Phytochemical Analysis and Antimicrobial Activity of Lawsonia inermis Leaf Extracts from Burkina Faso

Lawsonia inermis is a hairless plant growing in various regions of North Africa, the Indian subcontinent, and the Middle East. It possesses many medicinal attributes, including curative properties against infectious dermatoses. This study was carried out to evaluate the phytochemical profile of the crude ethanolic extract of the plant leaves and its fractions as well as their antimicrobial activities. The phytochemical profile was performed using high-performance thin-layer chromatography (HPTLC), gas chromatography-mass spectrometry (GC-MS), and high-performance liquid chromatography (HPLC). Additionally, the phenolic and flavonoid contents were determined using the Folin-Ciocalteu spectrophotometric and the aluminum trichloride methods. Antimicrobial activity was tested using disc diffusion and microdilution methods. The presence of flavonoids, tannins, sterols, and triterpenes was revealed. GC-MS detected twelve compounds main compounds consisting of saturated and unsaturated fatty acids and phenolic and terpenoid compounds among twenty-seven components. HPLC also detected high contents of phenolic acids and flavonoids. The most abundant triterpene and sterols were ursolic acid (around 43.14 g/100g DW, 13.9 g/100g dry weight (DW), and 0.68 g/100g DW) in the crude ethanolic extract of leaves (FeLi), hexane fraction (FHLi) and dichloromethane fraction (FDLi), respectively and, β-sitosterol in FeLi (56.7 mg/100g DW), FHLi (10.55 g/100g DW), FDLi (106.1 mg/100g DW) and butanol fraction (FBLi) (357.4 mg/100g DW). Among the flavonoids, rutin = 3.24 g/100g and quercetin = 0.63 g/100g in the ethanolic extract, rutin = 15.73 g/100g in the dichloromethane fraction, and rutin = 0.23 g/100g) in the aqueous fraction;and among phenolic compounds, caffeic acid (37.65 g/100g DW) and vanillic acid (22.70 g/100g DW) were the most important in the ethyl acetate fraction (FAeLi). All organic fractions exhibited interesting antibacterial and antifungal activities against the tested strains, with the best activity recorded with the dichloromethane and ethyl acetate fractions. The leaf extracts’ phytochemical profile and antimicrobial activity support the use of Lawsonia inermis against infectious skin diseases.

Antioxidant,antimicrobial,and α-glucosidase inhibitory activities of saponin extracts from walnut(Juglans regia L.) leaves

Objective:To investigate the relationship between triterpenoid saponin content and antioxidant,antimicrobial,and α-glucosidase inhibitory activities of 70%ethanolic,butanolic,aqueous,supernate and precipitate extracts of Juglans regia leaves.Methods:Triterpenoid saponins of different Juglans regia leaf extracts were measured by the vanillin method.Antioxidant activity was evaluated against DPPH and ABTS free radicals.We also assessed α-glucosidase inhibitory and antimicrobial activities of the leaf extracts.Pearson’s correlation coefficient was evaluated to determine the correlation between the saponin content and biological activities.Results:The butanolic extract was most effective against DPPH with an IC50of 6.63μg/mL,while the aqueous extract showed the highest scavenging activity against ABTS free radical with an IC50of 42.27μg/mL.Pearson’s correlation analysis indicated a strong negative correlation (r=-0.956) between DPPH radical scavenging activity (IC50) and the saponin content in the samples examined.In addition,the aqueous extract showed the best α-glucosidase inhibitory activity compared with other extracts.All the extracts had fair antibacterial activity against Bacillus subtilis,Escherichia coli,and Klebsiella pneumoniae except for the aqueous extract.Conclusions:Juglans regia extracts show potent antioxidant,antimicrobial,and α-glucosidase inhibitory activities.There is a correlation between saponin levels in Juglans regia leaf extracts and the studied activities.However,additional research is required to establish these relationships by identifying the specific saponin molecules responsible for these activities and elucidating their mechanisms of action.

