Investigation of a new horizon antifungal activity with enhancing the antimicrobial efficacy of ciprofloxacin and its binary mixture via their encapsulation in nanoassemblies: in vitro and in vivo evaluation

The main goal of this study was to prepare and evaluate nanosponges containing ciprofloxacin (CIP) or its binary mixture with N-acetyl carnosine (NAC). Nanosponges were prepared by ultrasound-assisted synthesis technique using hydroxypropyl βeta-cyclodextrin (HPβ-CD), as the polymer and diphenyl carbonate (DPC) as the crosslinker. Entrapment efficiency (EE%) of CIP or its binary mixture with NAC in nanosponges was deduced spectrophotometrically. Nanosponges were characterized using several methods. EE% of CIP or its binary mixture with NAC inside nanosponges ranged from 98.63 ± 3.1 to 100 ± 0.07%. Particle size of nanosponges ranged from 66.7 to 90.1 nm. Release of drugs from nanosponges was biphasic and the release pattern followed Korsmeyer–Peppas model. Ex vivo and in vivo studies results showed that the antibacterial effect was enhanced with encapsulation of drugs in the nanosponge system. Furthermore, a potent antifungal activity was obtained from all examined formulae against Candida albicans (10231). The study revealed that successful encapsulation of CIP or its binary mixture with NAC in nanosponge formulations has innovated a new promising therapeutic activity for both drugs.     

Investigation of the antimicrobial and anticancer activity of aminonaphthoquinones

In this study, we report on the inhibitory activity of synthesized aminonaphthoquinones against two bacterial and one fungal species to determine their antimicrobial properties. A minimum inhibitory concentration (MIC) of 7.8 μg/mL was obtained against the fungus, Candida albicans, which was better than that of Amphotericin B (MIC = 31.25 μg/mL). Escherichia coli (Gram -), was inhibited at a MIC of 23.4 μg/mL and Staphylococcus aureus (Gram +) at a MIC of 31.3 μg/mL. The aminonaphthoquinones were also screened against HCT116 colon, PC3 prostate and HepG2 liver cancer cell lines to evaluate their cytostatic effects. They had potent activity (GI₅₀ = 5.87–9.90 μM) which was about three-6-fold better than that of parthenolide (GI₅₀ = 25.97 μM) against the prostate cancer cell line. These compounds were generally more selective for cancer cells than for normal human lung fetal fibroblasts (WI-38).     

Antibacterial,antifungal and cytotoxic activities of salviasperanol isolated from Amorphophallus campanulatus

Salviasperanol, a diterpenoid isolated from Amorphophallus campanulatus (Roxb.) Bl. (Araceae) was studied for in vitro antibacterial, antifungal, and cytotoxic activities. The disc diffusion technique was used to determine in vitro antibacterial and antifungal activities. Cytotoxicity was determined against brine shrimp nauplii. In addition, minimal inhibitory concentration (MIC) was determined using serial dilution technique to determine antibacterial potency. The MIC values against these bacteria ranged from 8 to 64 μg/mL. The compound showed significant antibacterial activity against four Gram-positive bacteria (Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus, Streptococcus β-haemolyticus) and six Gram-negative bacteria (Escherichia coli, Shigella dysenteriae, Shigella sonnei, Shigella flexneri, Pseudomonus aeruginosa, Salmonella typhi). The compound showed weak antifungal activity against a number of fungi. In the cytotoxicity determination, the LC₅₀ of the compound against brine shrimp nauplii was 8.02 μg/mL.     

