quercetin-3-sophoroside, quercetin-3-sophoroside-7-glucoside, and quercetin-3-(caffeoylsophoroside)-7-glucoside are identified for the first time in maize tissue.

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors

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