Static magnetic field mitigates Cadmium uptake and enhances secondary metabolite production in Matricaria chamomilla suspension cultures

Abstract

Matricaria chamomilla is a well-known medicinal plant rich in bioactive compounds. Cadmium (Cd) toxicity, a form of heavy-metal stress, can impede growth and secondary metabolite production. This work examined responses to Cadmium stress (0–10 µM) in chamomile cell-suspension cultures, focusing on total phenolic and flavonoid levels, DPPH radical scavenging capacity, PAL activity, gene expression, and Cadmium accumulation, and also explored the effect of pairing Cadmium with a static magnetic field (SMF, 4 mT for 1 h). Results showed that Cadmium stress increased phenolic and flavonoid contents, an effect amplified by SMF (219.6 and 67.14 µg mg⁻¹ DW at 7.5 µM Cd + SMF). SMF partially restored DPPH radical scavenging capacity of methanol-soluble compounds and limited Cadmium accumulation (181.2 vs. 251.5 µg mg⁻¹ DW at 10 µM). Additionally, SMF enhanced PAL gene expression and activity (0.48 U mg⁻¹ protein), indicating significant activation of the phenylpropanoid pathway. Electron microscopy (TEM) revealed that Cadmium induced damage to cell walls and organelles, whereas the combination of Cd + SMF partially alleviated these structural damages and reduced cellular Cadmium accumulation. These results suggest that a short SMF exposure can mitigate Cd uptake and stimulate the phenylpropanoid pathway in chamomile cells, offering a simple physical approach to enhance valuable secondary metabolites under metal stress.