Chemical composition and antioxidant properties of native Ecuadorian fruits: Rubus glabratus Kunth , Vaccinium floribundum Kunth, and Opuntia soederstromiana

Abstract

The native berries of South America present promising marketing opportunities owing to their high antioxidant content, notably rich in anthocyanin and phenolic compounds. However, Ecuador's endemic fruits, primarily found in the wild, lack comprehensive data regarding their phytochemical composition and antioxidant capacity, underscoring the need for research in this area. Accordingly, this study evaluated the total phenolic, anthocyanin, flavonoid, resveratrol, ascorbic acid, citric acid, sugars, and antioxidant content of three native Ecuadorian fruits: mora de monte (Rubus glabratus Kunth), mortiño (Vaccinium floribundum Kunth), and tuna de monte (Opuntia soederstromiana). Determination of resveratrol, ascorbic acid, citric acid, and sugars was determined by HPLC analysis, and UPLC analysis was used to determine tentative metabolites with nutraceutical properties. Antioxidant capacity was assessed using cyclic voltammetry and the DPPH method; differential pulse voltammetry was used to evaluate antioxidant power. Analysis of results through UPLC-QTOF mass spectrometry indicated that R. glabratus Kunth and V. floribundum Kunth are important sources of various compounds with potential health-promoting functions in the body. The DPPH results showed the following antioxidant capacities for the three fruits: R. glabratus Kunth > O. soederstromiana > V. floribundum Kunth; this trend was consistent with the antioxidant capacity results determined using the electrochemical methods.

Keywords: Antioxidant capacity; Bioactive compounds; DPPH method; Ecuadorian fruit; Electrochemical techniques.

Fig. 1

Cyclic voltammogram for the redox coupling of O₂^•- with increasing concentration of extracts (indicated in the insert) in C₂H₆OS + tetrabutylammonium hexafluorophosphate, scan rate 17 mV s⁻¹. (A) R. glabratus Kunth, (B) V. floribundum Kunth and (C) O. soederstromiana.

Fig. 2

Dimensionless parameter [$({Ip}_a^0$-${Ip}_a^s)/{Ip}_a^0$] vs concentration of fruit extract. (A) R. glabratus Kunth, (B) V. floribundum Kunth and (C) O. soederstromiana.

Fig. 3

Differential pulse voltammogram for the ethanolic extract of each fruit in acetate buffer, pH 4.5, scan rate of 17 mV s⁻¹ (A) R. glabratus Kunth, (B) V. floribundum Kunth, and (C) O. soederstromiana.