Antimicrobial studies on three species of Hypericum from the Canary Islands

The antimicrobial activity of several extracts and fractions of the aerial parts of Hypericum canariense, Hypericum glandulosum and Hypericum grandifolium was investigated using the disc diffusion and broth microdilution methods against twelve reference microorganisms (eight bacterial and four fungal strains). The methanol extract and chloroform fraction of H. canariense, as well as the methanol extracts, butanol and chloroform fractions of both H. glandulosum and H. grandifolium exhibited a good antibacterial activity against four Gram-positive bacteria (Bacillus cereus var. mycoides, Micrococcus luteus, Staphylococcus aureus and Staphylococcus epidermidis) and the Gram-negative bacterium Bordetella bronchiseptica with the diameters of growth inhibition area in the range 10-25 mm and MICs values between 0.03 and 0.29 mg/ml. Neither the infusions and aqueous fractions of the species studied nor the butanol fraction of H. canariense showed any antibacterial activity against the tested microorganisms. Amongst the active extracts, the minimum inhibitory concentration (MIC) determination showed that the H. canariense chloroform fraction was the most active against M. luteus, S. aureus and S. epidermidis. No antifungal activity was seen with any of the extracts or fractions tested. The results of this study support the use of these species in Canarian traditional medicine to treat skin infections.     

Synergistic antibacterial activity between Thymus vulgaris and Pimpinella anisum essential oils and methanol extracts

Essential oils (EOs) and methanol extracts obtained from aerial parts of Thymus vulgaris and Pimpinella anisum seeds were evaluated for their single and combined antibacterial activities against nine Gram-positive and Gram-negative pathogenic bacteria: Staphylococcus aureus, Bacillus cereus, Escherichia coli, Proteus vulgaris, Proteus mirabilis, Salmonella typhi, Salmonella typhimurium, Klebsiella pneumoniae and Pseudomonas aeruginosa. The essential oils and methanol extracts revealed promising antibacterial activities against most pathogens using broth microdilution method. Maximum activity of Thymus vulgaris and Pimpinella anisum essential oils and methanol extracts (MIC 15.6 and 62.5mug/ml) were observed against Staphylococcus aureus, Bacillus cereus and Proteus vulgaris. Combinations of essential oils and methanol extracts showed an additive action against most tested pathogens especially Pseudomonas aeruginosa.     

Evaluation of the flora of northern Mexico for in vitro antimicrobial and antituberculosis activity

The aim of the present study was to evaluate the potential antimicrobial activity of 14 plants used in northeast México for the treatment of respiratory diseases, against drug-sensitive and drug-resistant strains of Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae type b and Mycobacterium tuberculosis. Forty-eight organic and aqueous extracts were tested against these bacterial strains using a broth microdilution test. No aqueous extracts showed antimicrobial activity, whereas most of the organic extracts presented antimicrobial activity against at least one of the drug-resistant microorganisms tested. Methanol-based extracts from the roots and leaves of Leucophyllum frutescens and ethyl ether extract from the roots of Chrysanctinia mexicana showed the greatest antimicrobial activity against the drug-resistant strain of Mycobacterium tuberculosis; the minimal inhibitory concentration (MIC) were 62.5, 125 and 62.5 microg/mL, respectively; methanol-based extract from the leaves of Cordia boissieri showed the best antimicrobial activity against the drug-resistant strain of Staphylococcus aureus (MIC 250 microg/mL); the hexane-based extract from the fruits of Schinus molle showed considerable antimicrobial activity against the drug-resistant strain of Streptococcus pneumoniae (MIC 62.5 microg/mL). This study supports that selecting plants by ethnobotanical criteria enhances the possibility of finding species with activity against resistant microorganisms.     

