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 ß-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.

Spiranthenones A and B, tetraprenylated phloroglucinol derivatives from the leaves of Spiranthera odoratissima.

Two new polyprenylated acylphloroglucinols, spiranthenones A (1) and B (2), a sesquiterpenoid, 6 α-acetoxy,1 ß-hydroxyeudesm-4(15)-ene (3), along with sesamin and ß-sitosterol, were isolated from the EtOAc extract of the leaves of Spiranthera odoratissima, and shown to display antiprotozoal activity. Their structures and relative stereochemistry were elucidated by NMR and mass spectrometry. These compounds exhibited moderate antiprotozoal activity, but without significant cytotoxicity against fibroblasts cell line NIH-3T3. Compound 3 was the most selective towards parasites.

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.

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 microg ml(-1). Extracts of Cerrado plants are of particular interest as source of new agents for the treatment of dermatophytic infections.

In vitro investigation of Brazilian Cerrado plant extract activity against Plasmodium falciparum, Trypanosoma cruzi and T. brucei gambiense.

The threatened Brazilian Cerrado biome is an important biodiversity hotspot but still few explored that constitutes a potential reservoir of molecules to treat infectious diseases. We selected eight Cerrado plant species for screening against the erythrocytic stages of Plasmodium falciparum, human intracellular stages of Trypanosoma cruzi and bloodstream forms of T. brucei gambiense, and for their cytotoxicity upon the rat L6-myoblast cell line. Bioassays were performed with 37 hexane, ethyl acetate and ethanol extracts prepared from different plant organs. Activities against parasites were observed for 24 extracts: 9 with anti-P. falciparum, 4 with anti-T. cruzi and 11 with anti-T. brucei gambiense activities. High anti-protozoal activity (IC50 values < 10 µg/mL) without obvious cytotoxicity to L6 cells was observed for eight extracts from plants: Connarus suberosus, Blepharocalyx salicifolius, Psidium laruotteanum and Myrsine guianensis. Overall, studies of plant extracts will contribute to increase the biodiversity knowledge essential for Cerrado conservation and sustainable development.

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.

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.

New ether diglycosides from Matayba guianensis with antiplasmodial activity.

Four new ether diglycosides (1-4), named matayosides A-D, were isolated from the root bark of Matayba guianensis, a plant exhibiting in vitro antiplasmodial activity. They were identified as hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-6-O-palmitoyl-beta-D-glucopyranoside, hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-4,6-di-O-acetyl-beta-D-glucopyranoside, hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-3,6-di-O-acetyl-beta-D-glucopyranoside and hexadecyl-[O-2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl-(1-->2)]-6-O-acetyl-beta-D-glucopyranoside, respectively. Their structures were established using one- and two-dimensional NMR techniques, mass spectrometry (MS) and MS/MS experiments. The compounds were found to inhibit the growth of Plasmodium falciparum in vitro with IC50 values ranging from 2.5 to 8.9 microg/mL.

Trypanocidal activity of a new diterpene from Casearia sylvestris var. lingua.

Bioassay-guided fractionation of the hexanic root bark extract of Casearia sylvestris var. lingua led to the isolation of a new clerodane diterpene, whose structure was elucidated as rel-(2 S,5 R,6 R,8 S,9 S,10 R,18 S,19 R)-19-acetoxy-18,19-epoxy-6-hydroxy-18-butanoyloxy-2-(2-methylbutanoyloxy)cleroda-3,13(16), 14-triene by spectroscopic means, including 1D and 2D NMR analyses. This compound showed pronounced activity on Trypanosoma cruzi, the casual agent of Chagas' disease, with minimal inhibitory concentration (MIC) at 0.59 microg/mL.