Turkish freshwater and marine macrophyte extracts show in vitro antiprotozoal activity and inhibit FabI, a key enzyme of Plasmodium falciparum fatty acid biosynthesis.Abstract
The ethanolic extracts of a number of Turkish freshwater macrophytes (Potamogeton perfoliatus, Ranunculus Ranunculus
a very large plant genus of family Ranunculaceae; the buttercups. All of them should be regarded as potentially poisonous. The species listed below have been reported as causing poisoning in animals. tricophyllus and Cladophora glomerata) and marine macroalgae (Dictyota dichotoma, Halopteris scoparia, Posidonia oceanica, Scinaia furcellata, Sargassum Sargassum (särgăs`əm), genus of brown algae that has given its name to the Sargasso Sea, where it is found in great abundance. See Phaeophyta; seaweed.
Any of the brown algae that make up the genus Sargassum. natans and Ulva lactuca) were assayed for their in vitro antiprotozoal activity. Trypanosoma brucei rhodesiense Trypanosoma brucei rho·de·si·en·se
A protozoan that is the causative agent of Rhodesian trypanosomiasis. , Trypanosoma cruzi, Leishmania donovani and Plasmodium falciparum were used as test organisms. The cytotoxicity of the extracts was also assessed against primary rat skeletal myoblasts (L6 cells). Whereas none of the extracts were active against T. cruzi, all crude extracts displayed appreciable trypanocidal activity against T. brucei rhodesiense, with S. natans being the most active one (I[C.sub.50] 7.4 [micro]g/ml). Except for the marine alga H. scoparia, all extracts also possessed leishmanicidal potential. The best antileishmanial activity was exerted by U. lactuca and P. oceanica (I[C.sub.50]'s 5.9 and 8.0 [micro]g/ml, respectively). Five extracts that demonstrated inhibitory activity towards P. falciparum (I[C.sub.50]'s 18.1-48.8 [micro]g/ml) were simultaneously assayed against FabI, a crucial enzyme of the fatty acid system of P. falciparum, to find out whether FabI was their target. The extracts of C. glomerata and U. lactuca efficiently inhibited the FabI enzyme with I[C.sub.50] values of 1.0 and 4.0 [micro]g/ml, respectively. None of the extracts were cytotoxic towards mammalian L6 cells. This work reports for the first time antiprotozoal activity of some Turkish marine and freshwater algae algae (ăl`jē) [plural of Lat. alga=seaweed], a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plant kingdom, the thallophytes (plants that , as well as a target-based antiplasmodial screening for the identification of P. falciparum FabI inhibitors from aquatic and marine macrophytes.
[c] 2005 Elsevier GmbH. All rights reserved.
Keywords: Algae; Trypanosoma; Leishmania Leishmania /Leish·ma·nia/ (lesh-ma´ne-ah) a genus of parasitic protozoa, including several species pathogenic for humans. In some classifications, organisms are placed in four complexes comprising species and subspecies: L. ; Plasmodium plasmodium, name for a stage in the life cycle of a slime mold. Also, Plasmodium is the name given to the genus of the protozoan parasite that causes malaria. ; Fatty acid synthase Fatty acid synthases (FAS) is enzymatic system composed of 272 kDa multifunctional polypeptide, in which substrates are handed from one functional domain to the next. ; Enoyl-ACP reductase reductase /re·duc·tase/ (-tas) a term used in the names of some of the oxidoreductases, usually specifically those catalyzing reactions important solely for reduction of a metabolite. (FabI)
Parasitic protozoans are single-celled organisms causing serious tropical diseases worldwide in both humans and animals. Malaria, trypanosomiasis trypanosomiasis (trəpăn'əsōmī`əsis), infectious disease caused by a protozoan organism, the trypanosome, which exists as a parasite in the blood of a number of vertebrate hosts. and leishmaniasis leishmaniasis (lēsh'mənī`əsĭs), any of a group of tropical diseases caused by parasitic protozoans of the genus Leishmania. are among the major parasitic diseases distributed throughout the world. Trypanosoma brucei rhodesiense is responsible for African trypanosomiasis (sleeping sickness), that affects half a million people on the African continent, while Trypanosoma cruzi is the causative parasite for Chagas' disease, which is widespread in South America (World Health Organization WHO, 1998). Leishmaniasis is a vector-borne infection afflicting 14 million people worldwide. Leishmania donovani is the causative agent of visceral leishmaniasis (VL), the most severe form of leishmaniasis, which is nearly always fatal if left untreated (Campos-Ponce et al., 2005). The World Health Organization (WHO, 2000) estimates that there are at least 300 million new cases of malaria annually and that 43% of the world population lives in malaria-endemic areas. Therapeutic treatment of parasitic diseases has made considerable progress in the last few decades; however, the presently used drugs possess adverse side effects, and do not provide complete eradication (Keiser et al., 2001). Moreover, resistance development by the parasites to the present drugs has become a major problem. Therefore, new chemotherapeutic agents and novel targets are urgently needed. One such new biological target is the fatty acid biosynthesis.
