An evaluation of the antioxidant properties of Arthrospira maxima extracts obtained using non-conventional techniques

In last decade, Arthrospira has been considered an important source of high-quality nutrients and therefore it is suggested as a suitable functional food. In this work, Arthrospira maxima extracts were obtained in different conditions, varying solvents, time, temperature and extraction techniques, such as microwave- and ultrasound-assisted extraction (MAE and UAE, respectively). Total carotenoids and polyphenols were measured using UV determination tests, while HPLC analyses were carried out to identify the main compounds. Antioxidant activity of A. maxima extracts was evaluated in vitro by Trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC). Acetone/hexane and acetone extracts were in general the richest in β-carotene and total carotenoids (20–33 and 40–70 mg/g extract, respectively). The best results were obtained under MAE at 90 °C for 10 min with the highest yields in terms of total carotenoids and β-carotene (>2.6 and >1.0 mg/g algae, respectively). MAE with ethanol (90 °C, 30 min) allowed maximization of total carotenoids and β-carotene amount (3.12 and 1.37 mg/g algae, respectively) thanks to the very good extraction yields. Moreover, this technique gave an extract with the highest antioxidant activity (812 and 519 µmol Trolox/g extract for TEAC and ORAC, respectively). Surprisingly, polyphenols were not detected in A. maxima extracts analyzed by HPLC.