Synthesis and antibacterial activities of 4-hydroxy-o-phenylphenol and 3,6-diallyl-4-hydroxy-o-phenylphenol against a cariogenic bacteriumStreptococcus mutans OMZ 176

For the purpose of survey of the antibacterial activity against a cariogenic bacterium Streptococcus mutans OMZ 176 with the introduction of hydroxyl and allyl groups to o-phenylphenol (Fig. 2, 1), 4-hydroxy-o-phenylphenol (2), and 3,6-diallyl-4-hydroxy-o-phenylphenol (4) were synthesized, successively. The synthesized compounds, 2 and 4 showed more potent antibacterial activity than the starting material, 1. The hydroxyl group was supposed to the essential element for the antibacterial activity and the introduction of allyl group to phenolic ring to be another element to increase the activity.     

Synergistic effect of lysozyme on bactericidal activity of magnolol and honokiol against a cariogenic bacterium,Streptococcus mutans OMZ 176

A combination of magnolol or honokiol with lysozyme isolated from the egg white of the Korean Ogol fowl (Korean natural monument No. 265) exhibited synergistic effect of bactericidal activity against a typical cariogenic bacterium,Streptococcus mutans OMZ 176. The synergistic ratio increased with time dependence.     

Isopanduratin A from Kaempferia pandurata as an active antibacterial agent against cariogenic Streptococcus mutans

An antibacterial compound active against Streptococcus mutans was isolated from Kaempferia pandurata and identified as isopanduratin A using 1H NMR, 13C NMR and EI-MS. The minimum inhibitory concentration (MIC) of isopanduratin A was 4 mg/l which was much lower than that of some other natural anticariogenic agents such as sanguinarine (12 mg/l), green tea extract and carvacrol (125 mg/l), thymol (250 mg/l) and isoeugenol and eucalyptol (500 mg/l). The bactericidal test showed that isopanduratin A completely inactivated S. mutans at 20 mg/l in 1 min. Significant inhibitory activity of isopanduratin A was also observed against S. sobrinus, S. sanguinis and S. salivarius with an MIC of 4 mg/l. Damage to the cell membrane and cell wall of S. mutans by isopanduratin A was shown using transmission electron microscopy (TEM). These results suggest that isopanduratin A could be employed as a potential antibacterial agent for preventing dental caries.     

Antibacterial substances from Albizia myriophylla wood against cariogenic Streptococcus mutans

Albizia myriophylla has been used for long by Thai traditional healers as an important ingredient herb in Thai herbal formulas for caries. In this study, three flavonoids lupinifolin (6), 8-methoxy-7,3′,4′-trihydroxyflavone (7), and 7,8,3′,4′-tetrahydroxyflavone (8), a triterpenoid lupeol (3) as well as four sterols β-sitosterone (1), stigmasta-5,22-dien-3-one (2), β-sitosterol (4), and stigmasterol (5) were isolated from A. myriophylla wood. The antibacterial activity of these compounds against Streptococcus mutans ATCC 25175 was performed using broth microdilution method. All compounds exhibited antibacterial activity against S. mutans with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) ranging from 1–256 and 2–256 μg/ml, respectively. Among the isolated compounds, lupinifolin (6) was found to be the most potent with MIC and MBC of 1 and 2 μg/ml, respectively. Lupinifolin (6) also showed a strong activity against ten clinical isolates of S. mutans with MIC and MBC ranging from 0.25–2 and 0.5–8 μg/ml, respectively. These results reported the bioactive ingredients of A. myriophylla which support its ethnomedical claims as well. Lupinifolin (6) may have a potential to be a natural anticariogenic agent.     

超声强化超临界流体萃取桂皮醛的工艺研究

目的对超声强化超临界流体(CO2)萃取肉桂中桂皮醛成分的工艺条件进行选择。方法采用超声超临界流体(CO2)萃取法,选取萃取温度、萃取压力、萃取时间和超声功率为因素,以桂皮醛为指标成份,采用正交试验对萃取方法进行优选。结果超临界萃取的最佳工艺条件为45℃,35 MPa,2 h,2 kW,桂皮醛平均提取率为18.76 mg/g。结论超声强化超临界技术提取肉桂挥发油中桂皮醛得率高于其他文献报道。该技术工艺合理,可行。     

Synthesis and evaluation of oxazaborolidines for antibacterial activity against Streptococcus mutans

Several representative oxazaborolidines have been synthesized and evaluated against S. mutans for antibacterial activity. This is the first reported antibacterial activity of this class of compounds. The minimal inhibitory concentration values ranged from 0.53 to 6.75 mM.     

