The potential of secondary metabolites from plants as drugs or leads against protozoan neglected diseases - part I

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 as such by WHO due to the neglect of financial investment into research and development of new drugs by a large part of pharmaceutical industry and neglect of public awareness in high income countries. Another major tropical protozoan disease is malaria (caused by various Plasmodium species), which -although not mentioned currently by the WHO as a neglected disease- still represents a major problem, especially to people living under poor circumstances in tropical countries. Malaria causes by far the highest number of deaths of all protozoan infections and is often (as in this review) included in the NTDs. The mentioned diseases threaten many millions of lives world-wide and they are mostly associated with poor socioeconomic and hygienic environment. Existing therapies suffer from various shortcomings, namely, a high degree of toxicity and unwanted effects, lack of availability and/or problematic application under the life conditions of affected populations. Development of new, safe and affordable drugs is therefore an urgent need. Nature has provided an innumerable number of drugs for the treatment of many serious diseases. Among the natural sources for new bioactive chemicals, plants are still predominant. Their secondary metabolism yields an immeasurable wealth of chemical structures which has been and will continue to be a source of new drugs, directly in their native form and after optimization by synthetic medicinal chemistry. The current review, published in two parts, 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.

Ion fluxes and hematological parameters of two teleosts from the Rio Negro, Amazon, exposed to hypoxia / Fluxos iônicos e parâmetros hematológicos em duas espécies de teleósteos do Rio Negro, Amazônia, expostos à hipoxia

The aim of this study was to describe the effect of hypoxia on whole body ion fluxes and hematological parameters in two Amazonian teleosts: Serrasalmus eigenmanni and Metynnis hypsauchen. The increase of Na+ and Cl- effluxes on M. hypsauchen exposed to hypoxia may be related to an increase of gill ventilation and effective respiratory surface area, to avoid a reduction in the oxygen uptake, and/or with the decrease of pHe, that could inhibit Na+ and Cl- transporters and, therefore, reduce influx of these ions. Effluxes of Na+ and Cl- were lower in hypoxia than in normoxia for S. eigenmanni, possibly because in hypoxia this species would reduce gill ventilation and oxygen uptake, which would lead to a decrease of gill ion efflux and, consequently, reducing ion loss. The increase on hematocrit (Ht) during hypoxia in M. hypsauchen probably was caused by an increase of the red blood cell volume (MCV). For S. eigenmanni the increase on glucose possibly results from the usage of glucose reserve mobilization. Metynnis hypsauchen showed to be more sensitive to hypoxia than Serrasalmus eigenmanni, since the first presented more significant alterations on these osmoregulatory and hematological parameters. Nevertheless, the alterations observed for both species are strategies adopted by fishes to preserve oxygen supply to metabolizing tissues during exposure to hypoxia.

O objetivo deste trabalho foi descrever o efeito da hipoxia no fluxo iônico corporal e nos parâmetros hematológicos em duas espécies de teleósteos da Amazônia: Serrasalmus eigenmanni e Metynnis hypsauchen. O aumento dos efluxos de Na+ e Cl- em M. hypsauchen expostos à hipoxia pode estar relacionado ao aumento da ventilação branquial e da eficiência da área da superfície respiratória, a fim de evitar redução na captação de oxigênio; e/ou com a diminuição do pHe, que pode inibir os transportadores de Na+ e Cl- e, então, reduzir o influxo destes íons. Os efluxos de Na+ e Cl- foram menores em hipoxia do que em normoxia para a espécie S. eigenmanni, possivelmente porque esta espécie em hipoxia poderia reduzir a ventilação branquial e a captação de oxigênio, a qual levaria a uma diminuição do efluxo branquial de íons e, conseqüentemente, à redução da perda de íons. O aumento do hematócrito (Ht) durante hipoxia em M. hypsauchen provavelmente foi causado pelo aumento do volume das células vermelhas do sangue (MCV). Para a espécie S. eigenmanni, o aumento da glicose possivelmente foi resultado do uso da mobilização da reserva de glicose. A espécie Metynnis hypsauchen mostrou ser mais sensível à hipoxia do que a espécie Serrasalmus eigenmanni, uma vez que a primeira espécie apresentou mais alterações significativas em seus parâmetros osmorregulatórios e hematológicos. Contudo, as alterações observadas em ambas as espécies são estratégias adotadas pelos peixes a fim de preservar o suprimento de oxigênio para metabolização nos tecidos durante exposição à hipoxia.

Colony membership is reflected by variations in cuticular hydrocarbon profile in a Neotropical paper wasp, Polistes satan (Hymenoptera, Vespidae)

Nestmate recognition is one the most important features in social insect colonies. Although epicuticular lipids or cuticular hydrocarbons have both structural and defensive functions in insects, they also seem to be involved in several aspects of communication in wasps, bees and ants. We analyzed and described for the first time the cuticular hydrocarbons of a Neotropical paper wasp, Polistes satan, and found that variation in hydrocarbon profile was sufficiently strong to discriminate individuals according to their colony membership. Therefore, it seems that small differences in the proportion of these compounds can be detected and used as a chemical-based cue by nestmates to detect invaders and avoid usurpation.