Evaluation of antimicrobial activity of the lichens Lasallia pustulata, Parmelia sulcata, Umbilicaria crustulosa, and Umbilicaria cylindrica

The antimicrobial properties of acetone, methanol, and aqueous extracts of the lichens Lasallia pustulata, Parmelia sulcata, Umbilicaria crustulosa, and Umbilicaria cylindrica were studied comparatively in vitro. Antimicrobial activities of the extracts of different lichens were estimated by the disk diffusion test for Gram-positive bacteria, Gram-negative bacteria, and fungal organisms, as well as by determining the MIC (minimal inhibitory concentration). The obtained results showed that the acetone and methanol extracts of Lasallia pustulata, Parmelia sulcata, and Umbilicaria crustulosa manifest antibacterial activity against the majority of species of bacteria tested, in addition to selective antifungal activity. The MIC of lichen extracts was lowest (0.78 mg/ml) for the acetone extract of Lasallia pustulata against Bacillus mycoides. Aqueous extracts of all of the tested lichens were inactive. Extracts of the lichen Umbilicaria cylindrica manifested the weakest activity, inhibiting only three of the tested organisms.     

Antimicrobial activity of extracts of the lichens <Emphasis Type="Italic">Cladonia furcata,Parmelia caperata,Parmelia pertusa,Hypogymnia physodes</Emphasis> and <Emphasis Type="Italic">Umbilicaria polyphylla</Emphasis>

Antimicrobial features of acetone, methanol and aqueous extracts of lichens of Cladonia furcata, Parmelia caperata, Parmelia pertusa, Hypogymnia physodes and Umbilicaria polyphylla were investigated by two different methods at the same time. Testing of antimicrobial activities of extracts from five species of lichens was performed by disc diffusion test in relation to Gram-positive and Gram-negative bacteria and fungal organisms, and through determination of minimal inhibitory concentration (MIC) by Broth Tube Dilution method. The obtained results indicated that acetone and methanol extracts of all investigated lichens in different concentrations manifested selective antibacterial and antifungal activity. That activity was more evident in relation to Gram-positive, than Gram-negative bacteria and fungal organisms. Acetone and methanol extracts of lichens Parmelia pertusa, Hypogymnia physodes and Umbilicaria polyphylla inhibited the growth of all tested microorganisms, most of all of lichens Cladonia furcata and Parmelia caperata. Although, the methanol extracts were generally the most active against the test organisms, the lowest MIC value was measured for acetone extract of species Cladonia furcata 0.39 mg/mL in relation to bacterium Bacillus subtilis. Aqueous extracts of investigated lichens were inactive against all tested organisms.     

Screening the antioxidant and antimicrobial properties of the lichens Parmelia saxatilis, Platismatia glauca, Ramalina pollinaria, Ramalina polymorpha and Umbilicaria nylanderiana.

The aim of this study is to investigate in vitro antimicrobial and antioxidant activities of the methanol extracts of Parmelia saxatilis (L) Ach., Platismatia glauca (L.) W.L. Club. & C.F. Culb., Ramalina pollinaria (Wesstr.) Ach., Ramalina polymorpha (Liljeblad) Ach. and Umbilicaria nylanderiana (Zahlbr.) H. Magn. Antioxidant activity was evaluated by two separate methods: scavenging of free radical DPPH and the inhibition of linoleic acid oxidation. Extracts of Parmelia saxatilis, Platismatia glauca., Ramalina pollinaria and Ramalina polymorpha did not exert any activity in both assays, whereas those of Umbilicaria nylanderiana provided 50% inhibition at 400.2 microg/ml concentration in the former and gave 53% inhibition at 2g/l concentration. Total phenolic constituents of extracts from lichen species tested (P. saxatilis, P. glauca, R. pollinaria, R. polymorpha and U. nylanderiana) were 1.0% (w/w), 1.1% (w/w), 1.0% (w/w), 0.8% (w/w) and (3.0% w/w), respectively (as gallic acid equivalent); implying that the observed activity could be related to the amount of polar phenolics. Extracts were also found to possess antimicrobial activity against some test bacteria and fungi and yeast.     

