Mechanism of antibacterial activity of liposomal linolenic acid against Helicobacter pylori. PLoS One. 2015;10:e0116519. [PMID: 25793403 DOI: 10.1371/journal.pone.0116519]

A new application of avocado oil to enrich the biological activities of polycaprolactone membranes for tissue engineering

The metabolites synthesized by plants to protect themselves serves as natural antimicrobial agents used in biomaterials. In this study, avocado oil (AO), was incorporated as a plant source and natural antimicrobial agent into polycaprolactone (PCL) membranes. The effects of varying AO ratios (25, 50, and 100 wt%.-PCL@25AO, PCL@50AO, PCL@100AO) on PCL membrane morphology, chemical structure, wettability, antimicrobial activity, and cell viabilities were investigated. It was demonstrated that the AO acts as a pore-forming agent in solvent-casted membranes. Young's modulus of the membranes varied between 602.68 and 31.92 MPa and more flexible membranes were obtained with increasing AO content. Inhibition zones of AO were recorded between 7.86 and 13.97 mm against clinically relevant microbial strains including bacteria, yeast, and fungi. Antimicrobial activity of AO was retained in PCL membranes at all ratios. Resazurin assay indicated that PCL@25AO membranes were cytocompatible with mouse fibroblast cells (L929 cell line) on day 6 showing 72.4% cell viability with respect to neat PCL membranes. Viability results were supported by scanning electron microscopy images and DAPI staining. The overall results of this study highlight the potential of PCL@25AO membranes as a biomaterial with antimicrobial properties, cytocompatibility, and mechanical strength suitable for various biomedical applications.

A comprehensive account on ethnobotany, phytochemistry and pharmacological insights of genus Celtis

The plants of Celtis L. genus have been traditionally used to cure aches, sore throats, fevers, cancer, sexually transmitted diseases, sexual weakness, diarrhea, stomach problems, amenorrhea, menstrual disorders, kidney stones, and pain. The review aims to give a comprehensive account of the current state of ethnopharmacology, phytochemistry, and biological activities of the Celtis genus, as well as to describe the potential area of future avenues. Information on the Celtis genus was obtained from internet sources such as Google Scholar, Web of Science, PubMed, ScienceDirect, and so on by using appropriate keywords, including ethnobotanical, pharmacological, pharmaceutical, bioactivity, phytochemistry, and botanical features of the Celtis genus. This review identified 14 species in the genus Celtis that have a phytopharmacological investigation, including C.africana Burm. f., C. australis L., C. occidentalis L., C. sinensis Pers., C. philippensis Blanco., C. tetrandra Roxb., C. tessmannii Rendle., C. jessoensis Koidz., C. adolfi-friderici Engl., C. iguanaea (Jacq.) Sarg., C. laevigata Wild., C. pallida Torr., C. zenkeri Engl., and C. tournefortii Lam. This genus contains many classified phytoconstituents, such as terpenoids, organic acids, flavonoids, and volatile compounds. Their extracts and pure substances have been shown to have the same anticancer, antibacterial, anti-inflammatory, antioxidant, hepatoprotective, cardioprotective, urease-inhibiting, and antidiarrheal properties as their traditional uses. In terms of current information on ethnopharmacology, phytochemicals, and pharmacological uses, the data acquired in this review could be beneficial and needed for future research. Some phytoconstituents (for instance, kaempferol, myricetin, quercetin, and eugenol) and extracts (for example, leaves, seeds, and ripe fruits extracts of C. australis) showed tremendous results in preliminary testing with promising antimicrobial, anticancer, and urease inhibitory effects. Further research and clinical investigations are needed to develop them as lead compounds and neutraceuticals, which may provide an advance over traditional medicinal systems.

Synthesis of New Multifunctional Linolenic Acid Vanillyl Ester and Investigation of Antioxidant and Antibacterial Activities

Vanillyl alcohol (VA) possesses potent antioxidant activity, yet its applicability is hindered by its limited solubility in emulsions or non-polar organic solvents. Conversely, long-chain polyunsaturated fatty acids exhibit antibacterial properties. The combination of these compounds offers the prospect of developing novel phenolic lipid compounds with dual antioxidant and antibacterial activities, alongside enhanced solubility capabilities. In this investigation, linolenic acid vanillyl ester (LAVE) was synthesized from VA and linseed oil (LO) through a transesterification reaction employing immobilized lipase. Optimization of LAVE production was achieved by varying reaction temperature, substrate concentration, and reaction time. LAVE demonstrated efficacy in scavenging both 2,2-diphenyl-1-picryhydrazyl and 2,2'-azino-bis (3-ethylbenthiazoline-6-sulphonic acid) radicals in organic solvents. Antioxidant testing via lipid oxidation analysis revealed that LAVE, when distributed within emulsions, effectively impeded the formation of conjugated dienes and conjugated trienes. Furthermore, LAVE exhibited antibacterial activity against four strains of spoilage bacteria: Bacillus subtilis, Bacillus coagulans, Pseudomonas fluorescens, and Alcaligenes faecalis. Zeta potential analysis substantiated the binding of LAVE to the bacterial cell surface. Propidium iodide uptake assay and fluorescence microscopy further elucidated that LAVE induces cell lysis by augmenting membrane permeability.

Site-specific delivery of cisplatin and paclitaxel mediated by liposomes: A promising approach in cancer chemotherapy

The site-specific delivery of drugs, especially anti-cancer drugs has been an interesting field for researchers and the reason is low accumulation of cytotoxic drugs in cancer cells. Although combination cancer therapy has been beneficial in providing cancer drug sensitivity, targeted delivery of drugs appears to be more efficient. One of the safe, biocompatible and efficient nano-scale delivery systems in anti-cancer drug delivery is liposomes. Their particle size is small and they have other properties such as adjustable physico-chemical properties, ease of functionalization and high entrapment efficiency. Cisplatin is a chemotherapy drug with clinical approval in patients, but its accumulation in cancer cells is low due to lack of targeted delivery and repeated administration results in resistance development. Gene and drug co-administration along with cisplatin/paclitaxel have resulted in increased sensitivity in tumor cells, but there is still space for more progress in cancer therapy. The delivery of cisplatin/paclitaxel by liposomes increases accumulation of drug in tumor cells and impairs activity of efflux pumps in promoting cytotoxicity. Moreover, phototherapy along with cisplatin/paclitaxel delivery can increase potential in tumor suppression. Smart nanoparticles including pH-sensitive nanoparticles provide site-specific delivery of cisplatin/paclitaxel. The functionalization of liposomes can be performed by ligands to increase targetability towards tumor cells in mediating site-specific delivery of cisplatin/paclitaxel. Finally, liposomes can mediate co-delivery of cisplatin/paclitaxel with drugs or genes in potentiating tumor suppression. Since drug resistance has caused therapy failure in cancer patients, and cisplatin/paclitaxel are among popular chemotherapy drugs, delivery of these drugs mediates targeted suppression of cancers and prevents development of drug resistance. Because of biocompatibility and safety of liposomes, they are currently used in clinical trials for treatment of cancer patients. In future, the optimal dose of using liposomes and optimal concentration of loading cisplatin/paclitaxel on liposomal nanocarriers in clinical trials should be determined.

