ABSTRACT
The rising of diseases caused by multidrug-resistant bacteria has encouraged researchers to explore more antimicrobial substances, as well as chemicals capable of potentiating the action of existing ones against multidrug-resistant bacteria. Anacardium occidentale produces a fruit known as cashew nut, filled with a dark, almost black, caustic, and flammable liquid called cashew nutshell liquid (CNSL). The goal of the study was to evaluate the intrinsic antimicrobial activity of the major compounds present in CNSL, called anacardic acids (AA), as well as their possible modulatory action as an adjuvant of Norfloxacin against a Staphylococcus aureus strain overproducing the NorA efflux pump (SA1199B). Microdilution assays were performed to determine the minimum inhibitory concentration (MIC) of AA against different microbial species. Norfloxacin and Ethidium Bromide (EtBr) resistance modulation assays were performed in the presence or absence of AA against SA1199-B. AA showed antimicrobial activity against Gram-positive bacterial strains tested but no activity against Gram-negative bacteria or yeast strains. At subinhibitory concentration, AA reduced the MIC values for Norfloxacin and EtBr against the SA1199-B strain. Furthermore, AA increased the intracellular accumulation of EtBr in this NorA overproducer strain, indicating that AA are NorA inhibitors. Docking analysis showed that AA probably modulates Norfloxacin efflux by spatial impediment at the same binding site of NorA.
Subject(s)
Anacardium , Staphylococcal Infections , Norfloxacin/pharmacology , Anti-Bacterial Agents/pharmacology , Staphylococcus aureus , Anacardium/metabolism , Anacardic Acids/pharmacology , Anacardic Acids/metabolism , Multidrug Resistance-Associated Proteins , Staphylococcal Infections/microbiology , Ethidium/metabolism , Ethidium/pharmacology , Microbial Sensitivity TestsABSTRACT
Microdilution assays were performed in order to evaluate the antimicrobial activity of the ethanoic extract from the leaves of Bauhinia forficate (EEBF) against different microorganisms. The extract did not present inner antimicrobial activities against the tested strains. However, EEBF was able to modulate the norfloxacin-resistance against Staphylococcus aureus SA1199-B that overproduce the NorA efflux pump, once sub-inhibitory concentrations of EEBF reduced the minimal inhibitory concentratio of the norfloxacin in 87.5%. This modulatory effect was also found when the antibiotic was replaced by ethidium bromide, suggesting that EEBF acts probably by inhibition of NorA, allowing the antibiotic accumulation intracellularly, and making the line more sensitive. These results point out the EEBF potential as a source of NorA inhibitors that could be used in combination with norfloxacin for treatment of infections caused by multidrug-resistant S. aureus.
Subject(s)
Bauhinia/chemistry , Drug Resistance, Microbial/drug effects , Norfloxacin/pharmacology , Staphylococcus aureus/drug effects , Anti-Bacterial Agents/pharmacology , Ethidium/pharmacology , Microbial Sensitivity Tests , Plant Extracts/pharmacology , Plant Leaves/chemistryABSTRACT
This study aims to obtain mesocarp films of Orbignya sp. (MB) and carboxymethylcellulose (CMC) for application as a drug release matrix. Tannic acid (TA) was used as a standard drug. The films were evaluated by infrared, swelling power, TA release profile, bioactivity and in vitro cytotoxicity. Infrared results indicated absorption at 1.205 cm-1, which is characteristic of ester group from the incorporated tannin. The MB-CMC film had 449.15% swelling power, release of 71.01% of TA of the matrix after 24 h. Films showed scavenger activity of radicals DPPH (79.07 ± 1.71% to 82.17 ± 1.94%) and ABTS+ (82.20 ± 0.30% to 88.90 ± 1.05). The MB-CMC film also showed in vitro cytotoxicity on sarcoma-180 (91.86 ± 9.97%) and on promastigote forms of Leishmania major (100%). Polymers showed good compatibility in the mixture and the results suggest the films obtained are promising as drug release matrices.
Subject(s)
Arecaceae/chemistry , Carboxymethylcellulose Sodium , Fruit/chemistry , Leishmania major/growth & development , Materials Testing , Membranes, Artificial , Tannins , Animals , Antiprotozoal Agents/chemistry , Antiprotozoal Agents/pharmacology , Carboxymethylcellulose Sodium/chemistry , Carboxymethylcellulose Sodium/pharmacology , Cell Line, Tumor , Mice , Tannins/chemistry , Tannins/pharmacologyABSTRACT
The Lippia origanoides H.B.K. ethanol extract (LOEE) and hexane (LOHEX), dichloromethane (LODCM), and ethyl acetate (LOEA) fractions were tested for their antimicrobial activity alone or in combination with antibiotics against a methicillin resistant Staphylococcus aureus (MRSA) strain. The natural products did not show antimicrobial activity against multidrug resistant strain at the clinically significant concentrations tested. However, a modulatory effect in the antibacterial activity of the neomycin and amikacin was verified when LOEE, LOHEX and LODCM were added to the growth medium at subinhibitory concentrations. A similar modulation was found when the natural products were changed for chlorpromazine, an inhibitor of bacterial efflux pumps, suggesting the involvement of resistance mediated by efflux system in the MRSA tested. The fractions LOHEX and LODCM showed a modulatory activity bigger than their majority compounds (carvacrol, thymol, and naringenin), indicating that this activity is not due to their majority compounds only, but it is probably due to a synergism between their chemical components. These results indicate that L. origanoides H.B.K. can be a source of phytochemicals able to modify the phenotype of resistance to aminoglycosides in MRSA.
