Finding valuable bioactive components from Jerusalem artichoke (Helianthus tuberosus L.) leaf protein concentrate in a green biorefinery concept

Jerusalem artichoke is widely known for its inulin-enriched tubers. Recently the opportunity has been arisen to involve the whole plant in biorefinery concept due to its high lignocellulose biomass and tuber production. This paper focuses on the repeatedly harvestable green biomass of Jerusalem artichoke. Ultra-High Performance Liquid Chromatography-Electrospray Ionization/Mass Spectrometry (UHPLC-ESI-MS) was applied to identify the phytochemicals in Jerusalem artichoke leaf protein concentrate (JAPC) thermally extracted from green biomass of three clones, i.e., Alba, Fuseau and Kalevala. Amino acid and fatty acid profiles as well as yield of JAPC were also analyzed. The UHPLC-ESI-MS analyses showed that no toxic phytochemicals were identified in JAPC. The results revealed, also, that JAPC is not only essential-amino acids-rich but also contains substantial amounts of polyunsaturated fatty acids (66-68%) such as linolenic and linoleic acids. Linolenic acid represented 39-43% of total lipid content; moreover, the ratio between ω-6 and ω-3 essential fatty acids in JAPC was ∼0.6: 1. Using UHPLC-ESI-MS, the following hydroxylated methoxyflavones were for the first time identified in JAPC, i.e., dimethoxy-tetrahydroxyflavone, dihydroxy-methoxyflavone, hymenoxin and nevadensin. These compounds are medically important since they are referred to as anti-cancer, anti-inflammatory and antioxidants. Also, liquiritigenin - estrogenic-like compound - was identified in JAPC alongside the following terpenes, i,e., loliolide and dihydroactinidiolide. However, no remarkable differences of phytochemicals, fatty acids and amino acids composition were seen among Jerusalem artichoke clones. The green biomass of tested clones ranged between 5 to 5.6 kg m-2 and JAPC yield varied from 28.6 to 31.2 g DM kg-1 green biomass with total protein content, on average, of 33.3%. According to our knowledge, this paper is the first scientific report highlighting bioactive substances in JAPC such as PUFA phytochemicals. These results clearly prove that JAPC is a valuable product which can direct towards human and animal nutrition as well as it can serve as basic material for different industrial purposes.