Antibacterial activity of alkyl gallates against Xanthomonas citri subsp. citri.

The plant-pathogenic bacterium Xanthomonas citri subsp. citri is the causal agent of Asiatic citrus canker, a serious disease that affects all the cultivars of citrus in subtropical citrus-producing areas worldwide. There is no curative treatment for citrus canker; thus, the eradication of infected plants constitutes the only effective control of the spread of X. citri subsp. citri. Since the eradication program in the state of São Paulo, Brazil, is under threat, there is a clear risk of X. citri subsp. citri becoming endemic in the main orange-producing area in the world. Here we evaluated the potential use of alkyl gallates to prevent X. citri subsp. citri growth. These esters displayed a potent anti-X. citri subsp. citri activity similar to that of kanamycin (positive control), as evaluated by the resazurin microtiter assay (REMA). The treatment of X. citri subsp. citri cells with these compounds induced altered cell morphology, and investigations of the possible intracellular targets using X. citri subsp. citri strains labeled for the septum and centromere pointed to a common target involved in chromosome segregation and cell division. Finally, the artificial inoculation of citrus with X. citri subsp. citri cells pretreated with alkyl gallates showed that the bacterium loses the ability to colonize its host, which indicates the potential of these esters to protect citrus plants against X. citri subsp. citri infection.

Chemopreventive activity of compounds extracted from Casearia sylvestris (Salicaceae) Sw against DNA damage induced by particulate matter emitted by sugarcane burning near Araraquara, Brazil.

Ethanolic extract of Casearia sylvestris is thought to be antimutagenic. In this study, we attempted to determine whether this extract and casearin X (a clerodane diterpene from C. sylvestris) are protective against the harmful effects of airborne pollutants from sugarcane burning. To that end, we used the Tradescantia micronucleus test in meiotic pollen cells of Tradescantia pallida, the micronucleus test in mouse bone marrow cells, and the comet assay in mouse blood cells. The mutagenic compound was total suspended particulate (TSP) from air. For the Tradescantia micronucleus test, T. pallida cuttings were treated with the extract at 0.13, 0.25, or 0.50 mg/ml. Subsequently, TSP was added at 0.3mg/ml, and tetrads from the inflorescences were examined for micronuclei. For the micronucleus test in mouse bone marrow cells and the comet assay in mouse blood cells, Balb/c mice were treated for 15 days with the extract-3.9, 7.5, or 15.0 mg/kg body weight (BW)-or with casearin X-0.3, 0.25, or 1.2 mg/kg BW-after which they received TSP (3.75 mg/kg BW). In T. pallida and mouse bone marrow cells, the extract was antimutagenic at all concentrations tested. In mouse blood cells, the extract was antigenotoxic at all concentrations, whereas casearin X was not antimutagenic but was antigenotoxic at all concentrations. We conclude that C. sylvestris ethanolic extract and casearin X protect DNA from damage induced by airborne pollutants from sugarcane burning.

Chemoprevention assessment, genotoxicity and cytotoxicity of flavonoids from Inga laurina leaves (FABACEAE).

This study aimed to identify and evaluate the cytotoxicity, genotoxicity, antigenotoxicity and chemoprevention assessment of flavonoids myricetin-3-O-(2″-O-galloyl)-α-rhamnopyranoside and myricetin-3-rhamnoside from Inga laurina leaves extract. The Quinone reductase induction as a biomarker for cancer chemoprevention was evaluated in murine hepatocellular carcinoma, the cytotoxicity was evaluated by sulforhonamide B assay and genotoxicity was evaluated by comet assay using HepG2 cell line. The results demonstrated that the flavonoids didn´t show cytotoxicity in HepG2 cells. In the chemoprevention evaluations were not able to promote the induction of Quinone Reductase and also no genotoxic effect was observed by evaluation of the comet assay in none of the concentrations tested. In the antigenotoxicity test, all compounds had a protective effect against damage induced by hydrogen peroxide and were repaired against damage. Although none of the flavonoids were capable of inducing the enzyme Quinone Reductase at the concentrations tested, the antigenotoxicity results showed a powerful chemoprotective action.

