• Food Science and Biotechnology
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• 제17권2호
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• pp.402-407
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• 2008

The synergistic antimicrobial effect of Achyranthes japonica Nakai (AJN) and Bifidobacterium extracellular factors against Clostridium difficile were measured using a turbidity method. Each broth supernatant of Bifidobacterium infantis ($68.8{\pm}0.02%$) and Bifidobacterium adolescentis ($33.2{\pm}0.2%$) obtained by adding ethyl acetate soluble fractionate from A. japonica Nakai ethanolic extracts (AJNEA, 100 ppm, no inhibition) showed high synergistic antimicrobial activity against C. difficile. In addition, the antimicrobial activity in a laboratory medium and yogurt products against C. difficile were evaluated. In yogurt prepared with a starter 5 (Lactobacillus acidophilus: Streptococcus thermophilus: B. adolescentis =1 : 1 : 1) and a starter 4 (L. acidophilus: S. thermophilus: B. infantis=1 : 1 : 1) and 0.5% AJNEA powder, high antimicrobial effects were recorded that measured 79.0 and 65.2%, respectively. The results indicated the potential of AJN extract for use as an antimicrobial agent. In addition, the efficiency of the antimicrobial activity of the extracts was further improved in combination with lactic acid bacteria, which suggests that they have the potential to be used as a highly effective antibiotic-tolerant microorganism prevention system. Such a strategy can be used for alternative drugs or functional food additives for treatment of antibiotic-associated diarrhea.

• Journal of Microbiology and Biotechnology
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• 제28권11호
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• pp.1814-1822
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• 2018

Most people use cosmetics to protect their skin. Preservatives are often used to prevent their contamination upon use. There has been a great demand for natural preservatives due to recent reports on the side effects of parabens. Therefore, we evaluated the antimicrobial activities of Lonicera japonica and Magnolia obovata extracts and determined their potential as natural preservatives. We found that the 50% ethanol extract from L. japonica had antibacterial activity only against S. aureus and P. aeruginosa, while the ethyl acetate fraction showed antimicrobial activity against all six microbial strains tested. On the other hand, the 70% ethanol extract and the ethyl acetate fraction from M. obovata showed antimicrobial activity against all six strains. A synergistic effect against S. aureus, B. subtilis, and C. albicans was confirmed when two ethyl acetate fractions having antimicrobial activity against all six strains were used in combination. Synergistic activity against B. subtilis was also confirmed through kill-time analysis. High-performance liquid chromatography was performed to identify the components of each extract. Based on the minimum inhibitory concentration and the results of a disc diffusion assay, we confirmed that caffeic acid and luteolin influenced the antimicrobial activity of L. japonica and that the antimicrobial activity of M. obovata was influenced by the interaction of magnolol and honokiol with other components. Therefore, this study suggests that the combination of L. japonica and M. obovata extracts may be used as a plant-derived natural preservative.

• 디지털융복합연구
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• 제14권8호
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• pp.547-553
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• 2016

본 연구에서는 피부상재균을 대상으로 단일오일의 항균효과를 살펴보는 동시에 2가지 이상의 오일을 혼합한 블랜딩 오일이 실제로 상승효과를 일으키는지 탐색해보고자 하였다. 항균실험에 사용된 에센셜 오일은 100% 유칼립투스(EU), 레몬(LE), 라벤더(LA) 오일이었으며, 2가지 오일 블랜딩의 상승효과를 알아보기 위하여 EU+LE, LE+LA, EU+LA을 1:1의 비율로, 3가지 오일 블랜딩의 상승효과를 알아보기 위해 각 오일을 1:1:1 비율로 혼합하여 배지의 표피포도상구균에 적용한 후 항균 영역 값을 평균 비교하였다. 그 결과, 단일오일에서는 LE이 가장 높은 항균력을 보였으며, LA는 가장 낮은 항균력을 보였다. 2가지오일 블랜딩에서는 EU+LA의 항균력이 단일오일의 항균력의 합보다 커 상승효과를 나타내었다. 그러나 3가지 오일 블랜딩의 항균효과는 아주 낮게 나타나 상승효과를 나타내지 않았다. 이러한 결과는 블랜딩 한 오일의 수 보다 오일을 구성하는 화학 성분들 간의 상호작용이 상승효과에 더욱 중요한 영향을 미친다는 것을 보여주었다. 따라서, 본 연구를 토대로 에센셜 오일 블랜딩에 대한 과학적 증거 마련이 더욱 필요할 것이라 사료된다.