Antimicrobial Activities of Solanum aculeastrum Fruit Extract against Escherichia coli, Staphylococcus aureus and Candida albicans: Significance of African Traditional Medicine in Combating Infections and Attaining Universal Health Coverage

Solanum aculeastrum, a member of the Solanum genus, has a rich history of traditional use in various populations throughout tropical and southern Africa for treating different ailments. This study investigated the antimicrobial activities of S. aculeastrum fruit extracts grown in Zambia against Escherichia coli (E. coli) (ATCC 25922), Staphylococcus aureus (S. aureus) (ATCC 25923), and Candida albicans (C. albicans). After being dried in an oven at 50°C for eight days, the fruits of S. aculeastrum were pulverised and subjected to extraction using methanol and distilled water as solvents. The resulting crude extract was then filtered, concentrated using a water bath, and packed into airtight containers separately. The disc diffusion method was employed to evaluate the antimicrobial activity of the extracts. The results showed that both the methanolic and aqueous extracts demonstrated antimicrobial activity against S. aureus and C. albicans, but not against E. coli. The zone of inhibition was greater in S. aureus than in C. albicans. This study highlights the importance of researching plants for their medicinal properties, which can pave the way for discovering natural product-based drugs with potential antimicrobial properties. These findings recommend further studies on plants used in African traditional medicine.

LC-MS Phytochemical Profiles of Phenolic Compounds and Antimicrobial, Antioxidant, and Antiplasmodial Activities of Ethanol Extracts of Pycnostachys erici-rosenii R.E.Fr and Leucas martinicensis (Jack.) R.Br (Lamiaceae)

This study has been conducted to analyze the chemical composition and antimicrobial, antioxidant and antiplasmodial properties of ethanol extracts of Pycnostachys erici-rosenii R.E.Fr and Leucas martinicensis (Jack.) R.Br that are not yet well known. The HPLC-DAD-MS-ESI+ method was used to investigate the chemical profile, the disc diffusion and microdilution method for the antimicrobial activities, the DPPH and FRAP assays for antioxidant property and SYBR Green I-based growth inhibition assay on Pf 3D7 (CQ-sensitive) strain for antiplasmodial properties. The results indicated significant amounts of hydroxybenzoic acid, flavonol and hydroxycinnamic acid in the two species. The total polyphenols analysis gave 209.0 ± 16.1 mg GAE/100g DW for P. erici-rosenii and 175.3 ± 1.6 mg GAE/100g DW for L. martinicensis while for total flavonoids analysis 33.4 ± 1.8 mg TE/100g DW was found for P. erici-rosenii and 39.6 ± 0.6 mg TE/100g DW for L. martinicensis. Moreover, antimicrobial tests revealed 0.125 mg/mL on E. faecalis ATCC25922 for ethanol extracts P. erici-rosenii and L. martinicensis. The antioxidant assays revealed IC50 56.17 μg/mL and 78.43 μg/mL for DPPH assay, and 112.03 μM TE/100mL and 90.46 μM TE/100mL) for FRAP assay for ethanol extracts of P. erici-rosenii and L. martinicensis respectively. Finally, for Antiplasmodial activity, IC50 was 4.07 μg/mL for P. erici-rosenii and 12.29 μg/mL for L. martinicensis. Therefore, the antimicrobial, the antioxidant, and the antiplasmodial results suggest that the ethanolic extracts of the aerial parts of P. erici-rosenii and L. martinicensis contain compounds with antimicrobial, antioxidant, and antiplasmodial properties, which can be searched in new drug discovery for treatment of infectious diseases.

Design of pH-responsive antimicrobial peptide melittin analog-camptothecin conjugates for tumor therapy

Melittin,a classical antimicrobial peptide,is a highly potent antitumor agent.However,its significant toxicity seriously hampers its application in tumor therapy.In this study,we developed novel melittin analogs with pH-responsive,cell-penetrating and membranelytic activities by replacing arginine and lysine with histidine.After conjugation with camptothecin(CPT),CPT-AAM-1 and CPT-AAM-2 were capable of killing tumor cells by releasing CPT at low concentrations and disrupting cell membranes at high concentrations under acidic conditions.Notably,we found that the C-terminus of the melittin analogs was more suitable for drug conjugation than the N-terminus.CPT-AAM-1 significantly suppressed melanoma growth in vivo with relatively low toxicity.Collectively,the present study demonstrates that the development of antitumor drugs based on pH-responsive antimicrobial peptide-drug conjugates is a promising strategy.

