Antileishmanial Activity and Immunomodulatory Effects of Tricin Isolated from Leaves of Casearia arborea (Salicaceae)

Bioactivity‐guided fractionation of antileishmanial active extract from leaves of Casearia arborea led to isolation of three metabolites: tricin ( 1 ), 1′,6′‐di‐O‐β‐d ‐vanilloyl glucopyranoside ( 2 ) and vanillic acid ( 3 ). Compound 1 demonstrated the highest activity against the intracellular amastigotes of Leishmania infantum, with an IC₅₀ value of 56 μm . Tricin ( 1 ) demonstrated selectivity in mammalian cells (SI > 7) and elicited immunomodulatory effect on host cells. The present work suggests that tricin modulated the respiratory burst of macrophages to a leishmanicidal state, contributing to the parasite elimination. Therefore, the natural compound tricin could be further explored in drug design studies for leishmaniasis treatment.     

Reduced cytotoxicity of polyhexamethylene biguanide hydrochloride (PHMB) by egg phosphatidylcholine while maintaining antimicrobial efficacy

Liposomes or oil-in-water emulsions containing egg yolk phosphatidylcholine (EPC) were combined with aqueous polyhexamethylene biguanide hydrochloride (PHMB). The bactericidal activity of these preparations against Pseudomonas aeruginosa and Staphylococcus aureus as well as their cytotoxicity on cultured murine fibroblasts (L929 cells) was then assayed for either 30 min or 60 min in the presence of cell culture medium containing 10% fetal bovine serum as surrogate for wound fluid. We used two assay designs: in the first bactericidal activity and cytotoxicity were determined in separate experiments; in the second both were determined in one experiment. Combining PHMB and EPC containing o/w emulsions or liposomes protects mammalian cells without neutralizing the antiseptic effect. From all tested combinations the o/w emulsions containing 0.05% PHMB proved to be superior in this respect to the aqueous preparation.     

Biodegradability of end-groups of the biocide polyhexamethylene biguanide (PHMB) assessed using model compounds

Polyhexamethylene biguanide (PHMB), a biocide used in a wide variety of disinfection and preservation applications, is a polydisperse mixture in which the end-groups may be any combination of amine, guanidine and cyanoguanidine. Using PHMB model compounds (1,6-diaminohexane; 1,6-diguanidinohexane; 1,6-di(cyanoguanidino)hexane; 4-guanidinobutyric acid), we have determined the biodegradation characteristics of each end-group in several strains of bacteria isolated for their ability to utilise PHMB as a sole source of nitrogen. Bacteria were screened for growth at the expense of each model compound (at non-inhibitory concentrations) as sole nitrogen source. None of the isolated bacteria was capable of utilising a cyanoguanidine end-group as growth substrate, whereas several bacteria were shown to utilise amine or guanidine end-groups. In particular, a strain of Pseudomonas putida was capable of extensive growth with 1,6-diguanidinohexane as a sole nitrogen source, with complete removal of guanidine groups from culture medium within 2 days, and with concomitant formation of unsubstituted urea, which in turn was also utilised by the organism. We conclude that whilst amine and guanidine end-groups in PHMB are likely to be susceptible to biodegradation, cyanoguanidine end-groups are likely to be recalcitrant.     

Differentiating Between Direct (Physiological) and Food-Chain Mediated (Bioenergetic) Effects on Fish in Metal-Impacted Lakes

The objectives of this field project were to test relationships between the physiological and population status of indigenous fish and (a) ecological factors (habitat quality, food resources), (b) toxicological factors (ambient and tissue metal concentrations), and (c) metal detoxification factors (metallothionein induction and subcellular metal partitioning). The sentinel species, yellow perch (YP: Perca flavescens), was collected from lakes with contrasting metal levels located on the Canadian Precambrian Shield, downwind and downstream from metal smelters. In lakes at the high end of our exposure gradient, metals (Cu, Ni, and especially Cd) accumulate in YP to concentrations well above background tissue values; increases in tissue Zn concentrations were much more modest, despite the existence of a very marked gradient in ambient [Zn]. Metal accumulation in YP is accompanied by metallothionein induction, but all evidence to date suggests that metal detoxification by metallothionein is incomplete. Indeed, direct effects of metal toxicity are detected at multiple levels of biological organization, from effects at the cellular level, to effects in organs and tissues, to individuals and populations, in a pattern linked to accumulated metal concentrations (i.e., along the contamination gradient). In addition to direct or physiological effects, we also documented indirect, food-web-mediated effects of metals on YP in the most contaminated lakes. The most common indication of such indirect effects on YP is severely stunted growth coupled with a high degree of zooplankton dependence throughout their life.     