Rational design of peptides with enhanced antimicrobial and anti‐biofilm activities against cariogenic bacterium Streptococcus mutans

Streptococcus mutans (S. mutans) is known to be a leading cariogenic pathogen in the oral cavity. Antimicrobial peptides possess excellent properties to combat such pathogens. In this study, we compared the antimicrobial activity of novel linear reutericin 6‐ and/or gassericin A‐inspired peptides and identified LR‐10 as the leading peptide. Antibacterial assays demonstrate that LR‐10 is more active against S. mutans (3.3 μM) than many peptide‐based agents without resistance selection, capable of killing many oral pathogens, and tolerant of physiological conditions. LR‐10 also presented a faster killing rate than chlorhexidine and erythromycin, and appeared to display selective activity against S. mutans within 10 s. S. mutans is usually encased in plaque biofilms. Biofilm inhibitory assays indicated that LR‐10 had excellent inhibitory effect on the biofilm formation of S. mutans and biofilm‐encased cells in vitro at low concentrations (6.5 μM). Consistent with most peptides, LR‐10 kills S. mutans mainly by disrupting the cell membranes. Notably, both hemolytic activity assays and cytotoxicity tests indicated that LR‐10 could keep biocompatible at the effective concentrations. Hence, LR‐10 could be a good candidate for clinical treatment of dental caries.     

In vitro antibacterial activity of the peptide PsVP-10 against Streptococcus mutans and Streptococcus sobrinus with and without glycocalyx

The antibacterial activity of the peptide PsVP-10 obtained from Pseudomonas sp. R10 against Streptococcus mutans and Streptococcus sobrinus was investigated. One hundred and twenty strains of S. mutans and 120 strains of S. sobrinus with and without glycocalyx were isolated from saliva samples in trypticase-yeast-cysteine-sucrose-bacitracin (TYCSB) agar. Bacterial identification was made by polymerase chain reaction. Glycocalyx production was observed in modified TYCSB agar and confirmed with a modified version of the microplate adherence assay. The minimum inhibitory concentration (MIC) of PsVP-10 bacteriocin was determined by means of the agar dilution method, and the time of bacterial death was calculated by means of colony-forming unit counts. The MIC of the bacteriocin PsVP-10 for both bacterial species with and without glycocalyx was < 2 mg/L and the time of bacterial death was less than 240 s for all the studied bacterial strains. Thus, bacteriocin PsVP-10 could be an interesting possibility to combat these cariogenic bacterial species.     

秦皮中化学成分的分离鉴定及其体外抑菌活性

目的研究中药秦皮(Fraxini Cortex)中的化学成分对耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)的体外抗菌活性。方法采用硅胶柱色谱、Sephadex LH-20柱色谱和制备液相色谱对秦皮的化学成分进行分离,通过理化性质和波谱方法鉴定其结构,运用微量稀释法和微量棋盘法进行体外抑菌活性测试。结果与结论从秦皮中分离得到16个已知化合物,分别为人参皂苷Rh1(1)、橄榄苦苷(2)、ligstroside(3)、plantainoside A(4)、calceolariolside A(5)、plantainoside B(6)、calceolariolside B(7)、秦皮啶(8)、苯甲酸(9)、大黄素(10)、5-羟甲基糠醛(11)、isolignstroside(12)、右旋松脂醇葡萄糖苷(13)、framoside(14)、木樨橄榄-11-甲酯(15)和hydroxyframoside A(16),其中,化合物1、4、6、10、11为首次从该植物中分离得到。化合物2、4、5、7、16具有显著的体外抑菌活性,体外对MRSA的最小抑菌浓度(MIC)分别为512、64、256、128、512 mg·L-1;化合物4与头孢唑林、头孢呋辛、青霉素均有协同作用。     

苦楝皮的化学成分

目的对中药苦楝皮(Melia azedarachL.Sied.)体积分数为95%的乙醇提取物的乙酸乙酯部位化学成分进行研究。方法采用硅胶柱色谱、Sephadex LH-20柱色谱等方法进行分离,利用理化性质和1H-NMR1、3C-NMR等谱学技术,对分离得到的化合物进行结构鉴定。结果从中分离得到6个化合物,其结构鉴定为羽扇豆醇(lupeol,1)、α-菠甾酮(-αspinasterone,2)、丁香树脂酚双葡萄糖苷(syringaresinol-di-O--βD-glucoside,3)、阿魏酸(ferulic acid,4)、β-谷甾醇(-βsitosterol,5)、胡萝卜苷(daucosterol,6)。结论化合物2、3和4均为首次从楝属植物中分离得到的已知化合物。     

The thuggacins, novel antibacterial macrolides from Sorangium cellulosum acting against selected Gram-positive bacteria

In our screening program we found an activity against some Gram-positive bacteria, including mycobacteria in the culture supernatant of Sorangium cellulosum strain So ce895. The antibiotic responsible for this activity was isolated and named thuggacin. Initial studies towards the mechanism of action showed that thuggacin A inhibits a late step of the respiratory chain of some bacteria.     

