Nematostatic activity of isoprenylated guanidine alkaloids from Pterogyne nitens and their interaction with acetylcholinesterase.

Although new nematicides have appeared, the demand for new products less toxic and more efficient for the control of plant-parasitic nematodes are still high. Consequently, studies on natural secondary metabolites from plants, to develop new nematicides, have increased. In this work, nineteen extracts from eleven Brazilian plant species were screened for activity against Meloidogyne incognita. Among them, the extracts of Piterogyne nitens showed a potent nematostatic activity. The alkaloid fraction obtained from the ethanol extract of leaves of P. nitens was more active than the coming extract. Due to the promising activity from the alkaloid fraction, three isoprenylated guanidine alkaloids isolated from this fraction, galegine (1), pterogynidine (2), and pterogynine (3) were tested, showing similar activity to the alkaloid fraction, which was comparable to that of the positive control Temik at 250 µg/mL. At lower concentrations (125-50 µg/mL), compound 2 showed to be the most active one. As several nematicides act through inhibition of acetylcholinesterase (AChE), the guanidine alkaloids were also employed in two in vitro AChE assays. In both cases, compound 2 was more active than compounds 1 and 3. Its activity was considered moderated compared to the control (physostigmine). Compound 2 was selected for an in silico study with the electric eel (Electrophorus electricus) AChE, showing to bind mostly to the same site of physostigmine in the AChEs, pointing out that this could be the mechanism of action for this compound. These results suggested that the guanidine alkaloids 1,2 and 3 from P. nitens are promising for the development of new products to control M. incognita, especially guanidine 2, and encourage new investigations to confirm the mechanism of action, as well as to determine the structure-activity relationship of the guanidine alkaloids.

Cytogenotoxic evaluation of the acetonitrile extract, citrinin and dicitrinin-A from Penicillium citrinum.

Endophytic fungi are promising sources of bioactive substances; however, their secondary metabolites are toxic to plants, animals, and humans. This study aimed toevaluate the toxic, cytotoxic, mutagenic and oxidant/antioxidant activities of acetonitrile extract (AEPc), citrinin (CIT) and dicitrinin-A (DIC-A) of Penicillium citrinum. For this, the test substances at 0.5; 1.0; 1.5 and 2 µg/mLwere exposed for 24 and 48 h in Artemia salina, and 48 h in Allium cepa test systems. The oxidant/antioxidant test was evaluated in pre-, co- and post-treatment with the stressor hydrogen peroxide (H2O2) in Saccharomyces cerevisiae. The results suggest that the AEPc, CIT and DIC-A at 0.5; 1.0; 1.5 and 2 µg/mL showed toxicity in A. saline, with LC50 (24 h) of 2.03 µg/mL, 1.71 µg/mL and 2.29 µg/mL, and LC50 (48 h) of 0.51 µg/mL, 0.54 µg/mL and 0.54 µg/mL, respectively.In A. cepa, the test substances also exerted cytotoxic and mutagenic effects. The AEPc, CIT and DIC-A at lower concentrations modulated the damage induced by H2O2 in the proficient and mutant strains of S. cerevisiae for cytoplasmic and mitochondrial superoxide dismutase. Moreover, the AEPc at 2 µg/mL and CIT at the two highest concentrations did not affect the H2O2-induced DNA damage in the test strains. In conclusion, AEPc, CIT and DIC-A of P. citrinum may exert their toxic, cytotoxic and mutagenic effects in the test systems possibly through oxidative stress induction pathway.

Bioprospecting as a strategy for conservation and sustainable use of the Brazilian Flora / Bioprospecção como estratégia para a conservação e uso sustentável da Flora Brasileira

