Crop Productivity, Phytochemicals, and Bioactivities of Wild and Grown in Controlled Environment Slender Amaranth (Amaranthus viridis L.)

Amaranthus viridis L. is a wild edible plant that occasionally is cultivated as an alternative crop because of its interest as a functional food and its adaptation to high-saline soils. In this work, leaves from A. viridis were compared with their grown in controlled environment (GCE) counterparts in a soilless system at electrical conductivities (EC) and different light exposures for assessing growth parameters, moisture, total phenolic and total flavonoid content, phenolic compound profiles, vitamin C, antioxidant activity, and antiproliferative activity against the HT–29 human colorectal cancer cell line. The highest biomass production was obtained using EC of 2.5 dS m⁻¹ and the AP67 Milk LED lamp. Vitamin C in wild samples ranged from 83.1 to 104.9 mg 100 g⁻¹ fresh weight (fw), and in GCE ones, it ranged from 112.3 to 236.7 mg 100 g⁻¹ fw. Measured by the DPPH and ABTS assays, the antioxidant activity was higher in wild than in GCE plants: the ranges for wild samples were in the 1.8–4.9 and 2.0–3.9 mmol of Trolox Equivalent (TE) 100 g⁻¹ dry weight (dw) ranges, and for GCE ones in the 1.3–1.9 and 1.5–2.2 mmol TE 100 g⁻¹ dw ranges, respectively. As for phenolic compounds, in wild samples, the range was from 14.65 to 22.70 mg 100 g⁻¹ fw, and these amounts were much higher than those found in their GCE counterparts, in which the range was from 2.58 to 5.95 mg 100 g⁻¹ fw. In wild plants three compounds, namely trans-p-coumaric acid, isorhamnetin–3–O–glucoside, and nicotiflorin, accounted for more than half of the total quantified phenolic compounds. The MTT assay revealed concentration- and time-dependent inhibitory effects on HT–29 cells for all checked extracts. Cancer cells were less influenced by extracts from GCE plants, which showed higher GI₅₀ compared to wild plants. This work improves knowledge on the growth parameters, phytochemical profiles, and biological activities of wild and GCE A. viridis.