Cícera Datiane de Morais Oliveira-Tintino

Evaluation of the tannic acid inhibitory effect against the NorA efflux pump of Staphylococcus aureus

During the early periods of antibiotic usage, bacterial infections were considered tamed. However, widespread antibiotic use has promoted the emergence of antibiotic-resistant pathogens, including multidrug resistant strains. Active efflux is a mechanism for bacterial resistance to inhibitory substances, known simply as drug efflux pumps. The bacterium Staphylococcus aureus is an important pathogenic bacterium responsible for an array of infections. The NorA efflux pump has been shown to be responsible for moderate fluoroquinolone resistance of S. aureus. The inhibition of the efflux pump was assayed using a sub-inhibitory concentration of standard efflux pump inhibitors and tannic acid (MIC/8), where its capacity to decrease the MIC of Ethidium bromide (EtBr) and antibiotics due to the possible inhibitory effect of these substances was observed. The MICs of EtBr and antibiotics were significantly reduced in the presence of tannic acid, indicating the inhibitory effect of this agent against the efflux pumps of both strains causing a three-fold reduction of the MIC when compared with the control. These results indicate the possible usage of tannic acid as an adjuvant in antibiotic therapy against multidrug resistant bacteria (MDR).

Inhibition of the essential oil from Chenopodium ambrosioides L. and α-terpinene on the NorA efflux-pump of Staphylococcus aureus

This study was carried out to test the essential oil from C. ambrosioides leaves and its main constituent, α-Terpinene, in an antibacterial activity assay. As well, it was evaluated ability reduce resistance to norfloxacin and ethidium bromide was compared the Staphylococcus aureus 1199B whith 1199 wild type strain. The MIC of the C. ambrosioides essential oil and α-Terpinene were determined by microdilution method. The MIC of the essential oil and α-Terpinene presented a value ≥ 1024 μg/mL. However, when associated with antibacterials, the essential oil from C. ambrosioides leaves significantly reduced the MIC of antibiotics and ethidium bromide, characterizing an efflux pump inhibition. The C. ambrosioides essential oil, despite having no direct antibacterial activity against the S. aureus 1199B strain, showed a potentiating action when associated with antibacterial agents, this being attributed to an inhibition of efflux pumps.

Anti-inflammatory and anti-edematogenic action of the Croton campestris A. St.-Hil (Euphorbiaceae) essential oil and the compound β-caryophyllene in in vivo models

BACKGROUND Inflammation makes up a set of vascularized tissue reactions acting in the defense of the body against harmful stimuli. Natural products are a lower cost alternative with better benefit, often used in popular medicine in the treatment of inflammatory processes. Several species from the genus Croton have scientifically proven anti-inflammatory action. PURPOSE This study aims to analyze the chemical composition of the Croton campestris A. St.-Hil essential oil (EOCC), derived from fresh leaves, as well as to evaluate the anti-inflammatory potential and the possible mechanisms of action of the EOCC and its constituent β-caryophyllene. METHODS The assays were performed in in vivo models of acute and chronic inflammation. Initially, the chemical composition of the EOCC was determined and its oral toxicity was evaluated, followed by the evaluation of its topical antiedematogenic effect through acute and chronic ear edema induced by Croton oil. For the systemic verification of an anti-inflammatory action, the abdominal contortions, formalin test, paw edema induced by carrageenan, dextran, histamine and arachidonic acid models, as well as a peritonitis test, vascular permeability and granuloma assays were performed. RESULTS The evaluation of the essential oil chemical composition revealed the presence of β-caryophyllene (15.91%), 1,8-cineol (16.98%) and germacrene-D (14.51%) as its main constituents. The EOCC had no relevant clinical toxicity on oral administration, with an LD50 of more than 5000 mg/kg. The tested substances showed anti-inflammatory action in the abdominal contortions, paw edema induced by carrageenan, dextran, histamine and arachidonic acid models, the formalin test, peritonitis test and vascular permeability; however, β-caryophyllene had no significant effect on the granuloma assay. This suggests as a hypothesis that both substances tested showed significant influence on the arachidonic acid and histamine pathway reducing edema in these models. CONCLUSION The tested substances have a clinically safe profile, additionally the EOCC and β-caryophyllene presented relevant anti-inflammatory activity. This study supports the hypothesis that β-caryophyllene, in association with other constituents present in the EOCC such as 1,8-cineole, contributed to the anti-inflammatory effect observed, in addition to suggesting that one of the mechanisms of action probably involves the inhibition of cytokines with the involvement of the arachidonic acid and histamine pathways.