Microparticles and nanoparticles-based approaches to improve oral treatment of Helicobacter pylori infection

Helicobacter pylori is a gram-negative, spiral-shaped, flagellated bacterium that colonizes the stomach of half the world's population. Helicobacter pylori infection causes pathologies of varying severity. Standard oral therapy fails in 15-20% since the barriers of the oral route decrease the bioavailability of antibiotics and the intrinsic factors of bacteria increase the rates of resistance. Nanoparticles and microparticles are promising strategies for drug delivery into the gastric mucosa and targeting H. pylori. The variety of building blocks creates systems with distinct colloidal, surface, and biological properties. These features improve drug-pathogen interactions, eliminate drug depletion and overuse, and enable the association of multiple actives combating H. pylori on several fronts. Nanoparticles and microparticles are successfully used to overcome the barriers of the oral route, physicochemical inconveniences, and lack of selectivity of current therapy. They have proven efficient in employing promising anti-H. pylori compounds whose limitation is oral route instability, such as some antibiotics and natural products. However, the current challenge is the applicability of these strategies in clinical practice. For this reason, strategies employing a rational design are necessary, including in the development of nano- and microsystems for the oral route.

Alkyl ferulic acid esters: Evaluating their structure and antibacterial properties

Ferulic acid (FA) is a natural antibacterial agent rich in plants, FA has excellent antioxidant and antibacterial properties. However, because of its short alkane chain and large polarity, FA is difficult to penetrate the soluble lipid bilayer in the biofilm to enter the cell to play an inhibitory role, limiting its biological activity. To improve the antibacterial activity of FA, with the catalytic condition of Novozym 435, four alkyl ferulic acid esters (FCs) with different alkyl chain lengths were obtained by fatty alcohols (including 1-propanol (C3), 1-hexanol (C6), nonanol (C9), and lauryl alcohol (C12)) modification. The effect of FCs on P. aeruginosa was determined by Minimum inhibitory concentrations (MIC), minimum bactericidal concentrations (MBC), Growth curves, alkaline phosphatase (AKP) activity, crystal violet method, scanning electron microscopy (SEM), membrane potential, PI, cell contents leakage. Results showed that the antibacterial activity of FCs increased after esterification, and the antibacterial activity significantly increased and then decreased with the extension of the alkyl chain of the FCs. Hexyl ferulate (FC6) showed the best antibacterial activities against E. coli and P. aeruginosa (MIC for E. coli was 0.5 mg/ml, MIC for P. aeruginosa was 0.4 mg/ml). And Propyl ferulate (FC3) and FC6 showed the best antibacterial activities S. aureus and B. subtilis (MIC for S. aureus was 0.4 mg/ml, The MIC of B. subtilis was 1.1 mg/ml). In addition, the growth, AKP activity, bacterial biofilm, bacterial cell morphology, membrane potential and cell contents leakage of P. aeruginosa after different FCs were investigated, which found that FCs could damage the cell wall of P. aeruginosa and showed different effects on the P. aeruginosa cell biofilm. FC6 showed the best inhibition on the biofilm formation of P. aeruginosa cells, which caused the surface of P. aeruginosa cells to be rough and wrinkled. Some P. aeruginosa cells showed aggregation and adhesion, even rupture. The membrane hyperpolarization was obvious, which appeared as holes, leading to cell contents leakage (protein and nucleic acid). All these results concluded that the antibacterial activities FCs against foodborne pathogens depended on different fatty alcohol esterification of FA. FC6 showed the best inhibition on P. aeruginosa due to its effect on P. aeruginosa cell walls and biofilms and the leak of the cell contents. This study provides more practical methods and a theoretical basis for giving full play to the bacteriostatic effect of plant FA.

Evaluation of the antimicrobial mechanism of biogenic selenium nanoparticles against Pseudomonas fluorescens

Selenium nanoparticles (SeNPs) can be biosynthesized by most Lactic acid bacteria thereby converting toxic sodium into SeNPs. However, few studies have reported the antimicrobial activity of biogenic SeNPs against Pseudomonas fluorescens which are the main species of psychrotrophic bacteria in raw milk. This study reported the synthesis and characterization of SeNPs from Lactobacillus casei ZK-AS 1.1482, and the antimicrobial mechanism against P. fluorescens ATCC 13525. The synthesized SeNPs were amorphous with sizes ranging from 52 to 103 nm. Fourier transform infrared spectroscopy (FT-IR) spectra showed the presence of proteins, polysaccharides, and lipids on the surface of particles, which evidently stabilized the SeNPs structure and morphology. Energy-dispersive X-ray (EDX) analysis revealed that the nanoparticles contained selenium. In addition, the minimal inhibitory concentration (MIC) of SeNPs against P. fluorescens ATCC 13525 was 0.1 mg ml^-1 and the biofilm inhibition rate was 43.52 ± 0.26%. SeNPs decreased the number of living bacteria observed by confocal laser scanning microscopy (CLSM). Meanwhile, after SeNPs treatment, the intracellular adenosine triphosphate (ATP) concentration and antioxidant enzyme activity decreased, the content of reactive oxygen species (ROS) and the malondialdehyde (MDA) content increased, and lipid peroxidation intensified. Real-time fluorescence quantitative PCR (RT-qPCR) assay showed that the expression of flgA, luxR, lapD, MCP, cheA, c-di-GMP, phoB, and pstC gene were down-regulated after SeNPs treatment. The rfbC and DegT/DnrJ/EryC1/StrS gene were significantly up-regulated, indicating that SeNPs could destroy the integrity of cell membrane and thus play an antimicrobial role. Biogenic SeNPs are expected to be developed as an efficient and novel antimicrobial agent for application in the food industry.

Effect of polyunsaturated free fatty acids on the membrane fusion mechanism

Membrane fusion is one of the important processes for the survival of eukaryotic cells and the entry of enveloped viruses into the host cells. Lipid composition plays a crucial role by modulating the organization and dynamics of the membrane, as well as the structure and conformation of membrane proteins. The diversity of the lipid acyl chain in its length and degree of unsaturation originates from the variation in free fatty acids (FFAs). We have studied the effect of linoleic (LA) and alpha-linolenic (ALA) acids on the depth-dependent organization, dynamics, and fusion of DOPC/DOPE (70/30 mol%) membranes utilizing steady-state and time-resolved fluorescence spectroscopic methods. Our results suggest that membranes with 5 mol% LA stabilize the stalk-intermediate and promote lipid mixing at the early stage of the process, i.e., the fusion follows the classical stalk model. Conversely, the extents of lipid and content mixing at the stalk intermediate are similar in the presence of 5 mol% of ALA, indicating the fusion mechanism as a nonclassical one like in the DOPC/DOPE (70/30 mol%) membranes. Our results provide an in-depth insight into the effect of the increasing degree of fatty acid tail unsaturation on membrane organization and dynamics and their impact on the membrane fusion mechanism.

A Bioluminescence-Based Drug Screen Identifies Activities of Fexinidazole and Its Metabolites against Helicobacter pylori

Helicobacter pylori is responsible for a wide range of gastric diseases, including gastric cancer and gastritis. With half of the world’s population infected by H. pylori and the current standard of care associated with suboptimal outcomes, a search for more effective drugs is critical. To facilitate drug screening for H. pylori, we developed a microtiter plate-based compound screening method that is faster and can screen multiple compounds. We identified activities of fexinidazole and its sulfoxide and sulfone metabolites against H. pylori. Both fexinidazole and its metabolites exhibited equipotency against SS1, 60190, and G27 strains, which were about 3–6-fold more potent than the currently used metronidazole. We also determined the minimal inhibitory concentration (MIC) of metronidazole, fexinidazole, and its metabolites against these strains by a traditional agar plate-based method. While MIC values of fexinidazole and metronidazole were similar against all the strains, both sulfoxide and sulfone showed lower MIC values than metronidazole against SS1 and 60190. Given the recent FDA approval of fexinidazole, our data on the in vitro antibacterial activities of fexinidazole and its metabolites support further evaluation of this drug with the goal of producing an alternative nitro-based antimicrobial with good safety profiles for the treatment of H. pylori infection.

Valorization of Soy Lecithin by Enzyme Cascade Reactions Including a Phospholipase A2, a Fatty Acid Double-Bond Hydratase, and/or a Photoactivated Decarboxylase

A huge amount of phospholipids or lecithin is produced as a byproduct in the vegetable oil industry. However, most are just used as a feed additive. This study has focused on enzymatic valorization of lecithin. This was exploited by enzymatic transformation of soy lecithin into lysolecithin liposomes, including functional free fatty acids, hydroxy fatty acids, hydrocarbons, or secondary fatty alcohols. One of the representative examples was the preparation of lysolecithin liposomes containing secondary fatty alcohols [e.g., 9-Hydroxyheptadec-11-ene (9) and 9-heptadecanol (10)] by using a phospholipase A2 from Streptomyces violaceoruber, a fatty acid double-bond hydratase from Stenotrophomonas maltophilia, and a photoactivated decarboxylase from Chlorella variabilis NC64A. The engineered liposomes turned out to range ca. 144 nm in diameter by dynamic light scattering analysis. Thereby, this study will contribute to application of functional fatty acids and their derivatives as well as valorization of lecithin for the food and cosmetic industries.

The Activity of Liposomal Linolenic Acid Against Helicobacter pylori In Vitro and Its Impact on Human Fecal Bacteria

Helicobacter pylori (H. pylori) infection is associated with a variety of gastrointestinal diseases. Here, we focused on the activity of a novel nanomedicine-liposomal linolenic acid (LipoLLA) against H. pylori and its impact on human fecal bacteria in vitro. The minimum inhibitory concentrations (MICs) of LipoLLA against 30 H. pylori clinical strains were determined in combination with amoxicillin (AMX), metronidazole (MTZ), levofloxacin (LVFX) and clarithromycin (CAM). Bactericidal activity was measured by generating concentration-bactericidal curves at different times and pH values. Leakage of glucose (GLU) and aspartate aminotransferase (AST) was detected, combined with detection of changes in morphology by electron microscopy, to study the mechanism of action of LipoLLA against H. pylori. The effect of LipoLLA on human fecal bacteria was studied by high-throughput sequencing of fecal samples. We observed a synergistic or additive effect when LipoLLA was combined with AMX, MTZ, LVFX and CAM. The concentration-sterilization curves were pH and time dependent. After treatment with LipoLLA, GLU and AST levels were increased (P<0.05), and the morphology of H. pylori changed significantly. Moreover, LipoLLA activity led to no significant changes in the intestinal flora in terms of alpha diversity, species composition, beta diversity, etc. In conclusion, LipoLLA showed good anti-H. pylori effects. It destroyed the outer membrane barrier and caused leakage of the bacterial contents to achieve anti-H. pylori effects. And LipoLLA had little effect on human fecal bacteria in vitro.

Targeting and Killing the Ever-Challenging Ulcer Bug

TreatingHelicobacter pylori(H. pylori) infections has been a never-ending challenge, which has contributed to the high incidence of gastric cancer. The antibiotics commonly used are not reaching the infection site in its active state and in a concentration high enough to effectively kill the bacteria. In this context, amoxicillin-loaded lipid nanoparticles with carefully chosen materials were developed, namely dioleoylphosphatidylethanolamine (DOPE) as a targeting agent and Tween®80 and linolenic acid as antimicrobial agents. This work shows the ability of these nanoparticles in (i) targeting the bacteria (imaging flow cytometry) and inhibiting their adhesion to MKN-74 cells (bacteria-gastric cells adhesion model); (ii) killing the bacteria even as an antibiotic-free strategy (time-kill kineticstudies, scanning electron microscopy, and bacterial membrane permeability studies); (iii)overcoming gastrointestinal features using a newly developedin vitroinfection model that includes both physical (epithelial cells and mucus) and the chemical (acid medium) barriers; and in (iv) being incorporated in a floating system that can increase the retention time at the stomach. Overall, this work presents an effective nanosystem to deal with the ulcer-bug. Besides, it also provides two innovative tools transferable to other fields-anin vitroinfection model and a floating system to incorporate nanoparticles.

Liposomes, new carriers for delivery of genes and anticancer drugs: a systematic review

Today, nanoscience has grown and developed in various fields of medicine and treatment, including cancer treatment. Currently, the existing treatments, including chemotherapy and radiotherapy, cause side effects that are unpleasant to the patient. Due to the fact that anticancer drugs cause severe and widespread side effects, liposomes are considered as new drug carriers to minimize the untimely destruction of the drug when it is delivered to the target tissue and to prevent the side effects of toxic drugs. This systematic review study examined the importance of using liposomes as new drug carriers for the delivery of genes and anticancer drugs. The articles published in English in the databases of Google scholar, WoS, PubMed, Embase, Scopus and science direct were reviewed. According to the results of this study, a new targeted nanosystem has been used for loading and delivering anticancer drugs, genes and controlled drug release which has a significant therapeutic effect compared to the same amount of free drug. In general, liposomal systems have been considered because of their capability in preserving the effect of the drug along with reducing the side effects and toxicity of the drug, especially in the case of anticancer drugs. Accumulation of the drug in a target tissue which results in a reduction of the drug entry into other tissues is the main reason for reducing the side effects of these drugs.

Revisiting Therapeutic Strategies for H. pylori Treatment in the Context of Antibiotic Resistance: Focus on Alternative and Complementary Therapies

The prevalence of Helicobacter pylori infection remains significant worldwide and it depends on many factors: gender, age, socio-economic status, geographic area, diet, and lifestyle. All successful infectious diseases treatments use antibiotic-susceptibility testing, but this strategy is not currently practical for H. pylori and the usual cure rates of H. pylori are lower than other bacterial infections. Actually, there is no treatment that ensures complete eradication of this pathogen. In the context of an alarming increase in resistance to antibiotics (especially to clarithromycin and metronidazole), alternative and complementary options and strategies are taken into consideration. As the success of antibacterial therapy depends not only on the susceptibility to given drugs, but also on the specific doses, formulations, use of adjuvants, treatment duration, and reinfection rates, this review discusses the current therapies for H. pylori treatment along with their advantages and limitations. As an alternative option, this work offers an extensively referenced approach on natural medicines against H. pylori, including the significance of nanotechnology in developing new strategies for treatment of H. pylori infection.

Using HPLC-DAD and GC-MS Analysis Isolation and Identification of Anticandida Compounds from Gui Zhen Cao Herbs (Genus Bidens): An Important Chinese Medicinal Formulation

Gui Zhen Cao is an herbal formulation that has been documented in Chinese traditional medicine as a remedy for diarrhea, dysentery, inflammation, and toxicity. The sources of this formulation (Bidens pilosa L., Bidens biternata (Lour.) Merr. & Sherff, Bidens bipinnata L.) are also listed in ethnomedicinal reports all over the world. In this study, all these plants are tested for in vitro anticandida activity. A quantitative evaluation of the phytochemicals in all these plants indicated that their vegetative parts are rich in tannins, saponins, oxalates, cyanogenic glycoside and lipids; moreover, the roots have high percentages of alkaloids, flavonoids, and phenols. The results indicated significant anticandida activity, especially for the hexane extract of B. bipinnata leaves which inhibited C. albicans (42.54%), C. glabrata (46.98%), C. tropicalis (50.89%), C. krusei (40.56%), and C. orthopsilosis (50.24%). The extract was subjected to silica gel chromatography and 220 fractions were obtained. Purification by High Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD) and Gas Chromatography tandem Mass Spectrometry (GC-MS/MS) analysis led to the identification of two anticandida compounds: dehydroabietic and linoleic acid having an inhibition of 85 and 92%, respectively.

Dairy Processing Affects the Gut Digestion and Microecology by Changing the Structure and Composition of Milk Fat Globules

Milk fat globules (MFGs) are the major source of energy for infants' dietary intake. In this study, the effects of changes in the structure and composition of MFG after dairy processing on lipolysis and immune regulation were investigated. Pasteurized MFG tends to form protein aggregates to prevent lipolysis. However, the aggregate is rich in neutrophil degranulation products, which are effective in killing pathogens. Homogenized MFG has the lowest hydrolysis rate due to the reconstituted anti-lipase barrier and exposed apolipoprotein. Simultaneously, the reconstituted barrier can compensate for the lack of the complement cascade. Spray-dried MFG had the highest hydrolysis rate attributable to the disrupted MFG barrier and the release of lipoprotein lipase and endothelial lipase. The immunomodulatory properties of spray-dried MFG proteins are mainly mediated by the toll-like receptor (TLR) signaling pathway. This research provides the improvement basis of dairy processing and functional infant formulas.

Lipid Nanoparticle Technology for Delivering Biologically Active Fatty Acids and Monoglycerides

There is enormous interest in utilizing biologically active fatty acids and monoglycerides to treat phospholipid membrane-related medical diseases, especially with the global health importance of membrane-enveloped viruses and bacteria. However, it is difficult to practically deliver lipophilic fatty acids and monoglycerides for therapeutic applications, which has led to the emergence of lipid nanoparticle platforms that support molecular encapsulation and functional presentation. Herein, we introduce various classes of lipid nanoparticle technology and critically examine the latest progress in utilizing lipid nanoparticles to deliver fatty acids and monoglycerides in order to treat medical diseases related to infectious pathogens, cancer, and inflammation. Particular emphasis is placed on understanding how nanoparticle structure is related to biological function in terms of mechanism, potency, selectivity, and targeting. We also discuss translational opportunities and regulatory needs for utilizing lipid nanoparticles to deliver fatty acids and monoglycerides, including unmet clinical opportunities.

Co-delivery of hesperidin and clarithromycin in a nanostructured lipid carrier for the eradication of Helicobacter pylori in vitro

Effective and precise eradication of Helicobacter pylori (H. pylori) is the most promising approach to avoid H. pylori-related gastrointestinal disorders. The present study was conducted to demonstrate the efficacy of the co-delivery of hesperidin (Hesp) and clarithromycin (CLR) in nanostructured lipid carriers (NLCs) against H. pylori. We have produced a new delivery system by combining bioflavonoid Hesp and CLR NLCs to address the failure in single antibiotic therapies. Briefly, a blend of solid lipid, liquid lipid, and surfactant was used. Homogeneous NLCs with all the formulations showed a nano size and surface-negative charge and presented high in vitro stability and slow release of the drug even after 24 h. Bioimaging studies by scanning electron microscopy, transmission electron microscopy, and imaging flow cytometry indicated that NLCs interacted with the membrane by adhering to the outer cell membrane and disrupted the membrane that resulted in the leakage of cytoplasmic contents. The prepared NLCs provide sustained and controlled drug release that can be used to increase the rate of H. pylori eradication.

Highlighting the use of micro and nanoparticles based-drug delivery systems for the treatment of Helicobacter pylori infections

Due to the high adaptability of Helicobacter pylori and the low targeting specificity of the drugs normally used in pharmacological therapy, the strains are becoming increasingly resistant to these drugs, making it difficult to eradicate the infection. Thus, the search for new therapeutic approaches has been considered urgent. The incorporation of drugs in advanced drug delivery systems, such as nano and microparticles, would allow the improvement of the retention time in the stomach and the prolongation of drug release rates at the target site. Because of this, the present review article aims to highlight the use of micro and nanoparticles as important technological tools for the treatment of H. pylori infections, focussing on the main nanotechnological systems, including nanostructured lipid carriers, liposomes, nanoemulsion, metallic nanoparticles, and polymeric nanoparticles, as well as microtechnological systems such as gastroretentive dosage forms, among them mucoadhesive, magnetic and floating systems were highlighted.

In vitro therapeutic evaluation of nanoliposome loaded with Xyloglucans polysaccharides from Tamarindus flower extract

Nanoparticles are interesting area of research developed for several diagnostic and therapeutic applications. Tamarind flower extract is rich in Xyloglucan, a starch like polysaccharide which promotes proliferation and various application areas like drug-delivery technology. In recent years researchers are evaluating nanoliposome using in vitro and in vivo studies to discover their biomedical applications. Considering the importance and feasibility of nanoliposome, the present study is focused on synthesis of liposomes via biological method. The biological molecules of Tamarindus indica flower were used for the synthesis of nanoliposome. The synthesized Tamarindus indica flower extract lipid nanoparticles (TifeLiNPs) loaded with xyloglucans were characterized and evaluated for therapeutic applications (antibacterial, antioxidant, antidiabetic, anticancer and anti-inflammatory activities) under in vitro condition. UV-Vis spectral analysis revealed the emission of peak at 232 nm. Further, the chemical characterization using FTIR revealed the presence of components in the functional group. EDX analysis exhibited the presence of O, Na, P and Cl, while DLS confirmed bilayer formation of xyloglucan and liposomes with uniform size (70-80 nm) and spherical shape. The Physicochemical characterization of tamarind flower extract for its chemical composition revealed the presence of carbohydrates, alkaloids, terpenoids, glycosides, saponins, tannins and flavonoids in confirmatory test. Presence of carbohydrate polymers such as rhamnose, arabinose, galactose, glucose and xylose revealed using high performance anion exchange (HPAE) chromatography under basic conditions on an ion chromatographic system were measured using Pulsed Amperometric Detection (PAD). The synthesized nanoliposome evaluated against Gram negative and Gram positive bacteria showed potential antibacterial activity. TifeLiNPs demonstrated significant in vitro antioxidant potential, antidiabetic, anti-cancer and anti-inflammatory activity. Overall, the present study exhibited the potential application of TifeLiNPs for biomedical purposes.

Antibacterial fatty acids: An update of possible mechanisms of action and implications in the development of the next-generation of antibacterial agents

The antibacterial activity of fatty acids (FA) is well known in the literature and represents a promising option for developing the next-generation of antibacterial agents to treat a broad spectrum of bacterial infections. FA are highly involved in living organisms' defense system against numerous pathogens, including multidrug-resistant bacteria. When combined with other antibacterial agents, the remarkable ability of FA to enhance their bactericidal properties is a critical feature that is not commonly observed in other naturally-occurring compounds. More reviews focusing on FA antibacterial activity, traditional and non-traditional mechanisms and biomedical applications are needed. This review is intended to update the reader on the antibacterial properties of recent FA and how their chemical structures influence their antibacterial activity. This review also aims to better understand both traditional and non-traditional mechanisms involved in these recently explored FA antibacterial activities.

Surface-bound reactive oxygen species generating nanozymes for selective antibacterial action

Acting by producing reactive oxygen species (ROS) in situ, nanozymes are promising as antimicrobials. ROS' intrinsic inability to distinguish bacteria from mammalian cells, however, deprives nanozymes of the selectivity necessary for an ideal antimicrobial. Here we report that nanozymes that generate surface-bound ROS selectively kill bacteria over mammalian cells. This result is robust across three distinct nanozymes that universally generate surface-bound ROS, with an oxidase-like silver-palladium bimetallic alloy nanocage, AgPd0.38, being the lead model. The selectivity is attributable to both the surface-bound nature of ROS these nanozymes generate and an unexpected antidote role of endocytosis. Though surface-bound, the ROS on AgPd0.38 efficiently eliminated antibiotic-resistant bacteria and effectively delayed the onset of bacterial resistance emergence. When used as coating additives, AgPd0.38 enabled an inert substrate to inhibit biofilm formation and suppress infection-related immune responses in mouse models. This work opens an avenue toward biocompatible nanozymes and may have implication in our fight against antimicrobial resistance.

DHA-enriched phospholipids from large yellow croaker roe regulate lipid metabolic disorders and gut microbiota imbalance in SD rats with a high-fat diet

Large yellow croaker roe phospholipids (LYCRPLs) have great nutritional value because they are rich in docosahexaenoic acid (DHA), which is an n-3 polyunsaturated fatty acid (n-3 PUFA). In previous research, we studied the effect of LYCRPLs on the inhibition of triglyceride accumulation at the cellular level. However, its lipid regulation effect in rats on a high-fat diet and its influence on the gut microbiota has not yet been clarified. In this study, a high-fat diet was used to induce the lipid metabolism disorder in SD rats, and simvastatin, low-dose, medium-dose and high-dose LYCRPLs were given by intragastric administration for 8 weeks. The rats' body weight, food intake, organ index, blood biochemical indicators, epididymal fat tissue and liver histopathology were compared and analyzed. High-throughput 16S rRNA gene sequencing technology and bioinformatics analysis technology were also used to analyze the diversity of gut microbiota in rats. We found that LYCRPLs can significantly regulate lipid metabolism, and improve the gut microbiota disorder induced in rats by a high-fat diet. These results can lay a foundation for the study of the regulation mechanism of LYCRPLs lipid metabolism, and also provide a theoretical basis for the development of LYCRPLs as functional food additives and excipients with hypolipidemic effects.

Infection with Helicobacter pylori Induces Epithelial to Mesenchymal Transition in Human Cholangiocytes

Recent reports suggest that the East Asian liver fluke infection, caused by Opisthorchis viverrini, which is implicated in opisthorchiasis-associated cholangiocarcinoma, serves as a reservoir of Helicobacter pylori. The opisthorchiasis-affected cholangiocytes that line the intrahepatic biliary tract are considered to be the cell of origin of this malignancy. Here, we investigated interactions in vitro among human cholangiocytes, Helicobacter pylori strain NCTC 11637, and the congeneric bacillus, Helicobacter bilis. Exposure to increasing numbers of H. pylori at 0, 1, 10, 100 bacilli per cholangiocyte of the H69 cell line induced phenotypic changes including the profusion of thread-like filopodia and a loss of cell-cell contact, in a dose-dependent fashion. In parallel, following exposure to H. pylori, changes were evident in levels of mRNA expression of epithelial to mesenchymal transition (EMT)-encoding factors including snail, slug, vimentin, matrix metalloprotease, zinc finger E-box-binding homeobox, and the cancer stem cell marker CD44. Analysis to quantify cellular proliferation, migration, and invasion in real-time by both H69 cholangiocytes and CC-LP-1 line of cholangiocarcinoma cells using the xCELLigence approach and Matrigel matrix revealed that exposure to 10 H. pylori bacilli per cell stimulated migration and invasion by the cholangiocytes. In addition, 10 bacilli of H. pylori stimulated contact-independent colony establishment in soft agar. These findings support the hypothesis that infection by H. pylori contributes to the malignant transformation of the biliary epithelium.

The Puzzle of Coccoid Forms of Helicobacter pylori: Beyond Basic Science

Helicobacter pylori (H. pylori) may enter a non-replicative, non-culturable, low metabolically active state, the so-called coccoid form, to survive in extreme environmental conditions. Since coccoid forms are not susceptible to antibiotics, they could represent a cause of therapy failure even in the absence of antibiotic resistance, i.e., relapse within one year. Furthermore, coccoid forms may colonize and infect the gastric mucosa in animal models and induce specific antibodies in animals and humans. Their detection is hard, since they are not culturable. Techniques, such as electron microscopy, polymerase chain reaction, loop-mediated isothermal amplification, flow cytometry and metagenomics, are promising even if current evidence is limited. Among the options for the treatment, some strategies have been suggested, such as a very high proton pump inhibitor dose, high-dose dual therapy, N-acetycysteine, linolenic acid and vonoprazan. These clinical, diagnostic and therapeutic uncertainties will represent fascinating challenges in the future.

Eradication of Helicobacter pylori: the power of nanosized formulations

Helicobacter pylori is a pathogen that is considered to cause several gastric disorders such as chronic gastritis, peptic ulcer and even gastric carcinoma. The current therapeutic regimens mainly constitute of a combination of several antimicrobial agents and proton pump inhibitors. However, the prevalence of antibiotic resistance has been significantly lowering the cure rates over the years. Nanocarriers possess unique strengths in this regard owing to the fact that they can protect the drugs (such as antibiotics) from the harsh environment in the stomach, penetrate the mucosal barrier and deliver drugs to the desired site. In this review we summarized recent studies of different antibacterial agents orally delivered by nanosized carriers for the eradication of H. pylori.

Chemical Constituents and Antileishmanial and Antibacterial Activities of Essential Oils from Scheelea phalerata

Scheelea phalerata Mart. ex Spreng (Arecaceae) is a palm tree found in the Brazilian cerrado. There are no topics related to volatile oils from S. phalerata leaves in the literature. This work determines its chemical composition and evaluates the biological activity under two different seasonal conditions (dry and rainy seasons). The dry essential oil yield was 0.034 ± 0.001% and the rainy essential oil yield was 0.011 ± 0.003%. Both essential oils presented different qualitative and quantitative compositions (99.4 and 98.5%). The main constituents of the dry essential oil were phytol (36.7%), nonadecane (9.7%), linolenic acid (9.1%), (Z)-hex-3-en-1-ol (4.2%), and squalene (4.0%). The main constituents of the rainy essential oil were phytol (26.1%), palmitic acid (18.7%), hexan-1-ol (15.6%), (Z)-hex-3-en-1-ol (9.7%), and oleic acid (4.0%). The antileishmanial activity against promastigotes of Leishmania amazonensis was observed only for the rainy season essential oil (IC₅₀ value of 165.05 ± 33.26 μg mL^-1). A molecular docking study showed that alcohols exert a paramount efficacy and that the action of some essential oil compounds may be similar to that of amphotericin B. Still, only the essential oil from the dry season showed moderate antibacterial activity against S. sanguinis (MICs 200-400 μg mL^-1). The cytotoxicity against Vero cells was identical (>512) for both essential oils. The novel data here for both chemical characterization and biological activity, in particular, evidence that the action of these compounds is similar to that of amphotericin B, provide valuable information to the drug-discovery field.

Antimicrobial lipids in nano-carriers for antibacterial delivery

Antimicrobial lipids have been recognised as broad-spectrum antibacterial agents. They can directly act on and lyse bacterial cell membrane, and inhibit bacterial growth through a range of mechanisms. Antimicrobial lipids include free fatty acids, monoglycerides, cholesteryl ester, sphingolipids and etc., with the first two being the most extensively studied. Their application is usually hindered by the low solubility of the compounds themselves, and nano-sized lipid-based carriers can endow druggability to these antimicrobial agents for they improve lipid solubility and dispersion in aqueous formulations. Nano-carriers also possess advantages in overcoming drug resistance. In this review we will discuss different kinds of antimicrobial lipids in nano-sized carriers for antibacterial delivery. CAL02 as a promising infection-controlling liposome consisted of cholesterol and sphingomyelin will also be included for it's a unique anti-infection approach, which signifies that the underlying antibacterial roles antimicrobial lipids needs to be further addressed. With the global emergence of antibiotic resistance, antimicrobial lipids formulated in nano-carriers might provide a novel alternative in combatting infectious diseases.

Delivering amoxicillin at the infection site - a rational design through lipid nanoparticles

Purpose

Amoxicillin is a commonly used antibiotic, although degraded by the acidic pH of the stomach. This is an important limitation for the treatment of Helicobacter pylori infections. The purpose of this work was to encapsulate amoxicillin in lipid nanoparticles, increasing the retention time at the site of infection (gastric mucosa), while protecting the drug from the harsh conditions of the stomach lumen.

Materials and methods

The nanoparticles were produced by the double emulsion technique and optimized by a three-level Box-Behnken design. Tween 80 and linolenic acid were used as potential therapeutic adjuvants and dioleoylphosphatidylethanolamine as a targeting agent to Helicobacter pylori. Nanoparticles were characterized regarding their physico-chemical features, their storage stability, and their usability for oral administration (assessment of in vitro release, in vitro cell viability, permeability, and interaction with mucins).

Results

The nanoparticles were stable for at least 6 months at 4°C. In vitro release studies revealed a high resistance to harsh conditions, including acidic pH and physiologic temperature. The nanoparticles have a low cytotoxicity effect in both fibroblasts and gastric cell lines, and they have the potential to be retained at the gastric mucosa.

Conclusion

Overall, the designed formulations present suitable physico-chemical features for being henceforward used by oral administration to treat Helicobacter pylori infections.

Antibacterial Effect of Black Pepper Petroleum Ether Extract against Listeria monocytogenes and Salmonella typhimurium

The aim of the present study was to evaluate the antibacterial effect of black pepper petroleum ether extract (BPPE) against Listeria monocytogenes ATCC 19115 and Salmonella typhimurium ATCC 14028. The results showed that the BPPE had a strong antimicrobial activity against L. monocytogenes and S. typhimurium, and 2-methylene-4,8,8-trimethyl-4-vinyl-bicyclo[5.2.0]nonane (9.36%) and caryophyllene oxide (4.85%) were identified as the two primary components of BPPE. The ability of cells to break down hyperoxide was decreased, and the activities of POD and CAT were inhibited. The activities of key metabolic enzymes shed some light on the biochemical mechanism of aglycon cell growth inhibition, indicating that the energetic metabolism of L. monocytogenes and S. typhimurium was markedly influenced by the BPPE. The contents of key organic acids varied significantly, resulting in remarkable abnormalities in the energetic metabolism of L. monocytogenes and S. typhimurium. Thus, the consecution of energetic metabolism was destroyed by the BPPE, which contributed to metabolic dysfunction, the suppression of gene transcription, and cell death.

Liposome: composition, characterisation, preparation, and recent innovation in clinical applications

In the last decades, pharmaceutical interested researches aimed to develop novel and innovative drug delivery techniques in the medical and pharmaceutical fields. Recently, phospholipid vesicles (Liposomes) are the most known versatile assemblies in the drug delivery systems. The discovery of liposomes arises from self-forming enclosed phospholipid bilayer upon coming in contact with the aqueous solution. Liposomes are uni or multilamellar vesicles consisting of phospholipids produced naturally or synthetically, which are readily non-toxic, biodegradable, and are readily produced on a large scale. Various phospholipids, for instance, soybean, egg yolk, synthetic, and hydrogenated phosphatidylcholine consider the most popular types used in different kinds of formulations. This review summarises liposomes composition, characterisation, methods of preparation, and their applications in different medical fields including cancer therapy, vaccine, ocular delivery, wound healing, and some dermatological applications.

Coating nanoparticles with gastric epithelial cell membrane for targeted antibiotic delivery against Helicobacter pylori infection

Inspired by the natural pathogen-host interactions and adhesion, this study reports on the development of a novel targeted nanotherapeutics for the treatment of Helicobacter pylori (H. pylori) infection. Specifically, plasma membranes of gastric epithelial cells (e.g. AGS cells) are collected and coated onto antibiotic-loaded polymeric cores, the resulting biomimetic nanoparticles (denoted AGS-NPs) bear the same surface antigens as the source AGS cells and thus have inherent adhesion to H. pylori bacteria. When incubated with H. pylori bacteria in vitro, the AGS-NPs preferentially accumulate on the bacterial surfaces. Using clarithromycin (CLR) as a model antibiotic and a mouse model of H. pylori infection, the CLR-loaded AGS-NPs demonstrate superior therapeutic efficacy as compared the free drug counterpart as well as non-targeted nanoparticle control group. Overall, this work illustrates the promise and strength of using natural host cell membranes to functionalize drug nanocarriers for targeted drug delivery to pathogens that colonize on the host cells. As host-pathogen adhesion represents a common biological event for various types of pathogenic bacteria, the bioinspired nanotherapeutic strategy reported here represents a versatile delivery platform that may be applied to treat numerous infectious diseases.

