Antibacterial Activities of 5-Nitro-2-uryl and 5-Nitro-2-Imidazolyl Derivatives of 1,3,4-Thiadiazole

Introduction: Nitrofurans and nitroimidazoles are broad-spectrum antimicrobial agents, which affect the microbial DNA. The aim of the present study was to evaluate the new derivatives of these two groups of antimicrobials against certain Gram-positive and Gram-negative bacterial strains. Materials and Methods: Seven new derivatives of nitrofurans and nitroimidazoles were synthesized, and 6.4 mg of each derivative was dissolved in dimethyl sulfoxide. Then, 8 serial dilutions (0.5, 1, 2, 4, 8, 16, 32, and 64 μg/ml) of each derivative was prepared using Muller-Hinton broth, and the minimum inhibitory concentration for each derivative was measured and compared to ciprofloxacin (standard). Results: All the derivatives had no antibacterial effects against Gram-negative bacteria (minimum inhibitory concentration > 64 μg/ml); only 2-(5-nitro-2-furyl)-5-(n-pentylsulfunyl)-1,3,4-thiadiazole exhibited mild antibacterial effects against Klebsiella pneumonia (minimum inhibitory concentration of 16-32 μg/ml). The antibacterial effects of the derivatives against Gram-positive bacteria also showed variations from complete inhibition of the growth of Staphylococcus epidermidis and Bacillus subtilis (minimum inhibitory concentration < 0.5 μg/ml) by 2-(5-nitro-2-furyl)-5-(n-buthylthio)-1,3,4-thiadiazole to no inhibition of S. epidermidis and streptococcus pyogenes. Conclusion: These compounds have weak antibacterial effects; only two derivatives showed antibacterial effects similar to that of the positive control

Synthesis and antibacterial activity of N-(5-benzylthio-1,3,4-thiadiazol-2-yl) and N-(5-benzylsulfonyl-1,3,4-thiadiazol-2-yl)piperazinyl quinolone derivatives

A series of N-(5-benzylthio-1,3,4-thiadiazol-2-yl) and N-(5-benzylsulfonyl-1,3,4-thiadiazol-2-yl) derivatives of piperazinyl quinolones was synthesized and evaluated for antibacterial activity against Gram-positive and Gram-negative microorganisms. Some of these derivatives exhibit high activity against Gram-positive bacteria; Staphylococcus aureus and Staphylococcus epidermidis, comparable or more potent than their parent N-piperazinyl quinolones norfloxacin and ciprofloxacin as reference drugs. The SAR of this series indicates that both the structure of the benzyl unit and the S or SO2 linker dramatically impact antibacterial activity

Synthesis and antibacterial activity of N-(5-benzylthio-1,3,4-thiadiazol-2-yl) and N-(5-benzylsulfonyl-1,3,4-thiadiazol-2-yl)piperazinyl quinolone derivatives

A series of N-(5-benzylthio-1,3,4-thiadiazol-2-yl) and N-(5-benzylsulfonyl-1,3,4-thiadiazol-2-yl) derivatives of piperazinyl quinolones was synthesized and evaluated for antibacterial activity against Gram-positive and Gram-negative microorganisms. Some of these derivatives exhibit high activity against Gram-positive bacteria; Staphylococcus aureus and Staphylococcus epidermidis, comparable or more potent than their parent N-piperazinyl quinolones norfloxacin and ciprofloxacin as reference drugs. The SAR of this series indicates that both the structure of the benzyl unit and the S or SO2 linker dramatically impact antibacterial activity

Antimutagenic activity of major fractions of Zataria multiflora Boiss by Ames method

Zataria activity and richness of flavonoids. Antimutagenicity effect of total extract of the plant has been reported previously. multiflora is a medicinal plant that has been interested in antimutagenicity effect because of its high antioxidant Aerial parts of Z. multiflora were extracted by petroleum ether, chloroform and 80% methanol by liquid‑liquid extraction method consequently. The fractions were concentrated in vacuum and dried at 40°C in oven. The genotype of two standard strains of Salmonella typhimurium (TA98, TA100) was confirmed by the evaluation of two important factors of histidine requirement and the presence of R factor. The minimum inhibition concentration (MIC) of the fractions against these two strains was determined by agar dilution method. From each fraction, various concentrations less than MIC were studied for anti‑mutagenic test. The sample along with bacterial strain and mutagen agent were incubated at 37°C for 48 h. The number of revertant colonies was counted and compared with control plates. Our results showed that all fractions especially petroleum ether and chloroform ones maintain the number of colonies in the standard range in control plates and prevent from the growth of many strains of bacteria and increase of revertant colonies enhancement in a concentration‑dependent manner. This effect was prominent against TA100 starin. Methanolic fraction exhibited anti‑mutagen activity just in the highest used concentration in the presence of TA98

