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Article

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

1
Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal
2
Departamento de Nutrición y Ciencia de los Alimentos, Facultad de Farmacia, Universidad Complutense de Madrid (UCM), Pza Ramón y Cajal s/n, E-28040 Madrid, Spain
*
Authors to whom correspondence should be addressed.
Academic Editors: Antonio De Haro Bailón and Fernando Cámara-Martos
Foods 2021, 10(4), 779; https://doi.org/10.3390/foods10040779
Received: 2 March 2021 / Revised: 29 March 2021 / Accepted: 30 March 2021 / Published: 5 April 2021
(This article belongs to the Special Issue Nutraceutical Components of Plants and Plant Seeds)
The vibrant colours of many plants are due to secondary metabolites, such as nitrogen-containing compounds, where betacyanins are included. These compounds can be found in plants such as Amaranthus caudatus L. that, due to their high nutritional benefits, have been overproduced, which leads to the accumulation of large amounts of bio-residues. Among these bio-residues, the flowers which have a very intense pink colour and present no economic value or subsequent destination can be exploited as sources of natural colouring agents (betacyanins). This work aimed at characterising the flower’s extract in terms of bioactive molecules such as tocopherols, organic acids, but essentially in terms of betacyanins, in order to obtain a natural colouring agent. For the extraction, ultrasound-assisted extraction (UAE) ideal conditions were obtained using the Response Surface Methodology (RSM), allowing the attainment of an enriched extract of betacyanins in high yields and purity. The obtained extracts were analysed for their bioactive potential, namely antioxidant, antimicrobial and cytotoxic properties. From the obtained results, three isoforms of tocopherols were detected, β-tocopherol (0.884 ± 0.003 mg/100 g dry weight (dw)) being the most abundant one. Regarding the organic acids, oxalic (2.48 ± 0.05 mg/100 g dw), shikimic (0.170 ± 0.003 mg/100 g dw) and traces of fumaric acid were found. Four betacyanins were identified and quantified, namely: amaranthine (171 ± 1 mg/g extract), isoamaranthine (38 ± 1 mg/g extract), betanin (1.6 ± 0.1 mg/g), and isobetanin (1.3 ± 0.1 mg/g extract). The obtained extract also presented antioxidant activity with inhibition concentration (IC50 values) of 29.0 ± 0.4 μg/mL and 114 ± 4 μg/mL for Δt of 60 min and 120 min, respectively in the oxidative haemolysis inhibition assay (OxHLIA) assay. The obtained extract also presented an interesting antibacterial activity with minimum inhibitory concentrations ranging from 5 to 20 mg/mL against pathogenic bacteria and revealed no toxicity for normal cells. View Full-Text
Keywords: Amaranthus caudatus L.; bioactive compounds; betacyanins; natural colorants; extraction process optimisation Amaranthus caudatus L.; bioactive compounds; betacyanins; natural colorants; extraction process optimisation
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MDPI and ACS Style

Roriz, C.L.; Xavier, V.; Heleno, S.A.; Pinela, J.; Dias, M.I.; Calhelha, R.C.; Morales, P.; Ferreira, I.C.F.R.; Barros, L. Chemical and Bioactive Features of Amaranthus caudatus L. Flowers and Optimized Ultrasound-Assisted Extraction of Betalains. Foods 2021, 10, 779. https://doi.org/10.3390/foods10040779

AMA Style

Roriz CL, Xavier V, Heleno SA, Pinela J, Dias MI, Calhelha RC, Morales P, Ferreira ICFR, Barros L. Chemical and Bioactive Features of Amaranthus caudatus L. Flowers and Optimized Ultrasound-Assisted Extraction of Betalains. Foods. 2021; 10(4):779. https://doi.org/10.3390/foods10040779

Chicago/Turabian Style

Roriz, Custódio L., Virginie Xavier, Sandrina A. Heleno, José Pinela, Maria I. Dias, Ricardo C. Calhelha, Patricia Morales, Isabel C.F.R. Ferreira, and Lillian Barros. 2021. "Chemical and Bioactive Features of Amaranthus caudatus L. Flowers and Optimized Ultrasound-Assisted Extraction of Betalains" Foods 10, no. 4: 779. https://doi.org/10.3390/foods10040779

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