The recent discovery of the apicoplast, a cryptic plastid plas·tid
1. Any of several pigmented cytoplasmic organelles found in plant cells and other organisms, having various physiological functions, such as the synthesis and storage of food. Also called trophoplast.
2. organelle organelle /or·ga·nelle/ (or?gah-nel´) a specialized structure of a cell, such as a mitochondrion, Golgi complex, lysosome, endoplasmic reticulum, ribosome, centriole, chloroplast, cilium, or flagellum. in Plasmodium and a number of other Apicomplexan parasites (McFadden et al., 1996) has opened a new door for the discovery of novel antiparasitic antiparasitic /an·ti·par·a·sit·ic/ (-par?ah-sit´ik) destructive to parasites, or an agent with this quality.
adj. agents. Type II fatty acid biosynthesis (FAS-II) is the first identified anabolic anabolic
pertaining to or arising from anabolism.
steroids with a tissue-building effect. Testosterone is an example of a natural anabolic steroid with the, sometimes undesirable, effect of causing masculinization. process that takes place in the apicoplast of P. falciparum (Waller et al., 1998). This biochemical process has been identified also in T. brucei (Morita et al., 2000) and probably exists in Leishmania sp. (Roberts et al., 2003). FAS-II is characterized by the presence of individual enzymes that are responsible for catalyzing one single step of fatty acid biosynthesis. This differs from the type I system (FAS-I) found in mammals (including human) and fungi, where the entire fatty acid biosynthesis is accomplished by a single, multifunctional fatty acid synthase enzyme. The significant organizational and structural differences between the malaria parasite and human make the type II FAS system an attractive target for malaria drug discovery. The unique enzyme enoyl-ACP reductase (FabI) of Plasmodium commits the final reduction step during the fatty acid elongation process, therefore representing an excellent target for the development of novel antiplasmodial agents (Surolia and Surolia, 2001).
Aquatic macrophytes comprise a phylogenetically phy·lo·ge·net·ic
1. Of or relating to phylogeny or phylogenetics.
2. Relating to or based on evolutionary development or history: a phylogenetic classification of species. diverse class of the plant kingdom. These organisms, particularly of marine origin, have gained increasing attention from researchers due to chemically interesting secondary metabolites with miscellaneous biological activities (Mayer and Hamann, 2002; Donia and Hamann, 2003). The goal of this study was to determine in vitro antitrypanosomal, antileishmanial and antiplasmodial activities of the ethanolic extracts of nine species of freshwater and marine algae found in Turkish waters, namely Potamogeton perfoliatus, Ranunculus tricophyllus, Cladophora glomerata, Dictyota dichotoma, Halopteris scoparia, Posidonia oceanica, Scinaia furcellata, Sargassum natans and Ulva lactuca. The extracts were also tested for their cytotoxicity on primary mammalian (L6) cells. Those extracts with antimalarial antimalarial /an·ti·ma·lar·i·al/ (-mah-lar´e-al) therapeutically effective against malaria, or an agent with this quality.
