IMMUNOSUPPRESIVE EFFECTS OF THE METHANOLIC EXTRACT OF CHRYSOPHYLLUM CAINITO LEAVES ON MACROPHAGE FUNCTIONS.

BACKGROUND: The aim of this work was to evaluate the immunomodulatory effect of the methanol extract (MeOH) from Chrysophyllum cainito leaves on the MΦs functions. MATERIAL AND METHODS: Peritoneal murine MΦs isolated from Balb/c mice were treated with the MeOH extract and stimulated with LPS. The effect on the phagocytosis was evaluated by flow cytometry assay. The nitric oxide (NO) and hydrogen peroxide (H2O2) production was measured by the Griess reagent and phenol red reaction, respectively. Levels of IL-6 and TNF-α was measured using an ELISA kit. Viability of MΦs and Vero cells was determined by the MTT method. RESULTS: The MeOH extract of C. cainito leaves inhibited significantly the phagocytosis, and decreased IL-6 and TNF-α production as well as NO and H2O2 released by the MΦs, in a concentration-dependent manner. In addition, MeOH extract of C. cainito showed low cytotoxicity effect against the cells. CONCLUSION: These results suggest that MeOH extract of C. cainito leaves has an immunosuppressive effect on murine MΦs, without effects on cell viability. GC-MS chromatogram analysis of MeOH extract showed that lupeol acetate and alpha-amyrin acetate are the principal compounds.

Seasonal phytochemical study and antimicrobial potential of Vetiveria zizanioides roots.

This paper describes the seasonal phytochemical variation and the antimicrobial potential of V. zizanioides roots collected in Brazil. Considering the high levels of chemical constituents and their biological activity in dichloromethane fraction, the plants were grown in different seasons and the respective dichloromethane fractions were analyzed by gas chromatography-mass spectrometry. The antimicrobial activity was evaluated against several pathogenic microorganisms by determining the minimum inhibitory concentration (MIC) using the agar dilution method. Yields of dichloromethane fractions from plants collected in the autumn and spring occurred in a higher proportion than in other seasons. Khusimol (2) was isolated by column chromatography and identified by NMR and CG-MS, along with other sesquiterpenes, including ß-vetivenene (1), vetiselinenol (3), isovalencenol (4), vetivenic acid (5), α-vetivone (6) and ß-vetivone (7). Some extracts showed promising antimicrobial effects, with MICs ranging from 31.25 to 500 µg mL-1. Kushimol was slightly active against the tested microorganisms.

Antimicrobial activity of extracts and fractions from aerial parts of selected plants (Garcinia achachairu, Macrosiphonia velame, Rubus niveus and Pilea microphylla) against some pathogenic microorganisms.

As part of the program of our research group to search for new and effective substances from the Brazilian biodiversity, the present work evaluates the antibacterial activity of four species from the Brazilian flora (Garcinia achachairu, Macrosiphonia velame, Rubus niveus and Pilea microphylla) against Bacillus subtilis, Staphylococcus aureus and S. saprophyticus (Gram-positive bacteria), Escherichia coli (Gram-negative bacterium) and Candida albicans (yeast). The extracts of R. niveus and M. velame showed promising antibacterial activity with MICs, ranging from 1000 to 125 microg/mL. Bio-guided fractionation of M. velame yielded four compounds, with the highest inhibition being observed for compound 3, with a MIC of 125 microg/mL against S. aureus. The combinations of fractions 2 and 4 showed beneficial effect against Gram-positive bacteria (additive effect), suggesting a possible synergistic effect.

The leishmanicidal effect of (3S)-16,17-didehydrofalcarinol, an oxylipin isolated from Tridax procumbens, is independent of NO production.

The in vitro leishmanicidal effect of (3S)-16,17-didehydrofalcarinol (1) isolated from Tridax procumbens whole plant against Leishmania mexicana, the causative agent of cutaneous leishmaniasis (chiclero's ulcer) in the New World, was investigated. This oxylipin showed significant in vitro activity against promastigotes and intracellular amastigotes of L. mexicana. Its inhibitory effect on amastigotes was not due to activation of NO in recombinant gamma-interferon-stimulated macrophages, since the production of NO was decreased in presence of the oxylipin. This is the first report on the leishmanicidal activity against the intracellular stage (amastigote) of the oxylipin (3S)-16,17-didehydrofalcarinol.

In vitro activity of Tridax procumbens against promastigotes of Leishmania mexicana.

ETHNOPHARMACOLOGICAL RELEVANCE: Tridax procumbens is an active herb against leishmaniasis. AIM OF THE STUDY: Leishmaniasis is a group of diseases caused by Leishmania protozoa. We investigated the antileishmanial activity of Tridax procumbens extracts and a pure compound against promastigotes of Leishmania mexicana, the causative agent of cutaneous leishmaniasis in the New World. MATERIALS AND METHODS: Extracts and (3S)-16,17-didehydrofalcarinol (1) were obtained by chromatographic methods from Tridax procumbens, and the latter identified by spectroscopic analysis. The effect of these extracts and 1 on the growth inhibition of promastigotes of Leishmania mexicana was evaluated. In order to test the safety of extracts and 1, mammalian cells were treated with them, and cell viability was assessed using trypan blue and MTT. RESULTS: We demonstrated that extracts of Tridax procumbens and 1 showed a pronounced activity against Leishmania mexicana. The methanol extract inhibited promastigotes growth of Leishmania mexicana with a 50% inhibitory concentration (IC(50)) of 3 microg/ml, while oxylipin 1 exhibited the highest inhibition at IC(50)=0.478 microg/ml. CONCLUSIONS: In this study we report the biological activity of extracts and (3S)-16,17-didehydrofalcarinol (1), obtained from Tridax procumbens, on the promastigote form of Leishmania mexicana, with no effect upon mammalian cells.

Leishmanicidal activity of Yucatecan medicinal plants on Leishmania species responsible for cutaneous leishmaniasis.

The leishmanicidal activity of 15 extracts and 4 pure metabolites obtained from Urechites andrieuxii, Colubrina greggii, Dorstenia contrajerva, and Tridax procumbens was evaluated using the newly developed MTS ({3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) assay, optimized for promastigotes of Leishmania major, Leishmania tropica, and Leishmania aethiopica, as well as for L. aethiopica axenic amastigotes. The assay was then used for calculating the percentage of viable stationary phase parasites after a 24-hr treatment with each plant extract or pure metabolite. The 3 most active samples, 2 from C. greggii (NCG-5C and DCG-3A) and 1 from T. procumbens (TPZ-2A), showed LD50 values of 62.4, 7.2, and 18.5 microg/ml, respectively, on stationary promastigotes, and of 94.2, 27.1, and 95.2 microg/ml, on amastigotes of L. aethiopica. Moreover, TPZ-2A and DCG-3A significantly reduced the percentage of infected monocyte-derived macrophages (THP-I). The percentage of infected cells decreased from 69.9% +/- 2.5% to 20.8% +/- 2% when the cells were treated with the DCG-3A fraction and to 14.9% +/- 0.5% when treated with TPZ-2A, without significantly decreasing the number of human cells. These findings indicate the presence of potentially bioactive metabolites in the roots of C. greggii and in T. procumbens and reflect the importance of pursuing the bioassay-guided purification of these metabolites.