Antileishmanial activity of fucosterol recovered from Lessonia vadosa Searles (Lessoniaceae) by SFE,PSE and CPC

Fucosterol, a triterpene derivative encountered in several alga species, provides a wide range of biological activities, such as protection against metabolic syndrome, or against UV-induced skin damage. We describe here the comparison of extraction by supercritical fluid (SFE) and pressurized solvent (PSE) of the brown alga Lessonia vadosa mainly abundant in the coastal water of Patagonia, followed by the isolation of fucosterol, using centrifugal partition chromatography (CPC), in association with HPLC–UV quantification. After collection, the seaweed was dried, ground and extracted either by PSE or by SFE under various conditions. The yield and the content in fucosterol of each extract were determined by HPLC–UV. Optimization of a biphasic solvent system and K_D calculation led to the isolation of pure fucosterol with high recovery rate. Extraction by SFE using CO₂ at 180 bar and 50 °C with 20 to 30 % of cellulose as modifier and CPC purification by cyclohexane/acetone/methanol/water 10/1/10/1 with lower layer as mobile phase led to the best results in terms of yield, purity, time and solvent consumption. Natural and semisynthetic steroid derivatives have been previously shown to be potential drug candidates against parasitic diseases including leishmaniasis. In this context fucosterol was evaluated and demonstrated noticeable antileishmanial activity (IC₅₀ < 10 μM) against intracellular amastigotes with limited or no cytotoxicity in host cell macrophages. These results make this compound a valuable starting scaffold for pharmacomodulation. Adaptation of the procedure by slight modifications of the extraction and/or isolation conditions could permit the exploitation of other alga species as raw material. Since SFE and CPC are available for pilot and batch production, this work may serve as a model for further scale-up and industrial development.     

Antiangiogenic and Antitumoral Effects Mediated by a Vascular Endothelial Growth Factor Receptor 1 (VEGFR-1)-Targeted DNAzyme

Antiangiogenesis is a promising antitumor strategy that inhibits tumor vascular formation to suppress tumor growth. DNAzymes are synthetic single-strand deoxyribonucleic acid (DNA) molecules that can cleave ribonucleic acids (RNAs). Here, we conducted a comprehensive in vitro selection of active DNAzymes for their activity to cleave the vascular endothelial growth factor receptor (VEGFR-1) mRNA and screened for their biological activity in a matrigel tube-formation assay. Among the selected DNAzymes, DT18 was defined as a lead molecule that was further investigated in several model systems. In a rat corneal vascularization model, DT18 demonstrated significant and specific antiangiogenic activity, as evidenced by the reduced area and vessel number in VEGF-induced corneal angiogenesis. In a mouse melanoma model, DT18 was shown to inhibit B16 tumor growth, whereas it did not affect B16 cell proliferation. We further assessed the DT18 effect in mice with established human nasopharyngeal carcinoma (NPC). A significant inhibition of tumor growth was observed, which accompanied downregulation of VEGFR-1 expression in NPC tumor tissues. To evaluate DT18 effect on vasculature, we performed dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) on the human NPC xenograft mice treated with DT18 and showed a reduction of the parameter of K^trans (volume constant for transfer of contrast agent), which reflects the condition of tumor microvascular permeability. When examining the safety and tolerability of DT18, intravenous administration of Dz18 to healthy mice caused no substantial toxicities, as shown by parameters such as body weight, liver/kidney function, and histological and biochemical analyses. Taken together, our data suggest that the anti-VEGFR-1 DNAzyme may be used as a therapeutic agent for the treatment of cancer, such as NPC.     

