• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.506-514
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• 2010

A new series of ligands N-[(benzoylamino)-thioxomethyl]-amino acid (HL) were synthesized by reaction of benzoylisothiocyanate with various amino acids namely aspartic acid [BATA] (1), glutamic acid [BATG] (2), methionine [BATM] (3), leucine [BATL] (4), and tryptophan [BATT] (5). The ligands were characterized by elemental analysis, IR and NMR spectra. Some transition metal complexes ($ML_2$) for these ligands (6-8) were prepared; [M=Cu(II), Co(II), or Ni(II)], and characterized by elemental analysis, IR and $^1H$ NMR spectra. Antibacterial study showed that all the ligands have no antibacterial activity, whereas ($ML_2$) complexes; [M = Cu(II), Co(II), or Ni(II)] have antibacterial activity towards (Gram -ive) Escherichia (NCTC5933) and (Gram +ive) Staphylococcus (NCTC6571) and have no toxicity on (BALB/C) Albino mice.

• Journal of Microbiology and Biotechnology
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• v.33 no.1
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• pp.61-74
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• 2023

The global increase in multidrug-resistant (MDR) bacteria has inspired researchers to develop new strategies to overcome this problem. In this study, 23 morphologically different, soil-isolated actinomycete cultures were screened for their antibacterial ability against MDR isolates of ESKAPE pathogens. Among them, isolate BOGE18 exhibited a broad antibacterial spectrum, so it was selected and identified based on cultural, morphological, physiological, and biochemical characteristics. Chemotaxonomic analysis was also performed together with nucleotide sequencing of the 16S rRNA gene, which showed this strain to have identity with Streptomyces lienomycini. The ethyl acetate extract of the cell-free filtrate (CFF) of strain BOGE18 was evaluated for its antibacterial spectrum, and the minimum inhibitory concentration (MIC) ranged from 62.5 to 250 ㎍/ml. The recorded results from the in vitro anti-biofilm microtiter assay and confocal laser scanning microscopy (CLSM) of sub-MIC concentrations revealed a significant reduction in biofilm formation in a concentration-dependent manner. The extract also displayed significant scavenging activity, reaching 91.61 ± 4.1% and 85.06 ± 3.14% of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), respectively. A promising cytotoxic ability against breast (MCF-7) and hepatocellular (HePG2) cancer cell lines was obtained from the extract with IC₅₀ values of 47.15 ± 13.10 and 122.69 ± 9.12 ㎍/ml, respectively. Moreover, based on gas chromatography-mass spectrometry (GC-MS) analysis, nine known compounds were detected in the BOGE18 extract, suggesting their contribution to the multitude of biological activities recorded in this study. Overall, Streptomyces lienomycini BOGE18-derived extract is a good candidate for use in a natural combating strategy to prevent bacterial infection, especially by MDR pathogens.

• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.287-295
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• 2023

Iron nanoparticles (Fe-NPs) were synthesized employing Lagenaria siceraria (LS) leaf aqueous extract as a reducing and capping medium to remove methylene blue (MB) dye and have antibacterial properties against G-negative (Escherichia coli) and G-positive bacteria (Staphylococcus aureus). The formation of LS-Fe-NPs (Lagenaria-siceraria-iron-nanoparticles) was confirmed by a change in color from pale yellow to dark brown. Characterization techniques, such as particle size analysis (PSA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), were employed to prove nano spherical particles of size range between 80-100 nm. Phytochemicals and the presence of iron in LS-Fe-NPs nanoparticles were proved by UV-visible spectrophotometry. Further, Fourier transform infrared spectroscopy (FTIR) analysis results confirmed the existence of bioactive molecules in the plants. The magnetic property was analyzed using a vibrating sample magnetometer (VSM), which displayed that the synthesized nanoparticles were superparamagnetic and exhibiting a saturation magnetization of 12.5 emu/g. Synthesized magnetic nanoparticles were used in methylene blue (MB) dye removal through adsorption. About 83% of 100 mg/L MB dye was removed within 120 min at pH 6 with a maximum adsorption capacity of 246.8 mg/g. Antibacterial efficacy of LS-Fe-NPs was screened against G-negative (Escherichia coli) and G-positive bacteria (Staphylococcus aureus), respectively, and found that LS-Fe-NPs were effective against Staphylococcus aureus.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.67-67
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• 2018

