In Vitro Activity of 10-Deacetylbaccatin III against Leishmania donovani Promastigotes and Intracellular Amastigotes

Abstract

Current treatments for leishmaniasis are unsatisfactory due to their route of administration, toxicity and expense but, most importantly, to the developed resistance of Leishmania to first-line drugs. Therefore, the identification of new effective targeted drugs is an urgent need. Since many studies have shown that medicinal plants contain compounds active against protozoa we have undertaken a study aiming to determine the antileishmanial activity of the taxoid 10-deacetylbaccatin III, isolated from dried needles and small branches of the European yew tree (Taxus baccata). Interestingly, 10-deacetylbaccatin III was found to selectively inhibit the growth of L. DONOVANI intracellular amastigotes within J774 murine macrophages in vitro at nanomolar concentrations with an IC(50) value of 70 nM. Concentrations of 10-deacetylbaccatin III as high as 5 microM did not affect J774 murine macrophages whereas 20 nM of taxol, used as a control, was toxic to macrophages. The compound also inhibited the growth of L. donovani promastigotes but at higher concentrations with a maximum level of inhibition of 35 %. Taxol inhibited promastigote growth at micromolar concentrations. Comparison of the effect of 10-deacetylbaccatin III to that of taxol on cell cycle progression and cellular morphology showed that their mechanisms of action are different. The 10-deacetylbaccatin III-treated promastigotes were slightly arrested in the G2/M phase whereas taxol-treated cells were blocked in the G2/M phase. In addition 10-deacetylbaccatin III treatment, contrary to taxol, did not affect cellular morphology.

Diterpenes as lead molecules against neglected tropical diseases

“…On the other hand, phorbol-myristate-acetate produced a killing effect of Leishmania infantum in macrophages primed with interleukin (IL)-15, as well as with interferon-gamma (IFN-γ), followed by an increase in the IL-12 synthesis (D'Agostino et al, 2004). Taxoid 10-deacetylbaccatin III is reported to arrest cell cycle at G2/M phases in Leishmania-infected murine macrophages (Georgopoulou et al, 2007), while 16alphahydroxycleroda-3,13 (14)Z-dien-15,16-olide caused an inhibition of recombinant DNA topoisomerase I in Leishmania donovani-infected hamsters (Misra et al, 2010). Dolabelladienetriol in Leishmania-infected macrophages was found to diminish the levels of nitric oxide (NO), IL-10, TNF-α, and TGF-β production (Soares et al, 2012).…”

“…The current review suggests that a number of diterpenes act through reduction of pathogenic infectionmediated oxidative species and pro-inflammatory and/or inflammatory mediators (Alfaro-Bustamante et al, 1997;Chen et al, 2009;Liou et al, 2008;Soares et al, 2012;Miranda et al, 2015), while augmenting the antiinflammatory and interferon levels (D'Agostino et al, 2004;Montero et al, 2004). The diterpene, 5-epiicetexone, is evident to cause cell death by arresting S/G2 phase in T. cruzi (Lozano et al, 2012a), while taxoid 10-deacetylbaccatin III acts on G2/M phase in Leishmania-infected murine macrophages (Georgopoulou et al, 2007). Additionally, apoptotic cell death is reported for a clerodane diterpene by caspase-3/-7 cleavage and DNA destabilization in L. donovani (Kathuria et al, 2014).…”

An inhibitor-driven study for enhancing the selectivity of indirubin derivatives towards leishmanial Glycogen Synthase Kinase-3 over leishmanial cdc2-related protein kinase 3

“…For the analysis of the cell cycle, the procedure described in Georgopoulou et al [28], was followed to prepare the samples for fluorescence-activated cell sorting. In order to determine the amount of cells, which display membrane fluidity perturbations, FACS analysis was performed using AnnexinV-FITC and propidium iodide (PI) staining (Apoptosis Detection kit, R & D Systems).…”

Development of new antileishmanial drugs – current knowledge and future prospects

“…A new taxoid from Taxus baccata, 10-deacethylbaccatin III, was reported to be highly active (IC 50 : 70 nM) against the intracellular amastigote stage. Contrary to other taxoids, this activity does not seem to be related to the interference with parasite tubulin [79]. The in vitro reduction of the amastigote load was obtained after macrophage activation by propolis and garlic extracts.…”