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Background & objectives: The purpose of this study was to show the dose response relationship of anti-inflammatory effect of methylsulfonylmethane (MSM) on carrageenan induced rat paw edema as an acute model of inflammation.
Methods: A total of 54 male, Sprague-Dawley rats, weighing 180-190 g, were used. One hundred, 200, 400, 800 and 1200 mg/kg of MSM were administered intraperitoneally to the rats 30 minutes before induction of paw edema with injection of 0.1% carrageenan. Diclofenac was used as a control drug. Rats were divided into three groups: MSM, diclofenac and normal saline, and their paw tissue were collected for the study of inflammatory and oxidative markers (MDA, GSH, TNF-α and IL-1 β). The relationship between the different concentrations of MSM and decrease in rat paw edema was calculated using a simple Emax model.
Results: the ED₅₀ value for effect of MSM on carrageenan induced rat paw edema was 193±9.7 mg/kg. A significant reduction in paw edema following administration of MSM at 200, 400, 800 and 1200 mg/kg was observed, but statistical analysis did not reveal any significant reduction in paw edema after administration of 100 mg/kg. MSM did not show statistically significant difference from control group in tissue level of GSH, but it was able to decrease MDA level significantly. MSM was able to significantly alleviate IL-1 β and TNF-alpha tissue levels.
Conclusion: The recommended anti-inflammatory dosing range of MSM is 200-800 mg/kg for pharmacological studies in rats and the average appropriate dose is 400 mg/kg. Also, it seems that anti-inflammatory effect of MSM is more profound than its anti-oxidant effects.
 

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Background & objectives: Pentavalent antimonials are the first-line drugs for treatment of leishmaniasis, which have multiple side effects such as drug toxicity. Moreover, parasite resistance to these drugs is rising around the world. Second-line drugs, including Amphotericin B and pantamidine have also side effects and expensive for patients. According to the cytotoxic effects of paraquat, this study was conducted to evaluate the effect of paraquat on Leishmania major promastigotes and HUVECs viability.
Methods: A number of 2.5×10⁶ of Leishmania major promastigotes were treated in each well of 96 well plates with different concentrations of paraquat. Cells were incubated for 48 hours in 24 °C. MTT test was performed for evaluating paraquat impact on promastigotes. The absorbance was measured using a microplate reader at 570 nm.  The trypan blue staining assay was performed to evaluate the number of viable Leishmania major promastigotes following paraquat treatment. Furthermore, the effect of paraquat concentrations on HUVECs viability was evaluated under the cell culture condition.
Results: The results of the MTT test showed that increasing concentrations of paraquat could significantly reduce the viability and the number of Leishmania major promastigotes in comparison to control group (p<0.05). In this study, the IC₅₀ for Leishmania major promastigotes was calculated as 272.46 µg/ml. Trypan blue results were in line with the finding of MTT assay. Moreover, we found that HUVECs were susceptible to paraquat (IC₅₀=188.99 µg/ml).
Conclusion: Paraquat has a strong inhibitory effect on Leishmania major promastigotes and human endothelial cells. Although more comprehensive studies on the effects of the topical use of paraquat on Leishmania major lesions in animal model and its side effects are necessary.

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Background & objectives: Nonsteroidal anti-inflammatory drugs (NSAIDs) - induced peptic ulcer disease is a common gastrointestinal disorder affecting many people worldwide. Rosa canina L. is a member of Rosa species that has been widely used as an herbal medicine in many countries. Rosa canina has therapeutic effects against various disorders through its antioxidant, anti-inflammatory and cytoprotective properties. The aim of the present study was to evaluate the potential beneficial effect of Rosa canina on indomethacin-induced ulceration in mice.
Methods: Experiments were performed on male Swiss albino mice. Indomethacin (80 mg/kg, orally) was used to induce gastric ulceration. The extract of Rosa canina fruits (200 and 400 mg/kg/day) was given orally five days before the administration of indomethacin. Normal mice were used as a normal control group.
Results: Macroscopic evaluation of gastric mucosa revealed that indomethacin administration (80 mg/kg) produced apparent gastric mucosal ulcers, while pretreatment with Rosa canina (200 and 400 mg/kg) effectively protected gastric mucosa against indomethacin induced ulcers. Rosa canina significantly increased the level of glutathione (GSH) and decreased the levels of malondialdehyde (MDA) and myeloperoxidase (MPO) in the gastric tissues compared with those in the control group.
Conclusion: Oral treatment with the Rosa canina fruit extract decreased the gastric ulcer induced by indomethacin through antioxidant and anti-inflammatory mechanisms

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Background & objectives: Paraquat is a toxic herbicide that is widely used in many countries. Paraquat selectively accumulates in the lung tissue and leads to severe pulmonary injury through the oxidative and inflammatory processes. The plant Rosa canina L. has been used for long years as an herbal medicine throughout the world. Rosa canina L. is a member of Rosacea family and shows therapeutic effects against numerous disorders by its antioxidant and anti-inflammatory properties. The aim of this study was to evaluate the antioxidant effect of Rosa canina fruits on the paraquat induced lung injury in a mouse model.
Methods: Animal experiments were performed on male NMRI mice. Paraquat was injected at a single dose (20 mg/kg, ip) to induce pulmonary damage in mice. The extract of Rosa canina fruits (200 and 400 mg/kg/day, orally) administered by gavage for four days after the injection of paraquat. The treated mice were compared to normal mice as a control group. At the end of the experiment, lung tissue samples were collected for biochemical analysis.
Results: The results showed that administration of paraquat caused an oxidant-antioxidant imbalance in the lung tissue. However, treatment with Rosa canina increased the levels of glutathione (GSH) and catalase (CAT) antioxidants and decreased the levels of malondialdehyde (MDA) and myeloperoxidase (MPO) in the lung tissues compared with those in the paraquat group.
Conclusion: Treatment of paraquat-exposed mice with the extract of Rosa canina fruits improved oxidant-antioxidant balance in the lung tissue of mice. In other words, the present study demonstrated that Rosa canina has remarkable antioxidant effects against paraquat induced oxidative damage.