Synergistic antibacterial effect of apigenin with β-lactam antibiotics and modulation of bacterial resistance by a possible membrane effect against methicillin resistant Staphylococcus aureus

BMSCs-derived Exosome CISH Alleviates Myocardial Infarction by Inactivating the NF-κB Pathway to Stimulate Macrophage M2 Polarization

Current myocardial infarction (MI) treatments are suboptimal, necessitating deeper pathogenesis understanding of MI. This research explored how exosomes (Exo) derived from bone marrow mesenchymal stem cells (BMSCs) contribute to MI mitigation and their therapeutic potential. Isolated BMSCs was identified by microscope, flow cytometry, alizarin red and oil red O staining. Exo were identified by TEM, NTA and western blot. HE staining, masson staining, and cardiac function parameters were used to assess the cardiac function in MI mice. TUNEL staining, western blot and qRT-PCR were used to detect apoptosis, inflammatory factors and M1/M2 markers. The NF-κB pathway activation was detected through western blot assays. Immunofluorescence, qRT-PCR, western blot, and flow cytometry were employed to evaluate macrophage polarization. MI mice showed cardiac injury, increased apoptosis and inflammation, while BMSCs-Exo treatment alleviated these effects. In MI mice, the macrophage M1 polarization was increased and the NF-κB pathway was activated, whereas BMSCs-Exo treatment reversed these changes. Furthermore, CISH expression was reduced in MI mice, but was elevated with BMSCs-Exo treatment. In vitro, LPS shifted RAW264.7 cells to M1 phenotype and activated the NF-κB pathway, yet BMSCs-Exo shifted them to M2 phenotype and inhibited the NF-κB pathway. Mechanistically, BMSCs-Exo induced macrophage M2 polarization by transmitting CISH to inhibit NF-κB activation. BMSCs-Exo mitigates MI by transmitting CISH to inhibit the NF-κB pathway, promoting macrophages to M2 type. This implies BMSCs-Exo could be a useful treatment for MI, and CISH could be a potential therapy target.

Synergism with Shikimic Acid Restores β-Lactam Antibiotic Activity against Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has evolved into a dangerous pathogen resistant to beta-lactam antibiotics (BLAs) and has become a worrisome superbug. In this study, a strategy in which shikimic acid (SA), which has anti-inflammatory and antibacterial activity, is combined with BLAs to restart BLA activity was proposed for MRSA treatment. The synergistic effects of oxacillin combined with SA against oxacillin resistance in vitro and in vivo were investigated. The excellent synergistic effect of the oxacillin and SA combination was confirmed by performing the checkerboard assay, time-killing assay, live/dead bacterial cell viability assay, and assessing protein leakage. SEM showed that the cells in the control group had a regular, smooth, and intact surface. In contrast, oxacillin and SA or the combination treatment group exhibited different degrees of surface collapse. q-PCR indicated that the combination treatment group significantly inhibited the expression of the mecA gene. In vivo, we showed that the combination treatment increased the survival rate and decreased the bacterial load in mice. These results suggest that the combination of oxacillin with SA is considered an effective treatment option for MRSA, and the combination of SA with oxacillin in the treatment of MRSA is a novel strategy.

Natural Extracts for Antibacterial Applications

Bacteria-induced epidemics and infectious diseases are seriously threatening the health of people around the world. In addition, antibiotic therapy has been inducing increasingly more serious bacterial resistance, which makes it urgent to develop new treatment strategies to combat bacteria, including multidrug-resistant bacteria. Natural extracts displaying antibacterial activity and good biocompatibility have attracted much attention due to greater concerns about the safety of synthetic chemicals and emerging drug resistance. These antibacterial components can be isolated and utilized as antimicrobials, as well as transformed, combined, or wrapped with other substances by using modern assistive technologies to fight bacteria synergistically. This review summarizes recent advances in natural extracts from three kinds of sources-plants, animals, and microorganisms-for antibacterial applications. This work discusses the corresponding antibacterial mechanisms and the future development of natural extracts in antibacterial fields.

