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Synthesis and antimicrobial properties of some new thiazolyl coumarin derivatives

Arshad A, Osman H, Bagley MC, Lam CK, Mohamad S, Zahariluddin AS

Eur J Med Chem, 2011 Sep;46(9):3788-94.
PMID: 21712145 DOI: 10.1016/j.ejmech.2011.05.044

Two novel series of hydrazinyl thiazolyl coumarin derivatives have been synthesized and fully characterized by IR, (1)H NMR, (13)C NMR, elemental analysis and mass spectral data. The structures of some compounds were further confirmed by X-ray crystallography. All of these derivatives, 10a-d and 15a-h, were screened in vitro for antimicrobial activity against various bacteria species including Mycobacterium tuberculosis and Candida albicans. The compounds 10c, 10d and 15e exhibited very good activities against all of the tested microbial strains.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Fulltext Antimicrobial properties of erythromycin and colistin impregnated bone cement. An in vitro analysis

Ruzaimi MY, Shahril Y, Masbah O, Salasawati H

Med J Malaysia, 2006 Feb;61 Suppl A:21-6.
PMID: 17042224

Deep surgical site infection is a devastating consequence of total joint arthroplasty. The use of antibiotic impregnated bone cement is a well-accepted adjunct for treatment of established infection and prevention of deep orthopaedic infection. It allows local delivery of the antibiotic at the cement-bone interface and sustained release of antibiotic provides adequate antibiotic coverage after the wound closure. Preclinical testing, randomised and clinical trials indicate that the use of antibiotic-impregnated bone cement is a potentially effective strategy in reducing the risk of deep surgical site infection following total joint arthroplasty. The purpose of this study was to assess antibacterial activity of erythromycin and colistin impregnated bone cement against strains of organisms' representative of orthopaedic infections including Gram-positive and Gram-negative aerobic organisms: Staphylococcus aureus, coagulase-negative Staphylococci, Enterococcus sp., Proteus sp., Klebsiella sp., Pseudomonas sp., and Escherichia coli. Pre-blended Simplex P bone cement with the addition of erythromycin and colistin (Howemedica Inc) was mixed thoroughly with 20ml liquid under sterile conditions to produce uniform cylindrical discs with a diameter of 14mm and thickness of 2mm. 24-48 hour agar cultures of Staphylococcus aureus, coagulase-negative Staphylococci, Enterococcus sp.,Proteus sp., Klebsiella sp.,Pseudomonas sp., and Escherichia coli were used for the agar diffusion tests. The agar plates were streaked for confluent growth followed by application of erythromycin and colistin impregnated bone cement disc to each agar plate. The plates were incubated at 30 degrees C and examined at 24, 48, 72 hours, and four and five days after the preparation of the impregnated cement. The susceptibility of Staphylococcus aureus to the control discs was most clearly demonstrated showing a distinct zone of inhibition. The zone observed around coagulase-negative Staphylococci, Klebsiella sp., Pseudomonas sp., and Escherichia coli were also significant. However, there was no zone of inhibition or signs of antibacterial activity at the cemented surface were detected around discs with Enterococcus sp. and Proteus sp. The results showed that Simplex P bone cement with the addition of erythromycin and colistin was effective against most of the broad spectrum organisms encountered during total joint arthroplasty. The activity of Simplex P bone cement impregnated with erythromycin and colistin is mainly during the first 72 hours.

Matched MeSH terms: Gram-Negative Bacteria/drug effects*
Resistoflavine, cytotoxic compound from a marine actinomycete, Streptomyces chibaensis AUBN1/7

Gorajana A, Venkatesan M, Vinjamuri S, Kurada BV, Peela S, Jangam P, et al.

