• 한국자원식물학회지
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• 제29권6호
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• pp.699-703
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• 2016

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious clinical and an urgent problem worldwide. Few new drugs are available against MRSA, because MRSA has the ability to acquire resistance to most antibiotics, which consequently increases the cost of medication. In the present study, the antibacterial activity of Hydnocarpi Semen was investigated. The most effective method is to develop antibiotics from the natural products without having any toxic or side effects. Therefore, there is a need to develop alternative antibacterial drugs for the treatment of infectious diseases. Five Clinical isolates (MRSA) were obtained from five different patients at Wonkwang University Hospital (Iksan, South Korea). The Other 2 strains were ATCC 33591 (Methicillin-resistant strain) and ATCC 25923 (Methicillin-susceptible strain). Antibacterial activity (Minimal Inhibitory Concentrations, MICs) was determined by broth dilution method, disk diffusion method, MTT test, and checkerboard dilution test. Antibacterial activity of n-hexane fraction was remarkable, and had a MICs ranging from $31.25-125{\mu}g/m{\ell}$. FICI values for HFH+AM and HFH+OX were 0.13-0.19 and 0.04-0.29, showing the increase of synergistic effect. When combined together, these antibacterial effects were dramatically increased.

• Journal of Microbiology and Biotechnology
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• 제20권3호
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• pp.501-505
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• 2010

1-Acetyl-$\beta$-carboline was isolated as an anti-MRSA agent from the fermentation broth of a marine actinomycete isolated from marine sediment. The producing strain was identified to be Streptomyces sp. by phylogenetic analysis of the 16S rRNA gene sequence. The anti-MRSA agent was isolated by bioactivity-guided fractionation of the culture extract by solvent partitioning, ODS open flash chromatography, and purification with a reversed-phase HPLC. Its structure was elucidated by extensive 2D NMR and mass spectral analyses. Combination of 1-acetyl-$\beta$-carboline with ampicillin exhibited synergistic antibacterial activity against MRSA.

• 대한수의학회지
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• 제50권4호
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• pp.279-284
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• 2010

Combination therapy of antibiotics is leading to improved efficacy or safety profiles with decrease emergence of bacterial resistance. Because of this benefit, many of antibacterial combinations have been used in veterinary practice for the past few decades. The purpose of this study was to examine the in vitro activity of an amoxicillin alone and in combination with other antibiotics against pathogenic bacteria of fish origin. Based on the fractional inhibitory concentration (FIC) index (FIC $$\leq_-$$ 0.5), a synergistic interaction was shown in combination of florfenicol with amoxicillin or cefuroxime. The combination of florfenicol and amoxillin showed higher antibacterial activity than that of florfenicol and cefuroxime. Ratio of amoxicillin and florfenicol in combination was 1 : 1, which showed the antibacterial activity against bacterial isolates of fish as compared with other ratios. A synergetic effect of the combination (amoxicillin and florfenicol) was further confirmed in the time-kill curve study. The study showed a better in vitro antibacterial activity of a 1 : 1 combination of amoxicillin and florfenicol than the individual antibacterial against bacterial isolates of fish. In conclusion, the combination of florfenicol and amoxicillin may serve as a potential antibacterial therapy in fishes infected pathogenic bacteria.

• Mycobiology
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• 제29권1호
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• pp.11-14
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• 2001

A preparation of water soluble components(EA) was made from carpophores of Elfvingia applanata(Pers.) Karst and its in vitro antibacterial activity on a number of bacterial species was examined by macrobroth dilution assay. Among 16 species of bacteria tested, the most potent antibacterial activity was observed against Staphylococcus epiderrnidis and Proteus vulgaris, of which MICs were 1.25 mg/ml. To investigate the antibacterial effects in combinations of EA with quinolone antibiotics, such as ciprofloxacin, enoxacin, lomefloxacin, norfloxacin, and ofloxacin, the fractional inhibitory concentrations(FICs) and the fractional inhibitory concentration indices(FICIs) for four bacterial strains were determined by macrobroth dilution checkerboard assay. Combinations of EA and quinolones exhibited either additive or indifferent effects of antibacterial activity in most instances. However, both synergistic and antagonistic effects were not observed in any cases.

• Journal of Applied Biological Chemistry
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• 제65권2호
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• pp.101-105
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• 2022

양파의 주요 flavonoid 성분인 quercetin에 대한 항균 활성은 일부 알려져 있으나, 식물 병원성 세균인 X. campestris와 E. carotovora에 대한 활성은 알려져 있지 않았다. 본 연구에서는 quercetin과 양파 추출물을 활용하여 이들 식물병원균에 대한 항균 활성과 농용 항생제인 streptomycin과의 synergistic 효과를 평가하였으나, E. carotovora에 대한 항균 활성은 없었다. 하지만, X. campestris에서는 다른 세균류에서 알려진 MIC보다 10배 이상 낮은 15.6 ㎍ mL^-1이었으며, MBC는 20.0 ㎍ mL^-1으로 X. campestris에 대해 높은 선택적 항균 활성을 확인할 수 있었다. 다만, 농업용 항생제로 사용중인 streptomycin과의 약효상승 효과는 없었다. 또한, quercetin은 양파껍질의 EtOAc와 EtOH 추출물로부터 확보할 수 있었으며, EtOAc 추출물에서 quercetin 순도가 높음을 확인하였고, 이에 따라 EtOH 추출물보다 2배 가량 높은 항균 활성(MIC = 500 ㎍ mL^-1)이 확인되었다.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1576-1581
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• 2009

