Table 1.
Anti-microbial effects of melittin against various protozoan parasites. Developmental forms of tested protozoa, methodologies, and key findings of the relevant studies have also been included
| Protozoan parasites | Identifier | Developmental forms | Methods | Key findings | References |
|---|---|---|---|---|---|
| Leishmania donovani | S-2 strain | Promastigotes | Evaluation of Ca2+ influx by fluorescence measurements |
Dose-dependent induction of Ca2+ influx across the plasma membrane Inhibition of melittin-induced Ca2+ influx by OBAA |
Catisti et al. (2000) |
| R9 strain | Promastigotes | Cell viability analysis using MTT assay | High killing activity against promastigotes (LD50: 0.3 μM) | Díaz-Achirica et al. (1998) | |
| Not mentioned | Autoclaved promastigotes | Measurements of sLA-induced cytokines in the collected whole blood samples from mice receiving melittin-adsorbed autoclaved L. donovani | Significant reductions in the mean levels of IL-10 (p = 0.00001), IFN-γ (p = 0.00008) and TNF-α (p = 0.000001) in comparison to the control (non-treated) group | Eltahir Saeed and Khalil (2017) | |
| Leishmania infantum | MHOM/BR/1972/LD strain | Amastigotes and promastigotes | Cell viability analysis using MTT assay, quantification of cytokines, and determination of NO and H2O2 production |
Direct inhibition of both amastigotes and promastigotes Indirect inhibition of intracellular amastigotes by immunomodulatory effects on macrophages (increasing IL-12 production and decreasing the levels of IL-10, TNF- α, NO, and H2O2) |
Pereira et al. (2016) |
| Leishmania major | Not mentioned | Promastigotes | Cell viability analysis using microplate Alamar blue assay | Induction of death in 50% of promastigotes at 74.01 ± 1.27 μg/mL | Pérez-Cordero et al. (2011) |
| Leishmania panamensis | Not mentioned | Promastigotes | Cell viability analysis using microplate Alamar blue assay | Ineffectiveness of melittin in killing 50% of promastigotes at > 100 μg/mL | Pérez-Cordero et al. (2011) |
| Plasmodium berghei | ANKA strain |
Ookinetes and gametocytes |
Analysis of the effects of melittin on ookinetes (in vitro) and sporogonic stages (Anopheles stephensi) of the parasite |
Complete obliteration of ookinetes after 30 min Significant reductions in both infection prevalence (p = 0.019) and infection intensity (p < 0.001) compared to those in control mosquitoes |
Carter et al. (2013) |
| Plasmodium falciparum | NF54 strain | Gametocytes | Analysis of the effects of melittin and multi-melittin arrays on sporogonic stages of Anopheles coluzzii | Significant reductions of infection intensity (p < 0.001) in mosquitoes fed on cultured P. falciparum spiked with melittin (native or modified peptide) compared to those in control mosquitoes | Habtewold et al. (2019) |
| NF54 strain | Gametocytes | Analysis of the effects of melittin on sporogonic stages of Anopheles gambiae | Significant decrements in both infection prevalence (p < 0.001) and infection intensity (p = 0.019) compared to those in control mosquitoes | Carter et al. (2013) | |
| Toxoplasma gondii | RHβ strain | Extracellular tachyzoites | β-galactosidase release assay for the assessment of lytic activity | Induction of cytosolic β-galactosidase release and cell lysis | Seeber, (2000) |
| Trypanosoma brucei brucei | M110 clone | Bloodstream forms | Evaluation of Ca2+ influx by fluorescence measurements | Dose-dependent induction of Ca2+ influx across the plasma membrane | Ruben et al. (1996) |
| AnTat1.1E clone | Procyclic forms | Evaluation of Ca2+ movement between organelles by luminescence measurements |
Transient retention of Ca2+ in mitochondria Contribution of acidic compartments to Ca2+ homeostasis during the signaling process |
Xiong et al. (1997) | |
| ILTar 1 procyclics | Trypomastigotes | Evaluation of Ca2+ influx by fluorescence measurements |
Dose-dependent induction of Ca2+ influx across the plasma membrane Inhibition of melittin effects on Ca2+ influx by OBAA, a PLA2 inhibitor Induction of Ca2+ release from intracellular stores in the absence of CaCl2 (and in the presence of 1 mM EGTA) |
Catisti et al. (2000) | |
| Trypanosoma cruzi | Y strain | Amastigotes | Evaluation of Ca2+ influx by fluorescence measurements |
Induction of Ca2+ influx Inhibition of melittin effects on Ca2+ influx by OBAA |
Catisti et al. (2000) |
| macrophagotropic Tehuantepec strain | Trypomastigotes | Light, fluorescence, and electron microscopies, evaluation of trypanocidal activity, and measurement of β-galactosidase release (before and after parasitic infection) |
Inhibition of the parasite motility Disruption of plasma membrane Reduction of the parasite infectivity No reduction in the growth of intracellular parasites |
Jacobs et al. (2003) | |
| M/HOM/AR/74/CA-I CL72 | Trypomastigotes | Determination of lethal concentration, evaluation of T. cruzi killing by dual peptide treatment, and recovery of AMP-treated cells after transfer to non-AMP containing media |
High killing activity against Trypanosoma cruzi Synergistic and additive anti-parasitic effects of melittin in combination with certain AMPs Inability of the parasite to recover after treatment with 10 μM of melittin |
Fieck et al. (2010) | |
| CL Brener clone | Epimastigotes and trypomastigotes | Evaluation of the parasite viability, flow cytometry analysis, and TEM |
Dose-dependent decrease in the number of T. cruzi cells Permeabilization of protozoan cell membrane (High percentages of PI-labeled epimastigotes and trypomastigotes) Induction of autophagy (epimastigotes) and apoptosis (trypomastigotes) |
Adade et al. (2012) | |
| CL Brener clone | Amastigotes, epimastigotes, and trypomastigotes | Evaluation of the parasite viability, treatment during the T. cruzi intracellular cycle, PI uptake assay, evaluation of mitochondrial membrane potential, TUNEL assay, SEM, TEM, and fluorometric analysis of MDC |
Induction of growth inhibition or killing of developmental forms of the parasite (< 2.5 μg/mL) Induction of structural changes (plasma membrane blebbing, mitochondrial swelling, and nuclear alterations) Induction of alterations in ΔΨm Disorganization of the kinetoplast DNA filaments Induction of alterations in flagellar structure Permeabilization of cell membrane Induction of apoptosis and autophagy |
Adade et al. (2013) |
ΔΨm Mitochondrial membrane potential, AMP Anti-microbial peptide, EGTA Ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid, H2O2 Hydrogen peroxide, IFN-γ Interferon-γ, IL-10 Interleukin-10, IL-12 Interleukin-12, LD50 Half lethal dose, MDC Monodansylcadaverine, MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, NO Nitric oxide, OBAA 3-(4-octadecyl)-benzoylacrylic acid; PI Propidium iodide, PLA2 Phospholipase A2, SEM Scanning electron microscopy; sLA: Soluble Leishmania donovani antigen, TEM Transmission electron microscopy, TNF-α Tumor necrosis factor-α, TUNEL Terminal deoxynucleotidyl transferase (TDT)-mediated dUTP-biotin nick end-labeling