Purpose: To investigate the effects of two elicitors, methyl jasmonat (MeJA) and silver nanoparticles (SNPs), on the production of secondary metabolite by Calendula officinalis L (marigold).

Methods: For the extract of the aerial part of the plant, membrane lipid peroxidation rate and 2, 2ˈdiphenylpicrylhydrazyl (DPPH) radical scavenging activity were assessed along with total anthocyanin, flavonoid, chlorophyll, carotenoids and saponin content. The effect of C. officinalis L extract with and without SNPs and MeJA on HeLa cell viability was also evaluated by methylthiazol tetrazolium (MTT) assay.

Results: The presence of SNPs and MeJA in marigold extract increased membrane lipid peroxidation but decreased DPPH radical scavenging activity. Anthocyanin and flavonoid content also decreased in all the treatments investigated. Exposure to SNPs decreased chlorophyll and carotenoid content in the plant by 30 - 50 %, while MeJA increased them. In comparison with the control group, treatment with 0.4 mM SNPs and 100 µM MeJA increased saponin content in the plants by up to 177 %. Exposure of HeLa cells to the extracts of marigold significantly reduced their viability and this reduction was more pronounced when the plants were treated with MeJA and SNPs.

Conclusion: Treatment of C. officinalis L. with SNPs and MeJA seems to be a simple and cost-effective method of improving the medicinal properties of this plant.