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has led to an urgent need for the discovery and development of new antibacterial agents. As part of an ongoing investigation into the antibacterial properties of natural products, 20-hydroxyecdysone (20E), isolated from the roots of Achyranthes japonica Nakai, was found to be active against MRSA, either alone or in combination with ampicillin (AM) or gentamicin (GM), via checkerboard assay. This study investigated the antibacterial activity of 20E, which exhibited poor antibacterial activity ($MIC=250-500\;{\mu}g/ml$) against MRSA tested. The combined activity of AM or GE plus 20E against MRSA resulted in fractional inhibitory concentractions (FICs) ranging from 4.00 to $0.031\;{\mu}g/ml$, respectively. Meanwhile, the FIC index ranged from 0.16-4.50, indicating a marked synergistic relationship between AM, GE, and 20E against MRSA. Time-kill assays also showed a remarkable decrease between the combination and the more active compound. Therefore, this study demonstrated that AM, GE, and 20E can act synergistically in inhibiting MRSA in vitro.

• Archives of Pharmacal Research
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• 제12권2호
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• pp.114-118
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• 1989

The effects of intraperitoneal injection of cephradine in a dose of 75 mg/kg and netilmicin in dose of 50 mg/kg and their combination on creatinine and urea serum levels of rabbits were studied as well as the antipseudomonal activity against three multiresistant clinicial isolates. The antibacterial activity was investigated by two methods: Checkerboard titration method and time-kill studies. Finally, the antibacterial activity of the sera obtained from the rabbits receiving the used drugs in the previous regimen was studied using time-kill study method against Pseudomonas aeruginosa isolates. Results obtained from this study indicated that both creatinine and urea serum levels of the rabbits receiving both drugs were not significantly different from those of the rabbits receiving either cephradine or netilmicin alone. At the same time the in vitro antibactrial activity (either of the prepared solutions of the used drugs and their combination or of the sera obtained from the rabbits receiving these drugs as mentioned before) showed a synergistic effect against the tested strains of Pseudomonas aeruginosa

• Journal of Microbiology and Biotechnology
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• 제20권1호
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• pp.82-87
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• 2010

Biotransformation is often used to improve chemical activity. We evaluated the antimicrobial activity of rhapontigeuin, converted from rhapontin after treatment with Pectinex. Rhapontigenin showed 4-16 times higher antimicrobial activity than rhapontin. The activity was higher against Gram-positive strains than Gram-negative strains. Minimum inhibitory concentrations (MICs) of rhapontigenin, retinol, and five antibiotics were determined by the microbroth dilution method for antibiotic-sensitive and -resistant Propionibacterium acnes. We also investigated the in vitro antibacterial activity of rhapontigenin in combination with antibiotic against antibiotic-resistant P. acnes. The antibiotic combination effect against resistant P. acnes was studied by the checkerboard method. The combination formulations (rhapontigenin and clindamycin, retinol and clindamycin) showed synergistic effects on the inhibition of the growth of clindamycin-resistant P. acnes. It is predictable that the combination of antibiotics with rhapontigenin is helpful to treat acne caused by antibiotic-resistant P. acnes. The antibacterial activity of rhapontigenin was enhanced by biotransformation.

• 생약학회지
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• 제31권4호
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• pp.407-411
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• 2000

Antibacterial activities of magnolol (MGL) and honokiol (HKL) in combination with four representative antibiotics-amoxicillin (AMPC), oxytetracyclin (OTC), gentamicin (GM) and chloramphenicol (CAP)-were evaluated against four bacterial strains. When tested by disk-plate method, five out of eight combinations such as HKL-AMPC, HKL-CAP, MGL- AMPC, MGL-OTC, and MGL-CAP showed additive to synergistic interaction against gram- negative bacterium Salmonella typhimureum. Of these, MGL-AMPC combination turned out to be antagonistic against Sarcina lutea and Bacillus thurungiensis. Against these two grain-positive bacteria, only HKL-GM combination showed additivity to synergism. All the other combinations showed no interactions. Despite these results, however, no synergism was observed in checkerboard titration assay.

• 대한약침학회지
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• 제25권2호
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• pp.101-105
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• 2022

Objectives: This study aims to determine the Fractional Inhibitory Concentration Index (FICI) of combinations of Melastoma malabathricum leaf fraction with ciprofloxacin or gentamicin against pathogenic bacteria, Escherichia coli, Staphylococcus aureus, and Bacillus cereus, isolated from Diabetic Foot Ulcer (DFU) patients. Methods: We tested concentrations of 45%, 55%, 65%, and 75% of gentamicin and ciprofloxacin using dilution and agar diffusion methods. The combination of M. malabathricum leaf extract with these antibiotics was tested in vitro against all three bacteria. Results: The combination of M. malabathricum leaf extract and ciprofloxacin gave a FICI value of 0.5, indicating synergistic antibacterial activity against the test bacteria. Conclusion: The results show that the antibacterial effect of a combination of high doses of the leaf extract with either antibiotic is greater than that of the leaf extract and the antibiotics in single use.