Antiquorum-sensing Activity Research Articles

Screening of Anti-Quorum Sensing Activity from Selected Chinese Herbs Against Chromobacterium violaceum

Overuse of antibiotics was contributed to the increasing of bacterial infection resistance against antibiotics and caused a serious issue to the public health. Anti-quorum sensing is a new alternative ways or treatments to fight bacterial pathogenicity. Traditional Chinese herbs were screened of their anti-quorum sensing activities. Six selected traditional Chinese herbs were screened for a simple anti-quorum sensing activity by using Chromobacterium violaceum as the biomonitor. Two out of these herbs were found to be able to exhibit anti-quorum sensing properties; Lycium barbarum and Zingiber officinale. Extraction from Lycium barbarum has stronger anti-quorum sensing activity than Zingiber officinale. Colonies of biomonitor C. violaceum treated with Lycium barbarum almost fully loss its purple pigment. The loss and lack of purple colour from the colonies of C. violaceum indicated that quorum sensing activity was inhibited by the herb’s extracted. It is believed that this herb contains rich source of compounds to fight or control pathogenic bacteria and potentially a new therapeutic way to reduce the development of antibiotic resistanc

Antimicrobial, Antiquorum-sensing and Ex-vivo Antispasmodic Activity of Adhatoda vasica

Aims: To investigate the antimicrobial, antiquorum-sensing and Ex-vivo antispasmodic activity of the stem extract, fractions and isolated compounds of Adhatoda vasica.
 Study Design: Preparation of the total extract, fractions of A. vasica and isolation of its phytoconstituents for investigation of antimicrobial, antiquorum-sensing and Ex-vivo antispasmodic activity.
 Place and Duration of Study: Faculty of Pharmacy, Mansoura University, Egypt and College of Pharmacy, Prince Sattam Bin Abdulaziz University, KSA, between November 2014 and May 2019.
 Methodology: Different phytoconstituents in obtained liquid-liquid fractionations were isolated by repeated column chromatography. The preliminary antimicrobial activity was measured via agar disc-diffusion method. The minimum inhibitory concentration (MIC) was further determined using broth microdilution method in 96-well plates. Antiquorum-sensing activity was tested against Chromobacterium violaceum in LB agar medium. While, antispasmodic activity was performed using Ach-induced contraction on rat ileum.
 Results: Seven compounds have been isolated from the stems extract of Adhatoda vasica viz., β-sitosterol, daucosterol palmitate, monopalmitin, vanillin, vanillic acid, vasicinolone and vasicinone. The petroleum ether fraction, daucosterol palmitate, monopalmitin, vanillin and vanillic acid showed strong antibacterial activity towards E. coli and S. aureus. Whereas daucosterol palmitate and vanillic acid showed pronounced antifungal activity against C. albicans. Antiquorum-sensing assay showed that β-sitosterol, vanillin and vanillic acid were the most active compounds. While, petroleum ether and methylene chloride fractions, vasicinolone and daucosterol palmitate showed moderate antiquorum-sensing activity. For antispasmodic activity, petroleum ether fraction showed a remarkable inhibition of Ach-induced contraction at 200 and 250 μg/mL (89.5 and 95.2%, respectively). Also, methylene chloride fraction showed remarkable inhibition (97.6%) at 150 μg/mL. Vasicinone and vasicinolone showed significant inhibition at 150 μg/mL (89.9% and 84.8%, respectively).
 Conclusion: The isolated compounds and extracts from the stem of the studied plant showed remarkable activities. This work provides further evidences for the traditional medicinal uses of A. vasica in treatment of various ailments.

