Antileishmanial activity of Urtica dioica extract against zoonotic cutaneous leishmaniasis.

BACKGROUND: Neglected parasitic diseases (NTDs) like cutaneous leishmaniasis (CL) have caused high mortality and morbidity rate in developing countries. This disease is considered as one of the six major tropical diseases, and has a great importance in HIV infected individuals as an opportunistic infection in those areas that both infections are endemic. This study evaluated the therapeutic effects of the Urtica dioica L (U. dioica) aqueous extract as an anti-leishmanial herbal drug in-vitro and in-vivo, and in addition to that, evaluated two vital immune system cytokines including gamma interferon (IFN-γ) and interleukin-4 (IL-4) plus nitric oxide (NO) and arginase activity against Leishmania major (L. major) infected mice. METHODOLOGY/PRINCIPAL FINDINGS: In-vitro anti-leishmanial activity of U. dioica aqueous extract was determined using MTT method and also Parasite Rescue Transformation Assay. Also, the footpad lesion size and parasite load in BALB/c mice infected with L. major were quantified for in-vivo assessment. Furthermore, for evaluating the immune responses, the levels of IFN-γ, IL-4, NO and arginase were measured in the BALB/c mice. These results indicated that U. dioica extract significantly reduced the L. major promastigotes viability. According to the in-vitro cytotoxicity assay of the extract on Leishmania parasites (CC50) and infected macrophages (EC50), the extract had no toxicity to the macrophages, however it efficiently killed the L. major amastigotes. In addition, the lesion size, parasite load, IL-4, and ARG were decreased in the treated infected mice, however IFN-γ and NO were significantly increased. CONCLUSIONS/SIGNIFICANCE: This study established satisfactory results in Leishmania parasite clearing both in-vivo and in-vitro. Therefore, U. dioica extract can be considered as an effective and harmless herbal compound for killing the parasite without toxicity to the host macrophages. Furthermore, it also can treat the CL by switching the mouse immune response towards a cell-mediated response (Th1); hence, it may be identified as a perfect therapeutic herbal drug for CL treatment.

Mechanism of action of stinging nettles.

OBJECTIVE: Inadvertent exposure to the ubiquitous weed, Urtica dioica, called "stinging nettles" produces an immediate stinging and burning sensation on the skin. This investigation evaluates the structural effect that stinging nettle spicules may have on the clinical manifestation of these symptoms. This hypothesis was investigated by exposing murine skin to stinging nettles and then evaluating the skin using electron microscopy. It was hypothesized that the mechanism of action of stinging nettles is both biochemical and mechanical, which may have clinical significance regarding treatment for acute exposure. METHODS: Fresh post-mortem dermis samples from the carcasses of genetically modified hairless mice were brushed under the stem and leaf of a stinging nettle plant, mimicking the clinical method of exposure a patient might experience. Another set of mouse skin samples was obtained but not exposed to the nettles. Both sets of skin samples were imaged with scanning electron microscopy. RESULTS: The skin samples that were not exposed to nettle leaves were uniform, with occasional striated hairs on the skin surface and no nettle spicules. The skin samples exposed to nettle leaves showed many smooth nettle spicules piercing the skin surface. A few spicules retained their bases, which appear empty of any liquid contents. CONCLUSIONS: The mechanism of action of stinging nettles dermatitis appears to be both biochemical and mechanical. Impalement of spicules into the skin likely accounts for the mechanical irritation in addition to the known adverse chemical effects of stinging nettles. Further investigation of treatment modalities is warranted.

The uncertainty of the toxic effect of stings from the Urtica nettle on hunting dogs.

This paper questions the effect of the sting from the Urtica species of nettle on hunting dogs, particularly in the US. Research in this area is limited and is reflected in the wide use of a particularly unsound literature reference on the subject. A general account is given of which types of "nettle" plant have a toxic sting, how the mechanism of the sting works, and the toxic substances it contains. The effects experienced by hunting dogs appear to represent a condition other than contact urticaria, which is normall the result of being stung by nettles (Urticas in particular). The possibility is discussed that the signs were caused by another plant, also commonly labelled a nettle, or that possibly they were caused by other than the direct stinging of soft tissues. Further research should be done on the toxic elements in the sting of Urtica chamaedryoides, indicated in some literature as the "guilty" plant.