Cytotoxic and antioxidant properties in vitro of functional beverages based on blackberry (Rubus glaucus Benth) and soursop (Annona muricata L) pulps

Abstract

Background:  There are many kinds of tropical fruit available in Venezuela. Two of these fruits are the focus of our study: blackberry (“mora”) and soursop (“guanábana”). These fruits have extraordinary bioactive components. For example, blackberry has antioxidant compounds such as anthocyanins, which are characteristic of the Rosaceae family. Acetogenins present in the Annonaceae family have been shown to possess cytotoxic properties that act against different types of tumor cells. In previous research, we have discovered how lyophilized soursop pulp has an elevated cytotoxic effect with a IC₅₀ of 7.1940±1.06 in human cervix carcinoma cells (HeLa) and 0.8460±1.29 in human prostate carcinoma cells (PC3).

Objective: This study focused on the health benefits and properties of the soursop and the blackberry. Our main focus was to determine the antioxidant and cytotoxic properties in a formulated beverage based on blackberry, soursop, and yogurt containing probiotics and prebiotics.

Methods: The research includes the study of soursop pulp (SP), blackberry pulp (BP), and two formulations of the functional beverage selected through a sensorial analysis, F2 (BP + SP + Yogurt + Truvía® + Sacarose) and F3 (BP + SP + Yogurt + Truvía® + Sacarose + Sodium tripolyphosphate). Cell viability of prostate carcinoma cells (PC3), breast carcinoma without over-expression of the HER2/c-erb-2 gene (MCF-7), breast carcinoma in which the HER2/c-erb-2 gene is over-expressed (SKBr3) and healthy cells of human connective tissue used as control (Fibroblasts).  The previous indicated samples were assessed using MTT (3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide). The antioxidant activity of the functional beverage was also done using a freshly preparation of 1,1-diphenyl-2-picrylhydrazyl (DPPH). 

Results: The BP demonstrated the highest cytotoxicity for both lines of breast cancer cell lines, MCF-7 and SKBR3. The values of the minimum concentration required to inhibit 50 % of the cell population (IC₅₀) was 0.12 ± 1.10 and 1.81 ± 1.68% v / v respectively, followed by SP in MCF-7 and PC3 with values of 1.40 ± 1.03 and 1.34 ± 1.06 respectively. At the same time, the effectiveness of the formulations used found that 3.60 ± 1.04% v / v of F2 beverage was necessary to achieve 50 % inhibition of cell viability of MCF-7 line. For the formulation F3, it was necessary to use a concentration of 5.21 ± 1.04% v / v for that tumor cell line. However, the F2 and F3 formulations demonstrated IC₅₀ values of 3.69 ± 1.08% v / v and 2.50 ± 1.08% v / v respectively for the PC3 cell line. On the other hand, the antioxidant capacity of BP and SP reached elevated values at 30 minutes of exposure to DPPH, obtaining a rate of 85.28 ± 0.11 and 80.94 ± 0.07 % respectively by using a concentration of 12.5 %, F2 and F3 formulations also reached values of 83.97 ± 0.46 and 85.62 ± 0.11 % at 100 % concentration of both drinks respectively.

Conclusion: We discovered that the cytotoxic activity of both formulations prepared as well as the pulps were fairly good, revealing highly effective consequences for the inactivation of breast tumor cells MCF-7 and prostate tumor cells PC3. Moreover, BP and SP demonstrated a high antioxidant activity, with a synergistic effect accomplished by the mixture on F2 and F3.

Keywords: Functional beverage, cytotoxic, antioxidant, soursop, blackberry, yogurt.