Antibacterial potential and synergistic interaction between natural polyphenolic extracts and synthetic antibiotic on clinical isolates

Emergence of antimicrobial resistance complicates treatment of infections by antibiotics. This has driven research on novel and combination antibacterial therapies. The present study evaluated synergistic antimicrobial activity of plant extracts and cefixime in resistant clinical isolates. Preliminary susceptibility profiling of antibiotics and antibacterial activity of extracts was done by disc diffusion and microbroth dilution assays. Checker-board, time-kill kinetics and protein content studies were performed to validate synergistic antibacterial activity. Results showed noteworthy quantities of gallic acid (0.24-19.7 µg/mg), quercetin (1.57-18.44 µg/mg) and cinnamic acid (0.02-5.93 µg/mg) in extracts of plants assessed by reverse-phase high performance liquid chromatography (RP-HPLC). Gram-positive (4/6) and Gram-negative (13/16) clinical isolates were intermediately susceptible or resistant to cefixime, which was used for synergistic studies. EA and M extracts of plants exhibited total synergy, partial synergy and indifferent characteristics whereas aqueous extracts did not show synergistic patterns. Time-kill kinetic studies showed that synergism was both time and concentration-dependent (2-8-fold decrease in concentration). Bacterial isolates treated with combinations at fractional inhibitory concentration index (FICI) showed significantly reduced bacterial growth, as well as protein content (5-62 %) as compared to extracts/cefixime alone treated isolates. This study acknowledges the selected crude extracts as adjuvants to antibiotics to treat resistant bacterial infections.

Genome Characterization of Bacteriophage KPP-1, a Novel Member in the Subfamily Vequintavirinae, and Use of Its Endolysin for the Lysis of Multidrug-Resistant Klebsiella variicola In Vitro

Multidrug-resistant members of the Klebsiella pneumoniae complex have become a threat to human lives and animals, including aquatic animals, owing to the limited choice of antimicrobial treatments. Bacteriophages are effective natural tools available to fight against multidrug-resistant bacteria. The bacteriophage KPP-1 was found to be strictly lytic against K. variicola, a multidrug-resistant isolate, producing clear plaques. The genome sequence analysis of KPP-1 revealed that it comprised 143,369 base pairs with 47% overall GC content. A total of 272 genes (forward 161, complementary 111) encode for 17 tRNAs and 255 open reading frames (ORFs). Among them, 32 ORFs could be functionally annotated using the National Center for Biotechnology Information (NCBI) Protein Basic Local Alignment Search Tool (BLASTp) algorithm while 223 were found to code for hypothetical proteins. Comparative genomic analysis revealed that the closest neighbor of KPP-1 can be found in the genus Mydovirus of the subfamily Vequintavirinae. KPP-1 not only markedly suppressed the growth of the host but also worked synergistically with ampicillin. Useful genes for pathogen control such as endolysin (locus tag: KPP_11591) were found to have activity against multidrug-resistant isolate of K. variicola. Further studies are necessary to develop a strategy to control the emerging pathogen K. variicola using bacteriophages such as KPP-1.

Antibacterial sensitizers from natural plants: A powerful weapon against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a drug-resistant bacterium that can cause a range of infections with high morbidity and mortality, including pneumonia, etc. Therefore, development of new drugs or therapeutic strategies against MRSA is urgently needed. Increasing evidence has shown that combining antibiotics with "antibacterial sensitizers" which itself has no effect on MRSA, is highly effective against MRSA. Many studies showed the development of antibacterial sensitizers from natural plants may be a promising strategy against MRSA because of their low side effects, low toxicity and multi-acting target. In our paper, we first reviewed the resistance mechanisms of MRSA including "Resistance to Beta-Lactams", "Resistance to Glycopeptide antibiotics", "Resistance to Macrolides, Aminoglycosides, and Oxazolidinones" etc. Moreover, we summarized the possible targets for antibacterial sensitizers against MRSA. Furthermore, we reviewed the synergy effects of active monomeric compounds from natural plants combined with antibiotics against MRSA and their corresponding mechanisms over the last two decades. This review provides a novel approach to overcome antibiotic resistance in MRSA.

