Abstract
Opuntia stricta var. Dillenii’s prickly pears are an underutilized fruit with a high content of betalains and phenolic compounds that could bring potential health benefits for humans. The aim of this study is the optimization of the “green” extraction of betalains and phenolic compounds from Opuntia stricta var. Dillenii’s whole fruits by ultrasound-assisted extraction (UAE), using a response surface methodology (RSM) by a central composite design (CCD) in order to obtain extracts rich in betalains and phenolic compounds with proven biological activities. For UAE optimization, the extraction temperature (20–50 °C), the amplitude (20–50%) and the ethanol volume in extraction solvent (15–80%, v/v) were selected as independent variables. All combinations were conducted at 2, 5, 10, 20 and 30 min to determinate the time effect. The betalain and phenolic compound content in Opuntia stricta var. Dillenii’s whole fruits and UAE extracts were identified by HPLC-DAD-ESI/MS and HPLC-DAD-MS/QTOF and the antioxidant (ORAC method) and the anti-inflammatory (hyaluronidase inhibition method) in vitro biological activities also were determined. The most efficient extraction time was 5 min and the best UAE parameter combination was 50% amplitude, 15% ethanol in solvent (ethanol/water, 15/85, v/v) and 20 °C temperature, obtaining 10.06 ± 0.10 mg of total major betalains/g dry weight, 2.32 ± 0.08 mg of piscidic acid/g dry weight and 0.38 ± 0.00 mg of total major flavonoids/g dry weight. All applied UAE combinations significantly improved the in vitro bioactive activities (antioxidant and anti-inflammatory) of the Opuntia stricta var. Dillenii’s extracts compared to the bioactivities of the extracts obtained by standard homogenization processes.
Highlights
In Spain, they grow in different regions, such as the Canary Islands, Murcia, Almeria, among other places
The main production of prickly pears occurs in the Canary Islands [4]
Piscidic acid was purified from prickly pear peels using a semi-preparative high-performance liquid chromatography (HPLC) reported by García-Cayuela et al [3]
Summary
L Mill.) are originally from Mexico [1] but due to their capacity to grow in arid areas, they are localized in different areas, such as Spain, Italy, India and Africa [2,3]. In Spain, they grow in different regions, such as the Canary Islands, Murcia, Almeria, among other places. The main production of prickly pears occurs in the Canary Islands [4]. Opuntia spp. has more than 200 species [2], being one of the most abundant genera within the Cactaceae family [5]. There are wild species, such as Opuntia stricta var. That extensively grow in the Canary Islands, Antioxidants 2021, 10, 1786.
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