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Watercress (Nasturtium officinale), a freshwater aquatic plant in the Brassicaceae family, is characterized by its high content of specialized metabolites, including flavonoids, glucosinolates, and isothiocyanates. Traditionally, commercial cultivation is conducted in submerged beds using river or spring water, often on soil or gravel substrates. However, these methods have significant environmental impacts, such as promoting eutrophication due to excessive fertilizer use and contaminating water sources with pesticides. This study aimed to explore two emerging cultivation strategies, i.e., hydroponics and aquaponics, to grow watercress and evaluate its specialized metabolite content using an untargeted metabolomic approach. The goal was to characterize metabolic profiles, identify component variations, and assess changes in metabolite accumulation at two harvest times. Two culture systems (hydroponic and aquaponic) and two harvest stages (‘baby leaf’ and traditional harvest) were examined. The results revealed 23 key metabolites, predominantly glucosinolates and flavonoids, that significantly influenced the metabolic profile discrimination, with the aquaponic system yielding the highest diversity and relative abundance of metabolites (variable importance in the projection (VIP) > 1). Important condition-related compounds were identified via cross-validation (area under the curve (AUC) > 0.7), including isorhamnetin sophoroside–glucoside and gluconasturtiin at the traditional harvest in the hydroponic system and glucoarabin at the ‘baby leaf’ stage in the aquaponic system. These findings highlight the potential of aquaponic and hydroponic systems as sustainable alternatives for watercress cultivation, offering environmental benefits and enhanced metabolite quality.

Eruca sativa is a leafy vegetable widely consumed fresh in salads and recognized for the presence of bioactive compounds, such as glucosinolates (GLS) and flavonols. This plant is traditionally cultivated in soils but adapts well to soilless cultures, such as hydroponics and aquaponics. However, despite the good results in the literature on E. sativa cultivation in soilless systems, the influence of the culture systems and harvest time on the specialized metabolite-based chemical composition of E. sativa leaves is not entirely understood. Based on the above, this study aimed to evaluate the specialized metabolite composition of three different cultivation types, i.e., using soil (SCS), nutrient film technique (NFT)-based hydroponic (HCS), and aquaponic (ACS) culture systems, along three growing cycles, and collected at two commercial harvest times, i.e., 21 days after transplanting (DAT) to get early plant material, namely “baby leaf”, and 42 DAT as the traditional harvest time. The chemical composition was obtained by liquid chromatography coupled with mass spectrometry (LC-MS), and multivariate statistics supported the analysis of the whole dataset. The SCS was characterized to promote an important accumulation of two antioxidant flavonols, i.e., (kaempferol and isorhamnetin diglucopyranosides) in young leaves (21 DAT). The hydroponically-grown plants exhibited a smaller number of various compounds. The ACS-cultivated leaves accumulated indole-containing glucosinolates and a marker associated with harvest time, spirobrassinin, a cruciferous oxindoline phytoalexin. These findings constitute the first report of those compounds relevantly accumulated by the effect of soilless cultures and a starting point for further studies related to the metabolite regulation of E. sativa under hydroponics and aquaponics.

Integrated surveys of metabolic profiles and antioxidant capacity from Chenopodium quinoa have been limited and have particularly focused on an examination of seeds and leaves. According to this, the main aim of the present study was to address an evaluation of the antioxidant activity of crude ethanolic extracts from different plant parts (leaves, stems, roots, flowers, and seeds) harvested at different times during growth and processed by two distinct drying methods: Air-drying and freeze-drying. In order to characterize the resulting extracts, the total content of phenolics (TPC) and flavonoids (TFC) was then measured through the Folin−Ciocalteu method, while antioxidant capacity was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH•) free radical scavenging and ferric-reducing antioxidant power (FRAP) methods. Parallel to this evaluation, extracts were profiled by LC-DAD-ESI-MS. Data analysis was supported by statistics. Most of the extracts obtained from freeze-dried samples showed higher TPC values ranging from 6.02 to 43.47 milligram of gallic acid equivalents per gram of plant material and a TFC between 1.30 and 12.26 milligram of quercetin equivalents per gram of plant material. After statistical analysis, a low correlation between TPC and TFC values was observed regarding antioxidant capacity from DPPH and FRAP measurements of both drying methods. A multivariate analysis showed that antioxidant components and antioxidant capacity in C. quinoa changed during growth and between plant parts and drying methods. These changes need to be taken into consideration when comparing the production/accumulation of beneficial bioactive compounds in this pseudocereal.