Bioactive Compounds and the Antioxidant Activity of Selected Vegetable Microgreens: A Correlation Study

In this study, the content of bioactive compounds and antioxidant activity was determined in five selected vegetable microgreens (daikon, i.e., Japanese radish; Chinese red radish; pea; beetroot; and onion). Total phenolics and chlorophylls were analyzed spectrophotometrically in all investigated microgreens. In addition, the content of betalains was determined spectrophotometrically in beetroot microgreens. HPLC analysis was used to identify and quantify individual phenolic compounds. The antioxidant activity of microgreens was determined by DPPH, ABTS and reducing power assays. The highest content of total phenolics, chlorophyll a and chlorophyll b was found in beetroot microgreens (639.85 mg GAE/100 g DW, 202.17 mg/100 g DW and 79.53 mg/100 g DW, respectively). In beetroot microgreens, the content of total betalains, betacyanins and betaxanthins was determined to be 57.27 mg/100 g DW, 43.58 mg BE/100 g DW and 13.68 mg VE/100 g DW, respectively. Among the investigated microgreens, beetroot microgreens showed the highest antioxidant activity, while pea microgreens exhibited the lowest antioxidant activity in all applied assays. The highest correlation was observed for the content of total phenolics and phenolic acids, as determined by HPLC analysis with antioxidant activity using all applied assays, indicating that these compounds were most important contributors to the antioxidant activity of the investigated vegetable microgreens.