Novel derivatives of plant monomeric phenolics: act as inhibitors of bacterial cell-to-cell communication

The aim of the present study was to synthesize novel active Anti-Quorum sensing derivatives from secondary metabolites viz. Gallic acid, Protocatechuic acid and Vanillic acid present in the plant Bergenia ciliata. Efficacy of all synthesized derivatives have been evaluated on the formation of bacterial biofilm and inhibition of cell-to-cell communication. Anti-Quorum Sensing activity and biofilm formation of all synthesized compounds was measured on biomonitor strain Chrobacterium violaceum, ATCC 12472 using standard paper disk-diffusion assay and quantification of violacein pigment. Among all derivatives, five derivatives 3,4,5-Trihydroxy-benzoic acid methyl ester (9a), 3,4-Dihydroxy-benzoic acid methyl ester (10a), 3,4,5-Tris-(2,4-dichloro-benzyloxy)-benzoic acid methyl ester (12), 3,4,5-Tris-(2,5-dichloro-benzyloxy)-benzoic acid methyl ester (13) and 4-(2,4-Dichloro-benzyloxy)-3-methoxy-benzoic acid methyl ester (15) has shown Anti-Quorum Sensing activity by inhibiting violacein pigment production and biofilm formation without interfering with its growth. The inhibitory effects in violacein pigment production were: positive control (C-30) 72%, (9a), (10a) 47.2%, (12) 27.3%, (13) 40.1% and (15) 22.7% at the concentration of 1 mg/mL and biofilm percent inhibition were found (C-30) 64% (9a) 46.2%, (10a) 40.3%, (12) 18.4%, (13) 35.2%, and (15) 17.3% when compared with the untreated control. Results reveal that synthesized derivatives seem to be good compounds for inhibition and formation of biofilm and AHL-mediated Quorum-sensing mechanism. The present article highlights the importance of derivatives derived from secondary metabolites as potent drug for biofilm formation and inhibition of cell-to-cell communication.

Antibacterial, Antibiofilm, Antiquorum Sensing, Antimotility, and Antioxidant Activities of Green Fabricated Ag, Cu, TiO2, ZnO, and Fe3O4 NPs via Protoparmeliopsis muralis Lichen Aqueous Extract against Multi-Drug-Resistant Bacteria.

Consideration of lichen organisms as the ecofriendly source of metal nanoparticles (MNPs) and metal oxide NPs (MONPs) synthesis is seldom. In this study, Ag and Cu MNPs as well as TiO2, ZnO, and Fe3O4 MONPs were green synthesized by Protoparmeliopsis muralis lichen aqueous extract. First, physicochemical characterization by UV-vis spectroscopy, XRD, FT-IR, FESEM, and TEM techniques demonstrated the presence possibility of secondary metabolites around formed MNPs/MONPs with different diameters and shapes (spherical, triangular, polyhedral, and cubic). The antibacterial, antibiofilm, antiquorum sensing, and antioxidant abilities of these MNPs/MONPs against multi drug resistant (MDR) bacterium (Staphylococcus aureus ATCC 43300) and reference bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) were then evaluated by in vitro tests. Results of disc diffusion and MIC/MBC assays of Ag NPs as an effective antibacterial agent illustrated a higher sensitivity of the P. aeruginosa pathogen than E. coli and S. aureus. In next steps, a significant reduction was observed in the biofilm formation of each bacterium and pyocyanin synthesis by P. aeruginosa under Ag NPs. This investigation presents novel clean production of five MNPs/MONPs with prominent advantages of being ecofriendly and cost-effective and having antipathogen properties.

Beet (Beta vulgaris) and Leek (Allium porrum) Leaves as a Source of Bioactive Compounds with Anti-quorum Sensing and Anti-biofilm Activity

The by-products resulted from the processing of raw vegetables contain sometimes appreciable amounts of bioactive compounds can be extracted, purified, concentrated and reused as antipathogenic agents. By altering the pathogenicity of microorganisms, the virulence of the pathogen is attenuated. The objective of this work is to analyze the antibacterial, anti-quorum sensing, anti-biofilm and antioxidant activity of Beta vulgaris (beet) and Allium porrum (leek) leaves as possible antipathogenic agents. The ethanolic extracts of dehydrated beet leaves (EEDBL) showed greater antioxidant activity and a higher concentration of polyphenols than those of ethanolic extract of dehydrated leek leaves (EEDLL). The EEDLL showed major antibacterial activity with a minimal inhibitory concentration (MIC) of 358.33 mg mL−1 and anti-quorum sensing activity at 53.75 mg mL−1 than the EEDBL. Moreover, the EEDLL showed anti-biofilm activity at 268.75 mg mL−1. The use of bioactives extracted from unused portions of different vegetables as antipathogenic substances it is proposed as an alternative to the use of traditional antibacterials.