Preventing or relieving the symptoms of malaria. activity were further assayed for their inhibition potential against the FabI enzyme of Plasmodium falciparum. Two extracts were identified to target plasmodial plas·mo·di·al
Relating to a plasmodium or a species of the genus Plasmodium. FabI. This is the first study reporting the broad spectrum antiprotozoal and FabI inhibiting activities of the freshwater and marine algae extracts.
Material and methods
Plant material and extraction
The marine brown algae of the Mediterranean Sea, namely Halopteris scoparia (L.) Sauvagau (syn. Stypocaulon scoparium (L.) Kutz) (Stypocaulaceae) and Dictyota dichotoma (Huds.) Lam. (Fucophyceae) were collected in August, 1999 from Alanya, Turkey. The other marine brown alga Scinaia furcellata (Turn.) J. Agardh (Galaxauraceae) was gathered from Tekirdag province located at the coast of the Marmara Sea, in September 2000. Samples of the marine brown alga Sargassum natans (L.) Gaill. (syn. Fucus natans L., Sargassum bacciferum (Turn.) Agardh) (Sargassaceae), the marine green alga Ulva lactuca L. (Ulvaceae), and the sea grass Posidonia oceanica L. Del. (Potamogetonaceae) were collected from the shore of Davutlar village, Kusadasi (the Aegean Sea), in August 2000. The freshwater plants, Potamogeton perfoliatus L. (Potamogetonaceae) and Ranunculus trichophyllus Chaix (Ranunculaceae) were collected from Mogan Lake, Ankara, in April 1999. The freshwater green alga Cladophora glomerata (Dilw.) Kutz (Chlorophyceae) was scooped from Ceyhan River, Elbistan in April 1999 and Beysehir Lake, Konya, in May 1999, respectively. The taxonomical identification of the organisms was done by one of us (T.A.) and the voucher specimens are kept at the Herbarium of the Department of Pharmacognosy pharmacognosy /phar·ma·cog·no·sy/ (fahr?mah-kog´nah-se) the branch of pharmacology dealing with natural drugs and their constituents.
n. , Faculty of Pharmacy, Gazi University, Ankara, Turkey. Following collection and air-drying at room temperature, each species was accurately weighed (5.0 g) and macerated with ethanol (95[degrees]) for 2 days. After filtration, the ethanolic extracts were dried under vacuum and used in the bioassays.
Trypanocidal activity against Trypanosoma brucei rhodesiense and cytotoxicity tests
T. brucei rhodesiense STIB 900 strain and the standard drug melarsoprol were used for the assay. Minimum Essential Medium (50 [micro]l) supplemented according to Baltz et al. (1985) with 2-mercaptoethanol and 15% heat-activated horse serum was added to each well of a 96-well microtiter plate. Serial drug dilutions were added to the wells. Then [10.sub.4] bloodstream forms of T. brucei rhodesiense in 50 [micro]l were added to each well and the plate incubated at 37[degrees]C (under a 5% C[O.sub.2] atmosphere) for 72h. Rezasurin (12.5 mg dissolved in 11 distilled water) was then added to each well and incubation continued for a further 2-4h (Raz et al., 1997). The plates were read in a microplate fluorescence scanner (Spectramax Gemini XS by Molecular Devices Cooperation, Sunnyvale, CA, USA) using an excitation wavelength of 536 nm and emission wavelength of 588 nm. From the sigmoidal inhibition curve, I[C.sub.50] values were calculated. Cytotoxicity was assessed by the same assay (Sperandeo and Brun, 2003) using rat skeletal muscle myoblasts (L6 cells) and the standard compound, phodophyllotoxin.