Biosynthesis of Copper Nanoparticles using an Extract of the root of Asparagus racemosus:Basic Synthesis,Antimicrobial,and Anti-oxidant Potentials

Copper nanoparticles(CuNPs)have emerged as a promising alternative due to their unique antimicrobial properties.The synthesis of CuNPs using Asparagus racemosus,commonly known as Shatavari,offers a sustainable and environmentally friendly approach to producing nanomaterials.Moreover,the resulting CuNPs have been found to possess excellent antibacterial,and antioxidant properties,which further expands their potential applications in medicine and environmental remediation.In this article,we discussed the in vitro characterization of the CuNPs.In vitro studies revealed that CuNPs have the potential for biomedical applications and as a base nanomaterial for the construction of drug delivery and targeting vehicles.

Biosynthesis of Silver Nanoparticles with Clerodendron phlomoides Leave Extract:Particle Morphology,Antimicrobial Potential and Application

Silver nanoparticles are versatile nanomaterials that have found numerous applications in various fields.The use of plant extract for the synthesis of silver is a green and sustainable approach.Clerodendron phlomoides leaves extract has been found to contain various phytochemicals,such as phenols,flavonoids,tannins,and alkaloids,which possess reducing and stabilizing properties that can aid the production of silver particles.In this paper,morphological and topographical analyses were performed on silver nanoparticles.The biosynthesized silver nanoparticles showed antimicrobial potential against wound pathogens.SEM and TEM micrographs revealed that the particles were sphere and nanosized,which makes them suitable for various biomedical applications.

A pilot survey on antimicrobial activity and diversity of soil-derived actinobacteria from different depths in Gudzhirganskoe saline lake in Eastern Siberia

To explore pharmaceutical actinobacteria from salty environments in Siberia,8 soil samples were collected from different depths of Gudzhirganskoe saline lake,the Republic of Buryatia,Russia.Totally,635 actinobacterial strains affiliated with 21 genera in 12 families of 7 orders were obtained by culture-dependent approaches.The predominant genus was Streptomyces(74.5%),followed by Microbacterium(4.9%),Agromyces(3.5%),Nocardiopsis(3.0%),and Kitasatospora(2.5%).Seven strains showed relatively low 16 S rRNA similarities(<98.65%)with validly described species.Seventy-seven strains were selected as representatives to evaluate their antimicrobial activities and underlying mechanisms by paper-disk diffusion method and a double fluorescent protein reporter system(pDualrep 2),respectively.Streptomyces sp.S 6 b 3-1 was highlighted due to its strong inhibitory activities against Gram-positive bacteria and underlying antibacterial mechanism by inducing the SOS response in the reporter system.LG-1,(R)-6-[1-(benzoyloxy)ethyl]-phenazine-1-carboxylic acid,an analogue of saphenamycin was finally isolated from the culture broth of Streptomyces strain.This study preliminarily explored the actinobacterial diversity of soil samples collected in the highly alkaline and saline lake Gudzhirganskoe by culture-dependent approach and their capacity to produce antibiotics for the first time,which revealed that it deserves to make more efforts to discover new actinobacterial species and potential new antibiotics from the saline lake in Eastern Siberia.

Synthesis, Structural Characterization and Antimicrobial Activity of a Novel Cobalt(II) Complex Based on 3-Methyl-1-Phenyl-4-(2-Thienoyl)-Pyrazol-5-One

New cobalt(II) complex, [Co(O2C15H11N2S)2(OH2)2]∙2H2O (1∙2H2O), has been synthesized upon reaction of cobalt chloride hexahydrate (Co(Cl)2∙6H2O) with 3-methyl-1-Phenyl-4-(2-thienoyl)-pyrazol-5-one (referred as HL) in ethanol at room temperature. Single crystal X-ray diffraction (XRD), spectroscopic methods, and microelemental analyses were used to characterize 1∙2H2O. Compound 1∙2H2O crystallizes in the orthorhombic crystal system with a Pbca space group and with the cobalt atom being pseudo-octahedral coordinated. The broth microdilution technique was used to screen the free ligand (HL) and the complex (1∙2H2O) for antimicrobial activities. HL has a low activity (MIC > 100 μg/mL) on all microorganisms, whereas compound 1∙2H2O displayed moderate activity (10 ∙2H2O exhibited bactericidal and fungicidal activity respectively on all the bacteria and yeasts tested. These findings reveal that the antimicrobial activity of HL was enhanced upon coordination to Co(II) ion against all microorganisms (bacteria and fungus).

