Determination by HPLC-DAD-ESI/MSn of phenolic compounds in Andean tubers grown in Ecuador

Abstract

In this work, the phenolic compounds of four Andean tubers grown in Ecuador, such as yacon (Smallantus sonchifolius), mashua (Tropaeolum tuberosum), melloco (Ullucus tuberosus) and purple-sweet potato (Ipomea batatas) were analyzed by HPLC–DAD–ESI/MSn. Non-flavonoid compounds, such as hydroxycinnamic derivatives were identified in yacon, purple sweet potato and melloco samples, accounting for 100, 26 and 15% of the total of phenolic compounds, respectively. Mashua sample revealed the presence of flavan-3-ol monomers that were not found in the other samples, being (-)-epicatechin the most abundant (9.22 μg/g DM). Quercetin-3-O-rutinoside (40.6 μg/g DM), kaempferol-O-dirhamnosil-hexoside (29.5 μg/g DM) and kaempferol-O-dihexoside (46.22 μg/g DM) were the main flavonols present in mashua, melloco and purple sweet potato, respectively, being this last specie which presented the highest concentration in flavonols (89.32 μg/g DM). Purple sweet potato also had anthocyanins (157.16 μg/g DM), not detected in the other samples. The presence of these compounds and the consideration of the total phenolic content suggest the use of these Andean tubers as promising sources of natural antioxidants of wide use in the food industry. Therefore, these tubers could be considered as novel and inexpensive sources of bioactive compounds for their potential use in functional foods and nutraceuticals.