Genotoxicity, cytotoxicity and chemical profile from Inga laurina (Fabaceae).

This study aimed to evaluate the cytotoxicity and genotoxicity from Inga laurina leaves extracts and fractions and obtain their chemical profile. The chemical profile of the crude extract from I. laurina leaves and its fractions was investigated through 1H NMR, RP-HPLC-PDA by co-injection with authentic standards and HPLC-MS. The quinone reductase induction as a biomarker for cancer chemoprevention was evaluated in murine hepatocellular carcinoma line, whereas the cytotoxicity was evaluated by sulforhodamine B assay (SRB) using HepG2 cell line and genotoxicity was evaluated by comet assay. The phytochemical analysis of the leaves crude extract and its fractions showed the presence of 2-hydroxyethyl-dodecanoate and the phenolic compounds: gallic acid, methyl gallate, p-coumaric acid, cinnamic acid, myricetin-3-O-(2″-O-galoyl)-α-rhamnopyranoside, proanthocyanidin A-2 and myricetrin. All the fractions tested were not considered cytotoxic against the selected human cancer cell lines, they did not cause genotoxic in some concentrations damage and induced the enzyme quinone reductase.

4'-Aminochalcones as novel inhibitors of the chlorinating activity of myeloperoxidase.

The excessive activation of neutrophils generates reactive oxygen species (ROS) and the secretion of primary granular enzymes, such as myeloperoxidase (MPO), which is implicated in numerous inflammatory diseases. The aim of this study was to evaluate chalcones as inhibitors of the chlorinating activity of MPO using in vitro and ex vivo assays. In addition to cytotoxic properties, the inhibition of respiratory burst, the scavenger capacity, and the oxidation potential were measured. 4'-Aminochalcone (1), 4'-amino-4- fluorochalcone (2), and 4'-amino-4-methylchalcone (3) exhibited potent inhibition of the chlorinating activity of MPO, as evaluated in a neutrophil system and a free cell system, to the following degree: (1) IC50 = 0.265 � 0.036 µmol L-1; (2) IC50 = 0.250 � 0.081 µmol L-1; and (3) IC50 = 0.250 � 0.012 µmol L-1. These values were similar to those for 5-fluorotryptamine (IC50 = 0.192 � 0.012 µmol L-1), a compound considered to be a potent MPO inhibitor. These aminochalcones were not toxic to neutrophils at concentrations below 100 µmol L- 1, as determined by the trypan blue exclusion assay. Compounds 1-3 presented a high oxidation potential (Epa1 ≉ 0.80 V), low scavenger capacity against DPPH• and HOCl, and low inhibition of respiratory burst. These data indicated that aminochalcones are potent inhibitors of MPO chlorinating activity, a new property for chalcone derivatives, given that they are neither antioxidant agents nor inhibitors of respiratory burst. In conclusion, the selected aminochalcones have potential as pharmacological agents for inflammatory diseases.

Alkyl hydroxybenzoic acid derivatives that inhibit HIV-1 protease dimerization.

The therapeutic potential of gallic acid and its derivatives as anti-cancer, antimicrobial and antiviral agents is well known. We have examined the mechanism by which natural gallic acid and newly synthesized gallic acid alkyl esters and related protocatechuic acid alkyl esters inhibit HIV-1 protease to compare the influence of the aromatic ring substitutions on inhibition. We used Zhang-Poorman's kinetic analysis and fluorescent probe binding to demonstrate that several gallic and protecatechuic acid alkyl esters inhibited HIV-1 protease by preventing the dimerization of this obligate homodimeric aspartic protease rather than targeting the active site. The tri-hydroxy substituted benzoic moiety in gallates was more favorable than the di-substituted one in protocatechuates. In both series, the type of inhibition, its mechanism and the inhibitory efficiency dramatically depended on the length of the alkyl chain: no inhibition with alkyl chains less than 8 carbon atoms long. Molecular dynamics simulations corroborated the kinetic data and propose that gallic esters are intercalated between the two N- and C-monomer ends. They complete the ß-sheet and disrupt the dimeric enzyme. The best gallic ester (14 carbon atoms, K(id) of 320 nM) also inhibited the multi-mutated protease MDR-HM. These results will aid the rational design of future generations of non-peptide inhibitors of HIV-1 protease dimerization that inhibit multi-mutated proteases. Finally, our work suggests the wide use of gallic and protocatechuic alkyl esters to dissociate intermolecular ß-sheets involved in protein-protein interactions.