Synthesis, antimicrobial evaluation, and molecular docking of some new angular allylbenzochromone derivatives

Different classes of antimicrobial compounds such as β-lactams, sulfonamides, aminoglycosides, tetracyclines, quinolines and others have been developed during the 20th century to control the growing antimicrobial resistance. Therefore, there is an urgent need to build up new and effective antimicrobial agents with different working mechanisms to suppress this resistance. Accordingly, the judicious design of antimicrobial organic compounds with antiquorum-sensing activities could be a major solution for this global challenge. Herein, the versatile precursor 6-allyl-3-formyl-4H-benzo[h]chromen-4-one (2) was used for the synthesis of various isolated and condensed naphthoyl or (chromenyl) nicotinonitriles, azalactone, thiazolidinone, xanthene, indenopyridine, Schiff bases, diazepine, imidazole and triazolopyrimidine derivatives 5-21via its reactions with several active carbon nucleophiles in addition to amines, benzil and hydrazine. Some of the newly synthesized compounds showed moderately and good antimicrobial activities. The compounds 2 and 14 were the best concerning effects. In addition, the antiquorum-sensing activities of the newly prepared compounds were assessed against Chromobacterium violaceum. Specifically, pharmaceutical evaluation, antimicrobial prediction, and molecular docking using computational tools illustrated that the complexes of the latter compounds may show substantial antimicrobial activity in comparison with the other derivatives.

Synthesis, molecular docking, antimicrobial, antiquorum-sensing and antiproliferative activities of new series of pyrazolo[3,4-b]pyridine analogs

New series of pyrazolo[3,4-b]pyridines were prepared and evaluated for antimicrobial activity toward six selected microorganisms. Compounds 2a, 3b, 3d and 3e exhibited good activity toward B. cereus. On the other hand, 2a and 3b evinced interesting activity over C. albicans, whereas 2a, 3b and 3e displayed promising activity over A. fumigatus. Antiquorum-sensing effectiveness of the new members over C. violaceum was also assessed, where compounds 2a and 3b exhibited higher activity than that of the reference compound, indole. In vitro antiproliferative assessment toward HepG2, HCT-116 and MCF-7 cancer cells evidenced that 2f has notable effectiveness on all examined cell lines, whereas 3a–c were active but to a lower extent. In vivo antitumor activity of 2f and 3a–c against EAC cells was also esteemed, where 2f and 3c showed considerable activity comparable to that of doxorubicin. Cytotoxicity screening over WI38 and WISH normal cells evinced that 2f and 3a–c are less cytotoxic than doxorubicin. Compounds 2a, 2f, 3a–c and 3e were evaluated for DNA-binding affinity and topoisomerase IIβ inhibitory activity. Analogs 2a, 2f, 3a and 3b illustrated strong DNA-binding affinity, whereas 2a, 2f and 3a exhibited interesting topoisomerase IIβ inhibitory activity. Compounds 2a and 2f were docked into topoisomerase IIβ, where 2f showed preferential binding to topoisomerase IIβ. Computational studies articulated that the new members are in compliance with Veber's standards and Lipinski’s rule.

Synthesis, molecular modeling and biological evaluation of new pyrazolo[3,4-b]pyridine analogs as potential antimicrobial, antiquorum-sensing and anticancer agents

New pyrazolo[3,4-b]pyridine analogs 2–9 were synthesized and subjected to antimicrobial testing toward chosen Gram-negative bacteria, Gram-positive bacteria and fungi. Compound 2 exhibited potent and extended-spectrum antimicrobial activity. Further, 6 and 9c demonstrated remarkable and extended-spectrum antibacterial activity. Antiquorum-sensing activity of the new members was tested over C. violaceum, whereas 9c demonstrated strong efficacy, while 2, 8b and 9b displayed moderate efficacy. In vitro anticancer assay toward HepG2, MCF-7 and Hela cancer cells manifested that 2 and 9c are powerful and extended-spectrum anticancer agents. Additionally, 8a, 8b and 9b showed excellent activity toward the three cancer cells. In vivo anticancer assay over EAC in mice indicated that 2 and 9c have the greatest activity. Moreover, cytotoxicity assay over WISH and W138 normal cells clarified that the checked analogs possess weak cytotoxicity toward the two normal cells. DNA-binding affinity was also tested, whereas 2, 3, 8b, 9b and 9c demonstrated great affinity. Molecular modeling studies revealed that the investigated compounds bind to DNA through intercalation similarly to doxorubicin. In silico studies revealed that the new members are anticipated to show excellent intestinal absorption.