In vitro antibacterial activity of roselle calyx and protocatechuic acid

The in vitro inhibitory effect of roselle calyx and protocatechuic acid, a compound derived from roselle calyx, on the growth of methicillin-resistant Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii was studied. The data from inhibition zone and minimum inhibitory concentration (MIC) values showed that both roselle calyx extract and protocatechuic acid inhibited effectively the growth of all test bacterial pathogens, the antibacterial activity of protocatechuic acid being significantly greater than roselle calyx (p < 0.05). Furthermore, heat treatment did not affect the antibacterial activity of roselle calyx and protocatechuic acid against all test pathogens. The time-kill data from protocatechuic acid showed this agent provided concentration dependent antibacterial activities in broth and human plasma (p < 0.05); however, protocatechuic acid showed less inhibitory activity in human plasma than in broth (p < 0.05). These agents based on their lower MIC values, heat tolerance and concentration dependent antibacterial activity may be useful in clinical infection prevention or therapy.     

Antimicrobial compounds from the Australian desert plant Eremophila neglecta

A crude extract from the Australian desert plant Eremophila neglecta has recently been shown to possess antibacterial activity in a survey of candidate plants that may bear novel antimicrobial compounds. Bioassay-directed fractionation of the Et(2)O extract of E. neglecta using a broth microdilution assay led to the isolation of three new serrulatane-type diterpenoids, 2,19-diacetoxy-8-hydroxyserrulat-14-ene (2), 8,19-dihydroxyserrulat-14-ene (3), and 8-hydroxyserrulat-14-en-19-oic acid (4), and a known o-naphthoquinone commonly referred to as biflorin (5). The structures of 2-5 were determined using 1D and 2D NMR, FTIR, and high-resolution mass spectrometry. Compounds 3-5 showed antimicrobial activity against Gram-positive bacteria including Staphylococcus aureus, Streptococcus pyogenes, and S. pneumoniae. The minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) ranged from 6.5 to 101.6 microM and 12.7 to 202.9 microM, respectively. No activity was observed for these compounds against Gram-negative bacteria.     

利用UPLC/Q-TOF-MS/MS主成分分析和T-test探讨生半夏与法半夏有毒成分的差异

目的：从化学成分探讨生半夏与法半夏的差异。方法：制备生半夏和法半夏样品并采用UPLC/Q-TOF-MS/MS测定,通过主成分分析(PCA)和T检验分析研究两组样品之间的差别,并确定相应的化学标记物。UPLC/Q-TOF-MS/MS可准确地测定得到荷质比和MS/MS 的碎片数据,通过参考文献或数据库对照相应数据我们可以鉴别相应化合物。结果：甘草苷、甘草素、溶血磷脂酰胆碱(LPC)是最具特征的化学标记物。由于LPC可导致炎症反应的发生,炮制前后LPC的减少是减毒的原因之一;甘草苷和甘草素有治疗炎症的作用且能减少肝损伤作用,其在炮制后的法半夏中的增加也是减毒的原因。结论：该方法不仅可探索传统中药炮制后减毒的机制还可分别对炮制前后中药的质量进行控制。     

苦参提取物体外抗菌实验研究

目的：探讨苦参总生物碱、总黄酮提取物及其混合物的体外抗菌效果。方法：采用液体二倍稀释法分析苦参总生物碱、苦参总黄酮提取物及其混合物对金黄色葡萄球菌、大肠埃希菌、福氏志贺菌、乙型副伤寒杆菌、铜绿假单胞菌、白色葡萄球菌、痢疾杆菌和柠檬色葡萄球菌的抗菌作用,并测定最小抑菌浓度（MIC）和最小杀菌浓度（MBC）。结果：苦参总生物碱对以上菌株的MIC分别为：9.00、3.38、8.25、9.00、4.50、13.50、6.75、7.13mg.mL-1,MBC分别为：13.50、14.25、8.25、9.00、14.25、14.25、13.13、14.25mg.mL-1;苦参总黄酮对以上菌株的MIC分别为3.00、2.63、3.56、3.38、1.50、2.44、3.56、2.35mg.mL-1,MBC分别为14.25、12.75、7.13、13.50、13.50、12.75、12.75、13.13mg.mL-1;苦参总生物碱与总黄酮混合物对以上菌株的MIC分别为：2.25、2.07、3.28、3.94、1.22、2.44、2.07、1.97mg.mL-1,MBC分别为9.00、13.13、6.75、6.38、13.88、7.50、6.38、7.13mg.mL-1。结论：苦参总生物碱和总黄酮提取物对上述菌株存在体外抑菌和杀菌活性,混合物呈现一定协同作用。     