Microbiol Res, 2007;162(4):322-7.
PMID: 16580188

In our systematic screening programme for marine actinomycetes, a bioactive Streptomycete was isolated from marine sediment samples of Bay of Bengal, India. The taxonomic studies indicated that the isolate belongs to Streptomyces chibaensis and it was designated as S. chibaensis AUBN1/7. The isolate yielded a cytotoxic compound. It was obtained by solvent extraction followed by the chromatographic purification. Based on the spectral data of the pure compound, it was identified as quinone-related antibiotic, resistoflavine (1). It showed a potent cytotoxic activity against cell lines viz. HMO2 (Gastric adenocarcinoma) and HePG2 (Hepatic carcinoma) in vitro and also exhibited weak antibacterial activities against Gram-positive and Gram-negative bacteria.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Biosynthesis and structural characterization of Ag nanoparticles from white rot fungi

Chan YS, Mat Don M

Mater Sci Eng C Mater Biol Appl, 2013 Jan 1;33(1):282-8.
PMID: 25428073 DOI: 10.1016/j.msec.2012.08.041

Five species of white rot fungi were screened for their capability to synthesize Ag nanoparticles (AgNPs). Three modes of AgNP bioreduction were developed. Pycnoporus sanguineus is found as a potential candidate for the synthesis of AgNPs with a yield at 98.9%. The synthesized AgNPs were characterized using UV-vis spectroscopy, DLS, FTIR, TEM, and SEM. Results showed that AgNP absorption band was located at a peak of 420 nm. Both the SEM and TEM confirmed that the formation of AgNPs were mainly spherical with average diameters of 52.8-103.3 nm. The signals of silver atoms' presence in the mycelium were observed by SEM-EDS spectrum.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Isolation and identification of antibacterial and cytotoxic compounds from the leaves of Muntingia calabura L

Sufian AS, Ramasamy K, Ahmat N, Zakaria ZA, Yusof MI

J Ethnopharmacol, 2013 Mar 7;146(1):198-204.
PMID: 23276785 DOI: 10.1016/j.jep.2012.12.032

Muntingia calabura (Elaeocarpaceae) is one of the most common roadside trees in Malaysia. Its leaves, barks, flowers and roots have been used as a folk remedy for the treatment of fever, incipient cold, liver disease, as well as an antiseptic agent in Southeast Asia. The aim of this study is to isolate and identify the antibacterial and cytotoxic compounds from the leaves of Muntingia calabura L.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Cyclopenta[b]benzofuran and Secodammarane Derivatives from the Stems of Aglaia stellatopilosa

Othman N, Pan L, Mejin M, Voong JC, Chai HB, Pannell CM, et al.

J Nat Prod, 2016 Apr 22;79(4):784-91.
PMID: 26974604 DOI: 10.1021/acs.jnatprod.5b00810

Four new 2,3-secodammarane triterpenoids, stellatonins A-D (3-6), together with a new 3,4-secodammarane triterpenoid, stellatonin E (7), and the known silvestrol (1), 5‴-episilvestrol (2), and β-sitosterol, were isolated from a methanol extract of the stems of Aglaia stellatopilosa through bioassay-guided fractionation. The structures of the new compounds were elucidated using spectroscopic and chemical methods. The compounds were evaluated for their cytotoxic activity against three human cancer cell lines and for their antimicrobial activity using a microtiter plate assay against a panel of Gram-positive and Gram-negative bacteria and fungi.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Surveillance study of bacteraemic episodes in febrile neutropenic children

