Hydroxycinnamic acids in cooked potato tubers from Solanum tuberosum group Phureja

Abstract

Hydroxycinnamic acids are phenolic compounds and are considered to have health promotion properties due to their antioxidant activity. Potato tubers of 113 genotypes of Solanum tuberosum group Phureja belonging to the Colombian Central Collection, landraces of potatoes, and commercial cultivars were evaluated for their hydroxycinnamic acids content. The composition of these compounds was analyzed using cooked tubers in two different agro-climatic conditions. The genotypes were analyzed for chlorogenic acid, neo-chlorogenic acid, crypto-chlorogenic acid, and caffeic acid by ultrahigh-performance liquid chromatography (UHPLC). Chlorogenic acid was the major representative and varied between 0.77 to 7.98 g kg^-1 DW (dry weight) followed by crypto-chlorogenic acid (from 0.09 to 1.50 g kg^-1 DW). Under moorland agro-climatic conditions even though the chlorogenic acid levels increased with respect to flatland agro-climatic conditions, the related isomer neo-chlorogenic acid decreased as compared to flatland conditions. The correlation between chlorogenic acid with the isomers, and with caffeic acid was positive. This study demonstrated that there is a wide variation in hydroxycinnamic acids contents in the germplasm studied, which can be exploited in breeding programs to contribute to human health.

Keywords: Antioxidants; Phenylpropanoid; Potato; Solanum tuberosum L. group Phureja; chlorogenic acid; diploid tuber; isomers.

Figure 1

Chromatographic profile of hydroxycinnamic acids in the genotype CCC102 recorded at 320 nm. Retention times were: 1: neo‐ChA (9.75 min); 2: ChA (11.14 min); 3: crypto‐ChA (11.57 min); 4: CaA (11.78 min). Inserts correspond to the UV spectrum of chromatographic peaks 1–4 from CCC102 [x axis: wavelength (nm), y axis milliunits of absorbance (mAU)] ChA, chlorogenic acid; CaA, caffeic acid.

Figure 2

Correlation and distribution of concentrations (Histograms with kernel density overlay) of hydroxycinnamic acids among cooked tubers of Solanum tuberosum group Phureja genotypes, sowed in Facatativá locality (2650 masl). Two‐dimensional scatter plots indicate hydroxycinnamic compounds correlation performance. Numbers indicate the absolute correlation values. Axis scales are in g kg⁻¹ dry weight. *P < 0.05, ***P < 0.001. ChA, chlorogenic acid; CaA, caffeic acid.

Figure 3

Hierarchical clustering analysis, over two principal components, of 113 genotypes of Solanum tuberosum group Phureja cooked tubers. Plot shows four groups. Cluster I (black dots) grouped genotypes with low‐medium hydroxycinnamic acid concentration, this group include commercial cultivars (ChA 0.77–3.14 g kg⁻¹ DW). Cluster II (red dots) mainly grouped genotypes with medium‐high hydroxycinnamic concentration (ChA 0.88–4.96 g kg⁻¹ DW). Cluster III (green dots) contains genotypes with high CaA (0.11–0.13 g kg⁻¹ DW). Cluster IV (blue dots) mainly consisted of genotypes with the highest ChA and isomers concentrations (ChA 3.61–7.98 g kg⁻¹ DW) Nariño landraces. Figure on the top right shows the direction vectors for the four hydroxycinnamic acids. ChA, chlorogenic acid; CaA, caffeic acid.