Evaluation of Antimicrobial and Anti-Quorum Sensing Activity of Mazouj and Ghalghaf Galls Extracts of Oak against Pseudomonas aeruginosa

Evaluation of Antimicrobial and Anti-Quorum Sensing Activity of Mazouj and Ghalghaf Galls Extracts of Oak against Pseudomonas aeruginosa

Phytochemical, antimicrobial and antiquorum-sensing studies of pulicaria undulata L.: a revision on the structure of 1β,2α,3β,19α,23-pentahydroxy-urs-12-en-28-oic acid

Phytochemical study of the aerial part of Pulicaria undulata L. led to the isolation of nine compounds. The structure of 1β,2α,3β,19α,23-pentahydroxy-urs-12-en-28-oic acid (4) was revised and confirmation of the stereochemical configuration of the hydroxyl groups was established using NOESY and selective decoupling experiments. The other compounds were identified as 1,2-dehydro-1,10α-dihydropseudoivalin (1), axillarin (2), grandifloric acid-15-β-glucoside (3), myrianthic acid (5), caffeic acid (6), quercetin (7), paniculoside IV (8) and caffeic anhydride (9). The structures were characterized by 1 D, 2 D NMR spectroscopy and confirmed with HRMS. Antimicrobial and antiquorum-sensing activities of the different extracts and isolated compounds of the plant were investigated. Generally, the phenolic rather than the terpenoidal compounds exhibited remarkable antimicrobial and antiquorum-sensing activity.

Antimicrobial and antiquorum-sensing activity of Ricinus communis extracts and ricinine derivatives

Ricinine (1), a known major alkaloid in Ricinus communis plant, was used as a starting compound for the synthesis of six ricinine derivatives; two new and four known compounds. The new derivatives; 3-amino-5-methyl-1H-pyrazolo[4,3-c]pyridin-4(5H)-one (2), and 3-amino-5-methyl-1-(phenylsulfonyl)-1H-pyrazolo[4,3-c]pyridin-4(5H)-one (3), as well as the previously prepared derivatives (4–7) were subjected for antimicrobial and antiquorum-sensing evaluation in comparison to different R. communis extracts. Acetyl ricininic acid derivative (5) showed the highest antimicrobial activity among all tested derivatives against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeuroginosa and Candida albicans. However, compound 7 (4-methoxy-1-methyl-2-oxo-1,2-dihydropyridine-3-carboxamide) showed the highest antiquorum-sensing activity among all tested compounds and extracts. These findings proved the usefulness of ricinine as a good scaffold for the synthesis of new antimicrobial and antiquorum-sensing derivatives in spite of its poor contribution to the antimicrobial activity of the plant extracts.

Research on Chemical Composition and Biological Properties Including Antiquorum Sensing Activity of Angelica pancicii Vandas Aerial Parts and Roots.

