Antimicrobial natural products

Our ethnopharmacological studies, in several Angolan regions, showed that Cymbopogon citratus (DC) Stapf., it´s applied in folk medicine to treat several diseases In order to validate antibacterial activity several studies were performed using 12 bacterial strains. The essencial oil samples of Cymbopogon citratus, obtained by hydro-distillation, were analysed by GC and GC-MS. Constituents were identified and tested for their antimicrobial activity by the disc agar diffusion technique and the dilution technique against Staphylococcus aureus (ATCC 25923) and Staphylococcus epidermidis (ATCC 12228) and other bacterial strains. Broad spectrum antibacterial activity was exhibited by the Cymbopogon citratus essential oil against both Gram-positive and Gram-negative bacteria as well as for MRSA that exhibited more sensitive towards the test substance compared to the non-MRSA. Our work was the first to show that Cymbopogon citratus essential oil has higher antibacterial activity against MRSA strains, than commercial antibiotics. These discover opens a new hope to fight against nosocomial infection.info:eu-repo/semantics/publishedVersio

Antibacterial and antimalarial activity of Angolan Cymbopogon citratus essential oil

Bacterial infections and malaria remain a major public health problem due to the emergence and spread of drug resistant strains. There is an urgent need to investigate new sources of antibacterial and antimalarial drugs, which are more effective. One of the potential sources of antibacterial and antimalarial drugs is traditional medicinal plants. Our ethnopharmacological studies, in several Angolan regions, showed that Cymbopogon citratus (DC) Stapf., has high bioactivity against bacterial infections and malaria. The constituents of Cymbopogon citratus essential oil (CCEO), obtained by hydro-distillation, were analysed by GC and GC-MS and identified from their retention indices and mass spectra. The antimicrobial activity of CCEO and major natural volatile compounds were tested against several bacterial strains. The antimalarial assays where performed in continuous in vitro cultures of asexual erythrocyte stages of P. falciparum using the parasite lactate dehydrogenase assay. CCEO exhibits broad-spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria. Our results showed that multi-resistant Stafilococus aureus (MRSA) isolates were more sensitive to CCEO than non-MRSA. When tested against MRSA resistant to amoxicillin-clavulanic acid combination, penicillin G and methicillin, CCEO shows a significant increase in bactericidal activity when compared with the commercial antibiotics. The same results were obtained using vancomycin resistant S. epidermidis and other strains. Regarding the anti-malaria activity, test samples where considered active for in vitro antimalarial activity exhibiting IC50 values of 5.34±1.01 μg/ml and 7.06±0.47 μg/ml. Our work shows that CCEO has higher antibacterial activity than commercial antibiotics against MRSA strains, as well as antimalarial activity. This offers opportunities for clinical treatments since preliminary in vivo studies showed no toxic effects and high antimalarial activity.info:eu-repo/semantics/publishedVersio

Cymbopogon citratus EO antimicrobial activity against multi-drug resistant Gram-positive strains and non-albicans-Candida species

We studied the antibacterial and antifungal activity of Cymbopogon citratus. These properties were studied on hospital isolated multidrug resistant strains Staphylococcus aureus, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumonia and their respective ATCC control strains. Pathogenic Candida albicans, Candida parapsilosis, and Candida tropicalis were also tested. Results of the present investigation provide evidence that the EO of Cymbopogon citratus could have a potential application in the treatment and prevention of diseases caused by Staphylococcus aureus methicillin-resistant strains and by vancomicin-resistant Staphylococcus epidermidis. Cymbopogon citratus EO is also effective against Candida albicans as well as the emerging Candida parapsilosis and Candida tropicalis pointing to its usefulness as an antifungal agent.info:eu-repo/semantics/publishedVersio

Study of Heparin in Intestinal Ischemia and Reperfusion in Rats: Morphologic and Functional Evaluation