Abstract In Brazil, research with natural products had a strong impulse when FAPESP supported the creation of the Laboratory of Chemistry of Natural Products of the Institute of Chemistry of USP (1966). In 1999, FAPESP launched the Research Program in the Characterization, Conservation, Restoration and Sustainable Use of Biodiversity (BIOTA-FAPESP), which intensified the sustainable exploitation of biodiversity, and which evolved to form the Biota Network for Bioprospection and Bioassays (BIOprospecTA), which integrates groups from all over the country, optimizing the use of the skills already installed for the bioprospecting of microorganisms, plants, invertebrates, vertebrates and marine organisms. Of the 104 projects related to plant sciences, 35 carried out bioprospection of Brazilian flora, belonging to the areas of Chemistry, Botany, Genetics, Plant Physiology, Plant Morphology, Plant (Chemo)taxonomy, Ecosystem Ecology, Plant Genetics. Physical Sciences, Forest Resources, Forestry Engineering, Agronomy, leading to thousands of publications, engagement of hundreds of students and a deeper understanding of natural products in different biological models through macromolecules analysis aided by computational and spectrometric strategies, in addition to pharmacological evaluations. The development of omics approaches led to a more comprehensive view of the chemical profile of an organism, and enabled integrated and concomitant studies of several samples, and faster annotation of known molecules, through the use of hyphenated and chemometric techniques, and molecular networking. This also helped to overcome the lack of information on the safety and efficacy of herbal preparations, in projects dealing with the standardization of herbal products, according to international standards. The BIOTA-FAPESP program has also focused on environmental aspects, in accordance with the principles of Green Chemistry and has had positive effects on international collaboration, on the number and impact of scientific publications and on partnership with companies, a crucial step to add value and expand the production chain of bioproducts. Also, the compilation, systematization and sharing of data were contemplated with the creation of the NUBBEDB database, of free access, and that integrates with international databases (ACD/labs, American Chemical Society - ACS), helping researchers and companies in the development from different areas of science, technology, strengthening the bioeconomy and subsidizing public policies.

Resumo No Brasil, as pesquisas com produtos naturais tiveram um forte impulso quando a FAPESP apoiou a criação do Laboratório de Química de Produtos Naturais do Instituto de Química da USP (1966). Em 1999, a FAPESP lançou o Programa de Pesquisa em Caracterização, Conservação, Restauração e Uso Sustentável da Biodiversidade (BIOTA-FAPESP), que intensificou a exploração sustentável da biodiversidade, e que evoluiu para formar a Rede Biota de Bioprospecção e Bioensaios (BIOprospecTA), que integra grupos de todo o país, otimizando o aproveitamento das competências já instaladas para a bioprospecção de microrganismos, plantas, invertebrados, vertebrados e organismos marinhos. Dos 104 projetos relacionados às ciências vegetais, 35 realizaram a bioprospecção da flora brasileira, em diversas áreas como Química, Botânica, Fisiologia e Morfologia Vegetal, (Quimio)taxonomia Vegetal, Ecologia de Ecossistemas, Genética Vegetal, Recursos Florestais, Engenharia Florestal, dentre outros, levando a milhares de publicações, ao engajamento de centenas de estudantes e ao entendimento mais profundo dos produtos naturais em diferentes modelos biológicos por meio da análise de micromoléculas auxiliada por estratégias computacionais e espectrométricas, além de avaliações farmacológicas. O desenvolvimento de abordagens ômicas ampliou a visão sobre perfil químico dos organismos, possibilitou o estudo integrado e concomitante de várias amostras, e a anotação mais rápida de moléculas conhecidas, por meio do uso de técnicas hifenadas, quimiométricas e redes moleculares. Isso também contribuiu para superar a falta de informação sobre a segurança e eficácia dos fitopreparados, em projetos que tratam da padronização de produtos fitoterápicos, de acordo com normas internacionais. O programa BIOTA-FAPESP também tem focado em aspectos ambientais, de acordo com os princípios da Química Verde e teve reflexos positivos na colaboração internacional, no número e no impacto das publicações científicas e na parceria com empresas, etapa crucial para agregar valor e expandir a cadeia produtiva de bioprodutos. Ainda, a compilação, sistematização e compartilhamento de dados foram contemplados com a criação da base de dados NUBBEDB, de livre acesso, e que se integra com bases internacionais (ACD/labs, American Chemical Society - ACS), auxiliando pesquisadores e empresas no desenvolvimento de diferentes áreas da ciência, tecnologia, fortalecendo a bioeconomia e subsidiando políticas públicas.

Antifungal effects of Streptococcus mutans extract on Candida strains susceptible and resistant to fluconazole: An in vivo study.