Antifungal activity of synthetic peptide derived from halocidin, antimicrobial peptide from the tunicate, Halocynthia aurantium

Halocidin is an antimicrobial peptide isolated from the hemocytes of the tunicate. Among the several known synthetic halocidin analogues, di-K19Hc has been previously confirmed to have the most profound antibacterial activity against antibiotic-resistant bacteria. This peptide has been considered to be an effective candidate for the development of a new type of antibiotic. In this study, we have assessed the antifungal activity of di-K19Hc, against a panel of fungi including several strains of Aspergillus and Candida. As a result, we determined that the MICs of di-K19Hc against six Candida albicans and two Aspergillus species were below 4 and 16 microg/ml, respectively, thereby indicating that di-K19Hc may be appropriate for the treatment of several fungal diseases. We also conducted an investigation into di-K19Hc's mode of action against Candida albicans. Our colony count assay showed that di-K19Hc killed C. albicans within 30s. Di-K19Hc bound to the surface of C. albicans via a specific interaction with beta-1,3-glucan, which is one of fungal cell wall components. Di-K19Hc also induced the formation of ion channels within the membrane of C. albicans, and eventually observed cell death, which was confirmed via measurements of the K+ released from C. albicans cells which had been treated with di-K19Hc, as well as by monitoring of the uptake of propidium iodide into the C. albicans cells. This membrane-attacking quality of di-K19Hc was also visualized via confocal laser and scanning electron microscopy.     

Evaluation of antimicrobial activity of the lichens <Emphasis Type="Italic">Lasallia pustulata,Parmelia sulcata,Umbilicaria crustulosa</Emphasis>, and <Emphasis Type="Italic">Umbilicaria cylindrica</Emphasis>

The antimicrobial properties of acetone, methanol, and aqueous extracts of the lichens Lasallia pustulata, Parmelia sulcata, Umbilicaria crustulosa, and Umbilicaria cylindrica were studied comparatively in vitro. Antimicrobial activities of the extracts of different lichens were estimated by the disk diffusion test for Gram-positive bacteria, Gram-negative bacteria, and fungal organisms, as well as by determining the MIC (minimal inhibitory concentration). The obtained results showed that the acetone and methanol extracts of Lasallia pustulata, Parmelia sulcata, and Umbilicaria crustulosa manifest antibacterial activity against the majority of species of bacteria tested, in addition to selective antifungal activity. The MIC of lichen extracts was lowest (0.78 mg/ml) for the acetone extract of Lasallia pustulata against Bacillus mycoides. Aqueous extracts of all of the tested lichens were inactive. Extracts of the lichen Umbilicaria cylindrica manifested the weakest activity, inhibiting only three of the tested organisms.     

一株蜂粮源拮抗细菌的分离鉴定及其抑菌物质特性

【目的】为发掘和利用蜂粮中拮抗菌资源,对分离获得的拮抗细菌菌株PC2进行分类鉴定,并测定其发酵液抑菌物质基本特性。【方法】采用改良牛津杯双层平板法测定菌株发酵液抑菌谱及温度、p H、紫外线和蛋白酶对其抑菌活性稳定性的影响,菌株鉴定结合形态学、生理生化特征和16S r RNA基因序列分析,硫酸铵沉淀法和盐酸沉淀有机溶剂提取法进行抑菌活性物质的初步分离。【结果】从3种蜂粮中分离筛选得到17株拮抗菌株,其中1株细菌PC2以马铃薯葡萄糖液体培养基发酵制备的无菌发酵液对7种供试菌株具有较强抑制作用,经形态、生理生化特征及16S r RNA基因序列分析,将其初步鉴定为解淀粉芽胞杆菌(Bacillus amyloliquefaciens)。菌株发酵液抑菌活性对温度、酸和紫外线具有较强的稳定性,对蛋白酶K、胃蛋白酶、碱性蛋白酶处理敏感。菌株发酵液存在抑菌蛋白和脂肽类物质。【结论】菌株PC2在食品保鲜和农业生防中具有潜在的开发应用价值。     

Antifungal activity of extracts of the lichens Parmelia reticulata,Ramalina roesleri,Usnea longissima and Stereocaulon himalayense