AbstractTo study whether treatment with heparin (HEP) attenuates intestinal dysfunction caused by ischemia (I) and reperfusion (R), rats were treated with HEP (100 U/kg intravenously) or saline solution (SS) before I (60 min), which was produced by occlusion of the superior mesenteric artery, and R (120 min). After I or I/R, we mounted 2-cm jejunal segment in an organ bath to study neurogenic contractions stimulated by electrical pulses or KCl, using a digital recording system. Thin jejunal slices were stained with hematoxylin and eosin for optical microscopy. Compared with the sham group, jejunal contractions were similar in the I + HEP and the I/R + HEP groups, but reduced in the I + SS and the I/R + SS groups. The jejunal enteric nerves were damaged in the I + SS and the I/R + SS, but not in the I + HEP and the I/R + HEP cohorts. These results suggested that HEP attenuated intestinal dysfunction caused by I and I/R

Linear and non-linear perturbations in dark energy models

I review the linear and second-order perturbation theory in dark energy models with explicit interaction to matter in view of applications to N-body simulations and non-linear phenomena. Several new or generalized results are obtained: the general equations for the linear perturbation growth; an analytical expression for the bias induced by a species-dependent interaction; the Yukawa correction to the gravitational potential due to dark energy interaction; the second-order perturbation equations in coupled dark energy and their Newtonian limit. I also show that a density-dependent effective dark energy mass arises if the dark energy coupling is varying.Comment: 12 pages, submitted to Phys. Rev; v2: added a ref. and corrected a typ

Growth inhibitory effects of 3′-nitro-3-phenylamino nor-beta-lapachone against HL-60: A redox-dependent mechanism

AbstractIn this study, the cytotoxicity, genotoxicity and early ROS generation of 2,2-dimethyl-(3H)-3-(N-3′-nitrophenylamino)naphtho[1,2-b]furan-4,5-dione (QPhNO2) were investigated and compared with those of its precursor, nor-beta-lapachone (nor-beta), with the main goal of proposing a mechanism of antitumor action. The results were correlated with those obtained from electrochemical experiments held in protic (acetate buffer pH 4.5) and aprotic (DMF/TBABF4) media in the presence and absence of oxygen and with those from dsDNA biosensors and ssDNA in solution, which provided evidence of a positive interaction with DNA in the case of QPhNO2. QPhNO2 caused DNA fragmentation and mitochondrial depolarization and induced apoptosis/necrosis in HL-60 cells. Pre-treatment with N-acetyl-l-cysteine partially abolished the observed effects related to the QPhNO2 treatment, including those involving apoptosis induction, indicating a partially redox-dependent mechanism. These findings point to the potential use of the combination of pharmacology and electrochemistry in medicinal chemistry

[vasopressin Intravenous Infusion Causes Dose Dependent Adverse Cardiovascular Effects In Anesthetized Dogs].

BACKGROUND: Arginine vasopressin (AVP) has been broadly used in the management of vasodilatory shock. However, there are many concerns regarding its clinical use, especially in high doses, as it can be associated with adverse cardiovascular events. OBJECTIVE: To investigate the cardiovascular effects of AVP in continuous IV infusion on hemodynamic parameters in dogs. METHODS: Sixteen healthy mongrel dogs, anesthetized with pentobarbital were intravascularly catheterized, and randomly assigned to: control (saline-placebo; n=8) and AVP (n=8) groups. The study group was infused with AVP for three consecutive 10-minute periods at logarithmically increasing doses (0.01; 0.1 and 1.0 U/kg/min), at them 20-min intervals. Heart rate (HR) and intravascular pressures were continuously recorded. Cardiac output was measured by the thermodilution method. RESULTS: No significant hemodynamic effects were observed during 0.01 U/kg/min of AVP infusion, but at higher doses (0.1 and 1.0 U/kg/min) a progressive increase in mean arterial pressure (MAP) and systemic vascular resistance index (SVRI) were observed, with a significant decrease in HR and the cardiac index (CI). A significant increase in the pulmonary vascular resistance index (PVRI) was also observed with the 1.0 U/kg/min dose, mainly due to the decrease in the CI. CONCLUSION: AVP, when administered at doses between 0.1 and 1.0 U/kg/min, induced significant increases in MAP and SVRI, with negative inotropic and chronotropic effects in healthy animals. Although these doses are ten to thousand times greater than those routinely used for the management of vasodilatory shock, our data confirm that AVP might be used carefully and under strict hemodynamic monitoring in clinical practice, especially if doses higher than 0.01 U/kg/min are needed.942213218, 229-234, 216-22

