The aqueous methanolic extracts of Melastoma malabathricum L. exhibited antibacterial activity when assayed against seven microorganisms by the agar diffusion method. Solvent fractionation afforded active chloroform and ethyl acetate fractions from the leaves and the flowers, respectively. A phytochemical study resulted in the identification of ursolic acid (1), 2α-hydroxyursolic acid (2), asiatic acid (3), β-sitosterol 3-O-β-D-glucopyranoside (4) and the glycolipid glycerol 1,2-dilinolenyl-3-O-β-D-galactopyanoside (5) from the chloroform fraction. Kaempferol (6), kaempferol 3-O-α-L-rhamnopyranoside (7), kaempferol 3-O-β-D-glucopyranoside (8), kaempferol 3-O-β-D-galactopyranoside (9), kaempferol 3-O-(2″,6″-di-O-E-p-coumaryl)-β-D-galactopyranoside (10), quercetin (11) and ellagic acid (12) were found in the ethyl acetate fraction. The structures of these compounds were determined by chemical and spectral analyses. Compounds 1-4, the flavonols (6 and 11) and ellagic acid (12) were found to be active against some of the tested microorganisms, while the kaempferol 3-O-glycosides (7-9) did not show any activity, indicating the role of the free 3-OH for antibacterial activity. Addition of p-coumaryl groups results in mild activity for 10 against Staphylococcus aureus and Bacillus cereus. Compounds 2-5, 7 and 9-12 are reported for the first time from M. malabathricum. Compound 10 is rare, being reported only once before from a plant, without assignment of the double bond geometry in the p-coumaryl moiety.
There has been considerable effort to discover plant-derived antibacterials against methicillin-resistant strains of Staphylococcus aureus (MRSA) which have developed resistance to most existing antibiotics, including the last line of defence, vancomycin. Pentacyclic triterpenoid, a biologically diverse plant-derived natural product, has been reported to show anti-staphylococcal activities. The objective of this study is to evaluate the interaction between three pentacyclic triterpenoid and standard antibiotics (methicillin and vancomycin) against reference strains of Staphylococcus aureus.
Allium hirtifolium Boiss. known as Persian shallot, is a spice used as a traditional medicine in Iran and, Mediterranean region. In this study, the chemical composition of the hydromethanolic extract of this plant was analyzed using GC/MS. The result showed that 9-hexadecenoic acid, 11,14-eicosadienoic acid, and n-hexadecanoic acid are the main constituents. The antibacterial activity of the shallot extract was also examined by disk diffusion and microdilution broth assays. It was demonstrated that Persian shallot hydromethanolic extract was effective against 10 different species of pathogenic bacteria including methicillin resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA), Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Escherichia coli, Escherichia coli O157:H7, Salmonella typhimurium, Proteus mirabilis, and Klebsiella pneumoniae. Specifically, the minimum concentration of the extract which inhibited bacterial growth (MIC values) was 1.88 mg/mL for most of the gram-positive bacteria. This concentration was not much different from the concentration that was safe for mammalian cells (1.50 mg/mL) suggesting that the hydromethanolic extract of Persian shallot may be a safe and strong antibacterial agent.
At present, approximately 25%of drugs in modern pharmacopoeia are derived from plant sources (phytomedicines) that can be developed for the treatment of diseases and disorders. Many other drugs are synthetic analogues built on the prototype compounds isolated from plants. Cocos nucifera Linn. (Arecaceae), which is commonly known as coconut, is a plant possessing a lot of potential as an ingredient in traditional medicines for the treatment of metabolic disorders and particularly as an anti-inflammatory, antimicrobial and analgesic agent. This review emphasizes on the recent literature and research findings that highlight the significant biological activities of C. nucifera Linn. such as its anti-inflammatory, antimicrobial and analgesic properties. This review can help researchers keen on exploiting the therapeutic potential of C. nucifera Linn. which may motivate them to further explore their commercial viability.
