Mechanism of escape from the antibacterial activity of metal-based nanoparticles in clinically relevant bacteria: A systematic review.

The emergency of antibiotic-resistant bacteria in severe infections is increasing, especially in nosocomial environments. The ESKAPE group is of special importance in the groups of multi-resistant bacteria due to its high capacity to generate resistance to antibiotics and bactericides. Therefore, metal-based nanomaterials are an attractive alternative to combat them because they have been demonstrated to damage biomolecules in the bacterial cells. However, there is a concern about bacteria developing resistance to NPs and their harmful effects due to environmental accumulation. Therefore, this systematic review aims to report the clinically relevant bacteria that have developed resistance to the NPs. According to the results of this systematic review, various mechanisms to counteract the antimicrobial activity of various NP types have been proposed. These mechanisms can be grouped into the following categories: production of extracellular compounds, metal efflux pumps, ROS response, genetic changes, DNA repair, adaptative morphogenesis, and changes in the plasma membrane.

Antimicrobial activity of the Flo peptide produced in Scenedesmus acutus and Nannochloropsis oculata.

The continuous increase of bacterial pathogen resistance to conventional antibiotics has challenged the research community to develop new antimicrobial strategies. Antimicrobial peptides (AMP) are a promising alternative to combat multidrug-resistant strains compared to conventional antibiotics because of their biocompatibility. In the present study, the Flo peptide, an AMP from the Moringa oleifera tree, was expressed in the chloroplast of the microalgae Nannochloropsis oculata and Scenedesmus acutus. The transgene insertion was verified by PCR amplification, and the homoplasmy was corroborated in spectinomycin-resistant lines. The identification and quantification of the peptide were performed using ELISA. The antimicrobial activity was studied against the Gram-negative Escherichia coli (ATCC 25,922) and Klebsiella pneumoniae (ATCC 700,603). The inflammatory response of the total soluble proteins of transplastomic N. oculata was assessed by measuring secretion of the cytokines IL-6, IL-10, and alpha-tumor necrosis (TNF-α), and cytotoxicity was assessed. These results provide a potential strategy to produce the Flo peptide in microalgae with antibacterial activities.

Phytochemical Screening and Bioactivities of Cactaceae Family Members Endemic to Mexico.

Mexico is a center of diversification for the Cactaceae family, with 69% of the species recorded as endemic. Certain members of the Cactaceae family have been chemically analyzed to relate their medicinal use with their phytochemistry. Here, the phytochemistry and bioactivity of ethanol extracts of Ferocactus echidne, F. latispinus, and Mammillaria geminispina were evaluated. A preliminary phytochemical analysis was performed, detecting the presence of saponins, tannins, cardiotonic glycosides, and sesquiterpene lactones. The presence of nicotinic acid in F. echidne and F. latispinus was identified by GC-MS. Other compounds found in the extracts of these three species were gentisic acid, diosmetin, chlorogenic acid, N-methyltyramide, and hordenine. The antioxidant activity was estimated with the DPPH free radical scavenging test. To determine the toxicity of the extracts, the in vivo model of Artemia spp. was used. In addition, the cytotoxicity of the extract was tested on C6, HaCaT, THP-1, and U937 cell lines, while the inflammatory activity was tested by measuring the secretion of cytokines using macrophage cells. The three species showed different bioactivities, including antioxidant, antimicrobial, cytotoxic, and anti-inflammatory activities. To the best of our knowledge, the results presented here are the first described for these species.

Antimycobacterial, cytotoxic, and anti-inflammatory activities of Artemisialudoviciana.