Phenolic and flavonoid contents, antioxidant and antimicrobial activities of leaf extracts from ten Algerian Ficus carica L. varieties

Objective: To determine the total phenolic and flavonoid contents, antioxidant and antimicrobial activities of methanolic leaf extracts of ten Algerian fig(Ficus carica L.)varieties(uniferous, biferous and caprifig tree).Methods: Phenolics were extracted by Soxhlet method and analyzed by the Folin–Ciocalteu colorimetric method. Flavonoids were determined by aluminum trichloride assay and the antioxidant capacity was determined by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. The antimicrobial activity was studied with the disc diffusion method and a macrodilution broth method was used to determine the minimal inhibitory concentrations and minimal lethal concentrations.Results: The mean extract yield was 14.10% ± 0.66%(n = 10). Leaf extract of biferous followed by uniferous varieties had the highest total phenolic contents [(52.296 ± 5.232)and(48.973 ± 2.015) mg gallic acid equivalent/g of dry plant extract respectively], flavonoids [(14.388 ± 0.333) and(14.136 ± 1.082) mg quercetin equivalent/g of dry plant extract] and antioxidant capacity [IC50(798.754 ± 108.590) and(825.004 ± 110.835) mg/m L]. Antioxidant capacity of fig leaves was significantly correlated with phenolic contents(r = 0.748). These extracts showed bactericidal activity and moderate antifungal activity, and the minimal inhibitory concentrations and minimal lethal concentrations were determined on Bacillus cereus and Staphylococcus aureus.Conclusions: All tested extracts contain phenolic compounds and exhibited an antioxidant activity and an antimicrobial effect against Gram-positive and Gram-negative bacteria. Further researches on identification and purification of phenolic compounds are required.

Antimicrobial activities of essential oil from Artemisiae argyi leaves

A study was conducted to determine the antimicrobial activities of essential oil from Artemisiae argyi leaves. The sample of the essential oil was analyzed by GC-MS. From 18 compounds representing the oils, Eucalyptole （18.42%）, Spathulenol （14.32）, 4-Methyl-1-（1-methylethyl）-3-cyclohexen-1-ol （3.10%）, 3-Carene （2.64%） appeared as the main components. The screening of antimicrobial activity of the essential oil was evaluated using agar diffusion and broth microdilution methods. Gram-positive bacterial were more sensitive than gram-negative bacterial of the 8 microorganisms, and Staphylococcus aureus ATCC 6538 showed the lowest MIC （0.3125%） and MBC （0.625%）. In the disc diffusion assay, Staphylococcus epidermidis ATCC 49134 and Bacillus subtilis ATCC 6633 showed obvious inhibitory activity. Survival curve showed that, 2MIC ofArtemisiae argyi essential oil had a lethal effect on Candida albicans within the first 1 h. Results presented here suggest that the essential oil of Artemisiae argyi leaves possesses antimicrobial properties, and provides scientific foundations for exploition ofArtemisiae argyi.

Synthesis, Structural Characterization and Antimicrobial Activity of a Novel Cobalt(II) Complex Based on 3-Methyl-1-Phenyl-4-(2-Thienoyl)-Pyrazol-5-One

New cobalt(II) complex, [Co(O2C15H11N2S)2(OH2)2]∙2H2O (1∙2H2O), has been synthesized upon reaction of cobalt chloride hexahydrate (Co(Cl)2∙6H2O) with 3-methyl-1-Phenyl-4-(2-thienoyl)-pyrazol-5-one (referred as HL) in ethanol at room temperature. Single crystal X-ray diffraction (XRD), spectroscopic methods, and microelemental analyses were used to characterize 1∙2H2O. Compound 1∙2H2O crystallizes in the orthorhombic crystal system with a Pbca space group and with the cobalt atom being pseudo-octahedral coordinated. The broth microdilution technique was used to screen the free ligand (HL) and the complex (1∙2H2O) for antimicrobial activities. HL has a low activity (MIC > 100 μg/mL) on all microorganisms, whereas compound 1∙2H2O displayed moderate activity (10 ∙2H2O exhibited bactericidal and fungicidal activity respectively on all the bacteria and yeasts tested. These findings reveal that the antimicrobial activity of HL was enhanced upon coordination to Co(II) ion against all microorganisms (bacteria and fungus).