Previous studies showed that the crude extract obtained from Streptococcus mutans inhibited the growth of Candida albicans reference strains. In this study, we evaluated whether the antifungal effects of S. mutans extract can be extended to clinical Candida isolates, including C. albicans and non-abicans strains with different susceptibilities to fluconazole. We verified that S. mutans extract increased the survival of Galleria mellonella larvae infected with C. albicans and C. glabrata and inhibited the fungal cells in hemolymph. These antifungal effects occurred for both fluconazole-susceptible and fluconazole-resistant strains. However, larvae infected by C. krusei were not affected by S. mutans extract. LAY SUMMARY: Streptococcus mutans crude extract shows antifungal effects on clinical Candida strains susceptible and resistant to fluconazole in Galleria mellonella model.

Citrinin against breast cancer: A cytogenotoxicological study.

Breast cancer is one of the most lethal types of cancer and a leading cause of mortality among Women worldwide. Citrinin (CIT), a polyketide extracted from the fungus Penicillium citrinum, exhibits a wide range of biological activities such as antibacterial, antifungal, and cytotoxic effects. The aim of the current study was to evaluate the antitumoral effects of CIT against 7,12-dimethylbenzanthracene (DMBA)-induced mammary carcinoma in Swiss mice For this, CIT, DMBA and the standard cyclophosphamide (CPA) induced behavioral changes in experimental animals, and these changes were screened by using the rota rod and open field tests. Additionally, hematological, biochemical, immuno-histochemical, and histopathological analyses were carried out. Results suggest that CIT did not alter behavioral, hematological, and biochemical parameters in mice. DMBA induced invasive mammary carcinoma and showed genotoxic effects in the breasts, bone marrow, lymphocytes, and hepatic cells. It also caused mutagenic effects in the formation of micronuclei, bridges, shoots, and binucleate cells in bone marrow and liver. CIT and CPA genotoxic effects were observed after 3 weeks of therapy, where CIT exhibited a repair capacity and induced significant apoptotic damage in mouse lymphocytes. In conclusion, CIT showed antitumoral effects in Swiss mice, possibly through induction of apoptosis.

Bacillus spp. metabolites are effective in eradicating Aedes aegypti (Diptera: Culicidae) larvae with low toxicity to non-target species.

The growing spread of dengue, chikungunya and Zika viruses demand the development of new and environmentally safe control methods for their vector, the mosquito Aedes aegypti. This study aims to find novel larvicidal agents from mutualistic (endophytic and rhizospheric) or edaphic bacteria that have no action against non-target organisms. Eleven out of the 254 bacterial strains tested were able to kill Ae. aegypti larvae. Larvicidal activity did not depend on presence of cells, since culture supernatants or crude lipopeptide extracts (CLEs) killed the larvae. Bacillus safensis BacI67 and Bacillus paranthracis C21 supernatants were the best performing supernatants, displaying the lowest lethal concentrations (LC50 = 31.11 µL/mL and 45.84 µL/mL, respectively). Bacillus velezensis B64a and Bacillus velezensis B15 produced the best performing CLEs (LC50 = 0.11 mg/mL and 0.12 mg/mL, respectively). Mass spectrometry analysis of CLEs detected a mixture of surfactins, iturins, and fengycins. The samples tested were weakly- or non-toxic to mammalian cells (RAW 264.7 macrophages and VERO cells) and non-target organisms (Caenorhabditis elegans, Galleria mellonella, Scenedesmus obliquus, and Tetrahymena pyriformis) - especially B. velezensis B15 CLE. The biosynthetic gene clusters related to secondary metabolism identified by whole genome sequencing of the four best performing bacteria strains revealed clusters for bacteriocin, beta-lactone, lanthipeptide, non-ribosomal peptide synthetases, polyketide synthases (PKS), siderophores, T3PKS, type 1 PKS-like, terpenes, thiopeptides, and trans-AT-PKS. Purification of lipopeptides may clarify the mechanisms by which these extracts kill Ae. aegypti larvae.

Streptococcus mutans Secreted Products Inhibit Candida albicans Induced Oral Candidiasis.

