Chemical and Bioactive Features of Amaranthus caudatus L. Flowers and Optimized Ultrasound-Assisted Extraction of Betalains

The vibrant colours of many plants are due to secondary metabolites, such as nitrogen-containing compounds, where betacyanins included. These compounds can be found in Amaranthus caudatus L. that, their high nutritional benefits, have been overproduced, which leads the accumulation large amounts bio-residues. Among these bio-residues, flowers a very intense pink colour and present no economic value or subsequent destination exploited sources natural colouring agents (betacyanins). This work aimed at characterising flower’s extract terms bioactive molecules tocopherols, organic acids, but essentially betacyanins, order obtain agent. For extraction, ultrasound-assisted extraction (UAE) ideal conditions were obtained using Response Surface Methodology (RSM), allowing attainment an enriched yields purity. extracts analysed for potential, namely antioxidant, antimicrobial cytotoxic properties. From results, three isoforms tocopherols detected, ?-tocopherol (0.884 ± 0.003 mg/100 g dry weight (dw)) being most abundant one. Regarding oxalic (2.48 0.05 dw), shikimic (0.170 dw) traces fumaric acid found. Four identified quantified, namely: amaranthine (171 1 mg/g extract), isoamaranthine (38 betanin (1.6 0.1 mg/g), isobetanin (1.3 extract). also presented antioxidant activity with inhibition concentration (IC50 values) 29.0 0.4 ?g/mL 114 4 ?t 60 min 120 min, respectively oxidative haemolysis assay (OxHLIA) assay. interesting antibacterial minimum inhibitory concentrations ranging from 5 20 mg/mL against pathogenic bacteria revealed toxicity normal cells.