Laila Salmen Espindola

Cytotoxic activity of Brazilian Cerrado plants used in traditional medicine against cancer cell lines

UNLABELLED The search for new anti-cancer drugs is one of the most prominent research areas of natural products. Numerous active compounds isolated from Brazilian Cerrado plant species have been studied with promising results. AIM OF THE STUDY To investigate the cytotoxic potential of 412 extracts from Brazilian Cerrado plants used in traditional medicine belonging to 21 families against tumor cell lines in culture. MATERIAL AND METHOD Maceration of 50 plant species resulted in 412 hexane, dichloromethane, ethanol and hydroalcohol extracts. The cytotoxicity of the extracts was tested against human colon carcinoma (HCT-8), melanoma (MDA-MB-435), and brain (SF-295) tumor cell lines, using the thiazolyl blue test (MTT) assay. Bioassay-guided fractionation was performed for one active extract. RESULTS AND CONCLUSIONS Twenty-eight of the 412 tested extracts demonstrated a substantial antiproliferative effect, at least 85% inhibition of cell proliferation at 50 microg/mL against one or more cell lines. Those extracts are obtained from different parts of Anacardiaceae, Annonaceae, Apocynaceae, Clusiaceae, Flacourtiaceae, Sapindaceae, Sapotaceae, Simaroubaceae and Zingiberaceae. Complete dose-response curves were generated and IC(50) values were calculated for these active extracts against four cell lines HCT-8, MDA-MB-435, SF-295 and HL-60 (leukemia), and their direct cytotoxic effects were determined. In summary, 14 extracts of 13 species showed toxicity in all tested tumor cell lines, with IC(50) values ranging from 0.1 to 19.1 microg/mL. The strongest cytotoxic activity was found for the hexane extract of Casearia sylvestris var. lingua stem bark, with an IC(50) of 0.1 microg/mL for HCT-8, 0.9 microg/mL for SF-295, 1.2 microg/mL for MDA-MB-435, and 1.3 microg/mL for HL-60, and Simarouba versicolor root bark, with an IC(50) of 0.5 microg/mL for HCT-8, 0.7 microg/mL for SF-295, 1.5 microg/mL for MDA-MB-435, 1.1 microg/mL for HL-60. Bioassay-guided fractionation of the last extract led to the isolation of glaucarubinone, which showed pronounced activity against the four cell lines studied. Further studies of the active extracts are necessary for chemical characterization of the active compounds and more extensive biological evaluations.

Antileishmanial and trypanocidal activity of Brazilian Cerrado plants

The side effects and the emerging resistance to the available drugs against leishmaniasis and trypanosomiasis led to the urgent need for new therapeutic agents against these diseases. Thirty one extracts of thirteen medicinal plants from the Brazilian Cerrado were therefore evaluated in vitro for their antiprotozoal activity against promastigotes of Leishmania donovani, and amastigotes of Trypanosoma cruzi. Among the selected plants, Casearia sylvestris var. lingua was the most active against both L. donovani and T. cruzi. Fifteen extracts were active against promastigotes of L. donovani with concentrations inhibiting 50% of parasite growth (IC50) between 0.1-10 microg/ml, particularly those of Annona crassiflora (Annonaceae), Himatanthus obovatus (Apocynaceae), Guarea kunthiana (Meliaceae), Cupania vernalis (Sapindaceae), and Serjania lethalis (Sapindaceae). With regard to amastigotes of T. cruzi, extracts of A. crassiflora, Duguetia furfuracea (Annonaceae), and C. sylvestris var. lingua were active with IC50 values between 0.3-10 microg/ml. Bioassay fractionations of the more active extracts are under progress to identify the active antiparasite compounds.

