Betalains in Edible Fruits of Three Cactaceae Taxa—Epiphyllum, Hylocereus, and Opuntia—Their LC-MS/MS and FTIR Identification and Biological Activities Evaluation

Abstract

<i>Epiphyllum</i>, <i>Hylocereus,</i> and <i>Opuntia</i> plants belong to the Cactaceae family. They are mostly known as ornamental plants but also for their edible fruits, which can potentially be sources of betalains, such as betanin, a natural pigment used in the food industry, e.g., under the European label code E 162. The aim of this work was the identification of betalains (using LC-MS/MS), evaluation of total betalain content (spectrophotometrically), analysis of functional groups (using FT-IR), evaluation of antioxidant activity (using DPPH, ABTS, FRAP, DCFH-DA, and reducing power methods) and evaluation of antimicrobial activity (<i>S. aureus</i>, <i>E. coli</i>, and <i>C. albicans</i>) in fruits of <i>Epiphyllum</i>, <i>Hylocereus</i>, and <i>Opuntia</i> taxa. A total of 20 betalains were identified in the studied Cactaceae fruits. The <i>Epiphyllum</i> pink hybrid had the highest values of total betalains amongst all samples. The highest antioxidant activity was observed in the <i>Epiphyllum</i> pink hybrid, in <i>Opuntia zacuapanensis</i> and <i>O. humifusa</i> fruits. The antimicrobial activity assay showed that cacti fruits were not able to effectively inhibit the growth of <i>E. coli</i>, <i>S. aureus</i>, or <i>C. albicans</i>. Our results prove that these fruits are good sources of natural pigments-betalains. They do not contain toxic compounds in significant amounts and they exhibit antioxidant activity.