Development of a reversed-phase high performance liquid chromatography (RP-HPLC) procedure for the simultaneous determination of phenolic compounds in peanut skin extracts

Summary

A reversed-phase high performance liquid chromatography (RP-HPLC) procedure was developed for simultaneous determination of fifteen phenolic compounds including five phenolic acids, two stilbenes and eight flavonoids in peanut skin extract from Runner, Virginia and Spanish peanuts.

Situation

Several hundred papers on the HPLC of phenolic compounds have been published in the past 20 years, yet HPLC of phenolic compounds can detect across only one, two or perhaps three classes of compounds in one analysis. Foods may contain several classes of phenolic compounds. Therefore, it is important to be able to identify and quantify sources of important health-promoting bioactive phenolic compounds in a food supply.

Response

We conducted a study to develop a RP-HPLC profiling method using diode array detection (DAD) for the identification and quantification of phenolic compounds in peanut skin extracts in a single chromatographic run. The method was validated for accuracy, precision, linearity, range and limit of detection and quantification. Phenolic compounds consisting of phenolic acids, stilbenes and flavonoids were eluted with good resolution within 95 min. The variation in recovery was 11% and reproducibility was 2.5%.

Impact

A reversed-phase high performance liquid chromatography (RP-HPLC) procedure was developed for simultaneous determination of five phenolic acids, two stilbenes and eight flavonoids in peanut skin extract. Phenolic compounds were eluted with good resolution within 95 min as follows: gallic, protocatechuic, epigallocatechin, catechin, b-resorcylic (internal standard), caffeic, procyanidin B2, epicatechin, epigallocatechin gallate, p-coumaric, ferulic, piceid, epicatechin gallate, catechin gallate, resveratrol and quercetin. This method was used to verify quantification of phenolic compounds in peanut skin extracts from Runner, Virginia and Spanish peanuts. Using the developed method, three phenolic acids, namely, protocatechuic acid, caffeic acid and p-coumaric acid, were identified and quantified from the peanut skin extracts. Protocatechuic acid was significantly higher in Virginia (34.03 ppm) followed by Spanish (15.45 ppm) and Runner skins (7.62 ppm). Caffeic acid was detected only in Spanish skins. p-Coumaric acid was highest in Runners (23.34 ppm), followed by Spanish (12.31 ppm) then Virginia (4.98 ppm). Virginia and Spanish peanut skins had significantly more epigallocatechin than Runner skins. In terms of total flavanol content (calculated as the sum of epigallocatechin, catechin and epicatechin), Spanish skins had 1962 ppm; Virginia had 1956 ppm and only 574 ppm for Runners. The flavonol quercetin was highest in Spanish peanut skin. Resveratrol but no piceid was detected in all peanut skin types. Resveratrol content was highest in Spanish skins (15.04 ppm) followed by Runners and Virginia skins (4.30 and 3.66 ppm, respectively). The method detected the natural forms of th ecompunds in peanut skin extracts directly without need for hydrolysis. Thus, the present method can determine quantitatively individual classes of flavonoids, phenolic acids and stilbenes in a single analysis run.

State Issue

Food, Nutrition and Health

Details

• Year: 2009
• Geographic Scope: University
• County: Spalding
• Program Areas:
  • Agriculture & Natural Resources