Evaluation of Homeopathic Dilutions on Cell Redox Homeostasis

Background: Redox homeostasis is crucial for cells, and it is well established that redox imbalance in favor of oxidant burden is a significant cause of several diseases. Any molecule or group of molecules that can help maintain cellular redox homeostasis is of potential interest and is defined as an antioxidant species. It has long been accepted that antioxidant compounds are molecules capable of scavenging reactive oxygen species (ROS) by monoelectronic reaction, but the concentrations that can be achieved in vivo cannot overcome the kinetic limitation of the chemical reaction. Only certain compounds, like glutathione, because of their reaction kinetics and high intracellular concentration, can react with ROS. On the contrary, it has been demonstrated in the last decades that most of these antioxidants provide cellular protection indirectly by enhancing cellular endogenous antioxidant defenses through a pro-oxidant signal. Here, we aimed to address the potential antioxidant capacity of different homeopathic dilutions of Arnica montana (AM) and Gelsemium sempervirens (GS) through their capacity to enhance endogenous antioxidant defences. Methods: We first analyzed in cellulo the radical-scavenging capacity of the homeopathic dilutions (3, 5, 9, 15, and 30CH) using electron paramagnetic resonance. Their antioxidant capacity was then investigated by comparing ROS production measured by fluorescence using H2DCFDA in SH-SY5Y cells pre-incubated with homeopathic dilutions or vehicle before and after menadione treatment, a potent ROS inducer. Results and Conclusion: The results clearly demonstrate a significant ability of AM 30CH compared with vehicle to protect cells from the toxicity of menadione after a 24-hour treatment, while pro-oxidant behavior was evidenced during the first 2 hours, underlining a classical antioxidant property. GS 15CH showed a mild endogenous antioxidant capacity after a 6-hour treatment, but this was not correlated to a pro-oxidant capacity, while a strong superoxide radical scavenging property was observed independently of the dilutions.