Ariffin H, Navaratnam P, Lin HP

Int J Clin Pract, 2002 May;56(4):237-40.
PMID: 12074201

We prospectively studied the type, frequency and outcome of infections in 513 patients with 762 consecutive episodes of febrile neutropenia (FN) over a five-year period between 1995 and 1999 in a single paediatric oncology unit. The findings were then compared with a similar study carried out in our unit between 1990 and 1994. The types of bacterial isolates and sensitivity patterns were also studied to identify trends and to gauge the suitability of antibiotics chosen for empirical therapy. Bacteraemia was documented in 35.4% of FN episodes, although 70% of patients did not have an obvious site of sepsis. The majority of isolates (61.9%) were gram-negative bacteria, a consistent finding throughout the study period. Resistance to ceftazidime, amikacin and imipenem among gram-negative bacteria was 26.3%, 21.2% and 0.7%, respectively. Methicillin resistance among gram-positive bacteria was 26.3%, while no vancomycin-resistant bacteria were encountered. There were 36 sepsis-related deaths. Factors associated with a fatal outome were prolonged capillary refill time, hypotension, fever above 39 degrees C and pneumonia. Rapid neutrophil recovery was associated with a good prognosis. A change to our current choice of empirical antibiotics for FN, comprising ceftazidime/ceftriaxone and amikacin appears necessary because of the relatively high resistance rates found.

Matched MeSH terms: Gram-Negative Bacteria/isolation & purification*
Antimicrobial screening of plants used for traditional medicine in the state of Perak, Peninsular Malaysia

Wiart C, Mogana S, Khalifah S, Mahan M, Ismail S, Buckle M, et al.

Fitoterapia, 2004 Jan;75(1):68-73.
PMID: 14693223

Seventy-two extracts (methanol) obtained from the leaves, barks, and roots of 50 plant species used in the traditional medicine of Perak, Peninsular Malaysia, have been screened for antibacterial and antifungal activities. Peristrophe tinctoria, Polyalthia lateriflora, Knema malayana, Solanum torvum, Celosia argentea, Eclipta prostrata, Ancistrocladus tectorius, Dillenia suffruticosa, Piper stylosum and Rafflesia hasseltii displayed the broadest spectrum of activity.

Matched MeSH terms: Gram-Negative Bacteria/drug effects*
Design, synthesis and antimicrobial evaluation of novel glycosylated-fluoroquinolones derivatives

Mohammed AAM, Suaifan GARY, Shehadeh MB, Okechukwu PN

Eur J Med Chem, 2020 Sep 15;202:112513.
PMID: 32623216 DOI: 10.1016/j.ejmech.2020.112513

Herein we report the design, synthesis and biological evaluation of structurally modified ciprofloxacin, norfloxacin and moxifloxacin standard drugs, featuring amide functional groups at C-3 of the fluoroquinolone scaffold. In vitro antimicrobial testing against various Gram-positive bacteria, Gram-negative bacteria and fungi revealed potential antibacterial and antifungal activity. Hybrid compounds 9 (MIC 0.2668 ± 0.0001 mM), 10 (MIC 0.1358 ± 00025 mM) and 13 (MIC 0.0898 ± 0.0014 mM) had potential antimicrobial activity against a fluoroquinolone-resistant Escherichia coli clinical isolate, compared to ciprofloxacin (MIC 0.5098 ± 0.0024 mM) and norfloxacin (MIC 0.2937 ± 0.0021 mM) standard drugs. Interestingly, compound 10 also exerted potential antifungal activity against Candida albicans (MIC 0.0056 ± 0.0014 mM) and Penicillium chrysogenum (MIC 0.0453 ± 0.0156 mM). Novel derivatives and standard fluoroquinolone drugs exhibited near-identical cytotoxicity levels against L6 muscle cell-line, when measured using the MTT assay.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Sesquiterpenes rich essential oil from Garcinia celebica L. and its cytotoxic and antimicrobial activities

Tan WN, Tan ZH, Zulkifli NI, Nik Mohamed Kamal NNS, Rozman NAS, Tong WY, et al.