Synthesis and antimicrobial activity of new 2‐piperazin‐1‐yl‐N‐1,3‐thiazol‐2‐ylacetamides of cyclopenta[c]pyridines and pyrano[3,4‐c]pyridines

In this study, we report the synthesis and antimicrobial activity of some new disubstituted piperazines. Thus, 3‐chlorocyclopenta[c]pyridines and 6‐chloropyrano[3,4‐c]pyridine 1 under mild reaction conditions with piperazine gave the 3(6)‐piperazine‐substituted cyclopenta[c]pyridines and pyrano[3,4‐c]pyridine 2 . Furthermore, the latter, by alkylation with 2‐chloro‐N‐1,3‐thiazol‐2‐ylacetamide, led to the formation of the target compounds. The evaluation of the antibacterial activity revealed that 3k was the most potent compound. The most sensitive bacterium was found to be Listeria monocytogenes, whereas Staphylococcus aureus was the most resistant one. Three compounds, 3d , 3g , and 3k , were tested also against the following resistant strains: methicillin‐resistant S. aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa. All three compounds appeared to be more potent than ampicillin against MRSA. Moreover, compound 3d showed a better activity than the reference drug ampicillin against P. aeruginosa, whereas 3g was more efficient against E. coli. The best antifungal activity was observed again for compound 3k . The most resistant fungi appeared to be Aspergillus fumigatus, whereas Trichoderma viride seemed the most sensitive one toward the compounds tested. Molecular docking studies on E. coli MurB, as well as on Candida albicans CYP51 and dihydrofolate reductase, were used for the prediction of the mechanisms of the antibacterial and antifungal activities, confirming the experimental results.     

Synthesis and antimicrobial activities of some new nitroimidazole derivatives

In this study, some new nitroimidazole derivatives were obtained from 2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethylamine dihydrochloride (4) and 1-(2-bromoethyl)-2-methyl-5-nitroimidazole (5), which were prepared using metronidazole. Compound 4 was reacted with arylisothiocyanates (6) to obtain 1-[2-(2-methyl-5-nitroimidazol-1-yl)ethyl]-3-arylthioureas (7) and the latter with alpha-bromoacetophenones (8) to give 3-[2-(2-methyl-5-nitroimidazol-1-yl)ethyl]-2-arylimino-4-aryl-4-thiazolines (9). Also 1-[2-(2-methyl-5-nitroimidazol-1-yl)ethyl]-2-phenyl-4-arylideneimidazolin-5-ones (11) were prepared by reaction of 4 with 2-phenyl-4-arylidene-5-oxazolones (10). The reaction of the other starting material 5 with 5-arylidenethiazolidin-2,4-dione (12) gave 3-[2-(2-methyl-5-nitroimidazol-1-yl)ethyl]-5-arylidenethiazolidin-2,4-dione (13) derivatives. Structural elucidation of the compounds was performed by IR, 1H-NMR and MASS spectroscopic data and elemental analysis results. Antimicrobial activities of the compounds were examined and moderate activity was obtained.     

冈村凹顶藻的倍半萜类化学成分及抗菌活性研究

目的 分离鉴定冈村凹顶藻中的倍半萜类成分,供抗菌活性筛选。方法 综合利用各种柱层析方法分离纯化化合物并利用光谱学方法解析化合物结构;选择4株真菌为实验菌株,对6个倍半萜进行体外抗真菌活性测定;选择2株细菌为实验菌株,对所有倍半萜进行体外抗细菌活性测定。结果 分离得到17个倍半萜,分别鉴定为海兔阿普里醇 (1)、劳藻过氧素 (2)、海兔阿普里醛 (3)、 α-异溴花侧伯烯 (4)、α-异花侧伯烯醇 (5)、花侧伯烯醚 (6)、月桂烷-11-烯-10-醇 (7)、劳藻酚 (8)、劳藻酚乙酰化物 (9)、去溴劳藻酚 (10)、异劳藻酚 (11)、异劳藻酚乙酰化物 (12)、约翰斯顿醇 (13)、帕西菲醇 (14)、10-溴-α-花柏烯 (15)、10-溴-β-花柏烯 (16)、9-羟基-3-氯-4,10-二溴-α-花柏烯 (17),并对所获得的倍半萜进行抗菌活性筛选。结论 化合物5和7为首次从冈村凹顶藻中分离得到;应用1D和2D NMR首次对化合物6的1H和13C NMR数据进行了全归属;化合物5和13对光滑假丝酵母菌显示了明显的抑制作用,其MIC80值分别为1和4 μg/mL,与两性霉素B（2 μg/mL）和氟康唑（1 μg/mL）相当,而化合物2、8和9对新生隐球菌均具有一定的抑制作用;另外,化合物2、8~10、15和17对金黄色葡萄球菌均显示了不同程度的抑制作用,其中化合物8和9具有良好的杀菌活性,其MIC80值分别为2.3和10.5 μg/mL。     

