Biological effects of essential oils - A review

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Principles Of Fluorescence Spectroscopy

Lipids and lipid metabolism in eukaryotic algae

/pdf/the-structure-biosynthesis-and-function-of-glycosylated-4rbegebbn2.pdf

The structure, biosynthesis and function of glycosylated phosphatidylinositols in the parasitic protozoa and higher eukaryotes.

A status review on the medicinal properties of essential oils

Trypanosoma cruzi: activity of essential oils from Achillea millefolium L., Syzygium aromaticum L. and Ocimum basilicum L. on epimastigotes and trypomastigotes.

Different cell death pathways induced by drugs in Trypanosoma cruzi: an ultrastructural study.

In the present work, we have investigated the effect of essential oils obtained from Origanum vulgare L. (oregano) and Thymus vulgaris L. (thyme) on growth and ultrastructure of diverse evolutive forms of Trypanosoma cruzi. Culture epimastigotes and bloodstream trypomastigotes were incubated for 24 h with different concentrations of oregano or thyme essential oils and with thymol (the main constituent of thyme), and the inhibitory concentration (IC)(50) was determined by cell counting. Crude extract of oregano essential oil inhibited epimastigote growth (IC(50)/24 h = 175 microg/ml) and also induced trypomastigote lysis (IC(50)/24 h = 115 microg/ml). Thyme essential oil presented IC(50)/24 h values of 77 microg/ml for epimastigotes and 38 mug/ml for trypomastigotes, while treatment with thymol resulted in an IC(50)/24 h of 62 microg/ml for epimastigotes and 53 microg/ml for trypomastigotes. Scanning electron microscopy of treated cells showed few morphological alterations at the plasma membrane. Observation by transmission electron microscopy showed cytoplasmic swelling with occasional morphological alterations in plasma and flagellar membrane. Our data indicate that oregano and thyme essential oils are effective against T. cruzi, with higher activity of thyme, and that thymol may be the main component responsible for the trypanocidal activity.

Effect of oregano (Origanum vulgare L.) and thyme (Thymus vulgaris L.) essential oils on Trypanosoma cruzi (Protozoa: Kinetoplastida) growth and ultrastructure.

Epimastigote forms of the pathogenic parasite Trypanosoma cruzi were used to study the endocytic process in a protozoon. These elongated unicellular organisms are highly polarized cells: endocytosis occurs only at the anterior region through the cytostome and the flagellar pocket membrane, areas of the plasma membrane where the cell cytoskeleton, formed by sub-pellicular microtubules, is absent. When the cells were incubated at 4 degrees C or 28 degrees C with gold-labeled transferrin, fixed and processed for routine transmission electron microscopy our observations show that this ligand initially binds to the cytosome and the membrane lining the flagellar pocket and is subsequently ingested through a clathrin-independent receptor-mediated endocytotic process, with formation of uncoated pits and vesicles. Ingested complexes are carried in uncoated vesicles to the reservosomes, large membrane-bound organelles found mostly at the posterior end of the cell. Immunocytochemical data from Lowicryl-embedded cells demonstrated that the reservosomes are acidic compartments (pH 6.0, as shown using DAMP as a pH probe) with no acid phosphatase or typical lysosome-associated membrane proteins (LAMP 1, LAMP 2 and lgp 120), but rich in cysteine proteinase. These data suggest that the reservosome is a pre-lysosomal compartment. Since cysteine proteinase of T. cruzi contains no phosphorylated mannose residues and the cation-independent mannose 6-phosphate receptor could not be immunocytochemically detected in the reservosomes, it is possible that lysosomal enzymes in the epimastigote forms of T. cruzi are targeted to compartments related to the endocytic pathway through a mechanism different from that which occurs in other eukaryotic cells.

Identification of a large pre-lysosomal compartment in the pathogenic protozoon Trypanosoma cruzi

Endocytosis was studied at the ultrastructural level in different developmental forms ofTrypanosoma cruzi after incubation of the parasites in the presence of gold-labeled proteins (albumin-Au, peroxidase-Au and transferrin-Au) and low-density lipoprotein (LDL-Au). Epimastigote (culture) forms actively ingested LDL and proteins. Initially, gold particles were seen adhering only to the cytostome and inside the flagellar pocket. In parasites incubated at 4°C with transferrin-Au or peroxidase-Au, labeling was found only at these two sites, showing that receptor-mediated endocytosis occurs in both regions. In the cytoplasm, gold particles were seen only inside two different compartments: membrane-bound vesicles and reservosomes. Incubation of epimastigotes with acridine orange followed by fluorescence microscopy revealed intense orange staining, indicating that the reservosomes have an acidic pH. This staining was abolished after incubation of the parasites in the presence of ammonium chloride. These data confirm that this compartment is the site of accumulation of ingested lipids and proteins. Little intracellular labeling with transferrin-Au was found in in vitro — derived amastigotes and trypomastigotes (both lack reservosomes). However, although in amastigotes very few gold particles were seen bound to the cells, in trypomastigotes they were observed bound to the membrane that encloses the cell body, the flagellar pocket, and the flagellum, suggesting that the receptors are more abundant in this form.

Maurilio J. Soares

Papers

Trypanosoma cruzi: activity of essential oils from Achillea millefolium L., Syzygium aromaticum L. and Ocimum basilicum L. on epimastigotes and trypomastigotes.

Different cell death pathways induced by drugs in Trypanosoma cruzi: an ultrastructural study.

Effect of oregano (Origanum vulgare L.) and thyme (Thymus vulgaris L.) essential oils on Trypanosoma cruzi (Protozoa: Kinetoplastida) growth and ultrastructure.

Identification of a large pre-lysosomal compartment in the pathogenic protozoon Trypanosoma cruzi

Endocytosis of gold-labeled proteins and LDL by Trypanosoma cruzi.