Protocatechuic acid alkyl esters: hydrophobicity as a determinant factor for inhibition of NADPH oxidase.

This study presents the increased efficiency of NADPH oxidase inhibition produced by esterification of protocatechuic acid (P0). Alkyl esters bearing chain lengths of 4 (P4), 7 (P7) and 10 (P10) carbons were synthesized and their oxidation potential, hydrophobicity, antiradical activity, inhibition of superoxide anion (O2°(-)), and the abilities to affect hypochlorous acid (HOCl) production by leukocytes and inhibit myeloperoxidase (MPO) chlorinating activity were studied. The increased hydrophobicity (logP, 0.81-4.82) of the esters was not correlated with a significant alteration in their oxidation potential (0.222-0.298 V). However, except for P10, the esters were ~ 2-fold more effective than the acid precursor for the scavenging of DPPH and peroxyl radicals. The esters were strong inhibitors of O2°(-) released by activated neutrophils (PMNs) and peripheral blood mononuclear cells (PBMCs). A correlation was found between the carbon chain length and the relative inhibitory potency. P7, the most active ester, was ~ 10-fold more efficient as NADPH oxidase inhibitor than apocynin. The esters strongly inhibited the release of HOCl by PMNs, which was a consequence of the inhibition of NADPH oxidase activity in these cells. In conclusion, as effective inhibitors of NADPH oxidase, the esters of protocatechuic acid are promising drugs for treatment of chronic inflammatory diseases. Moreover, this is the first demonstration that, besides the redox active moiety, the hydrophobicity can also be a determinant factor for the design of NADPH oxidase inhibitors.

Anticholinesterasic, nematostatic and anthelmintic activities of pyridinic and pyrazinic compounds.

In the search for acetylcholinesterase inhibitors as a potential target for the discovery of anthelmintic drugs, a series of 27 pyridinic and pyrazinic compounds have been designed on the basis of molecular hybridization of two known AChE inhibitors, namely, tacrine and (-)-3-O-acetylspectaline, and on the concept of isosterism. The synthesized compounds generally presented moderate anticholinesterasic activities when compared with the positive control physostigmine, but one compound (ethyl 2-[(6-chloropyrazin-2-yl)sulfanyl] acetate) exhibited an in vitro ability to immobilize the root-knot nematode Meloidogyne incognita that was highly comparable to that of the positive control Temik. Moreover, in anthelmintic assays against the gastrointestinal parasitic nematode Nippostrongylus brasiliensis (L4), some of the compounds, such as (6-chloropyrazin-2-yl)sulfanyl ethanol (32, EC50 = 33 nM), presented activities that were considerably stronger than that of the positive control albendazole (EC50 = 340 nM). In the light of the positive results obtained in the anthelmintic evaluations, the acute oral toxicity of the representative compound diethyl 2,2'-[(3-nitropyridine-2,6-diyl) bissulfanediyl] diacetate was determined in rats, and the drug was shown to be non-toxic at a dose of 2000 mg/kg. These results, allied with the relatively simple structures of the active compounds and their facile synthesis, highlight their potential use as anthelmintic or nematicidic agents.

Cryptomoscatona D2 de Cryptocarya mandioccana: atividade citotóxica contra linhagem celular de carcinoma cervical humano / Cryptomoschatone D2 from Cryptocarya mandioccana: cytotoxicity against human cervical carcinoma cell lines