In the oral cavity, Candida species form mixed biofilms with Streptococcus mutans, a pathogenic bacterium that can secrete quorum sensing molecules with antifungal activity. In this study, we extracted and fractioned culture filtrate of S. mutans, seeking antifungal agents capable of inhibiting the biofilms, filamentation, and candidiasis by Candida albicans. Active S. mutans UA159 supernatant filtrate components were extracted via liquid-liquid partition and fractionated on a C-18 silica column to resolve S. mutans fraction 1 (SM-F1) and fraction 2 (SM-F2). We found anti-biofilm activity for both SM-F1 and SM-F2 in a dose dependent manner and fungal growth was reduced by 2.59 and 5.98 log for SM-F1 and SM-F2, respectively. The SM-F1 and SM-F2 fractions were also capable of reducing C. albicans filamentation, however statistically significant differences were only observed for the SM-F2 (p = 0.004). SM-F2 efficacy to inhibit C. albicans was confirmed by its capacity to downregulate filamentation genes CPH1, EFG1, HWP1, and UME6. Using Galleria mellonella as an invertebrate infection model, therapeutic treatment with SM-F2 prolonged larvae survival. Examination of the antifungal capacity was extended to a murine model of oral candidiasis that exhibited a reduction in C. albicans colonization (CFU/mL) in the oral cavity when treated with SM-F1 (2.46 log) and SM-F2 (2.34 log) compared to the control (3.25 log). Although both SM-F1 and SM-F2 fractions decreased candidiasis in mice, only SM-F2 exhibited significant quantitative differences compared to the non-treated group for macroscopic lesions, hyphae invasion, tissue lesions, and inflammatory infiltrate. Taken together, these results indicate that the SM-F2 fraction contains antifungal components, providing a promising resource in the discovery of new inhibitors for oral candidiasis.

The Postbiotic Activity of Lactobacillus paracasei 28.4 Against Candida auris.

Candida auris has emerged as a medically important pathogen with considerable resistance to antifungal agents. The ability to produce biofilms is an important pathogenicity feature of this species that aids escape of host immune responses and antimicrobial agents. The objective of this study was to verify antifungal action using in vitro and in vivo models of the Lactobacillus paracasei 28.4 probiotic cells and postbiotic activity of crude extract (LPCE) and fraction 1 (LPF1), derived from L. paracasei 28.4 supernatant. Both live cells and cells free supernatant of L. paracasei 28.4 inhibited C. auris suggesting probiotic and postbiotic effects. The minimum inhibitory concentration (MIC) for LPCE was 15 mg/mL and ranges from 3.75 to 7.5 mg/mL for LPF1. Killing kinetics determined that after 24 h treatment with LPCE or LPF1 there was a complete reduction of viable C. auris cells compared to fluconazole, which decreased the initial inoculum by 1-logCFU during the same time period. LPCE and LPF1 significantly reduced the biomass (p = 0.0001) and the metabolic activity (p = 0.0001) of C. auris biofilm. There was also a total reduction (~108 CFU/mL) in viability of persister C. auris cells after treatment with postbiotic elements (p < 0.0001). In an in vivo study, injection of LPCE and LPF1 into G. mellonella larvae infected with C. auris prolonged survival of these insects compared to a control group (p < 0.05) and elicited immune responses by increasing the number of circulating hemocytes and gene expression of antimicrobial peptide galiomicin. We concluded that the L. paracasei 28.4 cells and postbiotic elements (LPCE and LPF1) have antifungal activity against planktonic cells, biofilms, and persister cells of C. auris. Postbiotic supplementation derived from L. paracasei 28.4 protected G. mellonella infected with C. auris and enhanced its immune status indicating a dual function in modulating a host immune response.

Antitumor effects of citrinin in an animal model of Sarcoma 180 via cytogenetic mechanisms.

Citrinin (CIT) is a cytotoxic, hepatotoxic, nephrotoxic and cardiotoxic metabolite obtained from Penicillium citrinum, that has been increasingly searched as an anticancer drug candidate. In this study, we assessed the antitumor effects of citrinin, using cytogenetic biomarkers for genotoxicity in Sarcoma 180 (S-180) ascitic fluid cells of mice. Citrinin, extracted from P. citrinum acetonitrile extract, was characterized by LC-MS. Cytotoxic assessment was done through using comet (alkaline version) and micronucleus assays. In S-180 cells, CI50 of CIT was 3.77 µg/mL, while at 12.5 and 100 µg/mL, CIT was as cytotoxic as doxorubicin (2 µg/mL). At 0.5, 1.0 and 2.0 µg/mL, it induced genotoxicity and mutagenicity in S-180 cells, especially at 2 µg/mL, triggering oxidative damage similar to hydrogen peroxide (10 mM). The antitumor effects were evidenced by a marked increase in S-180 cells apoptosis and necrosis due to clastogenic and/or aneugenic cytogenetic effects (micronucleus formation), as well as by induction of nucleoplasm bridges and nuclear buds, culminating in S-180 apoptosis and necrosis. CIT has potential as drug candidate for antitumor purposesbyinvolving cytogenetic mechanisms.