Host-Directed Evolution of a Novel Lactate Oxidase in Streptococcus iniae Isolates from Barramundi (Lates calcarifer)

In Streptococcus iniae, lactate metabolism is dependent upon two proteins, lactate permease that mediates uptake and lactate oxidase, a flavin mononucleotide-dependent enzyme that catalyzes oxidation of α-hydroxyacids. A novel variant of the lactate oxidase gene, lctO, in Australian isolates of S. iniae from diseased barramundi was found during a diagnostic screen using LOX-1 and LOX-2 primers, yielding amplicons of 920 bp instead of the expected 869 bp. Sequencing of the novel gene variant (type 2) revealed a 51-nucleotide insertion in lctO, resulting in a 17-amino-acid repeat in the gene product, and three-dimensional modeling indicated formation of an extra loop in the monomeric protein structure. The activities of the lactate oxidase enzyme variants expressed in Escherichia coli were examined, indicating that the higher-molecular-weight type 2 enzyme exhibited higher activity. Growth rates of S. iniae expressing the novel type 2 enzyme were not reduced at lactate concentrations of 0.3% and 0.5%, whereas a strain expressing the type 1 enzyme exhibited reduced growth rates at these lactate concentrations. During a retrospective screen of 105 isolates of S. iniae from Australia, the United States, Canada, Israel, Réunion Island, and Thailand, the type 2 variant arose only in isolates from a single marine farm with unusually high tidal flow in the Northern Territory, Australia. Elevated plasma lactate levels in the fish, resulting from the effort of swimming in tidal flows of up to 3 knots, may exert sufficient selective pressure to maintain the novel, high-molecular-weight enzyme variant.Streptococcus iniae is a major pathogen of farmed fish, resulting in severe economic losses globally estimated at U.S. $150 million annually (27). S. iniae is essentially a blood pathogen, with infection resulting in a generalized septicemia and meningitis (1). During infection the pathogen avoids phagocytosis by means of an antiopsonic capsule (4, 18, 22) and by binding host serum components including immunoglobulins (3) and fibrinogen (2). Little is known, however, about the metabolism of S. iniae during infection although lactic acid bacteria may produce l-lactate from fermentation of glucose. In S. iniae a lactate oxidase gene, lctO, has been characterized previously (11). The product of the lctO gene in S. iniae is a flavin enzyme (l-lactate 2-monooxygenase, EC 1.13.12.4), which catalyzes the oxidation of lactate to pyruvate, coupled with reduction of O₂ to H₂O₂ (11). Lactate oxidase has been extensively characterized, both structurally and functionally, in the cold-water marine pathogen Aerococcus viridans (9, 30, 35, 36); thus, the catalytic activities of these enzymes are relatively well understood. In S. iniae, lactate can be utilized as an energy source through an aerobic but nonrespiratory mode of metabolism (11), a mechanism that is coupled to hydrogen peroxide production in Streptococcus pyogenes (26).Since the discovery of the lactate oxidase gene in S. iniae, its presence has been routinely used for PCR-based diagnosis, overcoming the lack of specificity of commercial biochemical diagnostic kits and other molecular methods. Confirmation of isolate identity as S. iniae by commercial bacterial identification kits is problematic because the biochemical profile is absent from databases supplied with the kits or because the databases are unable to identify atypical strains with confidence (25). Identification of isolates by molecular methods such as PCR is more reliable since isolates with atypical biochemical profiles can confidently be identified. PCR has been used to amplify sections of the 16S rRNA gene (37), the chaperonin HSP60 (12), and the 16S-23S rRNA gene intergenic spacer region (5) for identification of S. iniae. The development of the lactate oxidase gene (lctO) PCR assay by Mata et al. (21) reported that the primer pair LOX-1/LOX-2 could be used successfully to aid in the identification of S. iniae via the generation of a specific 870-bp product. Moreover, the LOX-1/LOX-2 primer pair overcame the problem of nonspecific amplification of Streptococcus difficilis that had previously been reported with the 16S rRNA gene primer pair described previously (21, 37).In Australia, S. iniae causes major economic loss in farmed barramundi (Lates calcarifer, Bloch) (1, 6). Barramundi, also known as Asian sea bass, are perciform euryhaline fish native to Australia and tropical southeast Asia. In Australia, barramundi have both cultural and commercial significance in terms of their iconic status among indigenous populations and the recent rapid growth of commercial farming. The value of intensive barramundi culture in Australia increased from Australian $15.5 million in 2004 to Australian $23.5 million in 2006 (34). There is also increasing farmed output of L. calcarifer in Malaysia, Indonesia, Taiwan, and Vietnam (33) and small to medium recirculating aquaculture ventures in the United States and United Kingdom using imported fingerlings.During routine diagnostic screening of S. iniae isolated throughout Australia from diseased barramundi, a novel variant of the lctO gene was found that resulted in amplicons of 920 bp following PCR using the LOX-1/LOX-2 primer pair. Isolates expressing the novel lactate oxidase gene were isolated only from a single site in the Northern Territory, Australia. In the present study, the novel lctO variant is investigated genetically and phenotypically in order to better understand how the larger gene product may have arisen from this single site.     