五倍子乙醇提取物对金葡菌的体外抗菌研究

目的观察五倍子乙醇提取物对金黄色葡萄球菌(MRSA和MSSA)的体外抗菌活性.方法采用中药抑菌实验方法对五倍子乙醇提取物进行了112株金黄色葡萄球菌的最低抑菌浓度测定.结果五倍子乙醇提取物对84株耐甲氧西林的金黄色葡萄球菌(methicillin-resistant staphylococcus aureus,MRSA)和28株甲氧西林敏感的金黄色葡萄球菌(methicillin-sensitive staphylococcus aureus,MSSA)的MIC50、MIC90分别为0.315、0.315和0.63、0.315 mg/mL.结论五倍子乙醇提取物对金黄色葡萄球菌(84株MRSA和28株MSSA)具有较强的抑菌活性.     

Antibacterial potential of Antarctic lichens against human pathogenic Gram-positive bacteria

Extracts from five Antarctic lichens (L3, Stereocaulon alpinum; L5, Ramalina terebrata; L6, Caloplaca sp.; L8, Lecanora sp.; and L17, Caloplaca regalis) were tested for antimicrobial activities against several clinically important microbes by disk diffusion. The minimum inhibitory concentration (MIC) of each extract was determined by a broth dilution method. Extracts from L3, L5, L6 and L8 were active against two Gram(+) strains. B. subtilis was more sensitive to lichen extracts (except L5) than S. aureus. The MIC of lichen extracts against B. subtilis and S. aureus was observed from 36.7 +/- 0.3 to 953.8 +/- 85.8 microg/mL and 68.5 +/- 0.6 to >1000 microg/mL, respectively. Comparisons of MIC values of Antarctic lichen crude extracts to previously published MIC values of some reported lichen metabolites against Gram(+) bacteria indicated that Antarctic lichens might be an enriched source of effective antibacterial agents against clinically relevant Gram(+) species.     

沙参体外抑菌活性的初步研究

目的对沙参提取物的体外抑菌活性进行初步研究。方法用水50%乙醇浸提有机溶剂萃取,以纸片法进行活性测定。结果提取物对金黄色葡萄球菌、绿脓杆菌有抑制作用,最低抑菌浓度为5 mg/m l,50%乙醇提取效果优于水,醋酸乙酯萃取液抑菌效果最明显。结论沙参提取物是一种有效的抑菌药物。     

镰形棘豆生物碱对临床9种致病菌的抑制作用研究

目的观察镰形棘豆生物碱提取物对9种常见致病菌的抗菌作用。方法以镰形棘豆为原料,提取生物碱,选择临床常见的4种革兰氏阳性菌和5种革兰氏阴性菌,采用琼脂扩散法对其体外抑菌活性进行评价,试管二倍稀释法测定其最低抑菌浓度(MIC)和最小杀菌浓度(MBC)。结果镰形棘豆生物碱提取物对9个菌种均有抑菌效果,抑菌作用敏感度与浓度呈良好的量效关系,其中对枯草杆菌和嗜麦芽窄食单胞菌的抑菌效果优于其他各菌,MIC和MBC分别为0.95 mg/mL和1.91 mg/mL,而其他各菌种的MIC和MBC范围在1.91~7.63 mg/mL之间。结论镰形棘豆生物碱提取物具有较为广谱的抑菌作用,对革兰氏阳性菌的抑制作用比革兰氏阴性菌强。     

