Gold nanoparticle-conjugated rosemary compounds mitigate inflammation in human PBMCs

Rosemary ( Rosmarinus officinalis ) is renowned for its numerous pharmaceutical properties. Gold nanoparticles (GNPs), which possess unique electrochemical characteristics, have been demonstrated to influence various bioprocesses in plants. In this study, we hypothesized that GNPs could alter the biosynthesis pattern of valuable compounds in rosemary, ultimately affecting its anti-inflammatory properties. GNPs were synthesized using the sodium citrate method and validated through SEM and spectrophotometry. Rosemary plants were treated with 30 ppm GNPs for 24 and 48 h. qPCR analysis revealed that the 24-hour GNP treatment upregulated the expression of key enzymes involved in rosmarinic acid synthesis, including RAS, Co-enzyme A, and HPPR. Furthermore, gas chromatography-mass spectrometry (GC-MS) analysis of rosemary essential oil (REO) exposed to GNPs showed significant changes in at least 15 components. Additionally, the impact of REO treated with GNPs at three different doses (30, 60 ppm, and pure) on human peripheral blood mononuclear cells (PBMCs) under inflammatory conditions was assessed. Surprisingly, prolonged exposure to GNPs shifted PBMCs towards apoptosis and decreased the number of necrotic cells, as demonstrated by flow cytometry analysis. Our findings suggest that GNPs can modulate the composition of compounds present in REO, potentially opening new avenues for the production and purification of valuable compounds. Importantly, GNPs did not alter the anti-inflammatory effects of REO. However, 60 ppm REO exhibited significant anti-inflammatory properties in human PBMCs, positioning it as a potential candidate for nonsteroidal anti-inflammatory drugs (NSAIDs) with minimal side effects.