Trichoderma species are a rich source of metabolites, but less known for biomedical potential. This work deals with antibacterial and antioxidant potentials of intracellular non-cytotoxic metabolites, extracted from Trichoderma atroviride (KNUP001). A total of 53 fractions was collected by column chromatography and tested for cytotoxicity by MTT assay. Only one fraction (F41) was found to be non-toxic to Vero cells with $95.4{\pm}0.61%$ of survival. The F41 was then subjected to chemical analysis, antibacterial and antioxidant assays. The F41 at $500{\mu}g.ml^{-1}$ showed the total antioxidant of $48.70{\pm}2.90%$, DPPH radical scavenging activity of $37.25{\pm}2.25$, nitric oxide (NO) radical scavenging activity of $54.55{\pm}1.95$ and $H_2O_2$ radical scavenging activity of $43.75{\pm}3.21$. The F41 at $25{\mu}g.ml^{-1}$ displayed antibacterial activity against E. coli ($14.25{\pm}0.2mm$), P. mirabilis ($10.4{\pm}0.6mm$), S. dysenteriae ($18.6{\pm}03mm$), S. paratyphi A ($14.1{\pm}1.1mm$), E. aerogenes ($5.6{\pm}0.4mm$) and S. marcescens ($14.25{\pm}0.2mm$). GC-MS analysis revealed the dominant presence of oleic acid C 18.1 (63.18%), n-hexadecanoic acid (6.17%), and ethyl oleate (4.93%) and potent molecules such as 8-[(2E)-2-(3-hydroxybenzylidene)hydrazinyl]-1,3,7-trimethyl-3,7-dihydro-1H-purine-2,6-dione, 2-(Dimethylamino)ethyl (1Z)-N-hydroxy-2-(4-morpholinyl)-2-oxoethanimidothioate, Fluorene in the F41, and virtual study revealed that these molecules are likely responsible for the antibacterial activities of F41. Hence, further investigation deserves on purification and characterization of the active metabolites from T. atroviride strain KNUP001 towards developing molecular leads to effective antibacterial drugs, and non-toxic to host cells.

• Journal of Microbiology and Biotechnology
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• v.11 no.6
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• pp.1061-1065
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• 2001

The antibacterial effects of water extracts of Scutellariate Radix (a dried root of Scutellaria baicalensis GEORGI) and its major flavonoid components, Baicalin and Baicalein, on Salmonella typhimurium, a representative enteric pathogen, were studied. Through a Kriby-Bauer disc analysis, the growth-inhibition activity of Scutellariae Radix against. S. typhimurium was found to be compatible with commercial antibiotics, such as ampicillin, chloramphenicol, and streptomycin. In contrast, the growth of a nonpathogenic E. coli strain was unaffercted by Scutellariae Radix. To examine the effect of polyphosphate kinase (ppk), a putative virulence factor, on the antibacterial activity of Scutellariae Radix, the growth profile of a ppk mutant of S. typhimurium was investigated in a tryptic soy broth containing different concentrations of water extracts of Scutellariae Radix. The ppk mutant was able to grow in 6 mg/ml of water extracts of Scutellariae Radix, whereas in 6 mg/ml of water extracts of Scutellariae Radix, whereas the wild-type could not, implying that the inactivation of ppk made S. typhimurium more resistant to the antibacterial activity of Scutellariae Radix. No enhanced resistance was observed in a ppk mutant of S. typhimurium complemented with a ppk expression vector. The attenuation of the virulence by ppk inactivation was also observed in a virulence assay using BLAB/c mice. Neither Baicalin nor Baicalein exhibited any growth-inhibition activity against S. typhimurium. The water extracts of Scutellariae Radix stimulated the transcription of ppk, especially in the early growth-stage of S. typhimurium.

• Microbiology and Biotechnology Letters
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• v.36 no.1
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• pp.82-85
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• 2008

Hyungbangjihwang-Tang (HT), an Oriental herbal formula, has been known to play a role which helps to recover vigor of human in the Orient. In this study, antibacterial substance (HTI) was purified from the ethyl-acetate extracts of HT by using $SiO_2$ column chromatography and HPLC, and the antibacterial effects of HTI were investigated. By using the CLSI broth micro-dilution assay, the activity of HTI was evaluated against human pathogenic Gram-positive and Gram-negative bacterial strains including the clinical isolates of methicillin-resistant Staphylococcus aureus. The results demonstrated that HTI showed broad spectrum antibacterial activities against all bacterial strains tested. In conclusion, HTI is an interesting new molecule for its potential in anti-infective drug discovery and for future studies on activity-structure relationship through analysis of its chemical structure.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.1038-1042
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• 2008

Mono and multilayer TiO2(Fe, $PEG_{600}$) films were deposited by the dip-coating on $SiO_2$/glass substrate using sol-gel method. In an attempt to improve the antibacterial properties of doped $TiO_2$ films, the influence of the iron oxides and polyethilenglycol ($PEG_{600}$) on the morphological, optical, surface chemical composition and biological properties of nanostructured layers was studied. Complementary measurements were performed including Spectroscopic Ellipsometry (SE), Scanning Electron Microscopy (SEM) coupled with the fractal analysis, X-Ray Photoelectron Spectroscopy (XPS) and antibacterial tests. It was found that different concentrations of Fe and $PEG_{600}$ added to coating solution strongly influence the porosity and morphology at nanometric scale related to fractal behaviour and the elemental and chemical states of the surfaces as well. The thermal treatment under oxidative atmosphere leads to films densification and oxides phase stabilization. The antibacterial activity of coatings against Escherichia Coli bacteria was examined by specific antibacterial tests.