Antimicrobial activities and mechanisms of extract and components of herbs in East Asia

Antibacterial drugs face increasing challenges due to drug resistance and adverse reactions, which has created a pressing need for the discovery and development of novel antibacterial drugs. Herbs have played an important role in the treatment of infectious diseases. This review aims to summarize, analyze and evaluate the antibacterial activities and mechanisms of components from popular herbs in East Asia. In this review, we have searched and summarized the scientific papers published during the past twenty-year period from electronic databases such as PubMed, ScienceDirect, and Web of Science. These herbs and their components, including alkaloids, flavonoids, essential oils, terpenes, organic acids, coumarins and lignans, display potential antimicrobial effects. Herbal medicine formulas (HMFs) usually show stronger antibacterial activity than single herbs. Herbs and HMFs bring forth antibacterial activities by damaging cell membranes and walls, inhibiting nucleic acid and protein synthesis, and increasing intracellular osmotic pressure. These herbs and their components can be developed as potential and promising novel antibacterial herbal products.

Suppression of CRLF1 promotes the chondrogenic differentiation of bone marrow-derived mesenchymal stem and protects cartilage tissue from damage in osteoarthritis via activation of miR-320

BACKGROUND

Osteoarthritis (OA) is the most prevalent chronic joint disease, and is hard to be cured at present. Cytokine receptor-like factor 1 (CRLF1) has been identified as an upregulated gene in OA cartilage. However, the precise identities and functions of CRLF1 in OA progression have remained to be fully elucidated.

METHODS

We used a murine model of injury-induced OA (destabilization of medial meniscus, DMM) and BMSCs to investigate the specific biological functions and mechanisms of CRLF1.

RESULTS

We found that CRLF1 was significantly increased in the DMM surgery-induced OA model and was down-regulated during chondrogenic differentiation of BMSCs. Luciferase reporter assays showed that CRLF1 was a direct target of miR-320 in BMSCs. miR-320 can reverse the effect of CRLF1 on cell proliferation, apoptosis and chondrogenic differentiation of BMSCs. Furthermore, knockdown of CRLF1 or over-expression of miR-320 can inhibit the apoptosis of primary chondrocytes.

CONCLUSION

Suppression of CRLF1 promotes the chondrogenic differentiation of BMSCs and protects cartilage tissue from damage in osteoarthritis via activation of miR-320.

From plants to antimicrobials: Natural products against bacterial membranes

Bacterial membrane barrier provides a cytoplasmic environment for organelles of bacteria. The membrane is composed of lipid compounds containing phosphatide protein and a minimal amount of sugars, and is responsible for intercellular transfers of chemicals. Several antimicrobials have been found that affect bacterial cytoplasmic membranes. These compounds generally disrupt the organization of the membrane or perforate it. By destroying the membrane, the drugs can permeate and replace the effective macromolecules necessary for cell life. Furthermore, they can disrupt electrical gradients of the cells through impairment of the membrane integrity. In recent years, considering the spread of microbial resistance and the side effects of antibiotics, natural antimicrobial compounds have been studied by researchers extensively. These molecules are the best alternative for controlling bacterial infections and reducing drug resistance due to the lack of severe side effects, low cost of production, and biocompatibility. Better understanding of the natural compounds' mechanisms against bacteria provides improved strategies for antimicrobial therapies. In this review, natural products with antibacterial activities focusing on membrane damaging mechanisms were described. However, further high-quality research studies are needed to confirm the clinical efficacy of these natural products.

Strategies to combat antimicrobial resistance in Indian scenario

Antimicrobial resistance (AMR) is one of the major public health crisis recognised globally. Microbial infections cause significant productivity losses in animals and humans. In livestock, these microbial infections reduce the growth rates and fertility, diminish production of meat and milk, and occasionally lead to mortality, and are therefore, a major concern for animal welfare. In the dearth of alternative prophylactic measures, antibiotics remain the principal tool for their management. Once an antibiotic is used rampantly, resistance against it is inevidently seen in the microbe population and the hunt for a new drug grows. Discovery and development of a new antimicrobial drug is a time taking and expensive procedure with limited assurance of success. As a result, the past few decades have witnessed only a very few new classes of antibiotics. If the AMR can be restricted or reverted, the success rate of antimicrobial therapy can be boosted and many public health issues be avoided. All these ask for a comprehensive plan to prevent or reduce the antimicrobial resistance and economic losses to the animal husbandry sector. The present review provides an overview of AMR in India, mechanism of its occurrence and the possible roadmap to combat the emerging threat of AMR in Indian scenario.

A paradigm shift in cell-free approach: the emerging role of MSCs-derived exosomes in regenerative medicine

Recently, mesenchymal stem/stromal cells (MSCs) due to their pro-angiogenic, anti-apoptotic, and immunoregulatory competencies along with fewer ethical issues are presented as a rational strategy for regenerative medicine. Current reports have signified that the pleiotropic effects of MSCs are not related to their differentiation potentials, but rather are exerted through the release of soluble paracrine molecules. Being nano-sized, non-toxic, biocompatible, barely immunogenic, and owning targeting capability and organotropism, exosomes are considered nanocarriers for their possible use in diagnosis and therapy. Exosomes convey functional molecules such as long non-coding RNAs (lncRNAs) and micro-RNAs (miRNAs), proteins (e.g., chemokine and cytokine), and lipids from MSCs to the target cells. They participate in intercellular interaction procedures and enable the repair of damaged or diseased tissues and organs. Findings have evidenced that exosomes alone are liable for the beneficial influences of MSCs in a myriad of experimental models, suggesting that MSC- exosomes can be utilized to establish a novel cell-free therapeutic strategy for the treatment of varied human disorders, encompassing myocardial infarction (MI), CNS-related disorders, musculoskeletal disorders (e.g. arthritis), kidney diseases, liver diseases, lung diseases, as well as cutaneous wounds. Importantly, compared with MSCs, MSC- exosomes serve more steady entities and reduced safety risks concerning the injection of live cells, such as microvasculature occlusion risk. In the current review, we will discuss the therapeutic potential of MSC- exosomes as an innovative approach in the context of regenerative medicine and highlight the recent knowledge on MSC- exosomes in translational medicine, focusing on in vivo researches.

Mesenchymal stem/stromal cell-derived exosomes in regenerative medicine and cancer; overview of development, challenges, and opportunities

Recently, mesenchymal stem/stromal cells (MSCs) and their widespread biomedical applications have attracted great consideration from the scientific community around the world. However, reports have shown that the main populations of the transplanted MSCs are trapped in the liver, spleen, and lung upon administration, highlighting the importance of the development of cell-free therapies. Concerning rising evidence suggesting that the beneficial effects of MSC therapy are closely linked to MSC-released components, predominantly MSC-derived exosomes, the development of an MSC-based cell-free approach is of paramount importance. The exosomes are nano-sized (30100nm) lipid bilayer membrane vesicles, which are typically released by MSCs and are found in different body fluids. They include various bioactive molecules, such as messenger RNA (mRNA), microRNAs, proteins, and bioactive lipids, thus showing pronounced therapeutic competence for tissues recovery through the maintenance of their endogenous stem cells, the enhancement of regenerative phenotypic traits, inhibition of apoptosis concomitant with immune modulation, and stimulation of the angiogenesis. Conversely, the specific roles of MSC exosomes in the treatment of various tumors remain challenging. The development and clinical application of novel MSC-based cell-free strategies can be supported by better understanding their mechanisms, classifying the subpopulation of exosomes, enhancing the conditions of cell culture and isolation, and increasing the production of exosomes along with engineering exosomes to deliver drugs and therapeutic molecules to the target sites. In the current review, we deliver a brief overview of MSC-derived exosome biogenesis, composition, and isolation methods and discuss recent investigation regarding the therapeutic potential of MSC exosomes in regenerative medicine accompanied by their double-edged sword role in cancer.

Synergistic Effect of Propolis and Antibiotics on Uropathogenic Escherichia coli

Urinary tract infections (UTIs) are the most common bacterial infections around the world. Uropathogenic Escherichia coli (UPEC) is among the main pathogens isolated in UTIs. The rate of UPEC with high resistance towards antibiotics and multidrug-resistant bacteria have increased dramatically and conduct to the difficulty to treat UTIs. Due to the rarefaction of new antibiotics molecules, new alternative strategies must be evaluated. Since many years, propolis has demonstrated an interesting antibacterial activity against E. coli. Here, we evaluated its activity added to antibiotics on a panel of UPEC with different resistance mechanisms. Minimal inhibitory concentrations (MICs) and time-kill curves of fosfomycin, ceftriaxone, ertapenem and ofloxacin, with and without propolis, were determined. Significant diminution of the MICs was observed using ceftriaxone or ofloxacin + propolis. Propolis alone had a bacteriostatic activity with time-dependent effect against UPEC. The addition of this nutraceutical improved the effect of all the antibiotics evaluated (except fosfomycin) and showed a synergistic bactericidal effect (fractional inhibitory concentrations index ≤ 0.5 and a decrease ≥ 2 log CFU/mL for the combination of propolis plus antibiotics compared with the antibiotic alone). Propolis is able to restore in vitro antibiotic susceptibility when added to antibiotics against UPEC. This study showed that propolis could enhance the efficiency of antibiotics used in UTIs and could represent an alternative solution.

Propolis as a novel antibacterial agent

Propolis (bee glue) is a bee glue, sticky resinous material released from various plant sources such as bud exudates, flowers, and leaves modified by bee secretions and wax propolis is composed of resins, waxes, polyphenols, polysaccharides, volatile materials, and secondary metabolites that are responsible for various bioactivity such as antibacterial, anti-angiogenic, antiulcer, anti-inflammatory, antioxidant, and anti-viral activities. The physico-chemical characteristics and the natural properties of various kinds of propolis have been studied for the past decade. Novel active anti-microbial compounds have been identified in propolis. Those compounds positively modulated the antimicrobial resistance of multidrug resistant bacteria. Published research has indicated that propolis and its derivatives has many natural antimicrobial compounds with a broad spectrum against different types of bacteria and that it enhanced the efficacy of conventional antibiotics. Besides, the combination of propolis with other compounds such as honey has been studied whereby, such combinations have a synergistic effect against bacterial strains such as Escherichia coli and Staphylococcus aureus. The activity of propolis is very much dependent on seasonal and regional factors, and Middle Eastern propolis have shown best antibacterial efficacy. Propolis and its main flavonoids ingredients should not be overlooked and should be evaluated in clinical trials to better elucidate their potential application in various fields of medicine. Clinical antibacterial potential and its use in new drugs of biotechnological products should be conducted. This review aims at highlighting some of the recent scientific findings associated with the antibacterial properties of propolis and its components.

Antimicrobial flavonoids as a potential substitute for overcoming antimicrobial resistance

BACKGROUND

Infectious diseases are the leading cause of death in 21^st century due to antimicrobial resistance and scarcity of new molecules to undertake rising infections. There could be a multiple reasons behind antimicrobial resistance whether it is increased drug metabolism or bacterial endotoxins. The demand of effective medication is increasing day by day to treat microbial infections and combat antimicrobial resistance. In recent years most of the synthetic antimicrobials developed resistance so natural products could provide better options to fulfill this demand. There has been increasing interest in the research on flavonoids because various flavonoids were found to be effective against pathogenic microorganisms.

OBJECTIVE

The objective of this article will be to explore antimicrobial activity of flavonoids with special focus on their possible mechanism of action.

METHODS

The article reviewed recent literature related to flavonoids with antimicrobial activity, which were isolated from various sources and the compounds showing fairly good activity against tested microbial species were discussed.

RESULTS

By throughout literature review it has been found that flavonoids show antimicrobial effect by inhibiting virulence factors, efflux pump, biofilm formation, membrane disruption, cell envelop synthesis, nucleic acid synthesis, and bacterial motility inhibition.

CONCLUSION

Most of the antimicrobial drugs available now a days are ineffective due to development of resistance to them. Flavonoids have the potential to overcome this emerging crisis as this class of natural products showed the antimicrobial activity by different mechanisms than those of conventional drugs, so flavonoid could be an effective treatment of pathogenic infections.

Advances of exosome isolation techniques in lung cancer

Lung cancer (LC) is among the leading causes of death all over the world and it is often diagnosed at advanced or metastatic stages. Exosomes, derived from circulating vesicles that are released from the multivesicular body, can be utilized for diagnosis and also the prognosis of LC at early stages. Exosomal proteins, RNAs, and DNAs can help to better discern the prognostic and diagnostic features of LC. To our knowledge, there are various reviews on LC and the contribution of exosomes, but none of them are about the exome techniques and also their efficiency in LC. To fill this gap, in this review, we summarize the recent investigations regarding isolation and also the characterization of exosomes of LC cells. Furthermore, we discuss the noncoding RNAs as biomarkers and their applications in the diagnosis and prognosis of LC. Finally, we compare the efficacy of exosome isolation methods to better fi + 6 + guring out feasible techniques.

Defying Multidrug Resistance! Modulation of Related Transporters by Flavonoids and Flavonolignans

Multidrug resistance (MDR) is a major challenge for the 21th century in both cancer chemotherapy and antibiotic treatment of bacterial infections. Efflux pumps and transport proteins play an important role in MDR. Compounds displaying inhibitory activity toward these proteins are prospective for adjuvant treatment of such conditions. Natural low-cost and nontoxic flavonoids, thanks to their vast structural diversity, offer a great pool of lead structures with broad possibility of chemical derivatizations. Various flavonoids were found to reverse both antineoplastic and bacterial multidrug resistance by inhibiting Adenosine triphosphate Binding Cassette (ABC)-transporters (human P-glycoprotein, multidrug resistance-associated protein MRP-1, breast cancer resistance protein, and bacterial ABC transporters), as well as other bacterial drug efflux pumps: major facilitator superfamily (MFS), multidrug and toxic compound extrusion (MATE), small multidrug resistance (SMR) and resistance-nodulation-cell-division (RND) transporters, and glucose transporters. Flavonoids and particularly flavonolignans are therefore highly prospective compounds for defying multidrug resistance.

microRNA-141-3p-containing small extracellular vesicles derived from epithelial ovarian cancer cells promote endothelial cell angiogenesis through activating the JAK/STAT3 and NF-κB signaling pathways

Paracrine signaling between tumor and surrounding stromal cells is critical for the maintenance of tumor microenvironment during ovarian cancer progression. Small extracellular vesicles (sEVs; exosomes in particular) are nano-sized vesicles secreted actively by many cells including tumor cells and are found to have fundamental roles in intercellular communication through shuttling functional RNAs. Although microRNAs (also called miRNAs or miRs), small non-coding RNAs regulating gene expression, are selectively accumulated in tumor sEVs and can mediate intercellular communication, the exact biological mechanisms underlying the functions of exosomal miRNAs in ovarian tumor angiogenesis remain unclear. In this study, sEVs were isolated from conditioned medium of the human ovarian carcinoma cell line SKOV-3 using ExoQuick Exosome Precipitation Solution, and characterized by scanning electron microscopy, dynamic light scattering, and immunoblotting. To elucidate the possible paracrine effects on ovarian tumor cell-derived sEVs (TD-sEVs), we investigated the angiogenesis-related signaling events triggered by TD-sEVs in endothelial cells. Due to the possible role in ovarian tumor pathogenesis, we focused on miR-141-3p which was detected to be enriched in TD-sEVs compared with their corresponding donor cells. We identified that sEV transfer of miR-141-3p considerably reduced the expression levels of cytokine-inducible suppressors of cytokine signaling (SOCS)-5 leading to up-regulated JAK-STAT3 pathway in endothelial cells. We also observed that sEV-shuttled miR-141-3p may up-regulate the expression of VEGFR-2 in endothelial cells which leads to promoting endothelial cell migration and angiogenesis. The putative role of miR-141-3p shuttled by TD-sEVs in regulating VEGFR-2 expression was demonstrated by the ability of anti-miR-141-3p to rescue the promoting effects of TD-sEVs on the expression of VEGFR-2 in endothelial cells. Our results also revealed that TD-sEVs trigger the intracellular reactive oxygen species (ROS)-dependent activation of NF-κB signaling in endothelial cells. Taken together, our findings propose a novel model in which sEV transfer of epithelial ovarian cancer-secreted miR-141-3p plays as a significant mediator of intercellular communication, promoting endothelial cell angiogenesis.