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2577-2583
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• 2011

We have designed a 20-residue hybrid peptide CA(1-8)-MA(1-12) (CAMA) incorporating residues 1-8 of cecropin A (CA) and residues 1-12 of magainin 2 (MA) with high bacterial cell selectivity. CAMA-P2 is an ${\alpha}$-helical antimicrobial peptide designed from a CAMA hybrid peptide and substitution of Gly-Ile-Gly hinge sequence of CAMA to Pro influences the flexibility at central part of CAMA. Based on structure-activity relationships of CAMA peptides, to investigate the effects of the total positive charges on antimicrobial activity of CAMA-P2, the $Ser^{14}{\rightarrow}$Lys analogue (CAMA-syn1) was synthesized. The role of tryptophan at C-terminal ${\alpha}$-helix on its antimicrobial activity as well as synergistic activity was also investigated using $Ser^{14}{\rightarrow}$Lys/$Phe^{18}{\rightarrow}$Trp analogue (CAMA-syn2). Also, we designed CAMA-syn3 by substitution of $Lys^{16}$ located opposite side of substituted $Lys^{14}$ of CAMA-syn1 with Leu residue, resulting in increase of hydrophobicity and amphipathicity of the peptide. All of CAMA-syn analogues showed good antimicrobial activities similar to those of CAMA and CAMA-P2. The CAMA-syn1 and CAMA-syn2 showed low hemolytic activity and cytotoxicity against human keratinocyte Haca-T cells while CAMA-syn3 showed hemolytic activity and cytotoxicity at its MIC value. We then investigated their abilities to act synergistically in combination with the antimicrobial flavonoids and synthetic compounds screened in our laboratory. The results showed that all peptides exhibited synergistic effects with dihydrobinetin, while only CAMA-syn2 exhibited synergistic effects with YKAs3001 against both S. aureus and MRSA, suggesting that Trp residue at C-terminus of CAMA-syn2 may facilitate the polar antibiotic flavonoids and synthetic compounds to permeabilize the membrane. This study will be useful for the development of new antibiotic peptides with potent antimicrobial and synergistic activity but without cytotoxicity.

• 대한본초학회지
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• 제31권5호
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• pp.93-98
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• 2016

Objectives : Hwangheuk-san is a complex prescription composed of oriental traditional medicine and has been reported for antioxidant, antimicrobial and anticancer effects in the recent study. Methicillin-resistant Staphylococcus aureus (MRSA) is one of important causes of fatal infectious diseases such as septicemia, endocarditis, toxic shock syndrome, pneumonia, skin and soft tissue infections (SSTIs). S. aureus is reported as being for a variety of human diseases and its epidemiological relevance is mainly due to their ability of becoming highly resistant to common antimicrobials such as tetracycline, penicillin, cphalosporin and aminoglycoside. The objective of this study is to determine the antimicrobial effect of Hwangheuk-san ethanol extracts (HHS) and synergistic effects with antibiotics oxacillin against MRSA.Methods : The antimicrobial activity of HHS was measured by the disc diffusion method, broth microdilution method and the checkerboard dilution test, time-kill curve assay was performed to investigate synergistic effects with antibiotics oxacillin against MRSA.Results : HHS showed antimicrobial activity against MRSA with a MIC value of 125 ㎍/㎖. In the checkerboard test, the interaction of HHS with antibiotics oxacillin produced almost synergy or partial synergy against MRSA. This study showed that HHS reduced the MICs of oxacillin tested, and a remarkable antibacterial effect of HHS, with membrane permeability enhancers.Conclusions : These results suggest that HHS has the antimicrobial effect and synergistic effects with antibiotics oxacillin against MRSA. This study thus can be a valuable source for the development of a new drug with low MRSA resistance.

• 한국식품과학회지
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• 제31권1호
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• pp.206-211
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• 1999

천연에서 발견되는 휘발성 물질인 isothiocyanate계(ITCs) 물질을 대상으로 Listeria monocytogenes, Bacillus subtilis, Pseudomonas fluorescens, Escherichia coli, Erwinia carotovora, Saccharomyces cerevisiae, Candida albicans, Aspergillus oryzae and Penicillium roqueforti 등 9종의 균주에 대한 증식 억제 효과를 측정하였으며 초산과 혼합하여 사용할 때 상승효과를 비교하였다. Allyl isothiocyanate (AIT), benzyl isothiocyanate (BIT) 및 ethyl isothiocyanate (EIT)가 대상 균주 모두에 $100{\sim}200\;{\mu}g/dish$ 수준의 최소증식저해농도(MIC)를 보였고 증식 저해 정도는 곰팡이>효모>Gram 음성 세균>Gram 양성 세균 순 이었다. 초산은 $50{\sim}500\;{\mu}g/dish$로 ITCs 보다 MIC가 낮았다. ITCs와 초산을 혼합하여 사용하는 경우 대부분의 실험 대상 균주에 대하여 증식 저해 상승효과가 인정되었고 AIT의 경우 AIT 단독 또는 초산 단독으로 사용할 때보다 $2{\sim}10$배 이상 효과가 상승하였으며 전체적으로 증식 억제 경향은 ITCs 단독 사용할 때와 같은 경향이었다.