Synthesis and antimicrobial evaluation of piperic acid amides and their lower homologues

Seven piperic acid amides along with their lower homologs (12) were synthesized using HATU-DIPEA coupling reagent. All the synthesized derivatives were evaluated for their antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, and vancomycin-resistant P. aeruginosa. They were found to be more active on P. aeruginosa than on S. aureus. However, they did not exhibit potent activity on Vancomycin resistant P. aeruginosa. Among the tested compounds, methylenedioxycinnamic acid amide of anthranilic acid (MDCA-AA, 2a) was found to be most active against S. aureus with MIC of 3.125 μg/ml. The PAS and INH amides of piperic acid were screened against Mycobacterium tuberculosis H37R_a strain. They were found to be most active among all the tested compounds but were found to be less active than the standard drug, isoniazid.     

Discovery and structure–activity relationship of plastoquinone analogs as anticancer agents against chronic myelogenous leukemia cells

Two series of amino‐1,4‐benzoquinones ( AQ1–18 ) based on the structural analogs of plastoquinones were synthesized and the structure–activity relationship against chronic myelogenous leukemia activity was examined. All of the synthesized compounds were tested for their cytotoxic effects on different leukemic cell lines. Of interest, AQ15 exhibited a better selectivity than the reference drug imatinib on cancer cells. Owing to this, AQ15 was selected for a further apoptosis/necrosis evaluation where AQ15 ‐treated K562 cells demonstrated similar apoptotic effects like imatinib‐treated cells at their IC₅₀ values. The inhibitory effects of AQ15 and the other three compounds with various activities against eight tyrosine kinases, including ABL1, were investigated. AQ15 showed weak activity against ABL1, and a correlation was observed between the anti‐K562 and anti‐ABL1 activities. The binding mode of AQ15 into the ATP binding pocket of ABL1 kinase was predicted in silico, showing the formation of some key interactions. In addition, AQ15 was shown to suppress the downstream signaling of BCR‐ABL in K562 cells. Finally, AQ15 obviously cleaved DNA in the presence of an iron(II) complex system, indicating that this can be the major mechanism of its antiproliferative action, whereas the mild inhibition of ABL kinase is just in‐part mechanism of its overall outstanding cellular activity.     

Di- and triorganotin(IV) esters of 3,4-methylenedioxyphenylpropenoic acid: synthesis, spectroscopic characterization and biological screening for antimicrobial, cytotoxic and antitumor activities

Nine biologically significant organotin(IV) esters of 3,4-Methylenedioxyphenylpropenoic acid (L) were synthesized with the general formulae [R2SnL2], where R includes Me(1), Et(3), But(4), Oct(5), Ph(8), and [R3SnL], in which R is Me(2), Cy(6), Ph(7), and But(9). The acid and its compounds were characterized by basic analytical techniques comprising elemental analysis, FTIR and mass spectrometry in solid state and by Multinuclear (1H, 13C and 119Sn) NMR in solution form, which provides some important information about the different coordination behaviors of metal in both solid and solution. Methylenedioxy moiety in these compounds enhances the biological activity of these compounds. These compounds were screened for a range of biological activities. Antibacterial activities were determined against six pathogenic bacterial strains, three gram-positive and three gram-negative, the activities were measured in terms of inhibition zones (mm). Results demonstrate that diorganotin derivatives are more active than triorganotin derivatives and ligand acid. Antifungal activity was determined against six pathogenic fungal strains, cytotoxicity by the brine shrimp lethality assay, and antitumor activity by crown gall tumor inhibition (potato disc) assay. Results for antifungal activity, cytotoxicity, and antitumor activity of these compounds demonstrate that triorganotin derivatives are more active than diorganotin derivatives and ligand. Finally, the results were compared with similar reports in the literature.     