Nat Prod Res, 2020 Dec;34(23):3404-3408.
PMID: 30773054 DOI: 10.1080/14786419.2019.1569012

Garcinia celebica L., locally known as "manggis hutan" in Malaysia is widely used in folkloric medicine to treat various diseases. The present study was aimed to examine the chemical composition of the essential oil from the leaves of G. celebica L. (EO-GC) and its cytotoxic and antimicrobial potential. EO-GC obtained by hydrodistillation was analysed using capillary GC and GC-MS. Twenty-two compounds were identified, dominated by α-copaene (61.25%), germacrene D (6.72%) and β-caryophyllene (5.85%). In the in vitro MTT assay, EO-GC exhibited significant anti-proliferative effects towards MCF-7 human breast cancer cells with IC50 value of 45.2 μg/mL. Regarding the antimicrobial activity, it showed better inhibitory effects on Gram-positive bacteria than Gram-negative bacteria and none on the fungi and yeasts tested.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Fulltext In vitro assessment of Pediococcus acidilactici Kp10 for its potential use in the food industry

Abbasiliasi S, Tan JS, Bashokouh F, Ibrahim TAT, Mustafa S, Vakhshiteh F, et al.

BMC Microbiol, 2017 May 23;17(1):121.
PMID: 28535747 DOI: 10.1186/s12866-017-1000-z

BACKGROUND: Selection of a microbial strain for the incorporation into food products requires in vitro and in vivo evaluations. A bacteriocin-producing lactic acid bacterium (LAB), Pediococcus acidilactici Kp10, isolated from a traditional dried curd was assessed in vitro for its beneficial properties as a potential probiotic and starter culture. The inhibitory spectra of the bacterial strain against different gram-positive and gram-negative bacteria, its cell surface hydrophobicity and resistance to phenol, its haemolytic, amylolytic and proteolytic activities, ability to produce acid and coagulate milk together with its enzymatic characteristics and adhesion property were all evaluated in vitro.
RESULTS: P. acidilactici Kp10 was moderately tolerant to phenol and adhere to mammalian epithelial cells (Vero cells and ileal mucosal epithelium). The bacterium also exhibited antimicrobial activity against several gram-positive and gram-negative food-spoilage and food-borne pathogens such as Listeria monocytgenes ATCC 15313, Salmonella enterica ATCC 13311, Shigella sonnei ATCC 9290, Klebsiella oxytoca ATCC 13182, Enterobacter cloaca ATCC 35030 and Streptococcus pyogenes ATCC 12378. The absence of haemolytic activity and proteinase (trypsin) and the presence of a strong peptidase (leucine-arylamidase) and esterase-lipase (C4 and C8) were observed in this LAB strain. P. acidilactici Kp10 also produced acid, coagulated milk and has demonstrated proteolytic and amylolactic activities.
CONCLUSION: The properties exhibited by P. acidilactici Kp10 suggested its potential application as probiotic and starter culture in the food industry.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Fulltext In vitro antibacterial activity of Quercus infectoria gall extracts against multidrug resistant bacteria

Wan Nor Amilah WA, Masrah M, Hasmah A, Noor Izani NJ

Trop Biomed, 2014 Dec;31(4):680-8.
PMID: 25776593 MyJurnal

Antimicrobial activities of plants have long been evaluated for their promising use as antimicrobial agent and in minimizing the unwanted resistance effects of microorganisms. The study was conducted to evaluate the antibacterial activity of Quercus infectoria gall crude extracts against multidrug resistant (MDR) bacteria in vitro. The screening test was determined by disc diffusion technique using sterile filter paper discs impregnated with 1 mg/ disc (50 mg/ml) aqueous and ethanol extracts of Q. infectoria galls tested on five selected MDR bacterial strains. The minimum inhibitory concentration (MIC) was determined using the twofold serial micro dilution technique at concentration ranging from 5.00 mg/ml to 0.01 mg/ml. The minimum bactericidal concentration (MBC) was determined by sub culturing the microtitre wells showing no turbidity on the agar plate to obtain the MBC value. Both extracts showed substantial inhibitory effects against methicillin resistant coagulase negative Staphylococcus (MRCoNS) and methicillin resistant Staphylococcus aureus (MRSA). A slightly reduced inhibitory zone diameter was observed with MDR Acinetobacter sp. while no inhibitory effect was displayed among the extended spectrum beta lactamases (ESBL) K. pneumoniae and ESBL E. coli isolates. A significant difference in the zone sizes between both extracts was only observed in MRSA (p < 0.05). The MIC values ranged from 0.08 mg/ml to 0.63 mg/ml for aqueous and ethanol extracts against MRSA, MRCoNS and MDR Acinetobacter sp. while their MBC to MIC ratio values were 2 and less. The Q. infectoria gall extracts have shown very promising in vitro antibacterial activities and may be considered as a potentially good source of antimicrobial agent especially against MDR Gram positive bacteria.

