en Toxicology Toxicology پژوهشي Orginal research papers <p dir="ltr" style="text-align: justify;">The current study was done to investigate the preclinical safety and toxicology of <em>Althaea officinalis</em> extract as naturopathic medicine in common carp (<em>Cyprinus carpio</em>). Specimens were treated with 0 (control), 2.5, 5 and 10 g of marshmallow extract for 45 days. Plasma biochemical parameters were measured after 15 and 45 days. Total protein, albumin and globulin levels (<em>p</em><0.05) &nbsp;were significantly higher in the fish fed with 10 g <em>A. officinalis</em> extract than that in control groups on day 45. Although, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) activities significantly decreased (<em>p</em><0.05) in fish fed with <em>A. officinalis</em> extract on day 15. The use of the <em>A. officinalis</em> extract (10 g) led to a significant increase in AST, lactate dehydrogenase (LDH) and ALP activities and cholesterol levels on day 45 (<em>p</em><0.05)<a name="OLE_LINK49"></a><a name="OLE_LINK46"> and a significant </a>decrease in plasma glucose and cholesterol levels on day 15 (<em>p</em><0.05). There was no significant difference in glucose levels and creatine kinase (CK) activity between all treatments and the control group on day 45 (<em>p</em>>0.05). During the experimental period, triglyceride levels noticeably decreased in fish fed with 2.5 g of <em>A. officinalis</em> extract (<em>p</em><0.05). Although, administration of marshmallow extract up to 5 g per kg of feed did not show any side effect on fishes, the use of the <em>A. officinalis</em> extract (10 g) led to cytotoxicity and modifications in blood biochemical parameters of fish. Therefore, we recommend the use of the lower concentrations than 10 g <em>A. officinalis</em> extract in prospective clinical studies.&nbsp;&nbsp;</p> Biochemical parameters, Common carp, Marshmallow, Medicinal plants, pre-clinical study 613 629 http://jifro.ir/browse.php?a_code=A-10-1272-190&slc_lang=en&sid=1 V. Soleimany 100319475328460016604 100319475328460016604 No M. Banaee mahdibanaee@yahoo.com 100319475328460016605 100319475328460016605 Yes M. Mohiseni 100319475328460016606 100319475328460016606 No B. Nematdoost Hagi 100319475328460016607 100319475328460016607 No L. Mousavi Dehmourdi 100319475328460016608 100319475328460016608 No