The essential oil, different extracts, and isolated compounds of Angelica pancicii Vandas (Apiaceae) were investigated for the first time. The GC-FID and GC-MS analyses revealed sesquiterpenoids as the main constituents of A. pancicii essential oil of aerial parts with bornyl acetate (8.08%), n-octanol (5.82%), kessane (4.26%), and β-selinene (4.26%) as the main constituents. Analysis of methanol extracts, using an HPLC-DAD/ESI-ToF-MS system, showed a total of 52 compounds in the aerial parts and 53 in the roots, indicating coumarins as the main constituents. In addition, new chromone (1) and six known furanocoumarins (2-7) were isolated from the roots and structurally elucidated by combined spectroscopic methods. The aerial part extracts exhibited higher polyphenolic contents and antioxidant activity evaluated by three radical scavenging assays. Using a microwell dilution method, the strongest antibacterial activity profiles were determined for ethanol and methanol root extracts (minimum bactericidal concentrations (MBCs) = 0.25-3.00 mg/mL), which were comparable to the activity of streptomycin (MBCs = 0.34-1.24 mg/mL), while the strongest antibacterial compound of A. pancicii was oxypeucedanin hydrate (MBCs = 0.50-8.00 mg/mL). Antifungal potential was in moderate extent, and the highest activity was obtained for root methanol extract (minimum fungicidal concentrations (MFCs) = 4.00-14.00 mg/mL). Tested sub-minimum inhibitory concentrations (subMICs) of the extracts and isolated compounds inhibited selected Pseudomonas aeruginosa PAO1 virulence determinants. The most reduced growth of P. aeruginosa colony was in the presence of isolated oxypeucedanin. Ethanol (17.36-46.98%) and methanol (34.54-52.43%) root extracts showed higher anti-biofilm activity compared to streptomycin (49.40-88.36%) and ampicillin (56.46-92.16%).

Antiquorum Sensing Activity of Seed Oils from Oleaginous Plants and Protective Effect During Challenge with Chromobacterium violaceum.

Seed oils from oleaginous plants are rich in fatty acids (FAs) that play important roles in the health of the consumers. Recent studies indicate that FA also can play an important role in communication and regulation of virulence in bacteria. Nevertheless, evidence demonstrating protection against bacterial infections mediated by their quorum sensing inhibition (QSI) activity is scarce. In this study, sunflower, chia, and amaranth oils, were assayed for their QSI capacity by inhibiting violacein production and alkaline exoprotease activity of Chromobacterium violaceum. In vitro assays revealed that the oils exhibited QSI activities, whereas in vivo they delayed death of mice inoculated intraperitoneally with the bacterium. Gas chromatography coupled with mass spectrometry analysis of the oils indicated the presence of saturated FA (SAFA) and unsaturated FA as main components. Through a structure-activity relationship study of free FAs, bactericidal effect was identified mainly for polyunsaturated FAs, whereas QSI activity was restricted to SAFA of chains 12-18 carbon atoms in length. These data correlate with a possible interaction suggested by molecular docking analysis of lauric, myristic, and stearic acids with the CviR protein. Our study highlights the antiquorum sensing potential of SAFA, which may be future antivirulence therapeutic agents for the treatment of bacterial infections.

Synthesis and biological evaluation of a new series of benzimidazole derivatives as antimicrobial, antiquorum-sensing and antitumor agents

New benzimidazole derivatives were synthesized and assessed for antimicrobial efficacy toward Escherichia coli, Bacillus cereus, Staphylococcus aureus, Candida albicans and Aspergillus fumigatus 293. Results indicated that compounds 3c and 3n have promising activity toward S. aureus, whereas 3i exhibited remarkable efficacy toward B. cereus. Moreover, compound 3c was proved to be the most active antifungal analog toward C. albicans. On the other hand, 3n displayed the highest activity against A. fumigatus 293. Antiquorum-sensing activity of the same compounds was also tested against Chromobacterium violacium ATCC 12472, whereas compounds 3c-f, 3i-k and 3m-o showed acceptable activity. In vitro antitumor testing of these compounds toward liver cancer (HepG2), colon cancer (HCT-116) and breast cancer (MCF-7) cell lines revealed that compound 3p has the highest potency against the three tested cell lines. Moreover, 3f, 3m and 3n displayed promising activity toward all tested cell lines. Compounds 3f, 3m, 3n and 3p were esteemed for in vivo antitumor activity against EAC cells. The active antimicrobial and antitumor analogs, 3a, 3c, 3f, 3i-k, 3m, 3n and 3p were assessed for DNA-binding affinity, and results indicated that 3c, 3f, 3i, 3k and 3n have strong DNA-binding affinity. The computational studies affirmed that almost all of the inspected compounds meet the optimal requirements for good absorption and oral bioavailability.