Matched MeSH terms: Gram-Negative Bacteria/drug effects*
Antibacterial evaluation of silver nanoparticles synthesized from lychee peel: individual versus antibiotic conjugated effects

Perveen S, Safdar N, Chaudhry GE, Yasmin A

World J Microbiol Biotechnol, 2018 Jul 14;34(8):118.
PMID: 30008019 DOI: 10.1007/s11274-018-2500-1

This paper describes the extracellular synthesis of silver nanoparticles from waste part of lychee fruit (peel) and their conjugation with selected antibiotics (amoxicillin, cefixim, and streptomycin). FTIR studies revealed the reduction of metallic silver and stabilization of silver nanoparticles and their conjugates due to the presence of CO (carboxyl), OH (hydroxyl) and CH (alkanes) groups. The size of conjugated nanoparticles varied ranging from 3 to 10 nm as shown by XRD. TEM image revealed the spherical shape of biosynthesized silver nanoparticles. Conjugates of amoxicillin and cefixim showed highest antibacterial activity (147.43 and 107.95%, respectively) against Gram-negative bacteria i.e. Alcaligenes faecalis in comparison with their control counterparts. The highest reduction in MIC was noted against Gram-positive strains i.e. Enterococcus faecium (75%) and Microbacterium oxydans (75%) for amoxicillin conjugates. Anova two factor followed by two-tailed t test showed non-significant results both in case of cell leakage and protein estimation between nanoparticles and conjugates of amoxicillin, cefixime and streptomycin. In case of MDA release, non-significant difference among the test samples against the selected strains. Our study found green-synthesized silver nanoparticles as effective antibacterial bullet against both Gram positive and Gram negative bacteria, but they showed a more promising effect on conjugation with selected antibiotics against Gram negative type.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Sulfur and nitrogen containing plasma polymers reduces bacterial attachment and growth

Siow KS, Abdul Rahman AS, Ng PY, Majlis BY

Mater Sci Eng C Mater Biol Appl, 2020 Feb;107:110225.
PMID: 31761201 DOI: 10.1016/j.msec.2019.110225

Role of sulfur (S) and nitrogen (N) groups in promoting cell adhesion or commonly known as biocompatibility, is well established, but their role in reducing bacterial attachment and growth is less explored or not well-understood. Natural sulfur-based compounds, i.e. sulfide, sulfoxide and sulfinic groups, have shown to inhibit bacterial adhesion and biofilm formation. Hence, we mimicked these surfaces by plasma polymerizing thiophene (ppT) and air-plasma treating this ppT to achieve coatings with S of similar oxidation states as natural compounds (ppT-air). In addition, the effects of these N and S groups from ppT-air were also compared with the biocompatible amine-amide from n-heptylamine plasma polymer. Crystal violet assay and live and dead fluorescence staining of E. coli and S. aureus showed that all the N and S coated surfaces generated, including ppHA, ppT and ppT-air, produced similarly potent, growth reduction of both bacteria by approximately 65% at 72 h compared to untreated glass control. The ability of osteogenic differentiation in Wharton's jelly mesenchymal stem cells (WJ-MSCs) were also used to test the cell biocompatibility of these surfaces. Alkaline phosphatase assay and scanning electron microscopy imaging of these WJ-MSCs growths indicated that ppHA, and ppT-air were cell-friendly surfaces, with ppHA showing the highest osteogenic activity. In summary, the N and S containing surfaces could reduce bacteria growth while promoting mammalian cell growth, thus serve as potential candidate surfaces to be explored further for biomaterial applications.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Antibacterial and antioxidant potential of biosynthesized copper nanoparticles mediated through Cissus arnotiana plant extract

Rajeshkumar S, Menon S, Venkat Kumar S, Tambuwala MM, Bakshi HA, Mehta M, et al.

