Differential effects of Zincum metallicum on cell models.

Introduction: Zinc is an essential trace element necessary for life. Traditional and complementary medicines use zinc-based formulations to treat different classes of diseases. Basic research on homeopathic preparations of zinc are rare and there are a few published clinical cases describing its effects on patients. The use of cell-based models in drug screening is a reliable source of evidence.

Methods: We sought to investigate experimental end-points using cell-based models to determine the effects of dilutions of Zincum metallicum prepared according to the Brazilian Homeopathic Pharmacopoeia. Murine RAW 264.7 macrophages and melanoma B16-F10 cell lines were cultured according to standard procedures. Cells were treated with either 5c, 6c or 30c Zincum metallicum and control cells with its respective vehicle (5c, 6c, or 30c Lactose). Macrophage activation by CD54 immunolabeling and intracellular reactive oxygen species (ROS) using DCFH-DA (2,7-dichlorodihydrofluorescein diacetate) were detected by flow cytometry. Phagocytic capacity (endocytic index) was quantified by light microscopy. Features of melanoma cells were analyzed by colorimetric assays to determine melanin content and cell proliferation rate. All obtained data were submitted to normality test followed by statistical analysis.

Results: Zincum metallicum 6c shifted high ROS-producing macrophages to a low ROS-producing phenotype. Macrophage CD54 expression was increased by Zincum metallicum 5c. No changes in endocytic index were observed. Melanoma cells were not affected by any treatment we tested.

Conclusions: Differing responses and non-linearity were found on macrophages challenged with Zincum metallicum at high dilutions. No changes in melanoma cells were observed. Customised assays using target cells can be useful to investigate high-dilution effects. Other cell types and conditions should be explored.