Anti Quorum Sensing Activity of Enterobacter spp. Isolated from Soil

Objectives: Screening and characterization of Quorum quenching bacteria from different soil and water samples. Methods/ Statistical Analysis: Quorum quenching bacteria were isolated from different soil and water samples by enrichment culture technique using minimal medium with AHL as sole source of carbon. The bacteria isolated were subjected to bioassay by using Chromobacterium violaceum (CV026) as bio indicator organism. Bacteria exhibiting quorum quenching activity were subjected to 16s r RNA analysis. Quorum quenching activity was further confirmed by subjecting samples to LCMS analysis. Findings: Of all the samples tested only six bacteria exhibited quorum quenching activity which was tested by using bio indicator strain Chromobacterium violaceum (CV026). To confirm the activity all the six samples were subjected to LCMS analysis. Maximum peak was observed at retention time of 4.43 with pure C6 AHL purchased from sigma Aldrich. These samples do not have any characteristic C6 AHL peak in LCMS analysis. This finding confirms the inactivation of AHL which may be enzymatic either by lactonases or acylases. Molecular characterization was done by 16 s rRNA sequencing for one isolate, identified as Enterobacter sp. and designated as Enterobacter sp. EYAR1. Applications: Quorum quenching enzymes help in reducing the development of antibiotic resistance in clinical pathogens by inactivating quorum sensing circuit expression of virulence genes, hence they can be explored as an alternative strategy in controlling infections.

Anti-Quorum Sensing Activity of Tetracera scandens and Aleurites moluccana Leaf Extracts against Chromobacterium violaceum

Anti-Quorum Sensing Activity of Tetracera scandens and Aleurites moluccana Leaf Extracts against Chromobacterium violaceum

Antimicrobial and anti-Quorum Sensing activities of selected medicinal plants of Ethiopia: Implication for development of potent antimicrobial agents.

BackgroundTraditional medicinal plants have been used as an alternative medicine in many parts of the world, including Ethiopia. There are many documented scientific reports on antimicrobial activities of the same. To our knowledge, however, there is no report on the anti-Quorum Sensing (Quorum Quenching, QQ) potential of traditional Ethiopian medicinal plants. As many of the opportunistic pathogenic bacteria depend on Quorum Sensing (QS) systems to coordinate their virulence expression, interference with QS could be a novel approach to control bacterial infections. Thus, the aim of this study was to evaluate selected medicinal plants from Ethiopia for their antimicrobial activities against bacterial and fungal pathogens; and to assess the interference of these plant extracts with QS of bacteria.MethodsAntimicrobial activities of plant extracts (oil, resins and crude extracts) were evaluated following standard agar diffusion technique. The minimum inhibitory concentrations (MIC) of potent extracts were determined using 96 well micro-titer plates and optical densities were measured using an ELISA Microplate reader. Interference with Quorum Sensing activities of extracts was determined using the recently established E. coli based reporter strain AI1-QQ.1 and signaling molecule N-(ß-ketocaproyl)-L-homoserine lactone (3-oxo-C6-HSL).ResultsPetroleum ether extract of seed of Nigella sativa exhibited the highest activity against both the laboratory isolated Bacillus cereus [inhibition zone (IZ), 44 ± 0.31 mm] and B. cereus ATCC 10987 (IZ, 40 ± 2.33 mm). Similarly, oil extract from mature ripe fruit husk of Aframomum corrorima and mature unripe fruit of A. corrorima revealed promising activities against Candida albicans ATCC 90028 (IZ, 35 ± 1.52 mm) and Staphylococcus aureus DSM 346 (IZ, 25 ± 1.32 mm), respectively. Antimicrobial activities of oil extract from husk of A. corrorima and petroleum ether extract of seed of N. sativa were significantly higher than that of the control antibiotic [Gentamycin sulfate, (IZ, 25–30 mm)]. The lowest MIC value (12.5 mg/mL) was recorded for oil from husk of A. corrorima against Pseudomonas aeruginosa. Of the total eighteen extracts evaluated, two of the extracts [Methanol extract of root of Albiza schimperiana (ASRM) and petroleum ether extract of seed of Justica schimperiana (JSSP)] interfered with cell-cell communication most likely by interacting with the signaling molecules.ConclusionTraditional medicinal plants from Ethiopia are potential source of alternative medicine for the local community and scientific research in search for alternative drugs to halt challenges associated with the emerging antimicrobial resistance. Furthermore, the Quorum Quenching activities observed in two of the plant extracts calls for more comprehensive evaluation of medicinal plants for the control of many bacterial processes and phenotypic behaviors such as pathogenicity, swarming, and biofilm formation. Being the first assessment of its kind on the potential application of Ethiopian traditional medicinal plants for interference in microbial cell-cell communication (anti-Quorum Sensing activities), the detailed chemistry of the active compounds and possible mechanism(s) of actions of the bio-molecules responsible for the observed interference were not addressed in the current study. Thus, further evaluation for the nature of those active compounds (bio-molecules) and detailed mechanism(s) of their interaction with microbial processes are recommended.