Antifungal activity of the hexane, dichloromethane, ethyl acetate, methanol and aqueous extracts of the lichens namely, Parmelia reticulata, Ramalina roesleri, Usnea longissima and Stereocaulon himalayense were evaluated against nine soil-borne pathogenic fungi namely Rhizoctonia bataticola, Sclerotium rolfsii, Alternaria alternata, Pythium debaryanum, Fusarium oxysporum, Rhizoctonia solani, Botrytis cinerea, Sclerotina sclerotium and Pythium aphanidermatum by food poison technique. ED₅₀ (Effective dose for 50% of inhibition) was calculated using Probit analysis. Hexane and dichloromethane extracts from all the four lichen species were found most active against the test fungi while aqueous extract was found to be least effective against all the test pathogenic fungi. The highest inhibition was recorded with hexane extracts of P. reticulata, R. roesleri, U.longissima and S. himalayense against R. bataticola with ED₅₀ 25.1, 24.50, 18.91 and 51.36 μg ml^?1, respectively.     

Application of S-thanatin,an antimicrobial peptide derived from thanatin,in mouse model of Klebsiella pneumoniae infection

Thanatin was first discovered from the hemipteran insect Podisus maculiventris and showed a promising antimicrobial activity. Multidrug-resistant (MDR) clinical isolates of Klebsiella pneumoniae have developed resistance to current therapies. As an attempt to resolve this problem, the efficacy of thanatin and its analogues against clinical isolates of K. pneumoniae was studied in vitro and in vivo. S-thanatin showed an improved antimicrobial activity with the tested MIC values was 2–8-fold lower than those of other thanatin analogs. Antimicrobial assay indicated a high activity of S-thanatin against K. pneumoniae in vitro with MIC between 4 and 8 μg/ml. Its in vivo activity was evaluated using a K. pneumoniae-infected mice model. Adult male ICR mice were randomly grouped and given an intraperitoneal (i.p.) administration of 2 × 10¹⁰ colony-forming units of K. pneumoniae (CI 120204205). Afterwards, mouse groups were subjected to i.p. administration of saline or S-thanatin (5, 10, or 15 mg/kg). After an inspection of 72 h, the mice were finally sacrificed for analysis of in vivo bacterial growth and plasma endotoxin level. The results showed that S-thanatin administration apparently improved the survival rate and reduced the bacterial CFU from intra-abdominal fluid in mice. The plasma endotoxin level was improved as well. All above implied that S-thanatin, as an alternative, may provide a novel strategy for treating K. pneumoniae infection and other infections due to multidrug-resistant bacteria.     

Assessment of the antimicrobial activity of the lipoidal and pigment extracts of Punica granatum L. leaves

Punica granatum L. is one of the famous and old species belonging to Family Punicaceae. The lipoidal and natural pigment extracts of the pomegranate were screened for their antimicrobial activity against nine different microbial pathogens. Three different doses of each extract (50, 100 and 150?μl) at three different contact times (15, 30 and 60?min) were examined. Results can be cleared that, all tested microbial pathogens were inhibited by 150?μl of both extracts at 60?min. Furthermore, the removal efficiency of n-hexane extract was powerful than the pigment extract. Also, the quantitative evaluation of the pigments in the leaves was performed using spectroscopical and HPLC analyses, carotenoids and chlorophylls content of P. granatum L. leaves were spectroscopically determined (mg/g) as 6.7?±?0.214 and 4.9?±?0.251, respectively. Chlorophyll a and b were 2.33?±?0.014 and 1.51?±?0.023, respectively. HPLC analysis of lutein and β-carotene were investigated as 3.652 and 1.915?mg/g. GC/MS analysis of the saponifiable and unsaponifiable fraction of n-hexane extract was carried out and α-amyrin acetate, ergosterol, and α-tocopherol were isolated, purified and identified using different spectroscopical methods. Toxicity assessment demonstrated their high biocompatibility since no toxic effect was recorded.     

Synthesis and antimicrobial activities of two novel amino sugars derived from chloraloses

The synthesis of 5-amino-5-deoxy-1,2-O-(S)-trichloroethylidene-β-l-arabinofuranose and 6-amino-6-deoxy-1,2-O-(S)-trichloroethylidene-α-d-glucofuranose is described by a simple three- or four-step route. Antibacterial potency of the new compounds was determined using an inhibition zone diameter test. The results show that these compounds have a broad-spectrum activity against Gram-positive, Gram-negative bacteria and Candida albicans.     