J. Photochem. Photobiol. B, Biol., 2019 Aug;197:111531.
PMID: 31212244 DOI: 10.1016/j.jphotobiol.2019.111531

Environment friendly methods for the synthesis of copper nanoparticles have become a valuable trend in the current scenario. The utilization of phytochemicals from plant extracts has become a unique technology for the synthesis of nanoparticles, as they possess dual nature of reducing and capping agents to the nanoparticles. In the present investigation we have synthesized copper nanoparticles (CuNPs) using a rare medicinal plant Cissus arnotiana and evaluated their antibacterial activity against gram negative and gram positive bacteria. The morphology and characterization of the synthesized CuNPs were studied and done using UV-Visible spectroscopy at a wavelength range of 350-380 nm. XRD studies were performed for analyzing the crystalline nature; SEM and TEM for evaluating the spherical shape within the size range of 60-90 nm and AFM was performed to check the surface roughness. The biosynthesized CuNPs showed better antibacterial activity against the gram-negative bacteria, E. coli with an inhibition zone of 22.20 ± 0.16 mm at 75 μg/ml. The antioxidant property observed was comparatively equal with the standard antioxidant agent ascorbic acid at a maximum concentration of 40 μg/ ml. This is the first study reported on C. arnotiana mediated biosynthesis of copper nanoparticles, where we believe that the findings can pave way for a new direction in the field of nanotechnology and nanomedicine where there is a significant potential for antibacterial and antioxidant activities. We predict that, these could lead to an exponential increase in the field of biomedical applications, with the utilization of green synthesized CuNPs, due to its remarkable properties. The highest antibacterial property was observed with gram-negative strains mainly, E. coli, due to its thin peptidoglycan layer and electrostatic interactions between the bacterial cell wall and CuNPs surfaces. Hence, CuNPs can be potent therapeutic agents in several biomedical applications, which are yet to be explored in the near future.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Antibiotics' susceptibility patterns of bacterial isolates causing lower respiratory tract infections in ICU patients at referral hospitals in Namibia

Simeon P, Godman B, Kalemeera F

Hosp Pract (1995), 2021 Dec;49(5):356-363.
PMID: 34436942 DOI: 10.1080/21548331.2021.1973825

BACKGROUND: Lower respiratory tract infections (LRTIs) are a particular public health concern especially among sub-Saharan African countries. This is especially the case in Namibia, where LRTIs are currently the third leading cause of death, 300 deaths in children under 5 years of age. To reduce the burden of LRTIs on health systems and ensure appropriate patient management, it is critical to know the most prevalent pathogens leading to LRTIs and their susceptibility patterns in the local setting. Consequently, the objective of this study was to formulate cumulative antibiograms for Intensive Care Units (ICUs) of referral hospitals in Namibia to guide future antibiotic use.
METHODS: A retrospective analytical cross-sectional study was conducted over 2 years. The cumulative antibiograms were constructed in accordance with current guidelines.
RESULTS: A total of 976 first isolate cultures were obtained from ICUs of the different referral hospitals. K. pneumoniae (8.8%, 8.1%) was a predominant pathogen in Windhoek Central hospital ICU in 2017 and 2018. In Oshakati intermediate hospital ICU, Enterobacter sp. (22.2%) and P. aeruginosa (37.5%) were the common pathogens in 2017 and 2018, respectively. A. baumannii isolates were >90% susceptibility to colistin, carbapenems, and tigecycline in 2017. In 2017, K. pneumoniae isolates were more susceptible to carbapenems (94% and 93.8% among isolates), amikacin (89.3%), and tigecycline (88.7%). In 2018, K. pneumoniae isolates were 100% susceptible amikacin, colistin, and carbapenems. S. maltophilia isolates were more than 80% susceptible to all the tested antibiotics. S. aureus isolates were 100% susceptible to linezolid, rifampicin, teicoplanin, and vancomycin in 2017 and in 2018. Its susceptibility to these antibiotics did not change.
CONCLUSION: The susceptibility patterns of the common isolated gram-negative pathogens were highly variable. Meropenem in combination with gentamicin is now the recommended antibiotic combination for empiric therapy for patients with LRTIs in Windhoek Central Hospital ICU.