Polycaprolactone (PCL) matrices loaded with doxycycline were produced by rapidly cooling suspensions of the drug powder in PCL solution in acetone. Drug loadings of 5%, 10%, and 15% (w/w) of the PCL content were achieved. Exposure of doxycycline powder to matrix processing conditions in the absence of PCL revealed an endothermic peak at 65°C with the main peak at 167°C, suggesting solvatomorph formation. Rapid "burst release" of 24%-32% was measured within 24 h when matrices were immersed in simulated vaginal fluid (SVF) at 37°C, because of the presence of drug at or close to the matrix surface, which is further confirmed by scanning electron microscopy. Gradual release of 66%-76% of the drug content occurred over the following 14 days. SVF containing doxycycline released from drug-loaded PCL matrices retained 81%-90% antimicrobial activity compared with the nonformulated drug. The concentrations of doxycycline predicted to be released into vaginal fluid from a PCL matrix in the form of an intravaginal ring would be sufficient to kill Neisseria gonorrhoea and many other pathogens. These results indicate that PCL may be a suitable polymer for controlled intravaginal delivery of doxycycline for the treatment of sexually transmitted infections.
The spread of drug-resistant bacteria has imparted a sense of urgency in the search for new antibiotics. In an effort to develop a new generation of antibacterial agents, we have designed de novo charged lipopeptides inspired by natural antimicrobial peptides. These short lipopeptides are composed of cationic lysine and hydrophobic lipoamino acids that replicate the amphiphilic properties of natural antimicrobial peptides. The resultant lipopeptides were found to self-assemble into nanoparticles. Some were effective against a variety of Gram-positive bacteria, including strains resistant to methicillin, daptomycin and/or vancomycin. The lipopeptides were not toxic to human kidney and liver cell lines and were highly resistant to tryptic degradation. Transmission electron microscopy analysis of bacteria cells treated with lipopeptide showed membrane-damage and lysis with extrusion of cytosolic contents. With such properties in mind, these lipopeptides have the potential to be developed as new antibacterial agents against drug-resistant Gram-positive bacteria.
Chlorhexidine (CHX) is known for its high antibacterial substantivity and is suitable for use to bio-inert medical devices due to its long-term antibacterial efficacy. However, CHX molecules require a crosslinking film to be stably immobilized on bio-inert metal surfaces. Therefore, polydopamine (PDA) was utilized in this study to immobilize CHX on the surface of 316L type stainless steel (SS316L). The SS316L disks were pre-treated, modified with PDA film and immobilized with different concentrations of CHX (10mM-50mM). The disks were then subjected to various surface characterization analyses (ATR-FTIR, XPS, ToF-SIMS, SEM and contact angle measurement) and tested for their cytocompatibility with human skin fibroblast (HSF) cells and antibacterial activity against Escherichia coli and Staphylococcus aureus. The results demonstrated the formation of a thin PDA film on the SS316L surface, which acted as a crosslinking medium between the metal and CHX. CHX was immobilized via a reduction process that covalently linked the CHX molecules with the functional group of PDA. The immobilization of CHX increased the hydrophobicity of the disk surfaces. Despite this property, a low concentration of CHX optimized the viability of HSF cells without disrupting the morphology of adherent cells. The immobilized disks also demonstrated high antibacterial efficacy against both bacteria, even at a low concentration of CHX. This study demonstrates a strong beneficial effect of the crosslinked PDA film in immobilizing CHX on bio-inert metal, and these materials are applicable in medical devices. Specifically, the coating will restrain bacterial proliferation without suffocating nearby tissues.
