A Novel Sterol Isolated from a Plant Used by Mayan Traditional Healers Is Effective in Treatment of Visceral Leishmaniasis Caused by Leishmania donovani

Abstract

*Corresponding Author: Phone: (614) .edu. Δ Author Contributions: G.G., K.J.P., and D.A. contributed equally to this work Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsinfecdis.5b00081. Procedures and spectral data for the stepwise synthesis of pentalinonsterol (PDF) NotesThe authors declare no competing financial interest. HHS Public AccessAuthor manuscript ACS Infect Dis. Author manuscript; available in PMC 2017 December 15. Author Manuscript Author Manuscript Author Manuscript Author ManuscriptVisceral leishmaniasis (VL), caused by the protozoan parasite Leishmania donovani, is a global health problem affecting millions of people worldwide. Treatment of VL largely depends on therapeutic drugs such as pentavalent antimonials, amphotericin B, and others, which have major drawbacks due to drug resistance, toxicity, and high cost. In this study, for the first time, we have successfully demonstrated the synthesis and antileishmanial activity of the novel sterol pentalinonsterol (PEN), which occurs naturally in the root of a Mexican medicinal plant, Pentalinon andrieuxii. In the experimental BALB/c mouse model of VL induced by infection with L. donovani, intravenous treatment with liposome-encapsulated PEN (2.5 mg/kg) led to a significant reduction in parasite burden in the liver and spleen. Furthermore, infected mice treated with liposomal PEN showed a strong host-protective TH 1 immune response characterized by IFN-γ production and formation of matured hepatic granulomas. These results indicate that PEN could be developed as a novel drug against VL. Graphical abstractKeywords visceral leishmaniasis; liposome; novel sterol synthesis; antileishmanial Visceral leishmaniasis (VL) is caused by the obligate intracellular parasites Leishmania donovani and Leishmania infantum chagasi via transmission by a sand fly vector. Half a million people are infected with VL, and over 60 000 succumb to the disease annually. The WHO classifies VL as a neglected tropical disease of global health concern. As a potentially life-threatening disease, VL is characterized by parasitic invasion of the blood and reticuloendothelial system, which affects internal organs such as the spleen, liver, and bone marrow. 1 There are currently no licensed vaccines, and chemotherapy is the mainstay to combat the disease. Generally, treatments utilize antileishmanial drugs such as sodium stibogluconate (SSG), pentamidine, amphotericin B (AmpB), liposomal AmpB, miltefosine, and others. 2 These drugs suffer from significant drawbacks, including the need for parenteral routes of administration, poor patient compliance due to long treatment lengths and toxicity, and/or high cost, which limit their use in disease-endemic regions. For more than 50 years, the most common treatment has been antimony, which has potentially cardiotoxic side effects. 3 Additionally, AmpB has been associated with nephrotoxicity. 4 The only promising oral treatment, miltefosine (Impavido, ...

The Potential of Traditional Knowledge to Develop Effective Medicines for the Treatment of Leishmaniasis

“…B.F.Hansen & Wunderlin, was active on promastigote forms of L. (L.) mexicana in vitro ( Lezama-Dávila et al, 2007 ) and BALB/c mice infected with L. (L.) mexicana treated with 10 μg of this extract by the topical route, once a day for six weeks, presented fewer parasites in the skin; in addition, treated animals produced high levels of IL-12 cytokine along with the expression of the costimulatory molecules CD40, CD80, and CD86 ( Lezama-Dávila et al, 2014 ), suggesting that, at least in part, the leishmanicidal activity in vivo may be associated with stimulation of innate immune cells. Further studies led to the identification of sterols from the roots of this plant that were active on intracellular amastigote forms of L. (L.) mexicana with an IC 50 between 0.03 and 14.5 μM ( Pan et al, 2012 ) , and the sterol pentalinonsterol encapsulated in liposomes, given by the intravenous route at 2.5 mg/kg, significantly reduced the number of viable parasites in the liver, spleen and bone marrow of BALB/c mice infected with L. (L.) donovani ; additionally, this molecule activated the Th1 immune response in treated animals ( Gupta et al, 2015 ). The genus Aspidospermum has been cited as a source of natural medicine against leishmaniasis, and bioactive alkaloids purified from different species of this genus may be responsible for the efficacy of plants observed in traditional communities ( Tanaka et al, 2007 ; Reina et al, 2014 ); however, studies involving experimental models of leishmaniasis ( in vivo ) have not been performed thus far.…”

Development of Broad-Spectrum Antiviral Agents—Inspiration from Immunomodulatory Natural Products

“…In mice immunized with OVA, the administration of pentalinonsterol increased the level of antibodies in the serum; meanwhile, splenocytes and lymph node cells isolated from treated mice secreted more cytokines, such as IFN-γ and IL-10, when compared with the control group [ 111 ]. In a study by Gupta, pentalinonsterol treatment to combat parasites was found to induce T cell proliferation and cytokine release [ 84 ]. The immunostimulatory effects of Andrographis paniculata extract and andrographolide ( Figure 9 ) were tested in vitro and in vivo.…”

Nano- and Microformulations to Advance Therapies for Visceral Leishmaniasis

“…Intracellular parasitic load can be determined by staining infected cells with Giemsa stain, wherein the parasites will significantly take up the stain above background. Alternatively, fluorescently labeled Leishmania - or luciferase-expressing parasites can be used spectrometrically to obtain intracellular parasite count . Promastigotes or axenic amastigotes can also be grown in suspension and treated with the drug formulation to evaluate the direct effects of the formulations on the parasite.…”