Anti-apoptotic effects of decyl gallate on the induction of apoptosis in A549 pneumocytes by Paracoccidioides brasiliensis gp43.

Apoptosis is considered an escape mechanism from the host immune system for the fungus Paracoccidioides spp, and it serves as a vehicle for entry into macrophages without stimulating microbicidal activities. Recently, gp43 of P. brasiliensis was demonstrated to be involved in this process. Therefore, as a new therapeutic alternative, it is very important to study compounds that could reduce the modulation of the induction of apoptosis caused by this fungus. Decyl gallate (G14) is a known antifungal compound, and we decided to investigate its anti-apoptotic properties. Our results demonstrate that G14 was effective against apoptosis induced by gp43, as observed in epithelial cells, and led to a reduction in DNA damage, Bak down-regulation and Bcl-2 up-regulation. Together, these data show that G14 presents promising anti-apoptotic activity.

Toxicity and Loss of Mitochondrial Membrane Potential Induced by Alkyl Gallates in Trypanosoma cruzi.

American trypanosomiasis or Chagas disease is a debilitating disease representing an important social problem that affects, approximately, 10 million people in the world. The main aggravating factor of this situation is the lack of an effective drug to treat the different stages of this disease. In this context, the search for trypanocidal substances isolated from plants, synthetic or semi synthetic molecules, is an important strategy. Here, the trypanocidal potential of gallates was assayed in epimastigotes forms of T. cruzi and also, the interference of these substances on the mitochondrial membrane potential of the parasites was assessed, allowing the study of the mechanism of action of the gallates in the T. cruzi organisms. Regarding the preliminary structure-activity relationships, the side chain length of gallates plays crucial role for activity. Nonyl, decyl, undecyl, and dodecyl gallates showed potent antitrypanosomal effect (IC50 from 1.46 to 2.90 µM) in contrast with benznidazole (IC50 = 34.0 µM). Heptyl gallate showed a strong synergistic activity with benznidazole, reducing by 10(5)-fold the IC50 of benznidazole. Loss of mitochondrial membrane potential induced by these esters was revealed. Tetradecyl gallate induced a loss of 53% of the mitochondrial membrane potential, at IC50 value.

Antifungal Activity of Decyl Gallate against Several Species of Pathogenic Fungi.

This work aims to demonstrate that the gallic acid structure modification to the decyl gallate (G14) compound contributed to increase the antifungal activity against several species of pathogenic fungi, mainly, Candida spp., Cryptococcus spp., Paracoccidioides spp., and Histoplasma capsulatum, according to standardized microdilution method described by Clinical Laboratory Standard Institute (CLSI) documents. Moreover this compound has a particularly good selectivity index value, which makes it an excellent candidate for broad-spectrum antifungal prototype and encourages the continuation of subsequent studies for the discovery of its mechanism of action.

Morphological and biochemical alterations activated by antitumor clerodane diterpenes.

Casearia sylvestris Swartz (Salicaceae) is a plant commonly widespread in the Americas. It has oxygenated tricyclic bioactive clerodane diterpenes with antimicrobial, antiulcer, larvicidal, chemopreventive, anti-inflammatory, antioxidant and antiproliferative properties. Due to this requirement for the developing of new anticancer drugs, it was initially evaluated the cytotoxic activity of a fraction with Casearins (FC) and its clerodane diterpenes Casearin B (Cas B), D (Cas D), X (Cas X) and Caseargrewiin F (Cas F) isolated from C.sylvestris leaves against 7 tumor cell lines, Sarcoma 180 cells (S180) and on normal peripheral blood mononuclear cells (PBMC). All substances tested showed cytotoxic potential. Cas F and X were the most active compounds. Cell death analyzes with Cas F (0.5 and 1µM) and Cas X (0.7 and 1.5µM) using the HL-60 leukemia line as experimental model showed DNA synthesis and membrane integrity reduction, DNA fragmentation and mitochondrial depolarization, specially after 24h exposure, cell cycle arrest in G0/G1 phase caused by Cas X, activation of the initiator -8/-9 and effector -3/-7 caspases and phosphatidylserine externalization, all biochemical features of apoptosis corroborated by chromatinic condensation, karyorrhexis, cytoplasmic vacuolation and rarefaction and cellular shrinkage, morphological findings specially observed after 12 and 24h of incubation. Therefore, Cas X and F were the most functional molecules with more pronounced lethal and discriminating effects on tumor cells and antiproliferative action predominantly mediated by apoptosis, highlighting clerodane dipertenes as promising lead antineoplastic compounds.