BIOASSAY SCREENING OF THE ESSENTIAL OIL AND VARIOUS EXTRACTS FROM 4 SPICES MEDICINAL PLANTS

Four commonly used spices plants in Iran were evaluated for cytotoxicity effect using Brine Shrimp Lethality (BSL) assay. Essential oils and various extracts of Heracleum persicum, Nigella arvensis, Cinnamomum zeylanicum and Zingiber officinale were assessed by two methods of disk and solution of BSL. Data were processed in probit-analysis program to estimate LC50 values. All of the tested fractions have exhibited more cytotoxicity in the solution method. Essential oils of H. persicum and C. zeylanicum have shown the most cytotoxicity with LC50 values 0.007 and 0.03 μg/ml respectively. None of aqueous extracts showed significant cytotoxicity. The analysis of the essential oil of H. persicum showed the hexyl butyrate and octyl acetate as the main compounds. These results suggest some limitation for using of these spices in diet. Furthermore, these plants could be considered as a source of cytotoxic compounds which might be studied in more details

Investigating the effects of various additives on surface activity and emulsification index of biosurfactant resulting from broth media of Bacillus subtilis PTCC 1023

Surfactants are amphipathic molecules which reduce surface tension and are widely used in pharmaceutical, cosmetic and food industries. In the present study, the production of biosurfactant by Bacillus subtilis PTCC 1023 was studied. B. subtilis was grown in the nutrient broth medium and biosurfactant production was evaluated by measuring the surface tension and emulsification index (E24) each 24 h. The bacterium’s biosurfactant production was investigated in different status with variable factors such as incubation time, temperature, aeration rate and presence of several additives. Then the best fermentation condition was investigated for maximum biosurfactant production and finally biosurfactant identity was investigated using some chemical and spectroscopy methods. The maximum biosurfactant production by B. subtilis PTCC 1023 was obtained when it was grown in brain-heart broth medium containing FeSO4 (4×10-3 M), MnSO4 (1.3×10-3 M), starch (4%) and castor oil (4%) which incubated in a 300 rpm rotary shaker at 30°C for 24 h. Lipopepetide natures in this biosurfactant was confirmed by biochemical and spectroscopic methods

Investigation of cellular hydrophobicity and surface activity effects of biosynthesed biosurfactant from broth media of PTCC 1561

Biosurfactants as surface active molecules that are synthesized by microorganisms. These substances include many advantages in comparison with chemical surfactants. For instance they have lower toxicity, higher biodegradability, better environmental compatibility, higher foaming activity, and specific activity at extreme temperatures, pH ranges, and the ability to be synthesized from renewable feed stocksin. In this study, the production of biosurfactant, produced by PTCC 1561 was studied. This bactrium was grown in a nutrient broth medium and the production of biosurfactant was evaluated by the surface tension and emulisification index (E24), each 24 h. The production of biosurfactant was studied in different conditions, including time of incubation, temperature, aeration rate and presence of several additives containing mineral salts and hydrocarbons. Finally, the optimum condition for production of the biosurfactant was determined and the biosurfactant identity was investigated using chemical and spectroscopy methods. The maximum biosurfactant production by Pseudomonas aeruginosa PTCC 1561, was exhibited when it was grown in Brain Hearth Broth medium containing Fecl3, ZnSO4, FeSO4, starch and olive oil incubated in a 200 rpm shaker incubator at 37°C for 24 h . The structure of produced biosurfactant sugar-lipid was confirmed by chemical and spectroscopy methods

Antitumor and antibacterial activity of four fractions from Heracleum persicum Desf. and Cinnamomum zeylanicum Blume

At the present study tumor inhibition and antibacterial activity of the essential oils of Heracleum persicum and Cinnamomum zeylanicum was investigated. Methanol and petroleum ether were extracted from C. zeylanicum by potato disk method. These fractions showed cytotoxic effects in brine shrimp lethality assay (BSL). The authors found both H. persicum (57.16%) and C. zeylanicum (72.90%) had inhibition effects on Agrobacterium tumefaciens which induced crown gall tumor on potato disk. These oils also exhibited antitumor activity where IC50 was applied and the values were 2.24 and 1.20 mg/mL, respectively, for H. persicum and C. zeylanicum. C. zeylanicum also inhibited the growth of all tested Gram- positive and Gram-negative strains. In all, the findings of the present study completely correspond to the results obtained in brine shrimp lethality

Bioassay Screening of the Essential Oil and Various Extracts of Nigella sativa L. Seeds Using Brine Shrimp Toxicity Assay

Background and Aim: Since cytotoxicity screening is the first step necessary for any new drug development, this study was designed to find out and compare the cytotoxicity effects of the essential oil and various extracts of Nigella sativa L. seeds using Brine Shrimp Lethality (BSL) assay. Materials and Methods: Essential oils and various extracts of N. sativa were assessed by two methods of disk and solution of BSL. Data analysis was carried out using SPSS statistical package version 17.0 (SPSS Inc., Chicago, IL, 250 USA). Data were processed in probit-analysis program to estimate LC50 values. Results: All of the tested fractions demonstrated more cytotoxicity in the solution method. Petroleum ether and chloroform extract of N. sativa showed the most cytotoxicity with LC50 values 7 and 21 μg/ml respectively; while aqueous and ethanolic had no significant cytotoxicity. Moreover, the GC/MS analysis of the essential oil of N. sativa showed the p-cymene (48.1%), α-thujone (14.38%) and dihydro carveol (9.11%) as the main compounds. Conclusion: These results suggest some limitation for using this spice in diet. Furthermore, this plant could be considered as a source of cytotoxic compounds which should be studied in details