Cationic amphipathic peptides, derived from bovine and human lactoferrins, with antimicrobial activity against oral pathogens

Peptides derived from the N-terminal domain that comprises an amphipathic alpha-helix in human lactoferrin (LFh 18-31 and LFh 20-38) and bovine lactoferrin (LFb 17-30 and LFb 19-37) were chemically synthesised. Since many positively charged amphipathic alpha-helices contain antimicrobial activity, the peptides were tested for their antimicrobial activity against various oral pathogens. Both peptides from bovine lactoferrin had more potent antimicrobial activities than the human equivalents. Peptide LFb 17-30, containing the largest number of positively charged amino acids, showed the highest antimicrobial activity to both Gram-positive and Gram-negative bacteria. Since native lactoferrin molecules had no killing activity, release of these peptides from the native protein should be investigated to explore the use in oral care products.     

植物叶片内生放线菌的分离、分类与拮抗活性

以四川采集的芍药和北京采集的三叶草的叶片为材料,经表面消毒程序后,分离出内生放线菌15株。通过表观特征比较和BOX-PCR基因指纹图谱分析的方法,将分离出的放线菌归并于12个不同的基因型,其中6个来自芍药,6个来自三叶草。结合16S rRNA基因序列分析可知,分离菌株除C4、C5属于假诺卡氏菌外,其余的13株都是链霉菌;菌株C12与最近模式种的16S rRNA基因序列相似性较低,为96.6%。对分离菌株的抗菌活性实验表明,有11株在一个或一个以上的测试中呈阳性;其中6株对植物致病菌立枯丝核菌有明显抗性,占阳性菌株的55%。     

Synthesis and antimicrobial activity of the Schiff base from chitosan and citral

Chitosan, a biocompatible, biodegradable, non-toxic polymer, is prepared from chitin, which is the second most naturally occurring biopolymer after cellulose. The Schiff base of chitosan was synthesized by the reaction of chitosan with citral working under high-intensity ultrasound. The effect of the molar ratio of chitosan to citral, reaction time, and temperature on the yield has been investigated. The optimal conditions were a temperature of 50 °C, a molar ratio of chitosan to citral of 1:6, and a reaction time of 10 h. The maximum yield achieved was 86.4% under optimum conditions. The structure of the Schiff base was characterized by FTIR spectroscopy, elemental analysis, and X-ray diffraction studies. The strong peaks at 1648.3 and 1610.6 cm⁻¹ are due to CN and CC stretching vibrations. The results confirmed that amino groups on chitosan reacted with citral to form the Schiff base. The antimicrobial activities of chitosan and Schiff base of chitosan were investigated against Escherichia coil, Staphylococcus aureus, and Aspergillus niger. The results indicate that the antimicrobial activity of the Schiff base increases with an increase in the concentration. It was also found that the antimicrobial activity of the Schiff base was stronger than that of chitosan.     

Peroxidase-like activity and antimicrobial properties of curcumin-inorganic hybrid nanostructure

For the first time in this study, curcumin was utilized as an organic component reacting with Cu (II) ion (Cu²⁺) as an inorganic component for fabrication of curcumin based Cu hybrid nanostructure (Cu-hNs). We also systematically examined the catalytic effect towards guaiacol and antimicrobial activities of Cu-hNs towards fish pathogen bacteria. For the characterization of Cu-hNs, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectrometry (FT-IR) analysis were used. We claimed that hydroxyl group might react with Cu²⁺ in phosphate solution (PO₄^-3) to form Cu-hNs. However, more uniform and spherical Cu-hNs were not seen owing to absence of more reactive functional groups like amine and carboxyl groups on structure of curcumin. In addition to our findings, synthesis of Cu-hNs were carried out in the various pH values to evaluate the effect of pHs on formation of Cu-hNs. The Cu-hNs exhibited remarkable catalytic activity throught the Fenton reaction in the presence of hydrogen peroxide (H₂O₂) and effective antimicrobial activities against Gram-positive/negative fish pathogen bacteria. In this study, cheap and efficient synthesis of nanoflowers (NFs) using plant extracts is proposed for biomedical applications rather than expensive molecules such as amino acids and DNA.     