Anti-trichophyton activity of protocatechuates and their synergism with fluconazole.

Dermatophytosis and superficial mycosis are a major global public health problem that affects 20-25% of the world's population. The increase in fungal resistance to the commercially available antifungal agents, in conjunction with the limited spectrum of action of such drugs, emphasises the need to develop new antifungal agents. Natural products are attractive prototypes for antifungal agents due to their broad spectrum of biological activities. This study aimed to verify the antifungal activity of protocatechuic acid, 3,4-diacetoxybenzoic, and fourteen alkyl protocatechuates (3,4-dihydroxybenzoates) against Trichophyton rubrum and Trichophyton mentagrophytes and to further assess their activities when combined with fluconazole. Susceptibility and synergism assays were conducted as described in M38-A2 (CLSI), with modifications. Three strains of Trichophyton rubrum and three strains of Trichophyton mentagrophytes were used in this work. The pentyl, hexyl, heptyl, octyl, nonyl, and decyl protocatechuates showed great fungicidal effects, with minimum inhibitory concentration (MIC) values ranging from 0.97 to 7.8 mg/L. Heptyl showed a synergistic activity (FIC index = 0.49), reducing the MIC of fluconazole by fourfold. All substances tested were safe, especially the hexyl, heptyl, octyl, and nonyl compounds, all of which showed a high selectivity index, particularly in combination with fluconazole. These ester associations with fluconazole may represent a promising source of prototypes in the search for anti-Trichophyton therapeutic agents.

Alkyl caffeates as anti-Helicobacter pylori and scavenger of oxidants produced by neutrophils.

Helicobacter pylori pathogenic action involves the colonization of the gastrointestinal tract and a large production of reactive oxygen species (ROS) by the neutrophils attracted to the site of infection. The aim of this study was to evaluate caffeic acid and its alkyl esters as inhibitors of the release of ROS by Helicobacter pylori activated neutrophils and their bactericidal effect. The increased hydrophobicity caused by esterification had direct consequence in their efficiency as bactericidal agents against H. pylori and inhibitors of the production of ROS by neutrophils. The minimum inhibitory concentration (MIC) decreased from higher than 1000 µg/mL (caffeic acid) to 250 µg/mL to butyl and heptyl caffeate. The release of total ROS, superoxide anion and hypochlorous acid by activated neutrophils was also significantly decreased and the esters were more efficient than the acid precursor. In conclusion, the alkyl esters of caffeic acid have two properties that are complementary for the treatment of H. pylori infections: bactericidal activity and inhibitory effect upon generation of ROS by neutrophils. Hence, we propose that these easily synthesized and non-expensive substances should be applied to in vivo experimental models of H. pylori induced gastric infections.

Endophytic fungi producing of esterases: evaluation in vitro of the enzymatic activity using pH indicator

A sensitive and efficient colorimetric method was optimized for detection of esterase enzymes produced by endophytic fungi for development of High-Throughput Screening (HTS). The fungi were isolated and obtained previously from plant species of Cerrado and Atlantic Forest located in areas of environmental preservation in the State of Sao Paulo / Brazil, as part of the project "Chemical and biological prospecting endophytic fungi associated to plant species of Cerrado and Atlantic Forest". The compounds ethyl butyrate, ethyl acetate and methyl propionate were used as standards esters which were hydrolyzed by extracellular enzyme from endophytic fungi (EC. 3.1.1.1 -carboxylesterases) for production of carboxylic acids. Thus, the reduction of the pH increases the protonated indicator concentration (bromothymol blue), changing the color of the reaction medium (from blue to yellow), that can be observed and measured by spectrophotometry at 616 nm. The methodology with acid-base indicator was performed on 13 microorganisms, aiming Periconia atropurpurea asapotential source of esterase for biotransformation of short chain esters. The results also evidenced that this methodology showed to be efficient, fast, cheap, having low consumption of reagents and easy development, and can be applied to screen carboxylic-ester hydrolases in a large number of microorganisms.

Free radical scavenging activity of Kielmeyera variabilis (Clusiaceae).