Dose-response evaluation of a copaiba-containing varnish against streptococcus mutans in vivo

Introduction

Dental caries is the most prevalent disease in humans and its incidence is particularly high during childhood. The use of medicinal plants is a common practice in Brazil.

The antibacterial activity of fluoroquinolones against gram-negative bacteria isolated from Gifu Prefecture (2005)

We investigated the susceptibility to 6 fluoroquinolones against 433 strains of Gram-negative bacteria isolated from 6 medical facilities in Gifu prefecture between January and September in 2005, determined by the agar dilution methods in according with the Japan Society of Chemotherapy. We also investigated the correlation between the degree of resistance to fluoroquinolones and the amino acid substitutions in the quinolone resistance-determining region (QRDR). The tested clinical isolates were as follows, Salmonella spp.; 17 strains, Escherichia coli; 112 strains Citrobacter freundii; 35 strains, Enterobacter cloacae; 31 strains, Klebsiella pneumoniae; 73 strains, Proteus spp.; 18 strains, Providencia spp.; 3 strains, Morganella morganii; 14 strains, Serratia marcescens; 27 strains and Pseudomonas aeruginosa; 103 strains. The number of the strains resistant to ciprofloxacin (CPFX) (MIC > or = 6.25 microg/mL) was twenty (E. coli; 14 strains, E. cloacae; I strain, Proteus spp.; 2 strains and P. aeruginosa; 3 strains). Among these strains, 12 strain (E. coli; 11 strains and E. cloacae; 1 strain) were highly resistant to CPFX (MIC > or =25 microg/mL). The E. coli strains highly resistant to CPFX had the multiple amino acid mutations in QRDR of ParC an GyrA. However in other strains, there was no strains possessing multiple mutations in both ParC and GyrA.     

黄柏等几种中草药对葡萄球菌的体外抗菌作用

目的 用新的中药抑菌实验方法进行黄柏、地榆、紫草及其不同配伍组方对120珠葡萄球菌的抗菌效果观察。方法 采用琼脂稀释法进行最低抑菌浓度（MIC）的测定。结果 黄柏、地榆、紫草对金黄色葡萄球菌和表皮葡萄球菌均有很好的抑菌作用，而且3种药物以一定比例混合后同样有很好的抑菌效果，当3者以1：1：2的比例配伍时抑菌效果优于单用黄柏、紫草或地榆。结论 黄柏、紫草、地榆及其不同配伍组方对葡萄球菌的抑菌效果均较好。     

Essential oils from Taiwan: Chemical composition and antibacterial activity against Escherichia coli

The chemical compositions of seven essential oils from Taiwan were analyzed by gas chromatography-mass spectrometry. The eluates were identified by matching the mass fragment patents to the National Institute of Standards and Technology (NIST) 08 database. The quantitative analysis showed that the major components of lemon verbena are geranial (26.9%) and neral (23.1%); those of sweet marjoram are γ-terpinene (18.5%), thymol methyl ether (15.5%), and terpinen-4-ol (12.0%); those of clove basil are eugenol (73.6%), and β-(Z)-ocimene (15.4%); those of patchouli are carvacrol (47.5%) and p-cymene (15.2%); those of rosemary are α-pinene (54.8%) and 1,8-cineole (22.2%); those of tea tree are terpinen-4-ol (33.0%) and 1,8-cineole (27.7%); and those of rose geranium are citronellol (28.9%) and 6,9-guaiadiene (20.1%). These components are somewhat different from the same essential oils that were obtained from other origins. Lemon verbena has the same major components everywhere. Tea tree, rose geranium, and clove basil have at least one major component throughout different origins. The major components and their amounts in sweet marjoram, patchouli, and rosemary vary widely from one place to another. These results demonstrate that essential oils have a large diversity in their composition in line with their different origins. The antibacterial activity of essential oils against Escherichia coli was evaluated using the optical density method (turbidimetry). Patchouli is a very effective inhibitor, in that it completely inhibits the growth of E. coli at 0.05%. Clove basil and sweet marjoram are good inhibitors, and the upper limit of their minimum inhibitory concentration is 0.1%.     