蟾酥体外抑菌活性的实验研究

目的：探讨蟾酥的体外抑菌活性。方法：采用琼脂扩散法和微量稀释法研究蟾酥对临床常见分离菌株的抑菌圈直径和最小抑菌浓度,以及不同抗菌药物与蟾酥联合作用对临床常见分离株最小抑菌浓度的改变。结果：醇提蟾酥对临床常见分离株均具有一定的抑菌效果,最小抑菌浓度可达3.125mg/mL。醇提蟾酥与不同的抗菌药物联合使用,可以降低抗菌药物的最小抑菌浓度。不同的提取方法影响蟾酥的体外抑菌活性。结论：乙醇能有效提取蟾酥抗菌活性成分。醇提蟾酥对常见临床分离株,特别是阴性杆菌具有一定的抑菌活性。蟾酥与不同抗菌药物具有协同抑菌作用。     

Antimicrobial and anti-inflammatory activity of folklore: Mallotus peltatus leaf extract

Since ages Mallotus peltatus (Geist) Muell. Arg. var acuminatus (Euphorbiaceae) leaf and stem bark is used in folk medicine to cure intestinal ailments and skin infections. In several intestinal ailments, localized inflammation is of common occurrence and hence we have evaluated the antimicrobial as well as anti-inflammatory activity of M. peltatus leaf extract. The crude methanol extract of M. peltatus leaves was found to be active against Staphylococcus aureus, Staphylococcus saprophyticus, Streptococcus faecalis, Bacillus subtilis, Escherichia coli and Proteus mirabilis and the dermatophytic fungi Microsporum gypseum. The minimum inhibitory concentration (MIC) ranges from 128 to 2000 microg ml(-1) for bacteria and 128 mg ml(-1) for fungi, while the minimum bactericidal concentration (MBC) was 2-4-fold higher than MIC. The methanol-water fraction of the extract showed similar activity against Staphylococcus, Streptococcus, Bacillus and Proteus isolates. The anti-inflammatory activity of the extract against carrageenan (acute model) and dextran-induced (subacute model) rat paw oedema and cotton pellet-induced granuloma (chronic model) in rats were studied using indomethacin (10 mg kg(-1)), a nonsteroid anti-inflammatory drug, as standard. The methanol extract at 200 and 400 mg kg(-1), and the n-butanol fractions A and B at 25 mg kg(-1), exhibited significant anti-inflammatory activity in Albino rats, compared with indomethacin. Phytochemical study revealed the presence of tannins, saponins, terpenoids, steroids and reducing sugars in the crude extract while the n-butanol fractions showed the presence of ursolic acid, beta-sitosterol and some fatty acids as major compounds. Further study with fractions showed that the antibacterial and anti-inflammatory activity is due to either fraction A (ursolic acid) alone or the combination of fractions A and B (beta-sitosterol and fatty acids) of the extract.     

Antibacterial activities and cytotoxicity of terpenoids isolated from Spirostachys africana

Spirostachys africana Sond. stem bark is used traditionally for the treatment of diarrhoea and dysentery in Limpopo Province of South Africa. Bioassay-guided fractionation of ethanolic extract from bark of Spirostachys africana led to the isolation of four known compounds, two triterpenoids, compound 1 [d-Friedoolean-14-en-oic acid (3-acetyl aleuritolic acid)] and compound 2 (Lupeol), and two diterpenes, compound 3 [ent-2,6alpha-dihydroxy-norbeyer-1,4,15-trien-3-one (diosphenol 2)] and compound 4 (ent-3beta-hydroxy-beyer-15-ene-2-one). Isolated compounds were tested for antibacterial activity using micro-dilution method. Compound 1, exhibited minimum inhibitory concentration (MIC) of 50 microg/ml against Staphylococcus aureus, Salmonella typhy, Vibrio cholera, Escherichia coli and Shigella dysentery. Compound 2 was not active against all tested microorganisms at 200 microg/ml, which was the highest concentration tested. At this concentration, all four compounds were not active against Shigella sonnei. Cytotoxicity of ethanol crude extracts and isolated compounds from Spirostachys africana was determined using the sodium-2,3-bis-[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) assay on Vero cells. Compounds 2 and 3, isolated from Spirostachys africana, had up to three times higher [50% inhibitory concentration (IC(50) values; 300.9 and 308.9 microg/ml)] than the ethanol crude extracts (102.8 microg/ml) suggesting higher toxicity of the crude extract as compared to these two compounds. In contrast, compounds 1 and 4 were not cytotoxic to Vero cell lines (African green monkey) in vitro at the concentrations tested (IC(50)>400 microg/ml). This is the first report on the antibacterial activity and cytotoxicity of purified compounds from Spirostachys africana.     