Antibacterial Free Fatty Acids and Monoglycerides: Biological Activities, Experimental Testing, and Therapeutic Applications

Antimicrobial lipids such as fatty acids and monoglycerides are promising antibacterial agents that destabilize bacterial cell membranes, causing a wide range of direct and indirect inhibitory effects. The goal of this review is to introduce the latest experimental approaches for characterizing how antimicrobial lipids destabilize phospholipid membranes within the broader scope of introducing current knowledge about the biological activities of antimicrobial lipids, testing strategies, and applications for treating bacterial infections. To this end, a general background on antimicrobial lipids, including structural classification, is provided along with a detailed description of their targeting spectrum and currently understood antibacterial mechanisms. Building on this knowledge, different experimental approaches to characterize antimicrobial lipids are presented, including cell-based biological and model membrane-based biophysical measurement techniques. Particular emphasis is placed on drawing out how biological and biophysical approaches complement one another and can yield mechanistic insights into how the physicochemical properties of antimicrobial lipids influence molecular self-assembly and concentration-dependent interactions with model phospholipid and bacterial cell membranes. Examples of possible therapeutic applications are briefly introduced to highlight the potential significance of antimicrobial lipids for human health and medicine, and to motivate the importance of employing orthogonal measurement strategies to characterize the activity profile of antimicrobial lipids.

Antibacterial Free Fatty Acids and Monoglycerides: Biological Activities, Experimental Testing, and Therapeutic Applications

Antimicrobial lipids such as fatty acids and monoglycerides are promising antibacterial agents that destabilize bacterial cell membranes, causing a wide range of direct and indirect inhibitory effects. The goal of this review is to introduce the latest experimental approaches for characterizing how antimicrobial lipids destabilize phospholipid membranes within the broader scope of introducing current knowledge about the biological activities of antimicrobial lipids, testing strategies, and applications for treating bacterial infections. To this end, a general background on antimicrobial lipids, including structural classification, is provided along with a detailed description of their targeting spectrum and currently understood antibacterial mechanisms. Building on this knowledge, different experimental approaches to characterize antimicrobial lipids are presented, including cell-based biological and model membrane-based biophysical measurement techniques. Particular emphasis is placed on drawing out how biological and biophysical approaches complement one another and can yield mechanistic insights into how the physicochemical properties of antimicrobial lipids influence molecular self-assembly and concentration-dependent interactions with model phospholipid and bacterial cell membranes. Examples of possible therapeutic applications are briefly introduced to highlight the potential significance of antimicrobial lipids for human health and medicine, and to motivate the importance of employing orthogonal measurement strategies to characterize the activity profile of antimicrobial lipids.

The impact of liposomal linolenic acid on gastrointestinal microbiota in mice

Background

The prevalence of Helicobacter pylori has long been a global health issue. Triple therapy, being the first-line treatment, has caused dysbiosis of the gastrointestinal tract that led to various complications. A novel nanomedicine – liposomal linolenic acid (LipoLLA) – has been proven to have great potential in eradicating H. pylori. However, the possible side effects of LipoLLA due to alteration of the gastrointestinal microbiota remain unknown.

Aim

This study focused on the impact of LipoLLA on gastrointestinal microbiota in mice in comparison with triple therapy in order to assess the safety profile.

Methods

Mice were divided into five groups: blank control group; H. pylori control group; triple therapy group; low-dose LipoLLA group (25 mg/kg); and high-dose LipoLLA group (50 mg/kg). Fecal samples were collected before and after the intake of corresponding formulas. Gastric tissues were obtained after mice dissection. These samples were analyzed with high-throughput sequencing.

Results

The analysis revealed that LipoLLA resulted in minor gut microbiota alteration at different levels. The altered proportions in the high-dose group were higher than that of the low-dose group. On the other hand, the triple therapy group showed dramatic shifts in the major community composition. It displayed a notable boost in the relative abundance of Proteobacteria and Firmicutes along with a decrease in that of Verrucomicrobia and Bacteroidetes. All of them belonged to the major phyla in the microbiome. Triple therapy also led to the growth of the family Enterobacteriaceae, Enterococcaceae, and Clostridiaceae_1 that may be associated with clinical illnesses. Gastric microbiota analysis reached similar conclusions.

Conclusion

Our findings indicated that LipoLLA causes minor gastrointestinal microbiota alterations while the triple therapy triggered dramatic changes. Thus, LipoLLA is not only promising but also a safe therapeutic medication to eradicate H. pylori infection.

Nanoparticle-based local antimicrobial drug delivery

Despite the wide success of antibiotics in modern medicine, the treatment of bacterial infections still faces critical challenges, especially due to the rapid emergence of antibiotic resistance. As a result, local antimicrobial treatment aimed at enhancing drug concentration at the site of infection while avoiding systemic exposure is becoming increasingly attractive, as it may alleviate resistance development. Meanwhile, therapeutic nanoparticles, especially liposomes, polymeric nanoparticles, dendrimers, and inorganic nanoparticles, are gaining traction to improve the therapeutic efficacy with many applications specifically focused on local antimicrobial treatment. This review highlights topics where nanoparticle-based strategies hold significant potential to advance treatment against local bacterial infections, including (1) promoting antibiotic localization to the pathogen, (2) modulating drug-pathogen interaction against antibiotic resistance, and (3) enabling novel anti-virulence approaches for 'drug-free' antimicrobial activity. In each area, we highlight the innovative antimicrobial strategies tailored for local applications and review the progress made for the treatment of bacterial infections.

Comparison of lipopolysaccharides composition of two different strains of Helicobacter pylori

BACKGROUND

Helicobacter pylori (H. pylori) is a Gram-negative, microaerophilic bacterium that is recognized as a major cause of chronic gastritis, peptic ulcers, and gastric cancer. Comparable to other Gram-negative bacteria, lipopolysaccharides (LPS) are an important cellular component of the outer membrane of H. pylori. The LPS of this organism plays a key role in its colonization and persistence in the stomach. In addition, H. pylori LPS modulates pathogen-induced host inflammatory responses resulting in chronic inflammation within the gastrointestinal tract. Very little is known about the comparative LPS compositions of different strains of H. pylori with varied degree of virulence in human. Therefore, LPS was analyzed from two strains of H. pylori with differing potency in inducing inflammatory responses (SS1 and G27). LPS were extracted from aqueous and phenol layer of hot-phenol water extraction method and subjected for composition analysis by gas chromatography - mass spectrometry (GC-MS) to sugar and fatty acid compositions.

