José Elias de Paula

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.

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.

Plants from Brazilian Cerrado with Potent Tyrosinase Inhibitory Activity

The increased amount of melanin leads to skin disorders such as age spots, freckles, melasma and malignant melanoma. Tyrosinase is known to be the key enzyme in melanin production. Plants and their extracts are inexpensive and rich resources of active compounds that can be utilized to inhibit tyrosinase as well as can be used for the treatment of dermatological disorders associated with melanin hyperpigmentation. Using in vitro tyrosinase inhibitory activity assay, extracts from 13 plant species from Brazilian Cerrado were evaluated. The results showed that Pouteria torta and Eugenia dysenterica extracts presented potent in vitro tyrosinase inhibition compared to positive control kojic acid. Ethanol extract of Eugenia dysenterica leaves showed significant (p<0.05) tyrosinase inhibitory activity exhibiting the IC50 value of 11.88 µg/mL, compared to kojic acid (IC50 value of 13.14 µg/mL). Pouteria torta aqueous extract leaves also showed significant inhibitory activity with IC50 value of 30.01 µg/mL. These results indicate that Pouteria torta and Eugenia dysenterica extracts and their isolated constituents are promising agents for skin-whitening or antimelanogenesis formulations.

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.

Mortalidade de larvas de Plutella xylostella tratadas com extratos etanólicos de Aspidosperma pyrifolium

The objective of this work was to assess the effects of Aspidosperma pyrifolium ethanol extracts on cabbage moth (Plutella xylostella) larvae. The ethanol extracts of the stem bark, fruits and roots of A. pyrifolium were obtained by classical phytochemical methods, and the resulting subfractions were tested on P. xylostella, using 4 and 5 mg L-1. The crude ethanol extract of the stem bark was more lethal. The alkaloid-rich aqueous subfraction derived from the stem bark extract caused 100% larval mortality at 4 mg L-1. Insecticidal activity was associated with the presence of the monoterpenoid indole alkaloids aspidofractinine, 15-demethoxypyrifoline, and N-formylaspidofractinine. These alkaloids presented excellent insecticidal properties against P. xylostella.

Characterization and biological properties of Pouteria torta extracts: a preliminary study

Hexane, ethanol and aqueous extracts and fractions from leaves of Pouteria torta (Mart.) Radlk (Sapotaceae), a perennial tree, widespread in the Brazilian Cerrado, were tested for cytotoxicity with the Artemia salina toxicity model. Only the aqueous crude extract and the MeCN:CHCl3 fraction of the ethanol extract presented toxicity (0.28 mg/mL and 0.27mg/mL, respectively). Lupeol acetate was isolated from the hexane extract. It is the first report of lupeol acetate from the genus Pouteria.

Efeito de extratos de plantas do Cerrado em Dipetalogaster maxima (Uhler) (Hemiptera, Reduviidae)

Chagas disease, also known as American Trypanosomiasis, is chiefly transmitted by faeces of haematophagous bugs (Triatominae) that ingested Trypanosoma cruzi from blood of infected people or other mammals. Pyrethroids have been the main insecticides used against these insects. However, some populations of insects have shown significant levels of resistance to several pyrethroids, indicating the need of new insecticides for the control of triatomines. Thus, the insecticidal activity of 83 Cerrado plant extracts belonging to 35 species were assayed on first instar nymphs of Dipetalogaster maxima (Uhler, 1894) (Hemiptera, Reduviidae), species found in Mexico. For the extract application on triatomines, 50 μg of the extract were topically applied in duplicate on dorsal tergites of ten insects. Insects topically treated with acetone, ethanol, as well as insects with no treatment were used as controls. Triatomines were observed over a 28-day period. The extracts showed no insect mortality, however, fruit hexane and stem bark ethanolic extracts of Simarouba versicolor (Simaroubaceae) inhibited the rate of ecdysis in D. maxima (40% and 25%, respectively). These preliminary data suggest that this extracts should be chemically investigated and monitored through biological assays in order to determine the components, so that it may be used as a molecular model or as biorational compounds for use in insect control programmes.

Discovery of the rapanone and suberonone mixture as a motif for leishmanicidal and antifungal applications.

Leishmaniasis and fungal infections are significant diseases impacting worldwide public health. Treatments have developed greatly over time, however, there is a necessity to discover less toxic drugs, which have greater efficacy and are more economically accessible. This work conducted a screening of Cerrado species extracts: Connarus suberosus Planch. (Connaraceae), Neea theifera Oerst. (Nyctaginaceae) and Myrcia linearifolia Cambess. (Myrtaceae) against Leishmania (Leishmania) amazonensis, dermatophytes and yeasts. Leishmanicidal and antifungal tests were conducted using MTT colorimetric assay and CLSI methodology, respectively. Connarus suberosus extracts presented the most promising results against the aforementioned microorganisms, which has not been described in the literature. The root bark EtOAc extract was selected for chemical fractionation resulting in a mixture of rapanone (1) and a previously unreported compound named as suberonone (2); a mixture of β-sitosterol (3) and stigmasterol (4); oleic acid (5); geranilgeraniol (6); and two derivatives obtained from 1 and 2 mixture. The rapanone and suberonone mixture demonstrated a MIC of 15.62 μg/mL against Candida albicans ATCC 10231.