Introduction According to the “silica hypothesis” formulated to explain homeopathy, the information of starting materials would be transferred to cells by silica nanoparticles detached from the glassware walls by serial dilution and agitation through epitaxy. We compared the biological activity, electrical current and silicon microparticle content (by means of scanning electron microscopy/energy-dispersive X-ray spectroscopy) of high dilutions (HDs) of arsenic prepared in plastic and glass vials to investigate the role of silica in their biological effects in vitro. Materials and Methods Co-cultures of macrophages and yeast (Saccharomyces cerevisiae) were treated with different HDs of arsenic prepared in plastic and glass vials. Macrophage morphology, phagocytosis index, nitric oxide (NO), and cytokine production were evaluated. Results Measurable amounts of silicon microparticles were detected only in the HDs prepared in glass vials, but ultra-centrifugation eliminated them. Specific and non-specific results were observed. Non-specific pro-inflammatory effects were seen in all dilutions prepared in plastic vials, including elevation of pro-inflammatory cytokines, NO and macrophage phagocytic index. Only the 200th centesimal dilution of arsenic produced specific decrease in interleukin-6 production in macrophages, and it was independent of the vial type or the presence of microparticles of silica in the medicine samples. The nature of the vials had an impact on the electric flow in the respective fluids. Conclusion The non-specific, pro-inflammatory effects might be attributed to organic residuals detached from the vials' plastic walls during manipulation. Instead, specific silica-independent effects of the homeopathic medicine can be attributed to the decrease of interleukin-6 after treatment with the 200th centesimal dilution of arsenic.

Mice bearing Leishmania (L) amazonensis infection and treated with Antimonium crudum (AC) 30cH presented significant reduction of the monocyte migration to the site of infection with clinical improvement. In vitro, the treatment of infected macrophages with AC 30cH produced inhibition of the parasite-induced peaks of CCL2 (a chemokine for monocytes migration) and inhibition of lysosome activity, explaining the results obtained previously in vivo. In the following studies, physical-chemical parameters of the remedy and respective controls were evaluated, to search for a correlation with the former described biological effects. The study of polarity changes in different water-based dilutions of AC using Cartwright´s method, revealed dilution-dependent variations in the absorbance of three solvatochromic dyes ET 33, BDN and methylene Violet (MV), used as “probes” to evaluate the dipole features of the medicine. The electrical activity of the homeopathic preparations appears to be dilution-dependent and related to their biological effects. Further experiments were performed using samples of the supernatant of infected macrophages after 96 hours of incubation with AC in different dilutions. These samples were processed using the same procedures as used for the original medicines and were analyzed by MV method. All tested potencies presented a sharp increase of absorbance at 580 nm, in relation to all controls (supernatant from untreated cells and cells treated with succussed water), as performed by one-way ANOVA, being F = 176.208; p = 0.001 and ?2 = 0.988. This results strongly suggest that biological systems could amplify the electric signal and the following changes in the medium polarity.