Chitosan derivatives co-delivering nitric oxide and methicillin for the effective therapy to the methicillin-resistant S. aureus infection

We developed a co-delivery system of nitric oxide (NO) and antibiotic for the antibiotic-resistant bacterial infection therapy. The NO could disperse the bacterial biofilms and convert the bacteria into an antibiotic-susceptible planktonic form. Using the chitosan-graft-poly(amidoamine) dendrimer (CS-PAMAM) as the co-delivery system, methicillin (MET) and NO were conjugated successively to form CS-PAMAM-MET/NONOate. The positive CS-PAMAM could efficiently capture the negatively charged bacteria and PAMAM provide abundant reaction points for high payloads of NO and MET. The CS-PAMAM-MET/NONOate displayed effective and combined antibacterial activity to the E. coli and S. aureus. Particularly, for the MET-resistant S. aureus (MRSA), the CS-PAMAM-MET/NONOate displayed the synergistic antibacterial activity. In vivo wound healing assays also confirmed that CS-PAMAM-MET/NONOate could heal the infection formed by MRSA and then accelerate the wound healing effectively. Moreover, CS-PAMAM-MET/NONOate showed no toxicity towards 3T3 cells in vitro and rats in vivo, providing a readily but high-efficient strategy to drug-resistant bacterial infection therapy.

A porous carbon absorbent based on high internal phase emulsion for separation and enrichment of trifluralin from soil

A porous carbon absorbent was obtained by using high internal phase emulsions (HIPEs) polymerization followed by high temperature carbonization under nitrogen protection. Graphene oxide (GO) and silica nanoparticles were doped into the HIPEs to enhance the adsorption ability and reusability. Fourier infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were used for characterization and several parameters of separation and enrichment of trifluralin. The results showed that a hyper-crosslink framework material was obtained with abundant porous (pore size of about 30 μm) and a good adsorption and separation efficiency. The adsorption rate was up to 100% and trifluralin was completely eluted from the absorbent by 2.0 mL of an acetic acid-acetonitrile mixture. Graphical abstractSchematic representation of synthesis of porous carbon absorbent by GO and SiO₂ doped HIPEs.POLYHIPES-GO&SiO₂: Polymerized High Internal Phase Emulsions doped with Silica and Graphene oxide.

Antibiotic hypersensitivity in MRSA induced by special protein aggregates

Emergence of multidrug-resistant bacteria is a major global concern. According to WHO, methicillin-resistant Staphylococcus aureus (MRSA) is a threatening pathogen resistant to a wide spectrum of antibiotics. Herein, to overcome drug resistance in MRSA, we successfully integrated traditional antibacterial methods but with a novel trick that included use of hen egg-white lysozyme's special aggregates generated by fibrillization. The minimum inhibitory concentration of oxacillin (Ox) for MRSA declined from 600 μM to <20 μM when using aggregates. Scanning and transition electron micrographs showed completely disrupted cells when treated with aggregated protein/Ox (20 μM). The assisting role of aggregates to induce antibiotic hypersensitivity was continuous and stable, but sub-inhibitory antibiotic concentration (20 μM) was required again after 8 h. Investigations regarding mechanism of antibiotic hypersensitivity revealed that aggregates were oligomers but not mature fibrils. Furthermore, reactive oxygen species levels rose significantly after treating bacteria with aggregated protein/Ox. Study of resistance mechanisms indicated that in response to wall structure alterations, mecA expression dropped significantly in the presence of aggregated protein/Ox (20 μM) relative to Ox (20 μM). This observation can be a breakthrough in finding alternatives where antibiotic dosage can be significantly reduced, thereby preventing emergence of new multidrug-resistant bacteria.

Antibacterial activity of 3,3'-dihydroxycurcumin (DHC) is associated with membrane perturbation

Curcumin is a plant diphenylheptanoid and has been investigated for its antibacterial activity. However, the therapeutic uses of this compound are limited due to its chemical instability. In this work, we evaluated the antimicrobial activity of diphenylheptanoids derived from curcumin against Gram-positive and Gram-negative bacteria, and also against Mycobacterium tuberculosis in terms of MIC (Minimum Inhibitory Concentration) and MBC (Minimum Bactericidal Concentration) values. 3,3'-Dihydroxycurcumin (DHC) displayed activity against Enterococcus faecalis, Staphylococcus aureus and M. tuberculosis, demonstrating MIC values of 78 and 156 µg/mL. In addition, DHC was more stable than curcumin in acetate buffer (pH 5.0) and phosphate buffer (pH 7.4) for 24 h at 37 °C. We proposed that membrane and the cell division protein FtsZ could be the targets for DHC due to that fact that curcumin exhibits this mode of antibacterial action. Fluorescence microscopy of Bacillus subtilis stained with SYTO9 and propidium iodide fluorophores indicated that DHC has the ability to perturb the bacterial membrane. On the other hand, DHC showed a weak inhibition of the GTPase activity of B. subtilis FtsZ. Toxicity assay using human cells indicated that DHC has moderate capacity to reduce viability of liver cells (HepG2 line) and lung cells (MRC-5 and A549 lines) when compared with doxorubicin. Alkaline comet assay indicated that DHC was not able to induce DNA damage in A549 cell line. These results indicated that DHC is promising compound with antibacterial and antitubercular activities.

