This study aimed to investigate the performance of accelerated solvent extraction (ASE) as a green approach for the recovery of polyphenols and pigments from wild nettle leaves (NL). ASE was operated at different temperatures (20, 50, 80 and 110 °C), static times (5 and 10 min) and cycle numbers (1–4) using ethanol (96%) as an extraction solvent. In order to compare the efficiency of ASE, ultrasound assisted extraction (UAE) at 80 °C for 30 min was performed as a referent. Polyphenol and pigment analyses were carried out by HPLC and antioxidant capacity was assessed by ORAC. Seven polyphenols from subclasses of hydroxycinnamic acids and flavonoids, along with chlorophylls a and b and their derivatives and six carotenoids and their derivatives were identified and quantified. Chlorogenic acid was the most abundant polyphenol and chlorophyll a represented the dominant pigment. ASE conditions at 110 °C/10 min/3 or 4 cycles proved to be the optimal for achieving the highest yields of analyzed compounds. In comparison with UAE, ASE showed better performance in terms of yields and antioxidants recovery, hence delivering extract with 60% higher antioxidant capacity. Finally, the potential of NL as a functional ingredient from natural sources can be successfully accessed by ASE.

Brassica oleracea var. acephala production and seed selection in the Mediterranean region is traditionally limited to private, family needs or small enterprises. In recent years it became popular, especially in the US, and known as a superfood due to the presence of specialized metabolites associated with health benefits, mainly from polyphenols, glucosinolates, and carotenoids groups. With the increasing popularity of this plant, there is a growing interest in its commercial production. Therefore, in the present work we aimed to study how seed origin influences the content of specialized metabolites in B. oleracea var. acephala. We grew plants from six different seed producers, in a hydroponic system under controlled conditions, and determined seed germination percentage, morphological characteristics, pigments, polyphenols, glucosinolates, and carotenoids content, as well as antioxidant activity. Seed origin influenced germination percentage, yield, and slightly morphological characteristic, but did not influence pigments, total polyphenols, phenolic acids, glucosinolates, and carotenoids content. However, content of flavonoids, ferulic, sinapinic, and, consequently, antioxidant activity was slightly different.