Among the substances isolated from Cryptocarya sp, some styrylpyrones, such as goniothalamin, demonstrate antiproliferative activity in a broad range of human cell lines. In the present study, we assessed the cytotoxicity of a styrylpyrone (cryptomoschatone D2), isolated from Cryptocarya mandiocanna, in HPV-infected (HeLa and SiHa) and uninfected (C33A) human cervical carcinoma cell lines and a human lung fibroblast line (MRC-5). The cytotoxicity was tested by the MTT assay. In this assay, cells were treated with cryptomoschatone D2 at 15, 30, 60 or 90 ?M for 6, 24 or 48 hours, as well as for 6 hours followed by a post-treatment recovery period of 24, 48 or 72 hours. High cytotoxicity (dose- and timedependent) was observed in HeLa, SiHa, C33A and MRC-5 cell lines. Although in general the styrylpyrone cytotoxicity was not significantly different among the cell lines tested, it was apparently stronger in HeLa and C33A than in MRC-5 and SiHa in the 24 or 48-hour treatments. Moreover, HeLa and SiHa were able to recover their ability to proliferate, in direct proportion to the post-treatment recovery time. On the other hand, C33A did not demonstrate a similar post-treatment recovery. We can conclude that cryptomoschatone D2 possesses high dose-dependent or time-dependent cytotoxicity.

Dentre as substâncias isoladas de Cryptocarya sp, algumas estirilpironas, como a goniotalamina, apresentam atividade antiproliferativa em diferentes linhagens celulares. No presente estudo, foram avaliadas as atividades citotóxica de uma estirilpirona (criptomoscatona D2) isolada de Cryptocarya mandiocanna, em linhagens celulares de carcinoma cervical humano infectada por HPV (HeLa e SiHa), não infectada (C33A) e fibroblasto pulmonar humano (MRC-5). A atividade citotóxica foi avaliada pelo ensaio do MTT. No ensaio do MTT, as células foram tratadas com criptomoscatona D2 em 15, 30, 60 e 90 ?M por 6, 24 e 48 horas e por 6 horas com período de recuperação de 24, 48 e 72 horas pós-tratamento. O tratamento com a estirilpirona (criptomoscatona D2) ocasionou elevada citotoxicidade dose-resposta e tempo-resposta em HeLa, SiHa, C33A e MRC-5. Embora não haja diferença estatisticamente significativa de citotoxicidade entre as linhagens, aparentemente a citotoxicidade foi maior em HeLa e C33A (tratamento de 24 e 48 horas) que em MRC-5 e SiHa. Ainda, no período de recuperação, HeLa e SiHa aparentemente restabelecem sua capacidade proliferativa, que é diretamente proporcional ao tempo de recuperação, enquanto o mesmo comportamento não é observado em C33A. Estes resultados sugerem que criptomoscatona D2 possui elevada atividade antiproliferativa dose-resposta ou o tempo resposta.

Comparative study of disk diffusion and microdilution methods for evaluation of antifungal activity of natural compounds against medical yeasts Candida spp and Cryptococcus sp / Estudo comparativo entre os métodos de difusão em disco e de microdiluição para avaliação de atividade antifúngica de produtos naturais contra as leveduras de interesse médico Candida spp e Cryptococcus sp

Antifungal activity of natural products has been tested by adapting methods designed for synthetic drugs. Inthis study, two methods for the determination of antifungal activity of natural products, agar diffusionand broth microdilution, the CLSI reference methods for synthetic drugs, are compared and discussed. Themicrodilution method was more sensitive. The minimal inhibitory concentrations (MIC) of crude extracts,fractions and pure substances from different species of the plant families Piperaceae, Rubiaceae, Clusiaceae, Fabaceae and Lauraceae, from the Biota project, were determined. Antifungal activities against Candida albicans, C.krusei, C.parapsilosis and Cryptococcus neoformans were produced by several samples

Atividade antifúngica de produtos naturais foi determinada após algumas adaptações de métodos preconizados para fármacos sintéticos. Neste estudo foram comparados e discutidos os métodos para determinação de atividade antifúngica de produtos naturais por duas metodologias, difusão em ágar e microdiluição em caldo, segundo método preconizado pelo CLSI para fármacos sintéticos. A concentração mínima inibitória foi determinada de extratos brutos, frações e de substâncias puras de diferentes espécies de plantas das famílias Piperaceae, Rubiaceae, Clusiaceae, Fabaceae and Lauraceae do projeto Biota. Vários apresentaram atividade antifúngica para as levedurasCandida albicans, C.krusei, C.parapsilosis and Cryptococcus neoformans.