Diversity of (dihydro) hydroxycinnamic acid conjugates in Colombian potato tubers

Abstract

In potato tuber, caffeic acid (the predominant hydroxycinnamic acid (HCA)), its conjugates (HCAcs; i.e. chlorogenic acid (ChA), crypto-ChA, and neo-ChA), and anthocyanin-linked HCAs have been extensively described in the literature. In contrast, only little information is available on the occurrence of other HCAcs and didydrohydroxycinnamic acid conjugates (DHCAcs). Fifteen Colombian potato cultivars were screened for these less commonly described conjugates by reversed-phase ultrahigh performance liquid chromatography coupled to a diode array detector and a heated electrospray ionisation mass spectrometer. A total of 62 HCAs/HCAcs/DHCAcs were found in extracts from peel and flesh. Among them, only twelve compounds were common to all cultivars in both peel and flesh. The less commonly described compounds accounted for 7.1–20.1% w/w of the total amount of HCAs/HCAcs/DHCAcs in whole tubers, highlighting their contribution to the total phenolic profile of potato tubers. Among all cultivars, the abundance (mg/100g DW whole tuber) of neo-ChA (0.8–7.4) ranged in similar quantities as the less commonly reported feruloyl octopamine (1.2–5.2), 5-O-feruloyl quinic acid (0.1–7.5), cis-ChA (1.1–2.2), caffeoyl putrescine (0.6–2.5), sinapoyl hexose (0.1–1.8), N1,N14-bis-(dihydrocaffeoyl) spermine (0.2–1.7), N1,N10-bis-(dihydrocaffeoyl) spermidine (1.1–2.6), and N1,N5,N14-tris-(dihydrocaffeoyl) spermine (trace – 11.1).