Journal of Medicinal Plants Biotechnology

Abstract Introduction and Objective: Medicinal plants, as valuable sources of secondary metabolites, play a vital role in various industries. However, the natural production of these compounds is often limited. This review article aims to systematically examine the role and mechanisms of action of nanoparticles (including metallic, non-metallic, and carbon types) as novel elicitors for enhancing the production of secondary metabolites in medicinal plants.
Method and Theoretical Principles: The foundation of this review is based on the analysis of existing scientific evidence, which indicates that nanoparticles activate plant defense signaling pathways by inducing mild oxidative stress and generating reactive oxygen species. This process, in turn, leads to the modulation of key gene expression and the regulation of enzyme activities involved in the biosynthesis of secondary metabolites.
Results: Nanoparticles boost biosynthesis of phenols (2.3‑fold), flavonoids (80%), alkaloids, and essential oils (230%). For instance, essential oil in yarrow rose by 230% and silymarin in milk thistle by 75%. This review covers the shared and distinct mechanisms of these nano‑elicitors in various plants.
Conclusion: In summary, nanoparticles represent a promising and powerful strategy for the sustainable enhancement of the production of plant metabolites with high commercial value. The future perspective of this field includes optimizing the type, size, and concentration of nanoparticles for specific species, more detailed investigation of signaling pathways at the molecular level, and comprehensive assessment of the safety and regulations associated with the use of this technology in agriculture and industry.

Abstract To investigate the effect of proline and gamma-aminobutyric acid on the quantitative and qualitative traits of medicinal plant chamomile (Matricaria chamomilla L.) under water deficit stress, an experiment was conducted according to split plots design with a completely randomized block arrangement with four replications during the spring and summer of 2024 in the research greenhouse at the University of Zanjan. The main factor consisted of two irrigation levels (70 and 100% of field capacity) and the subplots included foliar applications of two levels of proline (0.5 and 1 mM), gamma-aminobutyric acid (0.5 and 1 mM) and control treatment (distilled water).
The results showed that the highest chlorophyll a content (1.40 mg/g fresh weight) was achieved under 100% field capacity irrigation combined with 1 mM proline. Foliar application of 0.5 mM proline under 70% irrigation level resulted in the highest phenolic content (4.78 mg gallic acid/g dry weight) and the greatest total antioxidant activity (51.75%). The maximum flavonoid content (1.49 mg quercetin/g dry weight) was observed with 0.5 M GABA treatment. Additionally, the highest thousand-seed weight (148 mg) was recorded under full irrigation (100% field capacity) with 1 mM proline, compared to the control. Overall, the combined application of 0.5 mM proline and GABA was most effective in mitigating the adverse effects of drought stress on chamomile.