Leishmania

The reservoir animals, sandfly vectors and strains of Leishmania from foci in the southern region of Israel were studied. The rodent host species are: Psammomys obesus, Meriones crassus and probably Nesokia indica. The vector species are Phlebotomus papatasi, which were caught at all collecting sites and Ph. sergenti, which were collected in the area of the Dead Sea and in the Central Arava. Strains of Leishmania major isolated from rodents, vectors and man were serologically and enzymologically identical with regard to their excreted factor (EF) serotypes, their malate dehydrogenase (MDH), glucose-phosphate isomerase (GPI) and glucose-6-phosphate dehydrogenase (G6PDH) enzyme variant types, but exhibited three variant subtypes of 6-phosphogluconate dehydrogenase (6PGDH). The distribution of the 6PGDH subtypes correlates with three different geographical locations. Scarcity of water is the main factor limiting the biotopes of the sandflies and the spread of leishmaniasis. The subject...

Several quinolines were synthesized and evaluated in vitro against several parasites (Trypanosoma brucei, T. cruzi, Leishmania infantum, L. amazonensis, Plasmodium falciparum). Then, they were evaluated in vitro (at 10 microM), against HTLV-1 transformed cells. A few of them displayed interesting activities, comparable to the reference drugs.

Infections with protozoan parasites are a major cause of disease and mortality in many tropical countries of the world. Diseases caused by species of the genera Trypanosoma (Human African Trypanosomiasis and Chagas Disease) and Leishmania (various forms of Leishmaniasis) are among the seventeen “Neglected Tropical Diseases” (NTDs) defined by the WHO. Furthermore, malaria (caused by various Plasmodium species) can be considered a neglected disease in certain countries and with regard to availability and affordability of the antimalarials. Living organisms, especially plants, provide an innumerable number of molecules with potential for the treatment of many serious diseases. The current review attempts to give an overview on the potential of such plant-derived natural products as antiprotozoal leads and/or drugs in the fight against NTDs.
In part I, a general description of the diseases, the current state of therapy and need for new therapeuticals, assay methods and strategies applied in the search for new plant derived natural products against these diseases and an overview on natural products of terpenoid origin with antiprotozoal potential were given.

The present part II compiles the current knowledge on natural products with antiprotozoal activity that are derived from the shikimate pathway (lignans, coumarins, caffeic acid derivatives), quinones of various structural classes, compounds formed via the polyketide pathways (flavonoids and related compounds, chromenes and related benzopyrans and benzofurans, xanthones, acetogenins from Annonaceae and polyacetylenes) as well as the diverse classes of alkaloids.

In total, both parts compile the literature on almost 900 different plant-derived natural products and their activity data, taken from over 800 references. These data, as the result of enormous efforts of numerous research groups world-wide, illustrate that plant secondary metabolites represent an immensely rich source of chemical diversity with an extremely high potential to yield a wealth of lead structures towards new therapies for NTDs. Only a small percentage, however, of the roughly 200,000 plant species on earth have been studied chemically and only a small percentage of these plants or their constituents has been investigated for antiprotozoal activity. The repository of plant-derived natural products hence deserves to be investigated even more intensely than it has been up to present.