Insecticidal,antimicrobial and antioxidant activities of bulb extracts of Allium sativum

Objective:To evaluate the insecticidal,antimicrobial and antioxidant activities of bulb extracts of Allium sativum(A.sativum).Methods:Dried bulbs of A.sativum were extracted with different solvents and evaluated for insecticidal,antimicrobial and antioxidant activities.Results: Aqueous and methanol extracts showed highest insecticidal activity(mortality rate of 81%and 64%respectively) against the larvae of Spodoptera litura(S.litura) at a concentration of 1000 ppm.With regard to antimicrobial activity,aqueous extract exhibited antibacterial activity against gram positive(Bacillus subtilis,Staphylococcus aureu,) and gram negative(Escherichia coli and Klebsiella pneumonia) strains and antifungal activity against Candida albicans.While methanol extract showed antimicrobial activity against all the tested micro organisms except two(Staphylococcus aureus and Candida albicans),the extracts of hexane,chloroform and ethyl acetate did not show any anti microbial activity.Minimum inhibitory concentration of aqueous and methanol extracts against tested bacterial and fungal strains was 100-150μg/mL. Antioxidant activity of the bulb extracts was evaluated in terms of inhibition of free radicals by 2.2’-diphenly-l-picrylhydrazyl.Aqueous and methanol extracts exhibited strong antioxidant activity(80%-90%of the standard).Conclusions:Antioxidant and antimicrobial activity of A.sativum against the tested organisms therefore,provides scientific basis for its utilization in traditional and folk medicine.Also,our results demonstrated the insecticidal efficacy of A. sativum against S.litura,a polyphagous insect.

Antimicrobial activities of the tissue extracts of Babylonia spirata Linnaeus,1758 (Mollusca:Gastropoda) from Thazhanguda,southeast coast of India

Objective:To investigate the antimicrobial activity of the tissue extracts of Babylonia spirata(B.spirala)against nine bacterial and three fungal patliogeiis.Methods:Crude extract of gastropod was tested for inhibition of bacterial and fungal growth.Antibacterial assay was carried out by disc diffusion method and in vitro antifungal activity was determined against Czapex Dox agar.The antimicrobial activity was measured accordingly based on the inhibition zone around the disc impregnated with gastropod extract.Molecular size of muscle protein was determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE).And fourier transform infrared spectroscopy(FT1R)spectro photometry analysis was also studied.Results:The maximum inhibition zone(12 mm)was observed against Pseudomonas aeruginosa in the crude ethanol extract of B.spirata and the minimum inhibition zone(2 mm)was noticed against Staphylococcus aureus in the crude methanol extract of B.spirala.Water extract of B.spirala showed the highest activity against Vibrio parahaemolyticus,Staphylococcus aureus and Candida albicans.Ethanol,acetone,methanol,chloroform and water extracts showed antimicrobial activity against almost all the bacteria and fungus.Compared with water extracts,ethanol and methanol extracts showed higher activity against all pathogens.The molecular weight of protein of the gastropod sample ranged from 2-110 kDa on SDS-PAGE.FTIR analysis revealed the presence of bioactive compounds signals at different ranges.Conclusions:The research shows that the great medicinal value of the gastropod muscle of B.spirata may be due to high quality of antimicrobial compounds.

