en Special Issue: “Leishmaniasis” Special Issue: “Leishmaniasis” پژوهشي Research <span style="font-size:12pt"><span style="line-height:150%"><span calibri="" style="font-family:"><b><span new="" roman="" style="font-family:" times="">Background:</span></b><span new="" roman="" style="font-family:" times=""> Pentavalent antimonial agents remain the primary therapeutic option for leishmaniasis; however, accumulating evidence highlights significant adverse effects, toxicity concerns, and emerging drug resistance associated with these compounds. Accordingly, the exploration of alternative therapeutic agents, particularly from natural sources, has gained increasing attention. The present study aimed to investigate the in vitro antileishmanial activity of <i>Calotropis procera</i> extract against both promastigote and amastigote forms of <i>Leishmania major</i>.</span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:150%"><span calibri="" style="font-family:"><b><span new="" roman="" style="font-family:" times="">Methods:</span></b><span new="" roman="" style="font-family:" times=""> Methanolic extract of <i>C. procera</i> flowers was obtained through the maceration technique. The antiproliferative activity of the extract on promastigotes was quantified using the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to assess cell viability and growth inhibition.</span></span></span></span><br> <span style="font-size:12pt"><span style="line-height:150%"><span calibri="" style="font-family:"><span style="color:#000000;"><b><span new="" roman="" style="font-family:" times="">Results:</span></b></span><a name="_Hlk229420678"><span style="color:#000000;"><span new="" roman="" style="font-family:" times=""> MTT assay findings demonstrated that <i>C. procera</i> extract markedly inhibited the proliferation of <i>L. major</i> promastigotes. The calculated IC₅₀ value for the extract alone was 387.91 &mu;g/mL, whereas the combination of <i>C. procera</i> extract with meglumine antimoniate exhibited enhanced inhibitory activity, yielding an IC₅₀ value of 211.26 &mu;g/mL.</span></span></a></span></span></span><br> <span style="font-size:12pt"><span style="line-height:150%"><span calibri="" style="font-family:"><b><span new="" roman="" style="font-family:" times="">Conclusion:</span></b><span new="" roman="" style="font-family:" times=""> The observed inhibitory effects suggest that <i>C. procera</i> possesses promising antileishmanial properties and may represent a potential natural candidate for the development of alternative therapeutic strategies against leishmaniasis.</span></span></span></span><br> &nbsp; Amastigote, Promastigote, Calotropis procera, Leishmania major, Extract 0 0 http://rmm.mazums.ac.ir/browse.php?a_code=A-10-1466-1&slc_lang=en&sid=1 Hadi Mirahmadi hmirahmadi59@gmail.com 100319475328460013685 100319475328460013685 Yes Clinical Immunology Research Center, Zahedan University of Medical Sciences, Zahedan, Iran. Ahmad Mehravaran ahmadmehravaran55@gmail.com 100319475328460013686 100319475328460013686 No Infectious Diseases and Tropical Medicine Research Center, Research Institute of Cellular and Molecular Science in Infectious Diseases, Zahedan University of Medical Sciences, Zahedan, Iran Abbas Safdari Adimi abbas.saf1347@gmail.com 100319475328460013687 100319475328460013687 No Infectious Diseases and Tropical Medicine Research Center, Research Institute of Cellular and Molecular Science in Infectious Diseases, Zahedan University of Medical Sciences, Zahedan, Iran