Matched MeSH terms: Gram-Negative Bacteria/drug effects*
Fulltext Development and Characterization of Calcium-Alginate Beads of Apigenin: In Vitro Antitumor, Antibacterial, and Antioxidant Activities

Aldawsari MF, Ahmed MM, Fatima F, Anwer MK, Katakam P, Khan A

Mar Drugs, 2021 Aug 20;19(8).
PMID: 34436306 DOI: 10.3390/md19080467

The objective of this work was to develop sustained-release Ca-alginate beads of apigenin using sodium alginate, a natural polysaccharide. Six batches were prepared by applying the ionotropic gelation technique, wherein calcium chloride was used as a crosslinking agent. The beads were evaluated for particle size, drug loading, percentage yield, and in vitro drug release. Particle size was found to decrease, and drug entrapment efficiency was enhanced with an increase in the polymer concentration. The dissolution study showed sustained drug release from the apigenin-loaded alginate beads with an increase in the polymer proportion. Based on the dissolution profiles, BD6 formulation was optimized and characterized for FTIR, DSC, XRD, and SEM, results of which indicated successful development of apigenin-loaded Ca alginate beads. MTT assay demonstrated a potential anticancer effect against the breast cancer MCF-7 cell lines. The antimicrobial activity exhibited effective inhibition in the bacterial and fungal growth rate. The DPPH measurement revealed that the formulation had substantial antioxidant activity, with EC50 value slightly lowered compared to pure apigenin. A stability study demonstrated that the BD6 was stable with similar (f2) drug release profiles in harsh condition. In conclusion, alginate-based beads could be used for sustaining the drug release of poorly water-soluble apigenin while also improving in vitro antitumor, antimicrobial, and antioxidant activity.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Fulltext Ingestion of bacteria overproducing DnaK attenuates Vibrio infection of Artemia franciscana larvae

Sung YY, Dhaene T, Defoirdt T, Boon N, MacRae TH, Sorgeloos P, et al.

Cell Stress Chaperones, 2009 Nov;14(6):603-9.
PMID: 19373565 DOI: 10.1007/s12192-009-0112-2

Feeding of bacterially encapsulated heat shock proteins (Hsps) to invertebrates is a novel way to limit Vibrio infection. As an example, ingestion of Escherichia coli overproducing prokaryotic Hsps significantly improves survival of gnotobiotically cultured Artemia larvae upon challenge with pathogenic Vibrio campbellii. The relationship between Hsp accumulation and enhanced resistance to infection may involve DnaK, the prokaryotic equivalent to Hsp70, a major molecular chaperone in eukaryotic cells. In support of this proposal, heat-stressed bacterial strains LVS 2 (Bacillus sp.), LVS 3 (Aeromonas hydrophila), LVS 8 (Vibrio sp.), GR 8 (Cytophaga sp.), and GR 10 (Roseobacter sp.) were shown in this work to be more effective than nonheated bacteria in protecting gnotobiotic Artemia larvae against V. campbellii challenge. Immunoprobing of Western blots and quantification by enzyme-linked immunosorbent assay revealed that the amount of DnaK in bacteria and their ability to enhance larval resistance to infection by V. campbellii are correlated. Although the function of DnaK is uncertain, it may improve tolerance to V. campbellii via immune stimulation, a possibility of significance from a fundamental perspective and also because it could be applied in aquaculture, a major method of food production.