A Novel Organotellurium Compound (RT-01) as a New Antileishmanial Agent

Leishmaniasis is a neglected disease and endemic in developing countries. A lack of adequate and definitive chemotherapeutic agents to fight against this infection has led to the investigation of numerous compounds. The aim of this study was to investigate the effect of RT-01, an organotellurane compound presenting biological activities, in 2 experimental systems against Leishmania amazonensis. The in vitro system consisted of promastigotes and amastigotes forms of the parasite, and the in vivo system consisted of L. amazonensis infected BALB/c mice, an extremely susceptible mouse strain. The compound proved to be toxic against promastigotes and amastigotes. The study also showed that treatment with RT-01 produces an effect similar to that treatment with the reference antimonial drug, Glucantime, in L. amazonensis infected mice. The best results were obtained following RT-01 intralesional administration (720 µg/kg/day); mice showed significant delay in the development of cutaneous lesions and decreased numbers of parasites obtained from the lesions. Significant differences in tissue pathology consisted mainly of no expressive accumulation of inflammatory cells and well-preserved structures in the skin tissue of RT-01-treated mice compared with expressive infiltration of infected cells replacing the skin tissue in lesions of untreated mice. These findings highlight the fact that the apparent potency of organotellurane compounds, together with their relatively simple structure, may represent a new avenue for the development of novel drugs to combat parasitic diseases.     

Antileishmanial activity and ultrastructural changes of sesquiterpene lactones isolated from Calea pinnatifida (Asteraceae)

Bioactivity-guided fractionation of antileishmanial active CH₂Cl₂ phase of MeOH extract from leaves of Calea pinnatifida led to isolation of two sesquiterpene lactones calein C (1) and calealactone C (2), which structures were stablished on the basis of spectroscopic analysis. Compounds 1 and 2 displayed potent activity against Leishmania amazonensis promastigotes with EC₅₀ of 1.7 and 4.6 µg mL⁻¹, respectively. Compound 2 presented low cytotoxicity for J774 macrophages and displayed activity against amastigote forms of L. amazonensis similar to miltefosine with CC₅₀ values of 31.73 and 27.18 µg mL⁻¹, respectively. Additionally, compounds 1 and 2 caused ultrastructural changes in promastigotes leading to a loss of their classical structural morphology, as evidenced by electron microscopy. Also compound 2 decreased the mitochondria membrane potential. To the best of our knowledge, this is the first occurrence of 1 and 2 in C. pinnatifida. The results obtained highlighted the importance of studying sesquiterpene lactones isolated from Calea pinnatifida in terms of antileishmanial activity, in order to understand the mechanism of action of the isolated compounds in promastigotes forms of L. amazonensis.     