LARVICIDAL ACTIVITY OF SOME CERRADO PLANT EXTRACTS AGAINST AEDES AEGYPTI

ABSTRACT One hundred ninety hexanic and ethanolic extracts from 27 plant species from the Cerrado biome of Brazil were tested for larvicidal activity against 3rd-stage Aedes aegypti larvae at 500 μg/ml. Fourteen extracts from 7 species showed activity (>65% mortality) against the larvae. Of these, Duguetia furfuracea, Piptocarpha rotundifolia, Casearia sylvestris var. lingua, Serjania lethalis, and Xylopia aromatica were active at 56.6, 162.31, 232.4, 285.76, and 384.37 μg/ml, respectively. Annona crassiflora and Cybistax antisyphilitica showed activity at 23.06 and 27.61 μg/ml. The larvicidal properties of these species are described for the first time, and may prove to be promising in active chemical compound isolation.

Evaluation of the antifungal potential of Brazilian Cerrado medicinal plants

Therapeutic limitations, development of fungal drug resistance, drug‐related toxicity, drug interactions and insufficient bioavailability of the currently available antifungal drugs have made the development of drugs necessary that would be able to treat the emerging fungal infections. The Cerrado is the second greater biome of Brazil and it was identified as one of the most distinguished biomes of South America, becoming an important source of innovative vegetal molecules to treat several conditions. Thus, the objective of this study was to evaluate the antifungal potential of Cerrado plants, mainly those used to treat infections and wounds. A total of 57 extracts were screened by the agar‐well diffusion technique against Candida albicans and Trichophyton rubrum. The most promising extracts were tested in smaller concentrations and their minimal inhibitory concentrations (MIC) were determined by microdilution method. Results were analysed statistically by anova tests. Extracts of Kielmeyera coriacea, Renealmia alpinia, Stryphnodendron adstringens and Tabebuia caraiba were very active against T. rubrum, presented geometric means of the MIC values between 170.39 and 23.23 μg ml−1. Extracts of Cerrado plants are of particular interest as source of new agents for the treatment of dermatophytic infections.

Antimicrobial and cytotoxic secondary metabolites from tropical leaf endophytes: Isolation of antibacterial agent pyrrocidine C from Lewia infectoria SNB-GTC2402.

Because of the symbiotic nature of endophytes, this survey aims to investigate the probability of discovering antibacterial, antifungal and cytotoxic activities in leaf endophytic microbes. We isolated 138 cultivable microbes (121 fungi, 3 bacteria and 14 unidentified or unknown microbes) from 24 plant species, a significant relative proportion of which exhibited antifungal and cytotoxic potential against Candida albicans ATCC 10213 and the human cell lines KB (uterine cervical carcinoma), MDA-MB-435 (melanoma), and MRC5 (normal human lung fibroblasts). Three active fungal extracts were fractionated, resulting in the isolation of eight compounds. Seven had been described in the literature including the following: acremonisol A, semicochliodinol A, cochliodinol, griseofulvin, pyrenocin A, novae zelandin A and alterperylenol. A previously unreported compound named pyrrocidine C was isolated from Lewia infectoria SNB-GTC2402 and identified by spectroscopic analysis. As in pyrrocidines A and B, this compound is a cis-substituted decahydrofluorene with a quaternary carbon at C-5 and opposite stereochemistry at C-8 corresponding to C-6 of pyrrocidines A and B.

Selection of the most promising 2-substituted quinoline as antileishmanial candidate for clinical trials

The antileishmanial evaluation of more than one hundred 2-substituted quinolines led us to identify three compounds for further studies: compound 1 (2-n-propylquinoline), compound 2 (2-(2methoxyethenyl)quinoline) and compound 3 (2-(2-hydroxyprop-2-enyl)quinoline). The final selection of a potential drug candidate was mainly based on chemical stability and acute oral toxicity as discriminating criteria. The most stable compound in various conditions was 2-n-propylquinoline (compound 1). Only reversible toxicity signs were observed for compound 1 at 1000 mg/kg after a treatment by oral route at a single dose and no sign was detected at 100 mg/kg. Interestingly, 2-substituted quinolines were active on a Leishmania donovani line, resistant to sitamaquine, a 8-aminoquinoline, suggesting that 2-substituted quinolines and 8-aminoquinoline probably affect a different target in L. donovani.

Search for antifungal compounds from the wood of durable tropical trees.