RESULTS

The major difference between the two strains of H. pylori is the presence of Rhamnose, Fucose and GalNAc in the SS1 strain, which was either not found or with low abundance in the G27 strain. On the other hand, high amount of Mannose was present in G27 in comparison to SS1. Fatty acid composition of lipid-A portion also showed considerable amount of differences between the two strains, phenol layer of SS1 had enhanced amount of 3 hydroxy decanoic acid (3-OH-C10:0) and 3-hydroxy dodecanoic acid (3-OH-C12:0) which were not present in G27, whereas myristic acid (C14:0) was present in G27 in relatively high amount.

CONCLUSION

The composition analysis of H. pylori LPS, revealed differences in sugars and fatty acids composition between a mouse adapted strain SS1 and G27. This knowledge provides a novel way to dissect out their importance in host-pathogen interaction in further studies.

Factors pivotal for designing of nanoantimicrobials: an exposition

Understanding the interplay between bacterial pathogens and antimicrobials is a key to realize the control over infections causing morbidity and mortality. An important current issue of contemporary medicine and microbiology is the search for new strategies for adequate therapy of infectious diseases associated with rapidly emerging multidrug-resistant (MDR) pathogens. Recently, a great deal of progress has been made in the field of nanobiotechnology towards the development of various nanoantimicrobials (NAMs) as novel therapeutic solution. Current microbiological studies, employing either synthetic antibiotics or natural antimicrobial, have demonstrated the ability of NAMs to tackle the issue of MDR by reverting the mechanisms of resistance. The present review critically discusses the various factors that can contribute to modulate the effects of NAMs on microbes. It includes essential features of NAMs including but not limited to composition, surface charge, loading capacity, size, hydrophobicity/philicity, controlled release and functionalization. In contrast, how microbial structural differences, biofilm formation, persister cells and intracellular pathogens contribute towards sensitivity or resistance towards antimicrobials is comprehensively analysed. These multilateral factors should be considered earnestly in order to make NAMs a successful alternative of the conventional antibiotics.

Bacterial factors associated with Helicobacter pylori antibiotic resistance

Helicobacter pylori (H. pylori) infection is the most widespread chronic bacterial infection and is closely associated with many diseases. In recent years, however, H. pylori is becoming increasingly difficult to eradicate due to the growing antibiotic resistance. Among the reasons for the failed eradication, some factors of H. pylori itself play a main role. H. pylori can resist antibiotics by producing inactivating enzymes, changing the drug targets, preventing oxidation-reduction electron transfer, decreasing membrane permeability and activating efflux pump, changing bacterial metabolic state and so on. Elucidating the mechanism of antibiotic resistance will be helpful in developing new targeted drugs to effectively eradicate H. pylori. Here, we review the bacteria factors associated with H. pylori antibiotic resistance.

In vitro synergistic effect of Hibiscus sabdariffa aqueous extract in combination with standard antibiotics against Helicobacter pylori clinical isolates

Context The increasing problem of drug-resistant strains has led to the failure of current treatment regimens of Helicobacter pylori (HP) infection. Recently, a new treatment strategy has been developed to overcome the problem by using natural products in combination with antibiotics to enhance the treatment efficacy. Objective The antimicrobial combinatory effect of the aqueous extract of Hibiscus sabdariffa L. (Malvaceae) (AEHS) with antibiotics (clarithromycin, CLA; amoxicillin, AMX; metronidazole, MTZ) has been evaluated in vitro against HP strains. Materials and methods Hibiscus calyces (35 g) were brewed in 250 mL of boiled water for 30 min, and minimum inhibitory concentrations (MICs) were determined by agar dilution method. The checkerboard assay was used to evaluate the antimicrobial combinatory effect according to the sum of fractional inhibitory concentration (∑FIC) indices. Results In this study, AEHS exerted remarkable bacteriostatic effect against all HP strains tested with MICs values ranging from 9.18 to 16.68 μg/mL. Synergy effect of AEHS with CLA or MTZ was obtained against four of seven HP strains tested with ∑FIC ranging from 0.21 to 0.39. The additive effect of AEHS with AMX was obtained against five of seven HP strains tested with ∑FIC ranging from 0.61 to 0.91. Conclusion This study presents AEHS as a potent therapeutic candidate alone, or in combination with antibiotics for the treatment of HP infection.

Nanotechnology Formulations for Antibacterial Free Fatty Acids and Monoglycerides

Free fatty acids and monoglycerides have long been known to possess broad-spectrum antibacterial activity that is based on lytic behavior against bacterial cell membranes. Considering the growing challenges of drug-resistant bacteria and the need for new classes of antibiotics, the wide prevalence, affordable cost, and broad spectrum of fatty acids and monoglycerides make them attractive agents to develop for healthcare and biotechnology applications. The aim of this review is to provide a brief introduction to the history of antimicrobial lipids and their current status and challenges, and to present a detailed discussion of ongoing research efforts to develop nanotechnology formulations of fatty acids and monoglycerides that enable superior in vitro and in vivo performance. Examples of nano-emulsions, liposomes, solid lipid nanoparticles, and controlled release hydrogels are presented in order to highlight the potential that lies ahead for fatty acids and monoglycerides as next-generation antibacterial solutions. Possible application routes and future directions in research and development are also discussed.

The antibacterial effect of fatty acids on Helicobacter pylori infection

Eradication of Helicobacter pylori is recommended for the management of various gastric diseases, including peptic ulcers and mucosa-associated lymphoid tissue lymphoma. Because of the increasing prevalence of antibiotic resistance, the eradication rates of antibiotic-based therapies have decreased. Therefore, alternative treatments should be considered. The antibacterial properties of fatty acids (FAs) have been investigated in various organisms, including H. pylori. Some FAs, particularly polyunsaturated FAs, have been shown to have bactericidal activity against H. pylori in vitro; however, their antibacterial effects in vivo remain controversial. Poor solubility and delivery of FAs may be important reasons for this discrepancy. Recently, a series of studies demonstrated the antibacterial effects of a liposomal formulation of linolenic acid against H. pylori, both in vitro and in vivo. Further research is needed to improve the bioavailability of FAs and apply them in clinical use.

Spectrum of Membrane Morphological Responses to Antibacterial Fatty Acids and Related Surfactants

Medium-chain saturated fatty acids and related compounds (e.g., monoglycerides) represent one class of membrane-active surfactants with antimicrobial properties. Most related studies have been in vitro evaluations of bacterial growth inhibition, and there is limited knowledge about how the compounds in this class destabilize lipid bilayers, which are the purported target within the bacterial cell membrane. Herein, the interaction between three representative compounds in this class and a supported lipid bilayer platform was investigated using quartz crystal microbalance-dissipation and fluorescence microscopy in order to examine membrane destabilization. The three tested compounds were lauric acid, sodium dodecyl sulfate, and glycerol monolaurate. For each compound, we discovered striking differences in the resulting morphological changes of supported lipid bilayers. The experimental trends indicate that the compounds have membrane-disruptive behavior against supported lipid bilayers principally above the respective critical micelle concentration values. The growth inhibition properties of the compounds against standard and methicillin-resistant Staphylococcus aureus bacterial strains were also tested. Taken together, the findings in this work improve our knowledge about how saturated fatty acids and related compounds destabilize lipid bilayers, offering insight into the corresponding molecular mechanisms that lead to membrane morphological responses.