Brassica sprouts exposed to microplastics: Effects on phytochemical constituents

Microplastics (MPs) can affect plant biomass, tissue composition, and root traits. However, the effects of MPs on the synthesis of secondary metabolites and on the accumulation of bioactive compounds remain poorly studied. The objective of this work was to analyze accumulation of bioactive compounds in broccoli and radish sprouts grown hydroponically in a substrate containing seven different toxic amounts (from very low to extremely high) of low-density polyethylene (PE). Radish was more severely affected by microplastic pollution than broccoli. The effect on the phytochemical composition was statistically significant in both species compared to control. In this aspect, glucosinolate (GSL) content was negatively affected by MPs decreasing from 182 to 124 mg 100 g^-1 at medium doses of MPs in broccoli, whereas these compounds drastically decreased from 253 to 151 mg 100 g^-1 at the same doses in radish. Anthocyanin content significantly increased until medium doses of MPs ranging from 6.28 to 11.44 mg 100 g^-1 in broccoli whereas in radish was from 2.44 to approximately 4 mg 100 g^-1. In addition, other morphological and physiological parameter were considered. The analysis of malondialdehyde (MDA) showed significant effects on broccoli and radish in all the MP treatments. The results revealed that high loads of MPs in the substrate affect growth parameters, lipid peroxidation rate estimated by MDA, and phytochemicals of broccoli and radish sprouts, with differences in response to MPs pollution and intensity between species.