New hydrazide–hydrazones of isonicotinic acid: synthesis,lipophilicity and in vitro antimicrobial screening

This study describes the synthesis, lipophilicity and in vitro antimicrobial assays of 15 new hydrazide–hydrazones of isonicotinic acid. New derivatives were obtained on the basis of the condensation reaction of isonicotinic acid hydrazide with different aromatic aldehydes. The chemical structure of synthesized compounds was confirmed by spectral methods. Experimental lipophilicity of new isonicotinic acid derivatives was determined using reversed‐phase thin‐layer chromatography. All synthesized compounds were subjected to in vitro antimicrobial assays against reference strains of Gram‐positive bacteria, Gram‐negative bacteria and fungi belonging to Candida spp. Some of the synthesized hydrazide–hydrazones proved to be significant antibacterial compounds and more potent than commonly used chemotherapeutic agents.     

香豆素苯并三唑的合成、抗微生物活性及其与氯霉素和氟康唑协同作用研究

以间苯二酚为起始原料,经过环化、醚化、N-烷化等多步反应合成了一系列新型香豆素苯并三唑类化合物,其结构经1H NMR、IR、MS和元素分析证实。体外考察了合成的香豆素类化合物抗革兰阳性菌、革兰阴性菌及真菌活性。结果表明香豆素苯并三唑能有效抑制细菌和真菌的生长,其中化合物11a～11e和13a～13c抗普通变形杆菌ATCC 6896活性强于氯霉素(chloromycin)。化合物11a和11b抑制金葡菌ATCC 25923和藤黄微球菌ATCC 4698的生长能力与氯霉素相当。化合物11a～11d抗烟曲霉菌ATCC 96918活性优于氟康唑(fluconazole)。此外,氯霉素或氟康唑与香豆素苯并三唑联用后,不仅减少了用药剂量,还拓宽了抗微生物谱,尤其增强了抑制耐甲氧西林的金葡菌N 315和氟康唑不敏感的烟曲霉菌的生长能力。     

A new secondary metabolite from the fermented mycelia of Streptomyces antibiotic H41-55

Abstract

An actinomycete strain, H41-55 from sea sediment was identified as Streptomyces antibiotic on the basis of its morphological, physiological and biochemical characteristics as well as 16S rDNA data. A new secondary metabolite, (2S,3R)-N-[3-(formylamino)-2-hydroxybenzoyl]-l-threonine propyl ester (1), together with five known compounds was isolated from fermentation product by use of silica gel and Sephadex LH-20 column chromatography, and preparative RP-C18 HPLC, and identified by HR-TOF-MS and NMR spectra. The cytotoxicities of these isolates against three cancer cell lines and their antifungal activities on Candida albicans were tested. Compounds 1, 3, 5, and 6 displayed moderate cytotoxicity. 5 and 6 showed inhibitory activity on C. albicans.     

Antimicrobial Screening of Actinobacteria using a Modified Cross-Streak Method

Out of the 30 actinobacterial cultures screened for antimicrobial activity, 28 cultures were found to produce active products against various pathogenic microorganisms such as Gram-negative, Gram-positive bacteria and yeast, using a modified cross streak method. The modified method helped in easy quantification of results and also in ruling out probable mutual antibiosis. The actinobacterial strains that showed the ability to produce antimicrobial compounds belonged to Streptomyces (53%), Micromonospora (13%) and Actinomadura (10%) genera. Streptomyces sp. strain MMA-5 showed the highest multispecific antibiosis efficiency score value. Broad antibiotic spectrum activity was exhibited by Streptomyces sp. strain MMA-2 and Micromonospora sp. strain MMA-8. The multidrug resistant human pathogenic yeast strain Candida albicans was inhibited by 18 actinobacterial strains.     