In vitro evaluation of antimicrobial and antioxidant activities of methanolic extract of Jasminum humile Leaves

Objective:To evaluate in vitro antimicrobial and antioxidant activities of methanolic extract of Jasminum humile（J.humile） leaves extract.Method:Methanolic extract of J.humile was evaluated for its antimicrobial activity by using agar well diffusion method & their possible antioxidant assay by two complementary test systems,namely DPPH and hydrogen peroxide scavenging activity.These various antioxidant activities were compared to standard antioxidants such as ascorbic acid for both the tests.Results:In the DPPH & hydrogen peroxide scavenging activity,the IC50 value of methanol extract was 70.43μg/mL & 60.79μg/mL respectively. Further,the extract showed inhibitory activity for Gram-positive and negative bacteria at different concentrations.The maximum antibacterial activity of extract was exhibited against Staphylococcus aureus（S.aureus） at concentration 50 mg/mL when compared with ciprofloxacin Conclusions:These results clearly indicate that J.humile is effective in scavenging free radicals and has the potential to be a powerful antioxidant.Thus,the results obtained in the present study indicate that J.humile leaves extract could be considered as a potential source of natural antioxidants and that could be used as an effective source against bacterial diseases.

Antimicrobial activities of the rhizome extract of Zingiber zerumbet Linn

Objective:To investigate antimicrobial effects of ethanolic extract of Zingiber zerumbet(Z.zerumbet)(L.)Smith and its chloroform and petroleum ether soluble fractions against pathogenic bacteria and fungi.Methods:The fresh rhizomes of Zingiber zerumbet were extracted in cold with ethanol(4.0 L)after concentration.The crude ethanol extract was fractionated by petroleum ether and chloroform to form a suspension of ethanol extract(15.0 g),petroleum ether fraction(6.6 g)and chloroform soluble fraction(5.0 g).The crude ethanol extract and its petroleum ether and chloroform fractions were evaluated for antibacterial and antifungal activity against thirteen pathogenic bacteria and three fungi by the disc diffusion method.Commercially available kanamycin(30μg/disc)was used as standard disc and blank discs impregnated with the respective solvents were used as negative control.Results:At a concentration of 400μg/disc,all the samples showed mild to moderate antibacterial and antifungal activity and produced the zone of inhibition ranging from 6 mm to 10 mm.Among the tested samples,the crude ethanol extract showed the highest activity against Vibrio parahemolyticus(V.parahemolyticus).The minimum inhibitory concentration(MIC)of the crude ethanol extract and its fractions were within the value of 128-256μg/mL against two Gram positive and four Gram negative bacteria and all the samples showed the lowest MIC value against V.parahemolyticus(128μg/mL).Conclusions:It can be concluded that,potent antibacterial and antifungal phytochemicals are present in ethanol extract of Z.zerumbet(L.).

One-pot Synthesis,Crystal Structures and Antimicrobial Activities of Two New 1,4-Disubstituted 1,2,3-Triazole-4-Carboxylates

Two new 1,4-disubstituted 1,2,3-triazoles-4-carboxylates were synthesized via click reaction. Compound 1a was synthesized by the interaction of 6-nitro-tetrazolo[1.5-a]-pyridine with ethyl propynoate at room temperature in the presence of Cu（OAc）2 as a catalyst and THF as solvent. Compound 1b was also synthesized by the same manner except that tert-butyl propionate, instead of ethyl propynoate, was used. The compounds were characterized by IR, 1H-NMR, 13C-NMR and single-crystal X-ray diffraction analysis. Compound 1a（C10H9N5O4） crystallizes in the triclinic system, space group P1 with a = 5.0894（9）, b = 8.9834（13）, c = 13.089（2） ？, α= 83.041（7）, β= 80.256（7）, γ=87.296（8）°, V = 585.24（16）？3, Z = 2, Mr = 263.22, crystal size（mm） = 0.37 × 0.20 ×0.18,（I 〉 2σ（I）） = 8557, 2493, 1229, Rint = 0.057. Compound 1b（C12H13N5O4） crystallizes in the monoclinic system, space group P21/c with a = 6.8854（5）, b = 21.783（2）, c = 9.3986（8） ？,β = 93.239（4）°, V = 1407.4（2）？3, Z = 4, Mr = 291.27, crystal size（mm） = 0.38 × 0.22 × 0.20,（I 〉 2σ（I）） = 11842, 3172, 1866, Rint = 0.047. Antimicrobial assay results showed that the title compounds display excellent activities to different bacterial and fungal strains.