As part of our ongoing research on antioxidant agents from Brazilian flora, we screened the free radical scavenging activity of two extracts and eight fractions of Kielmeyera variabilis (Clusiaceae) using DPPH· (2,2-diphenyl-1-picrylhydrazyl-hydrate) and ABTS·+ [2,2'-azinobis(3-ethylenebenzothiazoline-6-sulfonic acid)] colorimetric assays. The ethyl acetate and n-butanol fractions of the leaves of K. variabilis displayed the strongest activity (IC50 of 3.5 ± 0.3 and 4.4 ± 0.2 µg mL⁻¹ for DPPH· and 6.6 ± 0.4 and 3.1 ± 0.1 µg mL⁻¹ for ABTS·+, respectively). Chromatographic fractionation of the most potent fractions led to identification of three flavonols with previously described antioxidant activity, quercitrin (1), quercetin-3-O-ß-glucoside (3), and quercetin-3-O-ß-galactoside (4), and of one biflavone, podocarpusflavone A (2). This is the first time that the presence of these flavonoids in Kielmeyera variabilis has been reported.

Endophytic fungi producing of esterases: evaluation in vitro of the enzymatic activity using pH indicator.

A sensitive and efficient colorimetric method was optimized for detection of esterase enzymes produced by endophytic fungi for development of High-Throughput Screening (HTS). The fungi were isolated and obtained previously from plant species of Cerrado and Atlantic Forest located in areas of environmental preservation in the State of Sao Paulo / Brazil, as part of the project "Chemical and biological prospecting endophytic fungi associated to plant species of Cerrado and Atlantic Forest". The compounds ethyl butyrate, ethyl acetate and methyl propionate were used as standards esters which were hydrolyzed by extracellular enzyme from endophytic fungi (EC. 3.1.1.1--carboxyl-esterases) for production of carboxylic acids. Thus, the reduction of the pH increases the protonated indicator concentration (bromothymol blue), changing the color of the reaction medium (from blue to yellow), that can be observed and measured by spectrophotometry at 616 nm. The methodology with acid-base indicator was performed on 13 microorganisms, aiming Periconia atropurpurea as a potential source of esterase for biotransformation of short chain esters. The results also evidenced that this methodology showed to be efficient, fast, cheap, having low consumption of reagents and easy development, and can be applied to screen carboxylic-ester hydrolases in a large number of microorganisms.

Chemical and antifungal investigations of six Lippia species (Verbenaceae) from Brazil.

The Lippia genus is used in ethnobotany as food, beverages, seasoning and antiseptic remedies, among others. The chemical compositions of fifteen extracts of six Lippia species were investigated comparatively by HPLC-PDA. To avoid data replication of previous works on this genus, Lippia lupulina Cham. root ethanol extract was selected for isolation procedures based on Principal Component Analyses (PCA) of such data. Seven compounds previously unreported in this genus were isolated from this extract (a triterpene, two furanonaphtoquinones, a furanochromone, an isoflavone, a stilbene and an iridoid). The activities of extracts, fractions and pure compounds towards Candida albicans, Candida krusei, Candida parapsilosis and Cryptococcus neoformans were investigated. Two fractions from the extract of Lippia salviaefolia leaves showed marked inhibition of fungal growth, in addition to verbascoside and asebogenin, which showed MICs lower than 15.6µg/ml and may be promising leads for the development of new antifungal agents, especially against C. neoformans.

Fast screening for antioxidant properties of flavonoids from Pterogyne nitens using electrochemical methods.

A fast, low-cost, convenient, and especially sensitive voltammetric screening approach for the study of the antioxidant properties of isoquercitrin and pedalitin from Pterogyne nitens is suggested in this work. These flavonoids were investigated for their redox properties using cyclic voltammetry in nonaqueous media using N,N-dimethylformamide and tetrabutylammonium tetrafluorborate as the supporting electrolyte, a glassy carbon working electrode, A6(see symbol in text)AgCI reference electrode, and Pt bare wire counter electrode. The comparative analysis of the activity of rutin has also been carried out. Moreover, combining HPLC with an electrochemical detector allowed qualitative and quantitative detection of micromolecules (e.g., isoquercitrin and pedalitin) that showed antioxidant activities. These results were then correlated to the inhibition of beta-carotene bleaching determined by TLC autographic assay and to structural features of the flavonoids.