In vitro antimicrobial activity of a chitooligosaccharide mixture against Actinobacillus actinomycetemcomitans and Streptococcus mutans.

The purpose of this study was to evaluate the in vitro antibacterial activity of a chitooligosaccharide mixture (MW 2000–30 000 Da) with a deacetylation degree of 91.5% against two representative oral pathogens, Actinobacillus actinomycetemcomitans and Streptococcus mutans. A 0.1% concentration of the chitooligosaccharides (derived from the exoskeletons of marine crustaceans) was used to estimate antibacterial activity. Approximately 2 log colony forming units (CFU)/ml of A. actinomycetemcomitans were inactivated by 0.1% chitosan after 30 min, while 120 min exposure inactivated about 4.5 log CFU/ml of this organism. In contrast, the level of inactivation against S. mutans was less than 0.5 log CFU/ml after an exposure of up to 120 min. Electron microscopy showed that the exposure of A. actinomycetemcomitans to the chitooligosaccharides resulted in the disruption of cell membranes and that it could be considered for the treatment of periodontal diseases associated with A. actinomycetemcomitans.     

3-aminoquinazolinediones as a new class of antibacterial agents demonstrating excellent antibacterial activity against wild-type and multidrug resistant organisms

The 3-aminoquinzolinediones represent a new series of antibacterial agents structurally related to the fluoroquinolones. They are inhibitors of bacterial gyrase and topoisomerase IV and demonstrate clinically useful antibacterial activity against fastidious Gram-negative and Gram-positive organisms, including multidrug- and fluoroquinolone-resistant organisms. These agents also demonstrate in vivo efficacy in murine systemic infection models.     

盐酸左氧氟沙星对325株分离细菌的体外抗菌活性研究

目的：研究左氧氟沙星的体外抗菌活性作用。方法：采用平板双倍稀释法测定盐酸左氧氟沙星的体外抗菌活性,并与其它2种常用氟喹诺酮类抗菌药物进行比较。结果：结果表明：盐酸左氧氟沙星的抗菌活性强,抗菌谱广。对金葡球菌、表葡球菌和肺炎链球菌的MIC90值分别为16mg/L,32mg/L,2mg/L,是氧氟沙星和环丙沙星的1／2－1／4,抑菌率为82．5％－94．7％;对大肠埃希氏菌、铜绿假单孢菌等革兰氏阴性菌的MIC50值为＜0．03mg/L-0.25mg/L,是氧氟沙星和环丙沙星的1／2－1／4,抑菌率为92．9％－100％。结论：盐酸左氧氟沙星是一种广谱菌药物。     

Neuroprotective effects of neolignans isolated from Magnoliae Cortex against glutamate-induced apoptotic stimuli in HT22 cells

In the course of screening for neuroprotective natural products, Magnoliae Cortex showed potent inhibition of hippocampal neuronal HT22 cell death. Obovatol, honokiol, and magnolol were isolated from the ethanolic extract of Magnoliae Cortex. Isolated compounds obovatol, honokiol, and magnolol were protective against 5 mM glutamate-induced cell death. When cells were stressed using glutamate, cell viability decreased to 16.98 ± 4.58% over the control (100.00 ± 10.15%). In contrast, 10 μM obovatol, 10 μM honokiol, and 50 μM magnolol increased cell viability to 91.80 ± 1.70%, 93.59 ± 1.93%, and 85.36 ± 7.40%, respectively. The neuroprotective effects of obovatol and honokiol were attributable to the inhibition of intracellular reactive oxygen species production, followed by protection of the mitochondrial membrane potential (ΔΨ_m), recovery of Bcl-2 and Bid levels, inhibition of apoptosis-inducing factor expression, and phosphorylation of mitogen-activated protein kinases such as p38 kinases, extracellular signal-regulated kinases, and c-Jun N-terminal kinases. On the contrary, magnolol did not show any significant effect on the ΔΨ_m and apoptotic factors. Among three compounds, obovatol most strongly scavenged 2,2-diphenyl-1-picrylhydrazyl radicals and inhibited the elevation of intracellular reactive oxygen species levels in glutamate-stressed HT22 cells. These data suggest that obovatol and honokiol may have clinical applications for preventing neurodegenerative disorders.