Trypanocidal activity against Trypanosoma cruzi
Rat skeletal muscle myoblasts (L6 cells) were seeded in 96-well microtiter plates at 2000 (cells/well) /100 [micro]l RPMI 1640 medium with 10% fetal bovine serum Fetal bovine serum ( or foetal bovine serum) is serum taken from the fetuses of cows. Fetal Bovine Serum (or FBS) is the most widely used serum in the culturing of cells. In some papers the expression foetal calf serum is used. (FBS FBS
fasting blood sugar
FBS Fasting blood sugar. See Fasting glucose. ) and 2 mM L-glutamine. After 24 h, 5000 trypomastigotes of T. cruzi (Tulahuen strain C2C4 containing the [beta]-galactosidase (Lac Z) gene) was added. After 48 h, the medium was removed from the wells and replaced by 100 [micro]l of fresh medium with or without a serial drug dilution. Seven 3-fold dilutions were used covering a range from 90 to 0.123 [micro]g/ml. The plates were incubated at 37[degrees]C in 5% C[O.sub.2] for 4 days. Then the substrate CPRG/Nonidet (50 ml) was added to all wells. The color reaction that developed during the following 2-6 h was read photometrically pho·tom·e·try
Measurement of the properties of light, especially luminous intensity.
photo·met at 540 nm. From the sigmoidal inhibition curve, I[C.sub.50] values were calculated. Benznidazole was the standard drug used.
The assay for L. donovani (strain MHOM/ET/67/L82) was done using the Alamar Blue assay as described for T. brucei rhodesiense. Briefly, axenic axenic /axen·ic/ (a-zen´ik) not contaminated by or associated with any foreign organisms; used in reference to pure cultures of microorganisms or to germ-free animals. Cf. gnotobiotic. amastigotes were grown in SM medium (Cunningham, 1977) at pH 5.4 supplemented with 10% FBS. One hundred micro liters of the culture medium with [10.sup.5] amastigotes from axenic culture with or without a serial drug dilution were seeded in 96-well microtiter plates. After 72 h of incubation, 10 [micro]l of Alamar Blue (12.5 mg resazurin dissolved in 100 ml distilled water) was added to each well and the plates incubated for another 2 h. Then the plates were read with a microplate fluorometer fluorometer /flu·o·rom·e·ter/ (fldbobr-rom´e-ter) the instrument used in fluorometry, consisting of an energy source (e.g., a mercury arc lamp or xenon lamp) to induce fluorescence, filters or monochromators for selection of the as previously described (Sperandeo and Brun, 2003). Miltefosine was used as a standard drug.
In vitro activity against erythrocytic stages of P. falciparum was determined by a modified [[.sup.3]H]-hypoxanthine incorporation assay (Matile and Pink, 1990), using the chloroquine- and pyrimethamine-resistant K1 strain and the standard drug artemisinin Artemisinin (IPA: [artɛˈmɪsɪnən]) is a drug used to treat multi-drug resistant strains of falciparum malaria. . Briefly, parasite cultures incubated in RPMI 1640 medium with 5% Albumax (without hypoxanthine hypoxanthine /hy·po·xan·thine/ (-zan´then) a purine base formed as an intermediate in the degradation of purines and purine nucleosides to uric acid and in the salvage of free purines. Complexed with ribose it is inosine. ) were exposed to serial drug dilutions in microtiter plates. After 48 h of incubation at 37[degrees]C in a reduced oxygen atmosphere, 0.5 [mu]Ci [.sup.3.H]-hypoxanthine was added to each well. Cultures were incubated for a further 24 h before they were harvested onto glass-fiber filters and washed with distilled water. The radioactivity was counted using a Betaplate[TM] liquid scintillation scintillation /scin·til·la·tion/ (sin?ti-la´shun)
1. an emission of sparks.
2. a subjective visual sensation, as of seeing sparks.
3. counter (Wallac, Zurich, Switzerland). The results were recorded as counts per minute (CPM) per well at each drug concentration and expressed as percentage of the untreated controls. I[C.sub.50] values were calculated from the sigmoidal inhibition curves using Microsoft Excel.
P. falciparum enoyl-ACP reductase (FabI) inhibition assay
The FabI enzyme assay was performed as previously described (Kirmizibekmez et al., 2004; Tasdemir et al., 2005a, b). Briefly, the extracts were dissolved in DMSO DMSO dimethyl sulfoxide.
Dimethyl sulfoxide; a colorless hygroscopic liquid obtained from lignin, used as a penetrant to convey medications into the tissues.
n. and tested at 100 [micro]g/ml concentration in the presence of 1 [micro]g (20 nM) enzyme and 200 [micro]M NADH NADH the reduced form of NAD.
The reduced form of NAD.
n.pr a coenzyme that incorporates niacin and involved in the Krebs cycle. . All measurements were performed on a Uvikon 941 Plus spectrophotometer (Kontron Instruments) in 1 ml of 20 mM Tris/HCI pH 7.4 and 150 mM NaCl. The reaction was started by addition of 50 [micro]M crotonoyl-CoA. The reaction mixture was read spectrophotometrically for 1 min by following the oxidation of NADH to NA[D.sup.+] at 340 nm ([epsilon] = 6.3 m[M.sup.-1][cm.sup.-1]). The I[C.sub.50] values were estimated from graphically plotted dose-response curves. Triclosan was used as a positive control (I[C.sub.50] 50 nM = 14 ng/ml).
The in vitro growth inhibitory activity of the ethanolic extracts of a number of macrophytes of both marine and aquatic origin, namely H. scoparia, D. dichotoma, S. furcellata, S. natans, U. lactuca, C. glomerata, P. oceanica, P. perfoliatus and R. trichophyllus were evaluated against four parasitic protozoa (T. brucei rhodesiense, T. cruzi, L. donovani and P. falciparum). Table 1 displays the I[C.sub.50] values determined for each extract as well as the standard compounds (artemisinin, benznidazole, melarsoprol and miltefosine). In order to determine the selectivity, the extracts were also tested on rat skeletal myoblasts (L6 cells) by using podophyllotoxin as positive control (Table 1). None of the extracts displayed activity versus T. cruzi even at the highest test concentrations (I[C.sub.50]'s > 90 [micro]g/ml). However, all nine extracts were found to possess inhibitory activity against the trypomastigote forms of T. brucei rhodesiense. The best trypanocidal activity was demonstrated by the marine brown alga S. natans (I[C.sub.50] 7.4 [micro]g/ml), followed by freshwater green alga C. glomerata (I[C.sub.50] 11.5 [micro]g/ml), marine brown algae D. dichotoma (I[C.sub.50] 17.1 [micro]g/ml) and S. furcellata (I[C.sub.50] 17.9 [micro]g/ml). The remaining extracts possessed milder trypanocidal activity with I[C.sub.50] values ranging between 22.3 and 43.9 [micro]g/ml. Except for the Mediterranean brown alga H. scoparia, all extracts also had leishmanicidal potential against axenic amastigotes of L. donovani. The most potent activities were shown by the marine green alga, U. lactuca (I[C.sub.50] 5.9 [micro]g/ml) and the sea grass P. oceanica (I[C.sub.50] 8.0 [micro]g/ml). The freshwater plant P. perfoliatus also displayed moderate antileishmanial effect (I[C.sub.50] 22.9 [micro]g/ml), whereas the remaining extracts had only weak activity. Five extracts (C. glomerata, D. dichotoma, S. furcellata, S. natans and U. lactuca) exhibited some antiplasmodial activity, with the marine brown alga S. natans being the most potent (I[C.sub.50] 18.1 [micro]g/ml). These five extracts were also evaluated for their ability to inhibit the recombinant FabI enzyme of P. falciparum in vitro. Two of them, C. glomerata and U. lactuca, efficiently inhibited the FabI enzyme with I[C.sub.50] values of 1.0 and 4.0 [micro]g/ml, respectively (data not shown). The other three extracts had no impact on FabI, indicating that their target was not the FabI enzyme of Plasmodium FAS-II system. All extracts were found to be safe for mammalian L6 cells as they did not possess any cytotoxicity (I[C.sub.50]'s>90 [micro]g/ml) even at the highest concentrations tested.