Quercus infectoria: a candidate for the control of methicillin-resistant Staphylococcus aureus infections

Acetone, ethyl acetate, 95% ethanol and aqueous extracts of Quercus infectoria (Q. infectoria) demonstrated significant antibacterial activities against all strains of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA). Inhibition zones were in the range 11.75-16.82 mm. Both MRSA and MSSA strains exhibited minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values at 0.13 and 0.13-1.00 mg/mL, respectively. At 2 MIC, the growth of two representative MRSA strains was continually inhibited for at least 20 h. Surviving MRSA cells were not detected within 12-14 h after treatment with the extract at 4 MIC concentration. Staphylococcus aureus ATCC 25923 demonstrated similar results.     

Antibacterial activities of medicinal plants used for the treatment of diarrhoea in Limpopo Province, South Africa

The ethnobotanical survey conducted in this study showed that 21 plant species belonging to 14 families are used in traditional medical practice in Limpopo Province, South Africa, for the treatment of diarrhoea. Methanol, ethanol, acetone and hot water extract from different plant parts (leaves, roots, bark and stem rhizome), of several of these plants (Indigofera daleoides, Punica granatum, Syzygium cordatum, Gymnosporia senegalensis, Ozoroa insignis, Elephantorrhiza elephantina, Elephantorrhiza burkei, Ximenia caffra, Schotia brachypetala and Spirostachys africana), were screened for antibacterial activity against Vibro cholera, Escherichia coli and Staphylococcus aureus, Shigella spp., Salmonella typhi. The antibacterial activity was determined by agar-well diffusion method and expressed as the average diameter of the zone of inhibition of bacterial growth around the wells. The minimum inhibitory concentration (MIC) of active extracts was determined by using the micro-plate dilution assay. Most of the extracts showed relatively high antibacterial activity against most of the tested microorganisms with the diameter of inhibition zones ranging between 10 and 31 mm. Of the plants studied, the most active extracts were those obtained from Punica granatum and Indigofera daleoides. All extracts from two plants, namely, Punica granatum and Ozoroa insignis, were active against all bacterial strains while only organic extracts of Indigofera daleoides inhibited the growth of all tested microorganisms. Water extract of Punica granatum were equally active as organic extracts against bacteria such as Staphylococcus aureus, Shigella sonnei and Shigella flexneri. All extracts of Elephantorrhiza elephantina, Elephantorrhiza burkei and Ximenia caffra and Schotia brachypetala were not active against Escherichia coli and Salmonella typhi. The MIC values for active extracts ranged between 0.039 and 0.6 mg/ml. The results obtained appeared to confirm the antibacterial potential of the plants investigated, and their usefulness in the treatment of diarrhoea.     

Chemical composition and antibacterial activities of the essential oil from Abies koreana

The essential oils from an alpine needle leaf of Abies koreana, which is a species native to Korea, was obtained by hydrodistillation with 0.9% (v/w) yield and analysed by GC and GC-MS. Sixty-eight constituents, accounting for more than 95.9% of the total oil composition, were identified. The main compounds with concentrations higher than 3% were borneol (27.9%), alpha-pinene (23.2%), beta-pinene (5.8%), terpinene-4-ol (3.8%), bornyl acetate (3.4%) and alpha-terpineol (3.1%). The antibacterial activity of the oil was evaluated against nine microorganisms using disc diffusion and broth microdilution methods. The essential oil exhibited some broad spectrum antibacterial activity against the tested organisms, including methicillin-resistant Staphylococcus aureus.     