In this present study, we reported broccoli (Brassica oleracea L.) as a potential candidate for the synthesis of gold and silver nanoparticles (NPs) in green chemistry method. The synthesized metal nanoparticles are evaluated their antimicrobial efficacy against different human pathogenic organisms. The physico-chemical properties of gold nanoparticles were analyzed using different analytical techniques such as a UV-Vis spectrophotometer, Field Emission Scanning Electron Microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and a Fourier Transform Infrared spectrophotometer. In addition, gold and silver NP antimicrobial efficacy was checked by disc diffusion assay. UV-Vis color intensity of the nanoparticles was shown at 540 and 450 nm for gold and silver nanoparticles respectively. Higher magnification of the Field Emission Scanning Electron Microscopy image shows the variable morphology of the gold nanoparticles such as spherical, rod and triangular shapes and silver nanoparticles were seen in spherical shapes. The average spherical size of the particles was observed in 24-38 nm for gold and 30-45 nm for silver NPs. X-ray diffraction pattern confirmed the presence of gold nanoparticles and silver nanoparticles which were crystalline in nature. Additionally, the functional metabolites were identified by the Fourier Transform Infrared spectroscopy. IR spectra revealed phenols, alcohols, aldehydes (sugar moieties), vitamins and proteins are present in the broccoli extract which are accountable to synthesize the nanoparticles. The synthesized gold and silver NPs inhibited the growth of the tested bacterial and fungal pathogens at the concentration of 50 μg/mL respectively. In addition, broccoli mediated gold and silver nanoparticles have shown potent antimicrobial activity against human pathogens.
Infectious diseases remain a significant threat to human health, contributing to more than 17 million deaths, annually. With the worsening trends of drug resistance, there is a need for newer and more powerful antimicrobial agents. We hypothesized that animals living in polluted environments are potential sources of antimicrobials. Under polluted milieus, organisms such as cockroaches encounter different types of microbes, including superbugs. Such creatures survive the onslaught of superbugs and are able to ward off disease by producing antimicrobial substances. Here, we characterized antibacterial properties in extracts of various body organs of cockroaches (Periplaneta americana) and showed potent antibacterial activity in crude brain extract against methicillin-resistant Staphylococcus aureus and neuropathogenic Escherichia coli K1. The size-exclusion spin columns revealed that the active compound(s) are less than 10 kDa in molecular mass. Using cytotoxicity assays, it was observed that pre-treatment of bacteria with lysates inhibited bacteria-mediated host cell cytotoxicity. Using spectra obtained with LC-MS on Agilent 1290 infinity liquid chromatograph, coupled with an Agilent 6460 triple quadruple mass spectrometer, tissues lysates were analysed. Among hundreds of compounds, only a few homologous compounds were identified that contained the isoquinoline group, chromene derivatives, thiazine groups, imidazoles, pyrrole-containing analogs, sulfonamides, furanones, and flavanones and known to possess broad-spectrum antimicrobial properties and anti-inflammatory, anti-tumour, and analgesic properties. Further identification, characterization, and functional studies using individual compounds can act as a breakthrough in developing novel therapeutics against various pathogens including superbugs.
Two new C15-acetogenins, 4-epi-isolaurallene (1) and 4-epi-itomanallene A (2) were isolated from a population of marine red alga Laurencia nangii Masuda from Carrington Reef. The structures of these compounds were determined intensively by NMR and HRESIMS data. Their configurations were elucidated by detailed comparison of chemical shifts, germinal protons splitting and NOE correlations with known and synthesized analogues. In addition, antibacterial activities of these compounds were evaluated. These compounds would serve as diastereomeric models for future reference. Since the isolaurallene, neolaurallene, 9-acetoxy-1,10,12-tribromo-4,7:6,13-bisepoxypentadeca-1,2-diene, itomanallene A and laurendecumallene A were isolated, compounds 1 and 2 were the sixth example of C15-acetogenin with dioxabicyclo[7.3.0]dodecene skeleton.
Two halogenated C15 acetogenins, named lembyne-A and lembyne-B, have been isolated from an unrecorded Laurencia species collected off the Malaysian waters. Their structures were deduced on the basis of spectroscopic evidence. Previously known elatol and iso-obtusol showed potent antibacterial activity against some marine bacteria.