新一代广谱抗生素药物筛选靶点肽脱甲酰基酶的研究进展

肽脱甲酰基酶(peptide deformylase，PDF)存在于所有原核生物中，是其生长、代谢、繁殖必不可少的关键酶，但不存在于人类与其他哺乳动物细胞内，因而被视为新一代广谱抗生素药物筛选的理想靶点。现介绍PDF的结构、功能、理化性质以及作为药物筛选靶点的优良特点，此外，还简单介绍该酶与其抑制剂相互作用机制和以该酶为靶点新药研究进展。     

Synthesis of new bis‐pyrazole linked hydrazides and their in vitro evaluation as antimicrobial and anti‐biofilm agents: A mechanistic role on ergosterol biosynthesis inhibition in Candida albicans

Literature reports suggest that pyrazoles and hydrazides are potential antimicrobial pharmocophores. Considering this fact, a series of nineteen conjugates containing hybrids of bis‐pyrazole scaffolds joined through a hydrazide linker were synthesized and further evaluated for their antimicrobial activity against a panel of Gram‐positive and Gram‐negative bacteria along with Candida albicansMTCC 3017 strain. Although the derivatives exhibited good antibacterial activity, some of the derivatives ( 13d , 13j , 13l , 13p , and 13r ) showed excellent anti‐Candida activity with MICs values of 3.9 μg/ml, which was equipotent to that of the standard Miconazole (3.9 μg/ml), which has inspired us to further explore their anti‐Candida activity. The same compounds were also tested for anti‐biofilm studies against various Candida strains and among them, compounds 13l and 13r efficiently inhibited the formation of fungal biofilms. Field emission scanning electron micrographs revealed that one of the promising compound 13r showed cell damage and in turn cell death of the Candida strain. These potential conjugates ( 13l and 13r ) also demonstrated promising ergosterol biosynthesis inhibition against some of the strains C. albicans, which were further validated through molecular docking studies. In silico computational studies were carried out to predict the binding modes and pharmacokinetic parameters of these conjugates.     

Synthesis and antimicrobial evaluation of new nitric oxide‐donating fluoroquinolone/oxime hybrids

A new series of nitric oxide‐donating fluoroquinolone/oximes was prepared in this study. The nitric oxide release from the prepared compounds was measured using a modified Griess colorimetric method. The antitubercular evaluation of the synthesized compounds indicated that ketone derivatives 2b and 2e and oximes 3b and 3d exhibited somewhat higher activity than their respective parent fluoroquinolones. Mycobacterial DNA cleavage studies and molecular modeling of Mycobacterium tuberculosis DNA gyrase were pursued to explain the observed bioactivity. More important, antibacterial evaluation showed that oximes 3c–e are highly potent against Klebsiella pneumoniae, with minimum inhibitory concentration (MIC) values of 0.06, 0.08, and 0.034 µM, respectively, whereas ketone 2c and oxime 4c are more active against Staphylococcus aureus than ciprofloxacin (MIC values: 0.7, 0.38, and 1.6 µM, respectively). Notably, the antipseudomonal activities of compounds 2a and 4c were much higher than those of their respective parent fluoroquinolones.     

Synthesis, antimicrobial and antineoplastic activities for agelasine and agelasimine analogs with a beta-cyclocitral derived substituent

Agelasines and agelasimines are antimicrobial and cytotoxic purine derivatives isolated from marine sponges (Agelas sp.). We have synthesized structurally simplified analogs of these natural products starting from beta-cyclocitral. The novel compounds were found to be strong inhibitors of a wide variety of pathogenic microorganisms (incl. Mycobacterium tuberculosis) as well as cancer cell lines. The biological activities were generally in the same range as those previously found for the structurally more complex agelasines and agelasimines isolated in small amounts from natural sources. We also report for the first time that agelasine and agelasimine analogs inhibit growth of protozoa (Acanthamoeba castellanii and Acanthamoeba polyphaga). Acanthamoeba keratitis is an increasingly common and severe corneal infection, closely associated with contact lens wear.     