Inhibition of Angiogenesis Mediated by Extremely Low-Frequency Magnetic Fields (ELF-MFs)

The formation of new blood vessels is an essential therapeutic target in many diseases such as cancer, ischemic diseases, and chronic inflammation. In this regard, extremely low-frequency (ELF) electromagnetic fields (EMFs) seem able to inhibit vessel growth when used in a specific window of amplitude. To investigate the mechanism of anti-angiogenic action of ELF-EMFs we tested the effect of a sinusoidal magnetic field (MF) of 2 mT intensity and frequency of 50 Hz on endothelial cell models HUVEC and MS-1 measuring cell status and proliferation, motility and tubule formation ability. MS-1 cells when injected in mice determined a rapid tumor-like growth that was significantly reduced in mice inoculated with MF-exposed cells. In particular, histological analysis of tumors derived from mice inoculated with MF-exposed MS-1 cells indicated a reduction of hemangioma size, of blood-filled spaces, and in hemorrhage. In parallel, in vitro proliferation of MS-1 treated with MF was significantly inhibited. We also found that the MF-exposure down-regulated the process of proliferation, migration and formation of tubule-like structures in HUVECs. Using western blotting and immunofluorescence analysis, we collected data about the possible influence of MF on the signalling pathway activated by the vascular endothelial growth factor (VEGF). In particular, MF exposure significantly reduced the expression and activation levels of VEGFR2, suggesting a direct or indirect influence of MF on VEGF receptors placed on cellular membrane. In conclusion MF reduced, in vitro and in vivo, the ability of endothelial cells to form new vessels, most probably affecting VEGF signal transduction pathway that was less responsive to activation. These findings could not only explain the mechanism of anti-angiogenic action exerted by MFs, but also promote the possible development of new therapeutic applications for treatment of those diseases where excessive angiogenesis is involved.     

表皮生长因子受体(EGFR)的细胞内信号传导

表皮生长因子受体（EGFR）是一种存在于细胞表面的多功能跨膜蛋白分子,具有酪氨酸蛋白激酶活性,EGFR与配体结合后启动细胞内信号传导通路,不同的通路之间存在交叉对话（Cross-talks）共同完成细胞生理功能.对EGFR的深入研究,不仅可阐明细胞生长和发育等重要的生命过程,而且在医药和工业上也将有广泛的应用.     

Non-Thermal Dielectric Barrier Discharge (DBD) Effects on Proliferation and Differentiation of Human Fibroblasts Are Primary Mediated by Hydrogen Peroxide

The proliferation of fibroblasts and myofibroblast differentiation are crucial in wound healing and wound closure. Impaired wound healing is often correlated with chronic bacterial contamination of the wound area. A new promising approach to overcome wound contamination, particularly infection with antibiotic-resistant pathogens, is the topical treatment with non-thermal “cold” atmospheric plasma (CAP). Dielectric barrier discharge (DBD) devices generate CAP containing active and reactive species, which have antibacterial effects but also may affect treated tissue/cells. Moreover, DBD treatment acidifies wound fluids and leads to an accumulation of hydrogen peroxide (H₂O₂) and nitric oxide products, such as nitrite and nitrate, in the wound. Thus, in this paper, we addressed the question of whether DBD-induced chemical changes may interfere with wound healing-relevant cell parameters such as viability, proliferation and myofibroblast differentiation of primary human fibroblasts. DBD treatment of 250 μl buffered saline (PBS) led to a treatment time-dependent acidification (pH 6.7; 300 s) and coincidently accumulation of nitrite (~300 μM), nitrate (~1 mM) and H₂O₂ (~200 μM). Fibroblast viability was reduced by single DBD treatments (60–300 s; ~77–66%) or exposure to freshly DBD-treated PBS (60–300 s; ~75–55%), accompanied by prolonged proliferation inhibition of the remaining cells. In addition, the total number of myofibroblasts was reduced, whereas in contrast, the myofibroblast frequency was significantly increased 12 days after DBD treatment or exposure to DBD-treated PBS. Control experiments mimicking DBD treatment indicate that plasma-generated H₂O₂ was mainly responsible for the decreased proliferation and differentiation, but not for DBD-induced toxicity. In conclusion, apart from antibacterial effects, DBD/CAP may mediate biological processes, for example, wound healing by accumulation of H₂O₂. Therefore, a clinical DBD treatment must be well-balanced in order to avoid possible unwanted side effects such as a delayed healing process.     

