Ultrasound-assisted extraction phenolic compounds from mexican raspberries (Rubus idaeus): cytotoxicity, antioxidant and anti- inflammatory activity

Abstract

Ultrasound-assisted extraction is a technology used as an alternative to conventional extraction methods to increase yield. In this research, the nutritional compositions, antioxidative, anti-inflammatory, and cytotoxic activity of organic Mexican raspberry were investigated to evaluate the effectiveness of ultrasound-assisted extraction of phenolic compounds from raspberry. Proximate composition was determined as 84.79% in moisture, 8.7 g/100 g d.b. protein, 5.9 g/100 g d.b. in fat, 40.6 g/100 g d.b. in total dietary fiber, and 3.4 g/100 g d.b. in ash. Ultrasound-assisted extraction was used to increase raspberry phenolic compounds extraction yield. Therefore, two samples were analyzed, raspberry extracts pretreated with ultrasound-assisted extraction (UAEp) and conventional raspberry extraction (N-UAEp). Total phenolics content was higher in UAEp (10.7 GAE mg/g DM) than in N-UAEp (8.2 GAE mg/g DM). Total anthocyanins content was similar in both UAEp and N-UAEp, 7.2 C3GE mg/g DM and 7.4 C3GE mg/g DM, respectively. Antioxidant activity measured by ABTS and DPPH assays in UAEp and N- UAEp extracts were 14.4 AAE mg/g DM and 8.3 AAE mg/g DM, 8.2 AAE mg/g DM and 6.1 AAE mg/g DM, respectively. UAEp raspberry extract showed a significant difference in antioxidative activity compared to N-UAEp. Ultra-high performance liquid chromatography analysis was performed for both sample groups, three anthocyanins were identified and quantified as most prevalent: cyanidin 3-glucoside, cyanidin 3- sophoroside and pelargonidin 3-glucoside. Arizona methodology was performed for the purpose of fractioning phenolic compound content found in raspberries. NIH/3T3 and CaCo-2 cells were used to determine cytotoxic capacity, here 70 treatments were assessed on each cell line. Treatments were design according to sample treatment (UAEp and N-UAEp), fractions (Arizona methodology) and doses (400-0 μg/L). The majority of UAEp treatments displayed high viability in NIH/3T3 and low viability for CaCo- 2, compared to N-UAEp. Based on cytotoxicity results, 16 treatments were chosen to test antioxidant and anti-inflammatory activity. Antioxidant activity was determined by the Oxygen Radical Antioxidant Capacity assay (27.4 – 72.2 % Cellular Antioxidant Activity) in CaCo-2 cells. RAW 264.7 cells were induced inflammation by lipopolysaccharides exposure to assess anti-inflammatory potential of all 16 treatments (38.9 – 10.9 % nitric oxide inhibition). Most cytotoxic, antioxidant and anti-inflammatory results display a dose- dependent behavior. Ultrasound-assisted extraction showed a significant favorable effect for the optimal extraction of phenolic compounds from raspberries.