Characterization and antimicrobial activity of the bioactive metabolites in streptomycete isolates

Twenty different streptomycete isolates were obtained from soils of southeast Serbia. Five isolates identified as Streptomyces hygroscopicus (SH100, SH101, SH102, SH103, and SH104) showed strong activity against Botrytis cinerea, a parasite found in domestic vines. These isolates were extensively studied for their in vitro antimicrobial activity against Gram-positive bacteria, Gram-negative bacteria, yeasts and fungi, and also antiviral activity against Herpes simplex. The results indicated that the obtained isolates were highly active against Botrytis cinerea, Candida albicans, and Herpes simplex, with an inhibition zone at ≥31 mm. The structure of the bioactive components was determined using elemental analysis, as well as UV/VIS, FTIR, and TLC.     

The activity of antimicrobial peptide S-thanatin is independent on multidrug-resistant spectrum of bacteria

In this study, the activity of S-thanatin (an analog of antimicrobial peptide derived from thanatin) against different bacterial pathogens frequently which can cause therapeutic problems was tested. The result showed minimal inhibitory concentrations (MICs) of S-thanatin against all isolates of the Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes, Klebsiella ornithinolytica and Klebsiella oxytoca were in the range of 4-16 μg/ml, no matter which antibiotic the bacterial was resistant or susceptible, while almost all MICs to Gram-positive bacterial were >128 μg/ml except Enterococcus faecium. S-thanatin was more effective toward Gram-negative strains, especially for Enterobacter and Klebsiella. The MICs of S-thanatin were no significantly different in the same species regardless of antibiotic sensitive or -resistant isolates to single or multiple antibiotic (P > 0.05). Likewise, no notable difference could be observed between E. coli, K. pneumoniae, E. cloacae, E. aerogenes, K. ornithinolytica which were sensitive to S-thanatin (P > 0.05). It was implied that the antimicrobial activity of S-thanatin was independent on multi-drug resistance spectrum of bacteria.     

Molecular structural studies of lichen substances with antimicrobial, antiproliferative, and cytotoxic effects from Parmelia subrudecta

Lecanoric acid (1), orsellinic acid methyl ester (2), orcinol (3), and usnic acid (4) were isolated from the lichen Parmelia subrudecta, collected on Palma of the Canary Islands, Spain. Compounds 1, 2, 3, and 4 were purified by solvent extraction, silica gel column chromatography, and preparative high-performance liquid chromatography (HPLC) consecutively. The structures of the four compounds were elucidated by one- and two-dimensional nuclear magnetic resonance (NMR) experiments and mass spectrometric investigations. These compounds showed activity against important gram-positive and gram-negative pathogens like mycobacteria and multiresistant staphylococci. This activity is combined with antiproliferative activity and cytotoxicity.     

In vitro antimicrobial activity of propolis and synergism between propolis and antimicrobial drugs

The aim of this study was to investigate antimicrobial properties of ethanolic extract of 13 propolis (EEP) samples from different regions of Serbia against 39 microorganisms (14 resistant or multiresistant to antibiotics), and to determine synergistic activity between antimicrobials and propolis. Antimicrobial activity of propolis samples was evaluated by agar diffusion and agar dilution method. The synergistic action of propolis with antimicrobial drugs was assayed by the disc diffusion method on agar containing subinhibitory concentrations of propolis. Obtained results indicate that EEP, irrespectively of microbial resistance to antibiotics, showed significant antimicrobial activities against Gram-positive bacteria (MIC 0.078%–1.25% of EEP) and yeasts (0.16%–1.25%), while Gram-negative bacteria were less susceptible (1.25&%ndash;>5%). Enterococcus faecalis was the most resistant Gram-positive bacterium, Salmonella spp. the most resistant Gram-negative bacteria, and Candida albicans the most resistant yeast. EEP showed synergism with selected antibiotics, and displayed ability to enhance the activities of antifungals. The shown antimicrobial potential of propolis alone or in combination with certain antibiotics and antifungals is of potential medical interest.