Research on antifungal compounds from the durable wood from French Guiana Amazonian forest trees highlights the correlation between the activity of their extracts against wood-rotting fungi and human pathogens. The fractionation of an ethyl acetate extract of Sextonia rubra wood led to the isolation of rubrenolide (1) and rubrynolide (2). The potential of compounds 1 and 2 is described through the evaluation of their activity against 16 pathogenic fungi and their cytotoxicity toward NIH-3T3 mammalian fibroblast cells.

Investigation of plant extracts in traditional medicine of the Brazilian Cerrado against protozoans and yeasts.

AIM OF THE STUDY To investigate the activities of the 217 plant extracts in traditional medicine of the Brazilian Cerrado against protozoans and yeasts. MATERIALS AND METHODS Plant extracts were prepared by the method of maceration using solvents of different polarities. The growth inhibition of chloroquine-resistant Plasmodium falciparum strain (FcB1) was determined by measuring the radioactivity of the tritiated hypoxanthine incorporated. Activity against Leishmania (Leishmania) chagasi and Trypanosoma cruzi was measured by the MTT colorimetric assay. The antifungal tests were carried out by using the CLSI method. The active extracts were tested also by cytotoxicity assay using NIH-3T3 cells of mammalian fibroblasts. RESULTS Two hundred and seventeen extracts of plants were tested against Plasmodium falciparum. The eleven active extracts, belonging to eight plant species were evaluated against L. (L.) chagasi, Trypanosoma cruzi, yeasts and in NIH-3T3 cells. The results found in these biological models are consistent with the ethnopharmacological data of these plants. The ethyl acetate extract of Diospyros hispida root showed IC(50) values of 1 microg/mL against Plasmodium falciparum. This extract demonstrated no toxicity against mammalian cells, resulting in a significant selectivity index (SI) of 435.8. The dichloromethane extract of Calophyllum brasiliense root wood was active against Cryptococcus gattii LMGO 01 with MIC of 1.95 microg/mL; and Candida albicans ATCC 10231 and Candida krusei LMGO 174, both with MIC of 7.81 microg/mL. The same extract was also active against Plasmodium falciparum and L. (L.) chagasi with IC(50) of 6.7 and 27.6 microg/mL respectively. The ethyl acetate extract of Spiranthera odoratissima leaves was active against Cryptococcus gattii LMGO 01 with MIC of 31.25 microg/mL, and against Plasmodium falciparum with IC(50) of 9.2 microg/mL and Trypanosoma cruzi with IC(50) of 56.3 microg/mL. CONCLUSION The active extracts for protozoans and human pathogenic yeasts are considered promising to continue the search for the identification and development of leading compounds.

Cytotoxicity of δ-tocotrienols from Kielmeyera coriacea against cancer cell lines.

In the search for new anti-cancer compounds, Brazilian Cerrado plant species have been investigated. The hexane root bark extract of Kielmeyera coriacea lead to a mixture of δ-tocotrienol (1) and its dimer (2). The structures of both compounds 1 and 2 were established based on detailed 1D and 2D NMR and EI-MS analyses. The cytotoxicity of the mixture was tested against four human tumor cell lines in the following cultures: MDA-MB-435 (melanoma), HCT-8 (colon), HL-60 (leukemia), and SF-295 (glioblastoma), and displayed IC(50) values ranging from 8.08 to 23.58μg/mL. Additional assays were performed in order to investigate the mechanism of action of the mixture (1+2) against the human leukemia cell line HL-60. The results suggested that the mixture suppressed leukemia growth and reduced cell survival, triggering both apoptosis and necrosis, depending on the concentration.

Antivascular and anti-parasite activities of natural and hemisynthetic flavonoids from New Caledonian Gardenia species (Rubiaceae)

A series of 16 flavonoids were isolated and prepared from bud exudate of Gardenia urvillei and Gardenia oudiepe, endemic to New Caledonia. Most of them are rare polymethoxylated flavones. Some of these compounds showed noticeable activity against Leishmania (Leishmania) amazonensis, Plasmodium falciparum and Trypanosoma brucei gambiense, in addition to tubulin polymerization inhibition at low micromolar concentration. We also provide a full set of NMR data as some of the flavones were incompletely described.