Current Issue : July - September Volume : 2020 Issue Number : 3 Articles : 5 Articles
Endophytic fungi were first isolated from the fresh root of the Chinese medicinal plant\nVernonia anthelmintica collected from the Hotan Prefecture within the Xinjiang Autonomous region\nof the Peopleâ??s Republic of China. This plant has been used in Uyghur traditional medicine to\ntreat vitiligo, a skin condition characterized by patches of the skin losing their pigment. In total,\nfifteen fungal strains were isolated. Among these, four endophytic fungi were identified by their\nDNA sequences and registered to GenBank with accession numbers. The isolates were identified\nas Schizophyllum commune XJA1, Talaromyces sp. XJA4, Aspergillus sp. XJA6, Aspergillus terreus XJA8.\nEthyl acetate extracts of all fungal strains were used to quantify melanin content and to identify\nin vitro biological activity assays including antimicrobial, antioxidant, cytotoxic, antidiabetic and\ntyrosinase activity on B16 cells. Among the extracts of all four identified strains, the ethyl acetate\nextract of the Aspergillus sp. XJA6 was chosen for further characterization because it presented the\nhighest biological activity against these tests. In addition, twenty four volatile compounds from the\npetroleum ether fraction were characterized by GCâ??MS....
With the increasing resistance of bacteria to current antibiotics, novel compounds are\nurgently needed to treat bacterial infections. Streptozotocin (STZ) is a natural product that has\nbroad-spectrum antibiotic activity, albeit with limited use because of its toxicity to pancreatic Beta cells.\nIn an attempt to derivatize STZ through structural modification at the C3 position, we performed\nthe synthesis of three novel STZ analogues by making use of our recently developed regioselective\noxidation protocol. Keto-STZ (2) shows the highest inhibition of bacterial growth (minimum inhibitory\nconcentration (MIC) and viability assays), but is also the most cytotoxic compound. Pre-sensitizing\nthe bacteria with GlcNAc increased the antimicrobial effect, but did not result in complete killing.\nInterestingly, allo-STZ (3) revealed moderate concentration-dependent antimicrobial activity and no\ncytotoxicity towards Beta cells, and deoxy-STZ (4) showed no activity at all....
In this work, the antibacterial activity of deflazacort and several of its synthetic precursors\nwas tested against a panel of bacterial pathogens responsible for most drug-resistant infections\nincluding Staphylococcus aureus, Enterococcus spp., Acinetobacter baumannii, Pseudomonas aeruginosa,\nKlebsiella pneumoniae, Escherichia coli, and Enterobacter spp. The derivative of deflazacort, PYED-1.....................
Recent scientific reports on the use of high dose tigecycline monotherapy\nas a â??drug of last resortâ? warrant further research into the use of this regimen for the treatment of\nsevere multidrug-resistant, Gram-negative bacterial infections. In the current study, the therapeutic\nefficacy of tigecycline monotherapy was investigated and compared to meropenem monotherapy in a\nnewly developed rat model of fatal lobar pneumoniaâ??septicemia. Methods: A Klebsiella pneumoniae\nproducing extended-spectrum Beta-lactamase (ESBL) and an isogenic variant producing K. pneumoniae\ncarbapenemase (KPC) were used in the study. Both strains were tested for their in vitro antibiotic\nsusceptibility and used to induce pneumoniaâ??septicemia in rats, which was characterized using\ndisease progression parameters. Therapy with tigecycline or meropenem was initiated at the moment\nthat rats suffered from progressive infection and was administered 12-hourly over 10 days. The\npharmacokinetics of meropenem were determined in infected rats. Results: In rats with ESBL\npneumoniaâ??septicemia, the minimum dosage of meropenem achieving survival of all rats was\n25 mg/kg/day. However, in rats with KPC pneumoniaâ??septicemia, this meropenem dosage was\nunsuccessful. In contrast, all rats with KPC pneumoniaâ??septicemia were successfully cured by\nadministration of high-dose tigecycline monotherapy of 25 mg/kg/day (i.e., the minimum tigecycline\ndosage achieving 100% survival of rats with ESBL pneumoniaâ??septicemia in a previous study).\nConclusions: The current study supports recent literature recommending high-dose tigecycline as a\nlast resort regimen for the treatment of severe multidrug-resistant bacterial infections. The use of\nESBL- and KPC-producing K. pneumoniae strains in the current rat model of pneumoniaâ??septicemia\nenables further investigation, helping provide supporting data for follow-up clinical trials in patients\nsuffering from severe multidrug-resistant bacterial respiratory infections....
The potential antimicrobial properties of a tridentate polypyridyl ligand 4-butoxy-N,N-bis(pyridin-2-ylmethyl)aniline (BUT) 1\nand its corresponding mixed ligand ruthenium complexes were investigated on drug-resistant and non-drug-resistant bacterial\nspecies. Theligand and its complexes were synthesized and successfully characterized by 1HNMR, UV/Vis, and FTIR spectra; ESIMS;\nand magnetic susceptibility. