Synergistic effects of plant growth regulators and fe₃o₄ nanoparticles on in vitro organogenesis and bioactive compound production in hypericum perforatum

This study investigated the combined effects of plant growth regulators (2,4-D and kinetin) and iron oxide nanoparticles (Fe₃O₄-NPs) on in vitro morphogenesis and secondary metabolite production in Hypericum perforatum L. The optimized treatment [2,4-D (0.5 mg/L) + kinetin (2 mg/L) + Fe₃O₄-NPs (4 mg/L)] significantly enhanced growth parameters, showing increases of 59.6% in plant height, 114.0% in root length, and 180.0% in shoot number, as well as a 198.3% increase in callus fresh weight compared with the control. This combination also improved regeneration efficiency (50.85%) and increased hypericin content by 66.6%. GC-MS profiling revealed high levels of hypericin, hyperforin, β-patchoulene, and hexadecanol, accounting for 93.36% of the total peak area, while total phenolic and flavonoid contents increased by up to 80.1%. These findings demonstrate the synergistic role of PGRs and Fe₃O₄-NPs in enhancing both organogenesis and bioactive compound accumulation, providing a promising strategy for the biotechnological improvement of medicinal plants.