role of female sex hormone receptors

Funding Information: Funding: This study was supported by grant IECT-FAPEMA-05796/18 and FAPEMA IECT 30/2018-IECT Saúde, by the Research Center of the Portuguese Oncology Institute of Porto (project no. PI86-CI-IPOP-66-2017); by European Investment Funds by FEDER/COMPETE/POCI—Operational Competitiveness and Internationalization Program, and national funds by FCT—Portuguese Foundation for Science and Technology under projects UID/AGR/04033/2020, UIDB/CVT/00772/2020 and by Base Funding-UIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology, and Energy—LEPABE—funded by national funds through the FCT/MCTES (PID-DAC); Project 2SMART-engineered Smart materials for Smart citizens, with reference NORTE-01-0145-FEDER-000054, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.A growing proportion of oropharyngeal squamous cell carcinomas (OPSCC) are associated with infection by high-risk human papillomavirus (HPV). For reasons that remain largely unknown, HPV+OPSCC is significantly more common in men than in women. This study aims to determine the incidence of OPSCC in male and female HPV16-transgenic mice and to explore the role of female sex hormone receptors in the sexual predisposition for HPV+ OPSCC. The tongues of 30-weeks-old HPV16-transgenic male (n = 80) and female (n = 90) and matched wild-type male (n = 10) and female (n = 10) FVB/n mice were screened histologically for intraepithelial and invasive lesions in 2017 at the Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), Por-tugal. Expression of estrogen receptors alpha (ERα) and beta (ERβ), progesterone receptors (PR) and matrix metalloproteinase 2 (MMP2) was studied immunohistochemically. Collagen remodeling was studied using picrosirius red. Female mice showed robust ERα and ERβ expression in intraepithelial and invasive lesions, which was accompanied by strong MMP2 expression and marked collagen remodeling. Male mice showed minimal ERα, ERβ and MMP2 expression and unaltered collagen patterns. These results confirm the association of HPV16 with tongue base cancer in both sexes. The higher cancer incidence in female versus male mice contrasts with data from OPSCC patients and is associated with enhanced ER expression via MMP2 upregulation.publishersversionpublishe

Global distribution of a key trophic guild contrasts with common latitudinal diversity patterns

Most hypotheses explaining the general gradient of higher diversity toward the equator are implicit or explicit about greater species packing in the tropics. However, global patterns of diversity within guilds, including trophic guilds (i.e., groups of organisms that use similar food resources), are poorly known. We explored global diversity patterns of a key trophic guild in stream ecosystems, the detritivore shredders. This was motivated by the fundamental ecological role of shredders as decomposers of leaf litter and by some records pointing to low shredder diversity and abundance in the tropics, which contrasts with diversity patterns of most major taxa for which broad-scale latitudinal patterns haven been examined. Given this evidence, we hypothesized that shredders are more abundant and diverse in temperate than in tropical streams, and that this pattern is related to the higher temperatures and lower availability of high-quality leaf litter in the tropics. Our comprehensive global survey (129 stream sites from 14 regions on six continents) corroborated the expectedlatitudinal pattern and showed that shredder distribution (abundance, diversity and assemblage composition) was explained by a combination of factors, including water temperature (some taxa were restricted to cool waters) and biogeography (some taxa were more diverse in particular biogeographic realms). In contrast to our hypothesis, shredder diversity was unrelated to leaf toughness, but it was inversely related to litter diversity. Our findings markedly contrast with global trends of diversity for most taxa, and with the general rule of higher consumer diversity at higher levels of resource diversity. Moreover, they highlight the emerging role of temperature in understanding global patterns of diversity, which is of great relevance in the face of projected global warming. © 2011 by the Ecological Society of America.Peer Reviewe