Repellent and Anti-quorum Sensing Activity of Six Aromatic Plants Occurring in Colombia

Essential oils (EOs) are widely used as biopesticides and to control bacterial infections. This study describes the ability of six EOs isolated from plants cultivated in Colombia to perform as repellents against Ulomoides dermestoides and as quorum sensing (QS) inhibitors. EOs from Aloysia triphylla, Cymbopogon nardus, Lippia origanoides, Hyptis suaveolens, Swinglea glutinosa and Eucalyptus globulus were repellents classified as Class IV, IV, IV, III, II, and II, respectively, whereas the commercial repellent IR3535 only reached Class II after 2 h exposure. All EOs presented small, but significant inhibitory properties against the QS system in Escherichia coli (pJBA132) at 25 μg/mL after 4 h exposure. These data suggest evaluated EOs from Colombia are sustainable, promising new sources of natural repellents and could be important as anti-quorum sensing molecules.

Synthesis, antimicrobial, antiquorum-sensing and cytotoxic activities of new series of benzothiazole derivatives

Abstract New series of benzothiazole derivatives were designed and synthesized. The newly synthesized compounds were screened for their antibacterial activity against Escherichia coli, Staphylococcus aureus and Bacillus cereus. Compounds 6j and 6o showed the highest activity against E. coli and S. aureus. The antifungal activity of these compounds was also tested against Candida albicans and Aspergillus fumigatus 293. Compounds 4c, 4g and 6j exhibited the highest activity against C. albicans. In addition, compounds 4a and 6j displayed promising activity against A. fumigatus 293. The same compounds were examined for their antiquorum-sensing activity against Chromobacterium violaceum ATCC 12472, whereas compounds 4a, 6j and 6p showed moderate activity. The in vitro cytotoxicity testing of the synthesized compounds was performed against cervical cancer (Hela) and kidney fibroblast cancer (COS-7) cell lines. Results indicated that all tested compounds have IC50 values >50 μmol/L against both cell lines. Molecular properties, toxicities, drug-likeness, and drug score profiles of compounds 4a–c, 5a, 6g,h, 6j, 6l, 6o and 7c,d were also assessed.

Synthesis, Antimicrobial, Antiquorum-Sensing, and Cytotoxic Activities of New Series of Isoindoline-1,3-dione, Pyrazolo[5,1-a]isoindole, and Pyridine Derivatives.

New series of isoindoline-1,3-diones 2-9, pyrazolo[5,1-a]isoindoles 10-14, and pyridines 16-18 were synthesized. Twenty of the synthesized compounds were screened for their antibacterial activity against S. aureus, B. cereus, and E. coli. Compound 5 was proved to be the most active member in this study, showing the highest antibacterial activity against the three selected microorganisms. The antifungal activity of these compounds was also tested against C. albicans and A. flavus 3375. Compounds 4, 5, 8, and 17a exhibited the best antifungal activity against A. flavus 3375. The same compounds were examined for their antiquorum-sensing activity against Ch. violacium ATCC 12472, whereas compound 5 displayed strong antiquorum-sensing activity. The in vitro cytotoxicity testing of compounds 4-9 and 17a against human normal lung fibroblast (W138) cell line revealed that compounds 4, 5, and 8 are the least cytotoxic analogs in this study. In vivo acute toxicity testing of compounds 4, 5, and 8 was performed. The DNA-binding affinity of compounds 4-9 and 17a was also tested and the obtained results showed that all tested compounds have moderate DNA-binding affinity.