In vitro and ex vivo evaluation of hydroalcoholic tobacco leaf extract as an anti-leishmanial agent against Leishmania major: A comparative study with Glucantime.

• This study demonstrates the potent in vitro and ex vivo anti-leishmanial effects of hydroalcoholic Nicotiana tabacum (tobacco) extract against Leishmania major. • The extract exhibited dose- and time-dependent reductions in promastigote mortality and amastigote infection rates, with efficacy comparable to Glucantime at higher concentrations. • These findings suggest that Nicotiana tabacum extract could serve as a promising natural alternative or adjunctive therapy for leishmaniasis, particularly in drug-resistant cases. Leishmaniasis, caused by protozoa of the genus Leishmania , remains a significant public health challenge, with Leishmania major as a predominant species in cutaneous leishmaniasis in Iran. Conventional treatments, including Glucantime, are hindered by drug resistance and adverse effects, highlighting the need for effective natural alternatives. This study investigates the in vitro and ex vivo anti-leishmanial effects of hydroalcoholic tobacco leaf extract (Nicotiana tabacum) against L. major. A 70 % hydroalcoholic extract of tobacco leaves was prepared and tested at concentrations of 12.5, 50, 100, and 200 µg/mL. In vitro assays evaluated promastigote mortality, while ex vivo assays assessed macrophage infection rates. Glucantime served as the positive control. Evaluations were conducted at 24, 48, and 72 h, with data analyzed using one-way ANOVA and Tukey's post-hoc test. The tobacco extract demonstrated a dose- and time-dependent reduction in promastigote mortality and amastigote infection rates. At 200 µg/mL, its efficacy was comparable to 100 µg/mL Glucantime, particularly after 72 h. Higher extract concentrations significantly reduced both parasite viability and macrophage infection rates, suggesting its potential as a potent anti-leishmanial agent. Hydroalcoholic tobacco leaf extract shows promising anti-leishmanial activity in vitro and ex vivo, suggesting its potential as a natural alternative to conventional treatments like Glucantime. Further in vivo studies are needed to confirm these findings and explore its use in leishmaniasis therapy, particularly in cases of drug resistance. [ABSTRACT FROM AUTHOR]