Chemotherapeutic Drugs Interfere with Gene Delivery Mediated by Chitosan-Graft-Poly(ethylenimine)

Combined chemo-gene therapy is one of the treatment modalities that have attracted extensive research interests; however, there is little information regarding the influence of drug application on gene transfer. This study bridges this gap by examining how chemotherapeutic drugs (teniposide, cis-diamminedichloroplatinum(II) and temozolomide) interfere with polyplex formation and transfection of chitosan-graft-poly(ethylenimine). Our results indicate that the degree of drug interference varies with the mechanism of drug action, with the transgene expression being severely suppressed when the plasmid is co-delivered with cis-diamminedichloroplatinum(II) or teniposide but not temozolomide. In addition, the interference with transfection by drugs varies with different gene/drug co-formulations. This is the first study to evidence that, though combined chemo-gene therapy has therapeutic potential, some chemotherapeutic drugs may reduce the treatment efficiency of gene therapy.     

白细胞介素-18基因肌肉注射产生明显抗肿瘤作用(英文)

 为了探讨人白细胞介素 (h IL ) - 1 8基因转导的抗肿瘤作用 ,构建了 h IL- 1 8c DNA真核表达质粒载体 pc DNA3/h IL- 1 8.将 pc DNA3/h IL- 1 8经脂质体包裹 ,按照 1 0 0μg/只的剂量注射入雄性Balb/c小鼠后肢肌肉 ,在设定时间处死小鼠取注射部位肉提取总 RNA,应用半定量反转录聚合酶链反应 (RT- PCR)及免疫组化法检测了 h IL- 1 8m RNA及其蛋白质在小鼠肌肉中不同时间点的表达水平 .随后 30只雄性 Balb/c小鼠于基因注射后第 7d腹部皮下 (i.d.)或腹腔内 (i.p.)接种 1×1 0 5个同系小鼠 S- 1 80肉瘤细胞 .观察了 S- 1 80肿瘤细胞在腹腔及皮下的生长情况、小鼠体重、肿瘤重量及存活时间 .结果发现 ,pc DNA3/h IL- 1 8注射后 2 d能检测到 h IL- 1 8m RNA表达 ,第 7d表达量较高 ,第 2 8d仍有 h IL- 1 8m RNA表达 .免疫组化染色显示了注射部位散在有 h IL- 1 8蛋白质颗粒 .h IL- 1 8基因注射组小鼠体重、肿瘤重量均比对照组轻 (P值分别小于 0 .0 0 5、0 .0 5) ,存活时间比对照组延长 .结果显示 ,真核表达系统 pc DNA3/h IL - 1 8经脂质体包裹肌注后能有效表达 ,具有明显的抑制肿瘤生长作用 .     

Reduction of Technetium(VII) by Desulfovibrio fructosovorans Is Mediated by the Nickel-Iron Hydrogenase

Resting cells of the sulfate-reducing bacterium Desulfovibrio fructosovorans grown in the absence of sulfate had a very high Tc(VII)-reducing activity, which led to the formation of an insoluble black precipitate. The involvement of a periplasmic hydrogenase in Tc(VII) reduction was indicated (i) by the requirement for hydrogen as an electron donor, (ii) by the tolerance of this activity to oxygen, and (iii) by the inhibition of this activity by Cu(II). Moreover, a mutant carrying a deletion in the nickel-iron hydrogenase operon showed a dramatic decrease in the rate of Tc(VII) reduction. The restoration of Tc(VII) reduction by complementation of this mutation with nickel-iron hydrogenase genes demonstrated the specific involvement of the periplasmic nickel-iron hydrogenase in the mechanism in vivo. The Tc(VII)-reducing activity was also observed with cell extracts in the presence of hydrogen. Under these conditions, Tc(VII) was reduced enzymatically to soluble Tc(V) or precipitated to an insoluble black precipitate, depending on the chemical nature of the buffer used. The purified nickel-iron hydrogenase performed Tc(VII) reduction and precipitation at high rates. These series of genetic and biochemical approaches demonstrated that the periplasmic nickel-iron hydrogenase of sulfate-reducing bacteria functions as a Tc(VII) reductase. The role of cytochrome c₃ in the mechanism is also discussed.     