ETHNOPHARMACOLOGICAL RELEVANCE: A third part of the world population has been exposed to the pathogen Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB). TB is a deadly disease, and its treatment has been hampered because of the lack of new antibiotics or the development of new antimycobacterial agents against this pathogen. The situation is aggravated because of the appearance of multidrug-resistant strains. In Mexican traditional medicine, records showed Artemisia ludoviciana for the treatment of TB. Thus, the combination of antibiotics and plant extracts might represent new antimycobacterial agents as an attractive alternative. MATERIALS AND METHODS: The biological activities of ethanol extract obtained from A. ludoviciana were evaluated for its antimycobacterial activities using an M. tuberculosis clinical isolate. Also, the toxicity of the extracts was assessed ex vivo and in vivo using the human-derived macrophages cell line (THP-1) and the Artemia spp. model, respectively. Lastly, the inflammatory response of macrophages exposed to the extracts was also evaluated. RESULTS: The ethanol extract of A. ludoviciana showed antimycobacterial activity with a MIC of 250 µg/mL against a clinical strain of M. tuberculosis. Ex vivo cytotoxicity using the THP-1 cell line incubated with the ethanol extract showed an IC50 of 20 µg/mL. On the other hand, the Artemia model's toxicity test showed moderate toxicity when the A. ludoviciana extract was tested with LC50 of 195.64 µg/mL. Analysis of the inflammatory response of THP-1 cells exposed to the same extract showed no increase in secreted interleukine-6 and -10. Also, no effect was observed in the pro-inflammatory tumor necrosis factor-α cytokine level. Moreover, a chemical profile of the extracts identified achillin as the major component in the ethanol extract, along with other minor components such as thujone and stigmasterol. CONCLUSIONS: We showed that the ethanol extract of A. ludoviciana possessed antimycobacterial activity and could potentially be used to supplement the antibiotic treatment of TB.

Antimicrobial, Cytotoxic, and Anti-Inflammatory Activities of Pimenta dioica and Rosmarinus officinalis Essential Oils.

Essential oils (EOs) are natural products composed of a mixture of volatile and aromatic compounds extracted from different parts of plants that have shown antimicrobial activities against pathogens. In this study, EOs extracted from Pimenta dioica (Myrtaceae) and Rosmarinus officinalis (Lamiaceae) were assessed for their antimicrobial activities using a panel of pathogenic Gram-positive, Gram-negative, and fungal strains. The antimicrobial activity was measured by the minimal inhibitory concentration required for the growth inhibition of the microorganisms. The cytotoxicity of the EOs was tested ex vivo using the model of human-derived macrophage THP-1 cells. In addition, an inflammatory response was evaluated using the anti-inflammatory cytokine IL-10 and the proinflammatory cytokines IL-6 and TNF-α. Results showed that both EOs had antimicrobial activity and different pathogens were exposed to concentrations ranging between 600 and 2000 µg/mL. In addition, the EOs showed no inflammatory activity when exposed to human macrophages, but a potent anti-inflammatory activity was measured when the oil from Rosmarinus officinalis was exposed to macrophages. This study demonstrates that the use of EOs is an effective alternative for pathogenic bacterial and fungal control, alone or in combination with antibiotic therapy. Moreover, the oil extracted from Rosmarinus officinalis could be used as potent anti-inflammatory agent.

Evaluation of the efficiency of allspice, thyme and rosemary essential oils on two foodborne pathogens in in-vitro and on alfalfa seeds, and their effect on sensory characteristics of the sprouts.

Seeds are usual source of contamination and their sprouts are commonly associated foodborne illness. Therefore, the aim of this study was to evaluate the antibacterial vapor phase efficiency of allspice, thyme and rosemary essential oils on two foodborne pathogens in in vitro and on alfalfa seeds, including the chemical profile of the tested EOs and their effect on the sensory characteristics of the sprouts. Antibacterial activity was determined through the minimal inhibitory concentration (MIC) of EOs in vapor phase to inhibit the growth of Listeria monocytogenes and Salmonella Typhimurium in culture media and on alfalfa seeds. Also, the germination and the effect on sensory characteristics of the sprouts were determined. Thyme EO was the most effective of the tested EOs on culture media and on alfalfa seeds, against both bacteria. When rosemary EO was tested against L. monocytogenes in alfalfa seeds, the MIC (4.0 mL/Lair) was higher, compared to the one obtained in culture media (2.7 mL/Lair). But when this EO was tested against S. Typhimurium, the MIC in alfalfa seeds was lower than in culture media (11.7 vs 13.3 mL/Lair). Allspice EO resulted more effective against both bacteria in alfalfa seeds (6.0 mL/Lair for L. monocytogenes and 6.7 mL/Lair for S. Typhimurium), compared to culture media (12.0 mL/Lair for L. monocytogenes and 13.3 mL/Lair for S. Typhimurium). Vapor phase EOs MICs resulted in significant (p ≤ 0.05) decreases of L. monocytogenes and S. Typhimurium counts compared to the control. There also was a significant (p ≤ 0.05) difference between systems (in vitro or on alfalfa seeds) despite the microorganism or the evaluated EO. Treatment alfalfa seed with vapor phase EOs, did not affect the seed germination. Sensory acceptability of the sprouts, obtained of treated seeds, did not were significant (p ≥ 0.05) different of the sprouts obtained from the non-treated seeds.