• Bulletin of the Korean Chemical Society
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• v.24 no.10
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• pp.1478-1484
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• 2003

CRAMP was identified from a cDNA clone derived from a mouse femoral marrow cells as a member of cathelicidin-derived antimicrobial peptide. Tertiary structure of CRAMP in TFE/$H_2O$ (1 : 1, v/v) solution has been determined by NMR spectroscopy previously and consists of two amphipathic $\alpha-helices$ from Leu4 to Lys10 and from Gly16 to Leu33. These two helices are connected by a flexible region from Gly11 to Gly16. Analysis of series of fragments composed of various portion of CRAMP revealed that an 18-residue fragment with the sequence from Gly16 to Leu33 (CRAMP-18) was found to retain antibacterial activity without cytotoxicity. The effects of two Phe residues at positions 14 and 15 of CRAMP-18 on structure, antibacterial activity, and interaction with lipid membranes were investigated by $Phe^{14,15}$ ${\rightarrow}$ Ala substitution (CRAMP-18-A) in the present study. Substitution of Phe with Ala in CRAMP-18 caused a significant reduction on antibacterial and membrane-disrupting activities. Tertiary structures of CRAMP-18 in 50% TFE/$H_2O$ (1 : 1, v : v) solution shows amphipathic ${\alpha}$-helix, from $Glu^2{\;}to{\;}Leu^{18}$, while CRAMP-18-A has relatively short amphipathic ${\alpha}$-helix from $Leu^4{\;}to{\;}Ala^{15}$. These results suggest that the hydrophobic property of $Phe^{14}{\;}and{\;}Phe^15$ in CRAMP-18 is essential for its antibacterial activity, ${\alpha}$-helical structure, and interactions with phospholipid membranes.

• Microbiology and Biotechnology Letters
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• v.48 no.2
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• pp.148-157
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• 2020

Eucalyptus oil is a rich source of bioactive compounds with a variety of biological activities and is widely used in traditional medicine. Eucalyptus citriodora is cultivated for the production of essential oils. However, the mode of antibacterial action of essential oils from E. citriodora is not well-known. This study aimed to determine the chemical components, microbial inhibitory effect, and mechanism of action of the essential oil from E. citriodora. The oil was extracted from E. citriodora leaves by hydro-distillation and the chemical components were analyzed using gas chromatography-mass spectrometry. The antibacterial activities of eucalyptus oil against gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus, and Staphylococcus intermedius) and gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) were screened by disc diffusion method and quantitative analysis was conducted by the microdilution method. The mechanism of action of the extracted essential oil was observed using SEM and analyzed by SDS-PAGE. The major components of E. citriodora oil were citronellal (60.55 ± 0.07%), followed by dl-isopulegol (10.57 ± 0.02%) and citronellol (9.04 ± 0.03%). The antibacterial screening indicated that E. citriodora oil exhibited prominent activity against all tested strains. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against B. subtilis were 0.5% and 1.0%, respectively. The MIC and MBC concentrations against S. aureus, S. intermedius, E. coli, and P. aeruginosa were 1% and 2%, respectively. As observed by SEM, the antibacterial mechanism of E. citriodora oil involved cell wall damage; SDS-PAGE revealed decrease in protein bands compared to untreated bacteria. Thus, E. citriodora oil showed significant antimicrobial properties and caused cellular damage.

• Mycobiology
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• v.47 no.3
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• pp.335-339
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• 2019

Endophytic fungi have the ability to live inside the host plant tissues without causing neither symptoms of diseases/or harm. Opportunistic infections are accountable for majority of the outbreaks, thereby putting a burden on the health system. To investigate and characterize the bioactive compounds for the control of bacteria of clinical importance, extracts from endophytic fungi were isolated from indigenous South African medicinal plants. Extracts from endophytic fungi were isolated from 133 fungal strains and screened against Gram positive and negative bacteria namely Bacillus cereus, Escherichia coli, Enterococcus faecium, and E. gallinarum using disk diffusion. Furthermore, gas chromatography-mass spectrometry was performed to identify the bioactive compounds. Sixteen out of one hundred and thirty-three (12%) fungi extracts exhibited antibacterial properties against some of the selected bacteria. E. coli was found to be the most susceptible in contrast to E. faecium and E. gallinarum which were the most resistant. The isolate MHE 68, identified as Alternaria sp. displayed the greater spectrum of antibacterial activities by controlling selected clinical bacteria strains including resistant E. faecium and E. gallinarum. The chemical analysis of the extract from MHE 68 indicated that linoleic acid (9,12-octadecadienoic acid (Z,Z)) and cyclodecasiloxane could be accountable for the antibacterial activity. This is the first study conducted on the secondary metabolites produced by endophytic fungal strains isolated from the Pelargonium sidoides DC. possessing antibacterial properties.