Antimicrobial activity of Curcuma zedoaria and Curcuma malabarica tubers

The antimicrobial activity of extracts of Curcuma zedoaria and Curcuma malabarica tubers was tested against six bacterial and two fungal strains using the agar well diffusion and broth dilution methods. Petroleum ether, hexane, chloroform, acetone and ethanol extracts exhibited antibacterial as well as antifungal activity. Acetone and hexane extracts of both tubers showed comparable antimicrobial activity as indicated by minimum inhibitory concentration (MIC) values, but other extracts of Curcuma malabarica showed significantly lower activity than those of Curcuma zedoaria. The MIC values for different strains and extracts ranged from 0.01 to 0.15 mg/ml in Curcuma zedoaria and from 0.01 to 0.94 mg/ml in Curcuma malabarica. Staphylococcus aureus (Gram positive) was inhibited by Curcuma malabarica but not by Curcuma zedoaria. This study is the first report of the antimicrobial properties of Curcuma malabarica. The findings also support the use of Curcuma zedoaria tubers in traditional medicine for the treatment of bacterial and fungal infections.     

Garlic natural health products exhibit variable constituent levels and antimicrobial activity against Neisseria gonorrhoeae, Staphylococcus aureus and Enterococcus faecalis

The composition of 19 garlic natural health products (NHPs) and fresh garlic extracts were determined, as was their antibacterial activity. The 19 NHPs and 5 fresh garlic extract standards were analysed for their principal active constituents. They were also extracted for 5, 10 or 15 min in water to fresh garlic equivalents of 200 mg/mL. The extract's minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) against three indicator microorganisms (Neisseria gonorrhoeae, Staphylococcus aureus and Enterococcus faecalis) were determined by the broth microdilution method. While 47% of the aqueous garlic NHP extracts exhibited activity against N. gonorrhoeae, only 16% of the aqueous extracts inhibited S. aureus or E. faecalis at all three timepoints. Generally, products with high antimicrobial activity contained higher levels of garlic constituents with comparable activity to fresh garlic extracts, while products with marginal antibacterial activity often contained lower concentrations of constituents than their product labels indicated. Different extraction times affected antibacterial activity only against N. gonorrhoeae and tended to be correlated with levels of allicin. Thus, many extracts showed discrepancies in both composition, allicin:alliin ratio and antimicrobial activity, raising concerns as to standards of preparation and quality control for these products.     

Antibacterial, anti-inflammatory, anti-cholinesterase and mutagenic effects of extracts obtained from some trees used in South African traditional medicine

Extracts obtained from 10 trees used in South African traditional medicine were screened for antibacterial, anti-inflammatory (COX-1 and COX-2) and anti-cholinesterase activities and investigated for potential mutagenic effects using the Ames test. Antibacterial activity was detected using the disc-diffusion and micro-dilution assays. The extracts were tested against Gram-positive bacteria: Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus and Gram-negative bacteria: Escherichia coli and Klebsiella pneumoniae. Of the 78 different plant extracts investigated, 80% showed activity against both Gram-positive and Gram-negative bacteria in the disc-diffusion assay. In the micro-dilution assay, 60% of the plant extracts showed minimum inhibitory concentration (MIC) values < or =1.56 mg ml(-1). The lowest MIC value (0.092 mg ml(-1)) was recorded for an ethyl acetate root extract of Acacia sieberiana against Staphylococcus aureus and Escherichia coli. In the anti-inflammatory assay, 70% of the investigated plant extracts (0.25 mg ml(-1)) inhibited both COX-1 and COX-2 activity (>50% and 70% for water and organic solvent extracts, respectively). An ethyl acetate leaf extract of Trichilia dregeana showed selective inhibition of COX-2 (81%). In the acetylcholinesterase inhibitory test, 21% of the plant extracts were active at a concentration < or =1 mg ml(-1) using the micro-dilution assay. The lowest IC(50) value was 0.04 mg ml(-1) obtained with an ethanol bark extract of Combretum kraussii. None of the investigated plants showed any potential mutagenic effects.