• Journal of Microbiology and Biotechnology
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• 제17권5호
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• pp.858-864
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• 2007

This study investigated the antibacterial activities of sophoraflavanone G from Sophora flavescens in combination with two antimicrobial agents against oral bacteria. The combined effect of sophoraflavanone G and the antimicrobial agents was evaluated using the checkerboard method to obtain a fractional inhibitory concentration(FIC) index. The sophoraflavanone G+ampicillin(AM) combination was found to have a synergistic effect against S. mutans, S. sanguinis, S. sobrinus, S. gordonii, A. actinomycetemcomitans, F nucleatum, P. intermedia, and P. gingivalis, whereas the sophoraflavanone G+gentamicin(GM) combination had a synergistic effect against S. sanguinis, S. criceti, S. anginosus, A. actinomycetemcomitans, F nucleatum, P. intermedia, and P. gingivalis. Neither combination exhibited any antagonistic interactions(FIC index>4). In particular, the MICs/MBCs for all the bacteria were reduced to one-half$\sim$one-sixteenth as a result of the drug combinations. A synergistic interaction was also confirmed by time-kill studies for nine bacteria where the checkerboard suggested synergy. Thus, a strong bactericidal effect was exerted through the drug combinations, plus in vitro data suggested that sophoraflavanone G combined with other antibiotics may be microbiologically beneficial rather than antagonistic.

• Journal of Microbiology and Biotechnology
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• 제32권12호
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• pp.1537-1546
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• 2022

Staphylococcus aureus is a cause of high mortality in humans and therefore it is necessary to prevent its transmission and reduce infections. Our goals in this research were to investigate the frequency of methicillin-resistant S. aureus (MRSA) in Taif, Saudi Arabia, and assess the relationship between the phenotypic antimicrobial sensitivity patterns and the genes responsible for resistance. In addition, we examined the antimicrobial efficiency and application of silver nanoparticles (AgNPs) against MRSA isolates. Seventy-two nasal swabs were taken from patients; MRSA was cultivated on Mannitol Salt Agar supplemented with methicillin, and 16S rRNA sequencing was conducted in addition to morphological and biochemical identification. Specific resistance genes such as ermAC, aacA-aphD, tetKM, vatABC and mecA were PCR-amplified and resistance plasmids were also investigated. The MRSA incidence was ~49 % among the 72 S. aureus isolates and all MRSA strains were resistant to oxacillin, penicillin, and cefoxitin. However, vancomycin, linezolid, teicoplanin, mupirocin, and rifampicin were effective against 100% of MRSA strains. About 61% of MRSA strains exhibited multidrug resistance and were resistant to 3-12 antimicrobial medications (MDR). Methicillin resistance gene mecA was presented in all MDR-MRSA strains. Most MDR-MRSA contained a plasmid of > 10 kb. To overcome bacterial resistance, AgNPs were applied and displayed high antimicrobial activity and synergistic effect with penicillin. Our findings may help establish programs to control bacterial spread in communities as AgNPs appeared to exert a synergistic effect with penicillin to control bacterial resistance.

• Food Science and Biotechnology
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• 제14권3호
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• pp.311-316
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• 2005

This study was performed to investigate the antimicrobial effect of Sophora angustifolia extracts against food-borne pathogens. First, Sophora angustifolia was extracted with methanol at room temperature, and the methanol extracts from Sophora angustifolia were fractionated using petroleum ether, chloroform, ethyl acetate, and methanol. The antimicrobial activity of the Sophora angustifolia extracts was determined using the paper disc method against food-borne pathogens and food spoilage bacteria. The methanol extracts of Sophora angustifolia showed the highest antimicrobial activity against Staphylococcus aureus and Salmonella typhimurium. A synergistic effect was found in the combined extracts of Sophora angustifolia and Portulaca oleracea, compared to the activity of each extract alone. Finally, the growth inhibition curve was determined using the methanol extracts of Sophora angustifolia against Staphylococcus aureus and Salmonella typhimurium. The methanol extract of Sophora angustifolia showed strong antimicrobial activity against Staphylococcus aureus at a concentration of 5,000 ppm. The 5,000 ppm methanol extract from Sophora angustifolia retarded the growth of S. aureus for more than 24 hours and of Salmonella typhimurium for up to 12 hours.

• Journal of Microbiology and Biotechnology
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• 제23권7호
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• pp.953-958
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• 2013

Selaginella tamariscina is a traditional herb used in medicine. Phytochemical amentoflavone, a biflavonoid class of flavonoids, was isolated from the plant of Selaginella tamariscina. In this study, the antibacterial effects and combination effects of amentoflavone and conventional antibiotics such as ampicillin, cefotaxime, and chloramphenicol were investigated. These results showed that amentoflavone had a considerable antibacterial effect and synergistic interaction with antibiotics against various bacterial strains (fractional inhibitory concentration index ${\leq}$ 0.5), except for Streptococcus mutans. To study the mechanism(s) involved in the synergistic activities between amentoflavone and antibiotics, we detected hydroxyl radical formation using 3'-(p-hydroxyphenyl) fluorescein and measured the $NAD^+/NADH$ ratio by $NAD^+$ cycling assay. The results indicated that the formation of hydroxyl radical would be a cause of the synergistic effect and that this oxidative stress originated from a transient NADH depletion. This study suggests that amentoflavone synergizes with antibiotics and has potential as a therapeutic agent for antimicrobial chemotherapy.