Matched MeSH terms: Gram-Negative Bacteria/metabolism
Fulltext Autoclave-assisted synthesis of AgNPs in Z. officinale extract and assessment of their cytotoxicity, antibacterial and antioxidant activities

Kalantari K, Afifi AM, Moniri M, Moghaddam AB, Kalantari A, Izadiyan Z

IET Nanobiotechnol, 2019 May;13(3):262-268.
PMID: 31053688 DOI: 10.1049/iet-nbt.2018.5066

In this study, the authors synthesised silver nanoparticles (AgNPs) using autoclave as a simple, unique and eco-friendly approach. The effect of Zingiber officinale extract was evaluated as a reducing and stabiliser agent. According to transmission electron microscopy results, the AgNPs were in the spherical shape with a particle size of ∼17 nm. The biomedical properties of AgNPs as antibacterial agents and free radical scavenging activity were estimated. Synthesised AgNPs showed significant 1,1-diphenyl-2-picryl-hydrazyl free radical scavenging. Strong bactericidal activity was shown by the AgNPs on Gram-positive and Gram-negative bacteria. A maximum inhibition zone of ∼14 mm was obtained for epidermidis at a concentration of 60 μg/ml for sample fabricated at 24 h. The AgNPs also showed a significant cytotoxic effect against MCF-7 breast cancer cell lines with an half maximal inhibitory concentration value of 62 μg/ml in 24 h by the MTT assay. It could be concluded that Z. officinale extract can be used effectively in the production of potential antioxidant and antimicrobial AgNPs for commercial application.

Matched MeSH terms: Gram-Negative Bacteria/drug effects
Fulltext L,L-diaminopimelate aminotransferase (DapL): a putative target for the development of narrow-spectrum antibacterial compounds

Triassi AJ, Wheatley MS, Savka MA, Gan HM, Dobson RC, Hudson AO

Front Microbiol, 2014;5:509.
PMID: 25309529 DOI: 10.3389/fmicb.2014.00509

Despite the urgent need for sustained development of novel antibacterial compounds to combat the drastic rise in antibiotic resistant and emerging bacterial infections, only a few clinically relevant antibacterial drugs have been recently developed. One of the bottlenecks impeding the development of novel antibacterial compounds is the identification of new enzymatic targets. The nutritionally essential amino acid anabolic pathways, for example lysine biosynthesis, provide an opportunity to explore the development of antibacterial compounds, since human genomes do not possess the genes necessary to synthesize these amino acids de novo. The diaminopimelate (DAP)/lysine (lys) anabolic pathways are attractive targets for antibacterial development since the penultimate lys precursor meso-DAP (m-DAP) is a cross-linking amino acid in the peptidoglycan (PG) cell wall of most Gram-negative bacteria and lys plays a similar role in the PG of most Gram-positive bacteria, in addition to its role as one of the 20 proteogenic amino acids. The L,L-diaminopimelate aminotransferase (DapL) pathway was recently identified as a novel variant of the DAP/lys anabolic pathways. The DapL pathway has been identified in the pathogenic bacteria belonging to the genus; Chlamydia, Leptospira, and Treponema. The dapL gene has been identified in the genomes of 381 or approximately 13% of the 2771 bacteria that have been sequenced, annotated and reposited in the NCBI database, as of May 23, 2014. The narrow distribution of the DapL pathway in the bacterial domain provides an opportunity for the development and or discovery of narrow spectrum antibacterial compounds.

Matched MeSH terms: Gram-Negative Bacteria

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