Chitosan is a polycationic natural polymer which is abundant in nature. Chitosan has gained much attention as natural polymer in the biomedical field. The up to date drug delivery as well as the nanotechnology in controlled release of drugs from chitosan nanofibers are focused in this review. Electrospinning is one of the most established and widely used techniques for preparing nanofibers. This method is versatile and efficient for the production of continuous nanofibers. The chitosan-based nanofibers are emerging materials in the arena of biomaterials. Recent studies revealed that various drugs such as antibiotics, chemotherapeutic agents, proteins and anti-inflammatory analgesic drugs were successfully loaded onto electrospun nanofibers. Chitosan nanofibers have several outstanding properties for different significant pharmaceutical applications such as wound dressing, tissue engineering, enzyme immobilization, and drug delivery systems. This review highlights different issues of chitosan nanofibers in drug delivery applications, starting from the preparation of chitosan nanofibers, followed by giving an idea about the biocompatibility and degradation of chitosan nanofibers, then describing how to load the drug into the nanofibers. Finally, the major applications of chitosan nanofibers in drug delivery systems.
MCR (mobile colistin resistance) enzymes catalyse phosphoethanolamine (PEA) addition to bacterial lipid A, threatening the "last-resort" antibiotic colistin. Molecular dynamics and density functional theory simulations indicate that monozinc MCR supports PEA transfer to the Thr285 acceptor, positioning MCR as a mono- rather than multinuclear member of the alkaline phosphatase superfamily.
The growing global awareness for environmental protection has inspired the exploration on producing active packaging films from bio-based materials. In present work, three types of active agents were studied by incorporating thymol(T), kesum(K), and curry(C) (10% wt.) into polylactic acid (PLA) to produce PLA-10T, PLA-10K, and PLA10-C packaging films via solvent casting method. The morphology, functional chemistry, thermal stability, permeability, and antimicrobial properties were evaluated for PLA films. Functional chemical analysis confirmed the presence of interfacial bonding between aromatic groups of active agents and PLA carbonyl group. PLA-10K exhibited the highest thermal resistance comparing to PLA-10T and PLA-10C while water vapor barrier was enhanced after incorporation of active agents. Qualitative observation had indicated that chicken meat could be preserved in the active films until 15 days, while odourless and firm texture properties retained in food sample. For disc diffusion assay (in vitro), it showed positive results against Gram-positive bacteria (Staphylococcus aureus) whereas with negative results against Gram-negative bacteria (Escherichia coli) and Aspergillus Brasiliensis due to embedded active agents within PLA matrix. We concluded that produced active agents filled PLA films potential to use in food packaging application to enhance the shelf life of meats, fruits and vegetables product.
A series of fourteen dispiropyrrolidines were synthesized using [3+2]-cycloaddition reactions and were screened for their antimycobacterial activity against Mycobacterium tuberculosis H(37)Rv in HTS (High Throughput Screen). Most of the compounds showed moderate to good activity with MIC of less than 20 μM. Compound 4'-(4-bromophenyl)-1'-methyldispiro[acenaphthylene-1,2'-pyrrolidine-3',2″-indane]-2,1″(1H)-dione (4c) was found to be the most active with MIC of 12.50 μM.
A series of novel hybrid heterocycles comprising arylidene thiazolidine-2,4-dione and 1-cyclopropyl-2-(2-fluorophenyl)ethanone were synthesized. These compounds were evaluated for their antimycobacterial activity against Mycobacterium tuberculosis H37Rv in High Throughput Screen. Most of the hybrid arylidene thiazolidine-2,4-diones displayed moderate to good activity with MIC of less than 50 μM. Compound 1m exhibited maximum potency being 5.87 fold more active at EC50 and 6.26 fold more active at EC90 than the standard drug pyrimethamine.