Antibacterial Properties of Propolis

Researchers are continuing to discover all the properties of propolis due to its complex composition and associated broad spectrum of activities. This review aims to characterize the latest scientific reports in the field of antibacterial activity of this substance. The results of studies on the influence of propolis on more than 600 bacterial strains were analyzed. The greater activity of propolis against Gram-positive bacteria than Gram-negative was confirmed. Moreover, the antimicrobial activity of propolis from different regions of the world was compared. As a result, high activity of propolis from the Middle East was found in relation to both, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) strains. Simultaneously, the lowest activity was demonstrated for propolis samples from Germany, Ireland and Korea.

A promising antibiotic, synergistic and antibiofilm effects of Vernonia condensata Baker (Asteraceae) on Staphylococcus aureus

Vernonia condensata Baker is traditionally used to treat several inflammatory and infectious processes. So, this study evaluated the antibiotic, synergistic and antibiofilm effects, and the mode of action of ethyl acetate fraction from V. condensata leaves (Vc-EAF) against Staphylococcus aureus. Five S. aureus ATCC^® and five methicillin-resistant S. aureus (MRSA) routine strains were used to determine Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration. The combinatory effect was evaluated by checkerboard and time kill methods; the mode of action through the bacterial cell viability and leakage of compounds absorbing at 280 nm; and the antibiofilm action by quantifying the percentage of adhesion inhibition. Vc-EAF was active against S. aureus (ATCC^® 6538^™), (ATCC^® 25923^™), (ATCC^® 29213^™), (ATCC^® 33591^™), (ATCC^® 33592^™), MRSA 1485279, 1605677, 1664534, 1688441 and 1830466, with MIC of 625 μg/mL for ATCC^®, and 1250, 1250, >2500, 2500 and 2500 μg/mL for MRSA, in this order, with bacteriostatic effect for both ATCC^® and MRSA strains. Vc-EAF plus ampicillin revealed a total synergic effect on MRSA 1485279, and Vc-EAF combined with chloramphenicol, a partial synergic action against S. aureus (ATCC^® 29213^™) and (ATCC^® 25923^™). The time kill data agreed with checkerboard results, and the treated cells number was reduced with release of bacterial content. An expressive bacterial adhesion inhibition for S. aureus (ATCC^® 25923^™) and MRSA 1485279 was detected. These results showed that V. condensata is a promising natural source of active substances against S. aureus, including multiresistant strains, interfering with their antibacterial growth and hampering their adhesion to surfaces.

Matricaria genus as a source of antimicrobial agents: From farm to pharmacy and food applications

Matricaria is a widespread genus of flowering plants of the family Asteraceae that grow in temperate regions of Europe, Asia, America and Africa. Some of the species are also naturalized in Australia. Some species of this genus such as Chamomiles are recognized medicinal plants and cultivated in several countries for commercial purposes: to obtain its blue essence, as herbal tea, and for pharmaceutical or cosmeceutical uses. The phytochemical composition of Matricaria spp. includes volatile terpenoids (e.g., α-bisabolol, bisabolol oxide A and B, β-trans-farnesene and chamazulene), sesquiterpene lactones such as matricin, and phenolic compounds (flavonoids, coumarins and phenolic acids). Their essential oil is obtained from the fresh or dried inflorescences by steam distillation, and additionally cohobation of the remaining water. The volatile composition of the essential oil, especially the content of the valuable components α-bisabolol and chamazulene, depends on the plant part, origin and quality of the source, genetic, and environmental factors. Moreover, other parameters, such as season of harvest and methods of extraction, can affect the extraction yield of the essential oils/extracts, their composition and, therefore, their bioactivity. Due to the importance of this genus and particularly M. recutita (M. chamomilla), this review focus on its cultivation, factor affecting essential oils' composition and their role in traditional medicine, as antibacterial agents and finally as food preservatives.