Optimization of ultrasonic assisted extraction of blackberry by response surface methodology and evaluation of its antiproliferative effects in combination with doxorubicin

The aim of this study was to obtain an extract rich in phenolic compounds from blackberry fruit and to evaluate its antiproliferative effects on 4T1 breast cancer cells, both alone and in combination with doxorubicin. Response surface methodology (RSM) was used to optimize ultrasound-assisted extraction conditions in terms of total phenolic content and antioxidant capacity. Polyphenolic profile in the optimum extract was determined by HPLC. Spectrophotometric method was used to determine total phenolic, antioxidant capacity and total anthocyanin amounts. The effects of the extract and doxorubicin, alone and together, on the viability of 4T1 cells were determined by MTT assay (synergism sentence). The optimum conditions were determined as follows: Solvent ratio was 48.87%, temperature was 69.83 °C, time was 89.20 min and solvent/solid ratio was 39.837 ml/g. TPC, DPPH scavenging capacity and total anthocyanin content of the optimum extract were found to be 64.178±6,68 mg GAE/g, 38.320±4,46 mg AAE/g and 9.231±0.302 mg C3G equivalent /g dry blackberry fruit (19.293±0.631 mg/g dry extract), respectively. Caffeic acid (10.354 mg/g DW), (−)-Epicatechin (5.545 mg/g DW), 2,5-dihydroxybenzoic acid (4.495 mg/g DW) and Naringin (1.814 mg/g DW) were high in the optimum extract. While the IC50 value of the optimum extract was calculated as 2.507 mg/mL, doxorubicin was calculated as 1.274 µM. In the combination of doxorubicin and optimum extract of blackberry, antagonism was generally observed for the Bliss (-18.22), Loewe (-10.65) and ZIP (-15.05) models evaluated. However, in the HSA model (average -7.43), it was evaluated as an additive effect since it was between -10 and 10. Further studies examining the mechanisms underlying this antagonistic effect, dose optimization and interactions of extract components and in vivo studies confirming the results should be conducted. Optimum blackberry extract may have the potential to be used in the protection against doxorubicin-induced cardiac damage, and this should be investigated with further studies.