Discovery to solve multidrug resistance: Design,synthesis, and biological evaluation of novel agents

Chemotherapy remains a pillar in the treatment and management of various cancers. However, multidrug resistance (MDR) becomes a severe problem after long‐term administration of chemotherapy drugs. Overexpression of P‐glycoprotein (P‐gp) is a significant cause for tumor MDR. Therefore, P‐gp inhibition is considered as an effective strategy to reverse MDR. A third‐generation P‐gp inhibitor tariquidar was selected as a lead compound, and a new series of triazol‐N‐ethyl tetrahydroisoquinoline based compounds were designed as novel P‐gp inhibitors and synthesized through click chemistry. These compounds presented higher reversal activities than the positive‐control verapamil (VRP). Among 18 compounds, compound 11 without cytotoxicity reversed MDR in a dose‐dependent manner, with a persistent longer chemosensitizing effect and reversibility compared to others. Mechanism studies discovered that compound 11 could escalate the intracellular accumulation of rhodamine‐123 and doxorubicin in K562/A02 cells as well as inhibit their efflux from cells. The results obtained suggest that compound 11 is more potent than VRP administered under the same conditions; it may be a potent and safe candidate for P‐gp modulation for further development.     

Ageritin from Pioppino Mushroom: The Prototype of Ribotoxin-Like Proteins,a Novel Family of Specific Ribonucleases in Edible Mushrooms

Ageritin is a specific ribonuclease, extracted from the edible mushroom Cyclocybe aegerita (synonym Agrocybe aegerita), which cleaves a single phosphodiester bond located within the universally conserved alpha-sarcin loop (SRL) of 23–28S rRNAs. This cleavage leads to the inhibition of protein biosynthesis, followed by cellular death through apoptosis. The structural and enzymatic properties show that Ageritin is the prototype of a novel specific ribonucleases family named ‘ribotoxin-like proteins’, recently found in fruiting bodies of other edible basidiomycetes mushrooms (e.g., Ostreatin from Pleurotus ostreatus, Edulitins from Boletus edulis, and Gambositin from Calocybe gambosa). Although the putative role of this toxin, present in high amount in fruiting body (>2.5 mg per 100 g) of C. aegerita, is unknown, its antifungal and insecticidal actions strongly support a role in defense mechanisms. Thus, in this review, we focus on structural, biological, antipathogenic, and enzymatic characteristics of this ribotoxin-like protein. We also highlight its biological relevance and potential biotechnological applications in agriculture as a bio-pesticide and in biomedicine as a therapeutic and diagnostic agent.     

Synthesis and antimicrobial activity of new 2-[p-substituted-benzyl]-5-[substituted-carbonylamino]benzoxazoles

A series of 23 new 2-[p-substituted-benzyl]-5-[p-substituted-phenyl/benzyl-carbonylamino]benzoxazole derivatives has been synthesized by reacting 5-amino-2-[p-substituted-benzyl]benzoxazoles with the appropriate carboxylic acid chlorides. The structures of the synthesized compounds were confirmed by IR and (1)H-NMR spectral data. Antimicrobial activities of the compounds were investigated using the twofold serial dilution technique against two gram-positive and two gram-negative bacteria and three Candida species in comparison with standard drugs. Microbiological results indicated that the newly synthesized 2-[p-substituted-benzyl]-5-[p-substituted-phenyl/benzyl-carbonylamino]benzoxazole derivatives (3-25) possessed a broad spectrum of activity, showing MIC values of 6.25-200 microg/mL against the gram-positive and gram-negative microorganisms tested. Moreover, they showed significant antifungal activity with MIC values of 3.12-100 microg/mL against the Candida species tested. Especially, with a MIC value of 3.12 microg/mL, 2-benzyl-5-[p-bromobenzyl-carbonylamino]benzoxazole 9 displayed the same activity against C. glabrata as the standard drug myconazol.