In the continuation of our search for antiprotozoal plants from Turkey, we selected nine macrophytes found in Turkish waters and studied their antiparasitic activities against four protozoa. Our results revealed P. oceanica and U. lactuca extracts to display remarkable inhibitory activity in antileishmanial assay. Besides, S. natans was highly active against both T. brucei rhodesiense and P. falciparum without any toxicity. FabI is a major point of regulation for type II fatty acid synthesis Fatty acids are formed by the action of Fatty acid synthases from acetyl-CoA and malonyl-CoA precursors. In humans fatty acids are predominantly formed in the liver and adipose tissue, and mammary glands during lactation. in P. falciparum and as such, a potential drug target for antimalarial drug discovery. Very recently, we reported the results of very first FabI enzyme-based antimalarial screening study performed on Turkish medicinal plants (Tasdemir et al., 2005a). This strategy also yielded the very first natural products, luteolin 7-O-glucoside and (-)-ningpogenin, targeting the plasmodial FabI enzyme (Kirmizibekmez et al., 2004; Tasdemir et al., 2005b). In the current study, we employed the same approach for the first time on freshwater and marine macrophyte mac·ro·phyte
A macroscopic plant.
macro·phytic adj. extracts. Two green algae, C. glomerata and U. lactuca, have emerged as potent inhibitors of the P. falciparum FabI enzyme in vitro. The moderate antiplasmodial activity of these extracts are most likely due to their poor penetration into the target organelle (the apicoplast) in parasite cells.
A review of the literature indicates that the most bioactive algal algal
pertaining to or caused by algae.
is very rare but systemic and udder infections are recorded. See protothecosis.
the algae Prototheca trispora and P. extracts show some overlap in their chemistry and biological activity. The brown alga Sargassum has been reported to be rich in polysaccharides, fatty acids, particularly dihomo-[gamma]-linolenic acid, which comprise approximately 10% of this alga (Zhukova and Svetashev, 1999; Orhan et al., 2003; Zhu et al., 2004). Sulfated polysaccharides obtained from several Sargassum sp. demonstrated strong antiviral and antitumor activities (Fujihara et al., 1984; Zhu et al., 2004). The genus Ulva is best known for bromophenolic compounds, but also proteins, lipids and polysaccharides (Abdel-Fattah and Sary, 1987; Lahaye and Ray, 1996; Wahbeh, 1997; Flodin et al., 1999; Pengzhan et al., 2003; Sanina et al., 2004) have been reported. The n-BuOH extract of U. lactuca (Immanuel et al., 2004) as well as a sphingosine-type compound isolated from U. fasciata (Garg et al., 1992) have pronounced antiviral effects. The Cladophora sp. are environmentally very important, as they accumulate and metabolize (detoxification) heavy metals and carcinogenic polycyclic polycyclic
having two or more usually fused chemical ring structures in their molecule.
thyroid initiators, i.e. they increase the incidence of thyroid tumors. aromatics (Vymazal, 1990; Kirso and Irha, 1998). A number of biological activities, e.g. antibacterial, antimycobacterial, antimycotic and cytotoxic, have been described from the genus (Demina and Mal'dov, 1981; Orhan et al., 2002; Kamenarska et al., 2004). The Cladophora is the source of native cellulose of high quality (Ek et al., 1998) and also contain sulphated polysaccharides (Ramana and Rao, 1991; Shanmugam et al., 2001), steroids, volatiles (Kamenarska et al., 2004; Abrahamsson et al., 2003) and fatty acids (Carballeira et al., 1997; Orhan et al., 2003). The sea grass P. oceanica is an endemic species to the Mediterranean Sea. The P. oceanica meadows are incredibly important for the local ecosystem since many other species find their nutrients and housing in them. Chemically, P. oceanica is characterized by the phenolic compounds (Cuny et al., 1995; Agostini et al., 1998) and long-chain ([C.sub.22]-[C.sub.24]) fatty acids (Nichols et al., 1982; Viso et al., 1993). We reported previously P. oceanica to contain shorter-chain fatty acids, e.g. palmitic ([C.sub.16]), oleic ([C.sub.18]) and stearic ([C.sub.18]) acids (Orhan et al., 2003). All these chemical constituents might underlie the antiprotozoal and FabI inhibitory activity of the algal extracts.
