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Leishmanicidal activity assessment of olive tree extracts
Joannis D Kyriazis1, Nektarios Aligiannis, Panagiotis Polychronopoulos
1Laboratory of Cellular Immunology, Hellenic Pasteur Institute, Athens, Greece.
Summary
Olive tree compounds, oleuropein and hydroxytyrosol, show potent anti-leishmanial activity against Leishmania parasites. Oleuropein demonstrated significant in vivo efficacy in reducing parasitic burden in a visceral leishmaniasis mouse model.
Area of Science:
- Parasitology
- Pharmacology
- Natural Product Chemistry
Background:
- Leishmaniasis is a significant global health issue, particularly in developing nations, with current treatments facing challenges like high cost, toxicity, and drug resistance.
- The Mediterranean basin is a region with high endemicity for leishmaniasis, necessitating the development of novel therapeutic strategies.
- Olive tree byproducts, such as leaves and wastewater, are rich sources of cost-effective bioactive compounds, including biophenols.
Purpose of the Study:
- To evaluate the anti-leishmanial activity of five natural products, focusing on oleuropein and hydroxytyrosol, against various Leishmania species.
- To assess the in vitro efficacy and selectivity of these compounds against both promastigote and amastigote forms of the parasite.
- To investigate the in vivo therapeutic potential of oleuropein in an experimental model of visceral leishmaniasis.
Main Methods:
- In vitro screening of five natural products for anti-promastigote and anti-amastigote activity against Leishmania infantum, L. donovani, and L. major.
- Determination of selectivity index for promising compounds against Leishmania donovani amastigotes within J774A.1 macrophages.
- In vivo assessment of oleuropein efficacy in L. donovani-infected BALB/c mice, evaluating parasitic burden in spleen, liver, and spleen post-treatment.
Main Results:
- Oleuropein and hydroxytyrosol exhibited the most significant inhibitory effects on both stationary and logarithmic phase promastigotes of tested Leishmania species.
- These compounds demonstrated the highest selectivity index against L. donovani amastigotes infecting macrophages.
- In vivo, oleuropein treatment in mice led to a >80% reduction in spleen parasitic burden shortly after treatment, with >95% depletion in liver and spleen observed 6 weeks post-treatment.
Conclusions:
- Oleuropein and hydroxytyrosol are promising natural compounds with potent anti-leishmanial properties, effective against multiple Leishmania species.
- Oleuropein shows sustained and enhanced efficacy in vivo, suggesting its potential as a safe and cost-effective therapeutic agent for visceral leishmaniasis.
- These findings support the development of natural products derived from olive tree sources as viable alternatives for treating leishmaniasis, addressing limitations of current therapies.
