Effect of Ferrum phosphoricum D12 on Mitochondrial Function and COX-2 Expression in Human Peripheral Blood Mononuclear Cells

Background: Ferrum phosphoricum D12 (FP D12) has both antioxidant and anti-inflammatory action with a proven therapeutic effect in the early stages of fever, inflammation, muscle fatigue, and anemia. However, experimental evidence for its molecular and cellular effects remains limited. Therefore, we aimed to investigate the effects of different concentrations of FP D12 on mitochondrial function and inflammation in human peripheral blood mononuclear cells (PBMCs). Methods: PBMCs isolated from healthy volunteers ( n = 12) were treated with two concentrations of FP D12 (0.0125 and 0.0250 mg/mL). Mitochondrial respiration was evaluated using the Seahorse XFp Analyzer, while mRNA expression of cyclooxygenase-2 (COX-2) and interleukin-1 β (IL-1β) was quantified via real-time PCR (qPCR). Results: Treatment did not affect basal respiration; however, PBMCs treated with FP D12 at 0.0250 mg/mL reached maximal respiration (MR) values of 16.94 ± 7.15 pmol/minute versus 5.96 ± 2.25 pmol/minute in controls ( p = 0.036) and exhibited increased spare respiratory capacity (SRC; 110.5 ± 41.14 vs. 76.66 ± 12.87, p = 0.0152). No significant differences were observed in proton leak, ATP production, or non-mitochondrial respiration. At the transcriptional level, FP D12 treatment led to a marked downregulation of COX-2 expression, demonstrating a statistically significant decrease at both tested concentrations (0.0125 mg/mL, p = 0.01; 0.0250 mg/mL, p = 0.03) compared with control cells. Though the reduction in IL-1β mRNA levels did not reach statistical significance, a downward trend was observed. Discussion: This study provides the first evidence that FP D12 enhances mitochondrial bioenergetic performance by suppressing inflammatory gene expression in human PBMCs. The increased MR and SRC suggest improved mitochondrial adaptability and resilience, potentially contributing to the compound’s protective effects against oxidative stress. Concurrently, the reduced COX-2 and IL-1β expression supports its anti-inflammatory potential. Conclusion: Our results suggest that FP D12 exerts a dual bioactive effect by stimulating mitochondrial respiration and reducing inflammation-related gene expression. These data support the potential use of FP D12 as a complementary therapeutic agent in conditions associated with acute inflammation.