Effects of C-terminal amidation and heptapeptide ring on the biological activities and advanced structure of amurin-9KY, a novel antimicrobial peptide identified from the brown frog, Rana kunyuensis

Rana kunyuensis is a species of brown frog that lives exclusively on Kunyu Mountain,Yantai,China.In the current study,a 279-bp cDNA sequence encoding a novel antimicrobial peptide (AMP),designated as amurin-9KY,was cloned from synthesized double-strand skin cDNA of R.kunyuensis.The amurin-9KY precursor was composed of 62 amino acid (aa) residues,whereas the mature peptide was composed of 14 aa and contained two cysteines forming a C-terminal heptapeptide ring (Rana box domain) and an amidated C-terminus.These structural characters represent a novel amphibian AMP family.Although amurin-9KY exhibited high similarity to the already identified amurin-9AM from R.amurensis,little is known about the structures and activities of amurin-9 family AMPs so far.Therefore,amurin-9KY and its three derivatives (amurin-9KY1-3) were designed and synthesized.The structures and activities were examined to evaluate the influence of C-terminal amidation and the heptapeptide ring on the activities and structure of amurin-9KY..Results indicated that C-terminal amidation was essential for antimicrobial activity,whereas both C-terminal amidation and the heptapeptide ring played roles in the low hemolytic activity.Circular dichroism (CD) spectra showed that the four peptides adopted an α-helical conformation in THF/H2O (v/v 1∶1) solution,but a random coil in aqueous solution.Elimination of the C-terminal heptapeptide ring generated two free cysteine residues with unpaired thiol groups,which greatly increased the concentration-dependent anti-oxidant activity.Scanning electron microscopy (SEM) was also performed to determine the possible bactericidal mechanisms.

Syntheses,Crystal Structures,and Antimicrobial Activities of 3-Bromo-N'-(2- chloro-5-nitrobenzylidene)benzohydrazide and 3-Bromo-N'-(4-nitrobenzylidene)benzohydrazide

Two new hydrazone compounds, 3-bromo-N＇-（2-chloro-5-nitrobenzylidene）-ben- zohydrazide 1 and 3-bromo-N＇-（4-nitrobenzylidene）benzohydrazide 2, have been synthesized and characterized by elemental analysis, IR spectra, 1H NMR, and single-crystal X-ray diffraction. Compound 1 crystallizes in monoclinic, space group P21/c with a=7.7924（10）, b=24.490（3）, c=7.8989（9） , β=94.987（6）°, V=1501.7（3） 3, Z=4, R=0.0345 and wR=0.0739. Compound 2 crystallizes in monoclinic, space group P21/c with a=7.4099（11）, b=24.868（4）, c=8.3255（12） , β=112.796（8）°, V=1414.3（4） 3, Z=4, R=0.0744 and wR=0.1912. Both compounds display E configurations with respect to the C=N double bonds. In the crystal structure of 1, molecules are linked through N-H…N and N-H…O hydrogen bonds, forming chains running along the c axis. In the crystal structure of 2, molecules are linked through N-H…O hydrogen bonds, forming chains running along the c axis. The preliminary antimicrobial activities were studied.

Synthesis of Stable Silver Nanoparticles with Antimicrobial Activities in Room-temperature Ionic Liquids

Stable silver nanoparticles was successfully synthesized by chemical reduction of silver nitrate in an ionic liquid,1-n-butyl-3-methylimidazolium tetrafluoroborate（[BMIM]·BF4） at room temperature.Results of UV-Vis diffuse reflectance spectroscopy show as-prepared Ag nanoparticles exhibit a typical emission peak at 400―430 nm.By varying the reaction temperature and the precursor concentration,the size and the shape of the silver nanoparticles could be easily controlled under mild conditions.Analyses of transmission electron micrographs,X-ray diffraction pattern and X-ray photoelectron spectrum further reveal that the silver nanoparticles were coated incompletely by [BMIM]·BF4.Microbial experiments indicate that as-prepared silver nanoparticles show a wide spectrum of antimicrobial activities and have better antimicrobial activities to Pseudomonas aeruginosa than silver nitrate with the same concentration of silver.