The need for new therapeutics and drug delivery systems has become necessary owing to the public health concern associated with the emergence of multidrug-resistant microorganisms. Among the newly discovered therapeutic agents is cefiderocol, which was discovered by Shionogi Company, Japan as an injectable siderophore cephalosporin. Just like the other β-lactam antibiotics, cefiderocol exhibits antibacterial activity via cell wall synthesis inhibition, especially in Gram negative bacteria (GNB); it binds to the penicillin-binding proteins, but its unique attribute is that it crosses the periplasmic space of bacteria owing to its siderophore-like attribute; it also resists the activity of β-lactamases. Among all the synthesized compounds with the modified C-7 side chain, cefiderocol (3) presented the best and well-balanced activity against multi-drug resistant (MDR) Gram negative bacteria, including those that are resistant to carbapenem. İn this article, an overview of the recent studies on cefiderocol was presented.
A novel series of 5-(3-Chlorophenyl)-2-((N-(substituted)-2-acetamoyl)sulfanyl)-1,3,4-oxadiazole derivatives was efficiently synthesized and screened for antibacterial, hemolytic and thrombolytic activities. The molecule 7c remained the best inhibitor of all selected bacterial strains and furthermore possessed very low toxicity, 8.52±0.31. Compound 7a 7b and 7f showed very good thrombolytic activity relative to Streptokinase employed as reference drug. In addition to low toxicity and moderately good thrombolytic activity, the synthesized compounds possessed excellent to moderate antibacterial activity, relative to ciprofloxacin. All compounds especially 7b and 7f can be consider for further clinical studies and might be helpful in synthesis of new drugs for treatment of cardiovascular diseases.
This research comprehends iron-oxide nanoparticle (IONP) production, the apparent metallic nanostructure with unique superparamagnetic properties. Durian-rind-extract was utilized to synthesize IONP and the color of reaction mixture becomes dark brown, indicated the formation of IONPs and the peak was observed at ∼330 nm under UV-visible spectroscopy. The morphological observation under high-resolution microscopies has revealed the spherical shape and the average size (∼10 nm) of IONP. The further support was rendered by EDX-analysis showing apparent iron and oxygen peaks. XRD results displayed the crystalline planes with (110) and (300) planes at 2θ of 35.73° and 63.53°, respectively. XPS-data has clearly demonstrated the presence of Fe2P and O1s peaks. The IONPs were successfully capped by the polyphenol compounds from durian-rind-extract as evidenced by the representative peaks between 1633 and 595 cm-1 from FTIR analysis. The antimicrobial potentials of IONPs were evidenced by the disk-diffusion assay. The obtained results have abundant attention and being actively explored owing to their beneficial applications.
Antiplasmodial nortriterpenes with 3,4-seco-27-norlanostane skeletons, almost entirely obtained from fruiting bodies, represent the main evidential source for bioactive secondary metabolites derived from a relatively unexplored phytopathogenic fungus, Ganoderma boninense. Currently lacking is convincing evidence for antimicrobial secondary metabolites in this pathogen, excluding that obtained from commonly observed phytochemicals in the plants. Herein, we aimed to demonstrate an efficient analytical approach for the production of antibacterial secondary metabolites using the mycelial extract of G. boninense. Three experimental cultures were prepared from fruiting bodies (GBFB), mycelium cultured on potato dextrose agar (PDA) media (GBMA), and liquid broth (GBMB). Through solvent extraction, culture type-dependent phytochemical distributions were diversely exhibited. Water-extracted GBMB produced the highest yield (31.21 ± 0.61%, p < 0.05), but both GBFB and GBMA elicited remarkably higher yields than GBMB when polar-organic solvent extraction was employed. Greater quantities of phytochemicals were also obtained from GBFB and GBMA, in sharp contrast to those gleaned from GBMB. However, the highest antibacterial activity was observed in chloroform-extracted GBMA against all tested bacteria. From liquid-liquid extractions (LLE), it was seen that mycelia extraction with combined chloroform-methanol-water at a ratio of 1:1:1 was superior at detecting antibacterial activities with the most significant quantities of antibacterial compounds. The data demonstrate a novel means of assessing antibacterial compounds with mycelia by LLE which avoids the shortcomings of standardized methodologies. Additionally, the antibacterial extract from the mycelia demonstrate that previously unknown bioactive secondary metabolites of the less studied subsets of Ganoderma may serve as active and potent antimicrobial compounds.