This paper describes the development of a novel microfluorimetric assay to measure the inhibition of Plasmodium falciparum based on the detection of parasitic DNA by intercalation with PicoGreen. The method was used to determine parasite inhibition profiles and 50% inhibitory concentration values of known or potential antimalarial drugs. Values for parasite inhibition with known anti-malarial drugs using the PicoGreen assay were comparable with those determined by the standard method based upon the uptake of 3H-hypoxanthine and the Giemsa stain microscopic technique. The PicoGreen assay is rapid, sensitive, reproducible, easily interpreted, and ideally suited for screening of large numbers of samples for anti-malarial drug development.

BackgroundPlinia cerrocampanensis is an endemic plant of Panama. The leaf essential oil of this plant has shown antibacterial activity. However, anti-malarial activity and chemical profiling by HS-SPME-GC-MS of this essential oil have not been reported before.MethodsAnti-malarial activity of the essential oil (EO) was evaluated in vitro against chloroquine-sensitive HB3 and chloroquine-resistant W2 strains of Plasmodium falciparum. Synergistic effect of chloroquine and the EO on parasite growth was evaluated by calculating the combination index. A methodology involving headspace solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) was developed to investigate the composition of Plinia cerrocampanensis EO.ResultsPlinia cerrocampanensis EO showed a high anti-malarial activity and a synergistic interaction with chloroquine. The Plinia cerrocampanensis EO inhibited P. falciparum growth in vitro at an IC50 of 7.3 μg/mL. Chloroquine together with the EO decreased the IC50 of chloroquine from 0.1 μg/mL to 0.05 μg/mL, and of the EO from 7.3 μg/mL to 1.1 μg/mL. The measured combination index was 0.58, which clearly indicates that the EO acts synergistically with chloroquine. Since the EO maintained its inhibitory activity on the chloroquine-sensitive strain of the parasite, it could be acting by a different mechanism of action than chloroquine. The best HS-SPME-GC-MS analytical conditions were obtained when the temperature of extraction was 49°C, incubation time 14 min, and the time of extraction 10 min. This method allowed for the identification of 53 volatile constituents in the EO, including new compounds not reported earlier.ConclusionsThe anti-malarial activity exhibited by the Plinia cerrocampanensis EO may lend support for its possible use as an alternative for anti-malarial therapy.

Cocos nucifera ( C . nucifera ) (the coconut palm tree) has been traditionally used to fight a number of human diseases, but only a few studies have tested its components against parasites such as those that cause malaria. In this study, C . nucifera samples were collected from a private natural reserve in Punta Patiño, Darien, Panama. The husk, leaves, pulp, and milk of C . nucifera were extracted and evaluated against the parasites that cause Chagas’ disease or American trypanosomiasis ( Trypanosoma cruzi ), leishmaniasis ( Leishmania donovani ) and malaria ( Plasmodium falciparum ), as well as against a line of breast cancer cells. While there was no activity in the rest of the tests, five and fifteen-minute aqueous decoctions of leaves showed antiplasmodial activity at 10% v/v concentration. Removal of some HPLC fractions resulted in loss of activity, pointing to the presence of synergy between the components of the decoction. Chemical molecules were separated and identified using an ultra-performance liquid chromatography (UPLC) approach coupled to tandem mass spectrometry (LC–MS/MS) using atmospheric pressure chemical ionization quadrupole–time of flight mass spectrometry (APCI–Q–TOF–MS) and molecular networking analysis, revealing the presence of compounds including polyphenol, flavone, sterol, fatty acid and chlorophyll families, among others.

This paper is a contribution to the study of the use of natural resources from tropical moist forests with a view to avoiding deforestation for farming purposes. This study analysed the moisture, fat, protein, ash, total dietary fibre, nitrogen-free extract, and gross energy content of various parts of the fruits of several Amazonian palms belonging to the Aracaceae (Palmae) family-Attalea racemosa, Euterpe precatoria, Mauritia flexuosa, Oenocarpus bataua, and Oenocarpus bacaba-and also the fatty acid content of the oils extracted from the fractions of the fruit with the highest fat content. The high fat content of the mesocarp makes these foods an excellent source of energy, particularly those from A. racemosa, M. flexuosa, and O. bacaba, with fat contents of 58.1, 49.1, and 30.2 g/100 g of sample, respectively. The kernels have a high level of nitrogen-free extract, consisting basically of carbohydrates, particularly those of O. bataua and M. flexuosa, which have 83.9 and 72.5 g/100 g of sample, respectively. Apart from A. racemosa mesocarp oil, the fatty acid content of these oils, particularly oleic acid, is quite similar to that of oils with a high market value, such as olive, sunflower, corn, and soya oil. The cultivation of these species in the forest, just as the natives have always done, should be encouraged, since in addition to being potential sources of high-quality vegetable oils, they are alternative foods for the population in that region because of their nutritive value. The sale of these oils could increase the resources of tropical moist forests, which would in turn contribute considerably to the conservation of the forests.