Evaluation of curcumin and CM11 peptide alone and in combination against amastigote form of Iranian strain of L. major (MRHO/IR75/ER) in vitro.

Curcumin (diferuloylmethane) is the main phytochemical of Curcuma longa Linn, an extract of the rhizome turmeric. For thousands of years, turmeric among other natural products has been used as a dietary spice and as a medicinal plant in Asian countries. The present study reports the leishmanicidal activity of curcumin in different concentrations (10 µM, 20 µM, 40 µM). It is also showing the effect of CM11 peptide (8 µM) alone and in combination with curcumin (10 and 20 µM) as a leishmanicidal drug. The experiments were performed with the amastigote form of Leishmania major (MRHO/IR/75/ER) in vitro and the leishmanicidal activity was analyzed after 12 and 24 h of incubation by Giemsa and DAPI staining. Further investigation was done by using semi-quantitative PCR with new designed common primer pair derived from an 18S rRNA gene belonging to the L. major and mouse, which amplified the above-mentioned gene segments simultaneously with different PCR product size. Our findings showed that curcumin had leishmanicidal activity in a dose and time-dependent manner and its lowest effective dose was at concentrations of 40 µM afetr12 h and 10 µM after 24 h. The IC50 value of curcumin against amastigote forms of L. major was 21.12 µM and 11.77 µM after 12 and 24 h, respectively. Treatment of amastigote form with CM11 (8 µM) alone and in combination with curcumin (10 µM and 20 µM) showed less leishmanicidal activity. Interestingly, CM11 in combination with curcumin (10 µM and 20 µM) had even less leishmanicidal effect compared to curcumin alone in the same concentrations (10 µM and 20 µM). The semi-quantitative PCR analysis confirmed the data achieved by Giemsa and DAPI staining and showed that curcumin reduced the PCR product derived from amastigote form in concentration and time-dependent manner compared to the genome of the host cells.

Efficacy of lapachol on treatment of cutaneous and visceral leishmaniasis.

Leishmaniasis is one of the most important neglected diseases worldwide. It is a life-threatening disease and causes significant morbidity, long-term disability, and early death. Treatment involves disease control or use of intervention measures, although the currently used drugs require long-lasting therapy, and display toxicity and reduced efficacy. The use of natural products isolated from plants, such as lapachol, an abundant naphthoquinone naturally occurring in South American Handroanthus species (Tabebuia, Bignoniaceae), is a promising option for the treatment of leishmaniasis. In this study, we investigated the leishmanicidal activity of lapachol in vitro and in vivo against Leishmania infantum and L. amazonensis, causative agents of visceral and cutaneous leishmaniasis, respectively. Low cytotoxicity in HepG2 cells (3405.8 ±â€¯261.33 µM), good anti-Leishmania activity, and favorable selectivity indexes (SI) against promastigotes of both L. amazonensis (IC50 = 79.84 ±â€¯9.10 µM, SI = 42.65) and L. infantum (IC50 = 135.79 ±â€¯33.04 µM, SI = 25.08) were observed. Furthermore, anti-Leishmania activity assays performed on intracellular amastigotes showed good activity for lapachol (IC50 = 191.95 µM for L. amazonensis and 171.26 µM for L. infantum). Flow cytometric analysis demonstrated that the cytotoxic effect of lapachol in Leishmania promastigotes was caused by apoptosis-like death. Interestingly, the in vitro leishmanicidal effect of lapachol was confirmed in vivo in murine models of visceral and cutaneous leishmaniasis, as lapachol (25 mg/kg oral route for 24 h over 10 days) was able to significantly reduce the parasitic load in skin lesions, liver, and spleen, similar to amphotericin B, the reference drug. These results reinforce the therapeutic potential of lapachol, which warrants further investigations as an anti-leishmaniasis therapeutic.