Mediated electrochemical detection of catechol by tyrosinase-based poly(dicarbazole) electrodes.

A new dicarbazole derivative functionalised by an N-hydroxysuccinimide group has been synthesised and electrochemically characterised. Upon oxidative electropolymerisation of this monomer in organic electrolytes, electroactive poly(dicarbazole) films were formed on platinum electrodes. The subsequent chemical grafting of tyrosinase on the poly(dicarbazole) film was easily performed by immersion in an enzymatic aqueous solution. The amperometric response of the resulting biosensors to catechol has been studied at -0.2 V vs. saturated calomel electrode (SCE). Since the reduction of quinone generates radicals which may induce electrode fouling, thionine, a phenothiazine dye, was covalently bound to the poly(dicarbazole) backbone as it mediates the reduction of quinoid products and therefore induces an enhancement of the performance of the tyrosinase-based biosensor.     

Antileishmanial, antimalarial and antimicrobial activities of the extract and isolated compounds from Austroplenckia populnea (Celastraceae)

Austroplenckia populnea (Celastraceae), known as "marmelinho do campo", is used in Brazilian folk medicine as antimicrobial, anti-inflammatory, and antitumoural agent. The aim of the present work was to evaluate the antimicrobial, antileishmanial and antimalarial activities of the crude hydroalcoholic extract of A. populnea (CHE) and some of its isolated compounds. The phytochemical study of the CHE was carried out affording the isolation of methyl populnoate (1), populnoic acid (2), and stigmast-5-en-3-O-beta-(D-glucopyranoside) (3). This is the first time that the presence of compound 3 in A. populnea is reported. The results showed that the CHE presents antifungal and antibacterial activities, especially against Candida glabrata and Candida albicans, for which the CHE showed IC50 values of 0.7 microg mL(-1) and 5.5 microg mL(-1), respectively, while amphotericin B showed an IC50 value of 0.1 microg mL(-1) against both microorganisms. Compounds 1-3 were inactive against all tested microorganisms. In the antileishmanial activity test against Leishmania donovani, the CHE showed an IC50 value of 52 microg mL(-1), while compounds 2 and 3 displayed an IC50 value of 18 microg mL(-1) In the antimalarial assay against Plasmodium falciparum (D6 and W2 clones), it was observed that all evaluated samples were inactive. In order to compare the effect on the parasites with the toxicity to mammalian cells, the cytotoxicity activity of the isolated compounds was evaluated against Vero cells, showing that all evaluated samples exhibited no cytotoxicity at the maximum dose tested.     

DNA Phosphodiester Bond Hydrolysis Mediated by Cu(II) and Zn(II) Complexes of 1,3,5,-Triamino-cyclohexane Derivatives

Abstract

The hydrolytic activity of the 1,3,5-triaminocycloxexane derivatives TACH, TACI and TMCA complexed to Zn(II) and Cu(II) towards a model phosphoric ester and plasmid DNA has been evaluated by means of spectroscopic and gel-electrophoresis techniques. At conditions close to physiological, a prominent cleavage effect mediated by the nature of the ligand and metal ion was generally observed. TACI complexes are the most active in relaxing supercoiled DNA, the effect being explained by the affinity of the hydroxylated ligand for the nucleic acid. As indicated by the dependence of cleavage efficiency upon pH, Zn(II)-complexes act by a purely hydrolytic mechanism. In the case of Cu(II)-complexes, although hydrolysis should be prominent, involvement of an oxidative pathway cannot be completely ruled out.