Body fat modulated activity of Gallus gallus domesticus Linnaeus (1758) and Meleagris gallopavo Linnaeus (1758) in association with antibiotics against bacteria of veterinary interest

In the Northeast of Brazil, ethnoveterinary studies have shown that the body fat from Gallus gallus domesticus and Meleagris gallopavo are used for diseases that affect domestic animals. The objective of this study was to identify the chemical composition and to evaluate the antibacterial activity of the Gallus gallus domesticus (OFGG) and Meleagris gallopavo (OFMG) fixed oils in isolation and in association with antibiotics. The OFGG and OFMG from the poultrys body fat were extracted using hexane as a solvent in Soxhlet. Their composition was indirectly determined using fatty acid methyl esters. The OFGG and OFMG antibacterial and modulatory activities against standard and multi-resistant bacterial strains were performed through the broth microdilution test. In the OFGG chemical composition, 4 constituents were identified. The saturated fatty acid (AGS) and unsaturated fatty acid (AGI) percentages were 35.1% and 64.91% respectively, with linoleic acid being the major component. In the OFMG, 3 constituents were identified. The AGS percentage was 27.71% and 72.29% for AGI, with oleic acid as the most abundant component. The oils did not present antibacterial activity when tested in isolation, presenting Minimum Inhibitory Concentrations (MICs) > 512 μg/mL. However, when associated with antibiotics the OFGG showed synergistic activity with the antibiotics Amikacin, Amoxicillin, Norfloxacin and Oxytetracycline, while the OFMG promoted a synergistic action with the antibiotics Amikacin, Amoxicillin and Norfloxacin.

Vitamin K enhances the effect of antibiotics inhibiting the efflux pumps of Staphylococcus aureus strains

The strain Staphylococcus aureus is commonly cited as being a major hospital-acquired pathogen. The emergence of S. aureus strains resistant to a wide distribution of antibiotics. The various antibiotic resistance mechanisms include efflux pumps, are ubiquitous proteins localized in the cytoplasmic membrane of all kind of cells. During the last two decades, numerous structurally diverse compounds have been studied and shown to have efflux-inhibitory activity. These include currently available drugs employed for other indications, as well as natural and synthetic molecules. Menadione (vitamin K3), is a fat-soluble vitamin that has long been recognized for its essential role in coagulation and, more recently, has been proposed as a key nutrient in the regulation of soft tissue calcification. Therefore, the aim of this study is to evaluate the effect of menadione efflux pumps in multidrug resistant strains of S.aureus. Were used RN4220 harboring plasmid pUL5054, which carries the gene encoding the MsrA macrolide efflux protein; and IS-58, which possesses the TetK tetracycline efflux protein; 1199B resists hydrophilic fluoroquinolones via a NorA-mediated mechanism and wild strain 1199B. Antibacterial activity test by minimal inhibitory concentration (MIC). Evaluation of possible inhibition of efflux pumps by reduction of MIC of ethidium bromide (EtBr) and antibiotics due the possible inhibitory effect of these substances. Efforts have been directed at identification of EPIs from natural sources. Some of the detrimental effects on bacterial cells can be attributed to the detergent properties of menadione on account of their amphipathic structure. Was observed what in strain 4220 and IS58 it occurred reduction the MIC, indicating possible effect on efflux pump.

Cytotoxic and anti-kinetoplastid potential of the essential oil of Alpinia speciosa K. Schum

Alpinia speciosa K. Schum, known as colônia (colony), is native to tropical Asia and found in parts of tropical America. Its leaves are used to wrap food, rhizomes for food preparation and seeds for health maintenance, and have been widely used by the population as a diuretic, antihypertensive, antiulcerogenic and sedative. The present study aimed to verify the leishmanicidal and trypanocidal potential, as well as the cytotoxicity, of the A. speciosa essential oil, in vitro. A. speciosa presented 1,8-cineole (28.46%), camphor (17.10%) and sabinene (9.95%) as major constituents. The cytotoxic activity of the essential oil presented a low value, while the antipromastigote and antiepimastigote activity presented values considered clinically relevant, since it had an action below 500 μg/mL. In relation to this study, it can be concluded that this is a pioneer in the potential of the A. speciosa essential oil and in the use against the parasites Trypanosoma cruzi Chagas and Leishmania brasiliensis Vianna, having its importance also rooted in this fact. Still in accordance with the results, A. speciosa was effective because it presented values of clinical relevance and low toxicity. It was also observed that the chemical constitution of the above identified compounds with remarkable antiparasitic activities.