Our literature survey also elucidated that although marine organisms are prominent sources of biologically active compounds, the list of marine extracts and/or natural products that have been evaluated for antiprotozoal properties is quite short. To our knowledge, this is the first report on antiprotozoal activity of marine and freshwater algae investigated here. The present study is also the first application of the FabI-target-based malaria screening on macroalgal extracts. We believe that the ethanolic extracts of S. natans, U. lactuca, C. glomerata and P. oceanica might represent alternative sources in the search of new antiprotozoal agents with novel mechanism of actions, i.e. FabI enzyme inhibition. The isolation and characterization of the active principle(s) of these macrophytes are in progress in our laboratory.
Deniz Tasdemir acknowledges the financial support provided by the Dr. Helmut Legerlotz Foundation of the University of Zurich History
The University of Zurich was founded in 1833 with existing colleges of theology (founded by Huldrych Zwingli in 1525), law and medicine merged together with a new faculty of Philosophy. .
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Mayer, A.M., Hamann, M.T., 2002. Marine pharmacology in 1999: compounds with antibacterial, anticoagulant, antifungal, anthelmintic anthelmintic /ant·hel·min·tic/ (ant?hel-min´tik)
1. vermifugal; destructive to worms.
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Acting against or destroying blood platelets.
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I. Orhan (a), B. Sener (a), T. Atici (b), R. Brun (c), R. Perozzo (d), D. Tasdemir (e,*)
(a) Department of Pharmacognosy, Faculty of Pharmacy, Gazi University, TR-06330 Ankara, Turkey
(b) Department of Biology, Faculty of Education, Gazi University, TR-06500 Ankara, Turkey
(c) Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute The Swiss Tropical Institute (STI, also known as Institut Tropical Suisse and Schweizerisches Tropeninstitut) is an Associated Institute of the University of Basel. It was founded in 1943 by Professor Rudolf Geigy as a public organization, with support from the Swiss Federal , Socinstrasse 57, CH-4002 Basel, Switzerland
(d) Department of Pharmaceutical Biochemistry, School of Pharmaceutical Sciences, University of Geneva The University of Geneva (Université de Genève) is a university in Geneva, Switzerland. It was founded by John Calvin in 1559. Initially a theological seminary, it also taught law. , Quai Ernest-Ansermet 30, CH-1211 Geneve 4, Switzerland
(e) Institute of Organic Chemistry, University of Zurich, Winterthurerstrasse 190. CH-8057 Zurich, Switzerland
*Corresponding author. Tel.: +41446354213; fax: +41 44635 68 12.
E-mail addresses: firstname.lastname@example.org, email@example.com (D. Tasdemir).
Table 1. In vitro antiprotozoal activity of the ethanolic extracts of Turkish macrophytes (I[C.sub.50] values are in [micro]g/ml) Plants T. brucei rhodesiense T. cruzi L. donovani Cladophora glomerata 11.5 >90 39.2 Dictyota dichotoma 17.1 >90 52.0 Halopteris scoparia 43.9 >90 >100 Posidonia oceanica 34.0 >90 8.0 Potamogeton perfoliatus 30.8 >90 22.9 Ranunculus tricophyllus 27.8 >90 52.3 Scinia furcellata 17.9 >90 64.4 Sargassum natans 7.4 >90 90.9 Ulva lactuca 22.3 >90 5.9 Standards 0.0098 (a) 1.06 (b) 0.102 (e) Plants P. falciparum Cytotoxicity (L6 cells) Cladophora glomerata 33.7 >90 Dictyota dichotoma 33.9 >90 Halopteris scoparia >50 >90 Posidonia oceanica >50 >90 Potamogeton perfoliatus >50 >90 Ranunculus tricophyllus >50 >90 Scinia furcellata 41.3 >90 Sargassum natans 18.1 >90 Ulva lactuca 48.8 >90 Standards 0.0022 (d) 0.08 (e) Standard compounds: (a) melarsoprol, (b) benznidazole, (c) miltefosine, (d) artemisinin, (e) phodophyllotoxin.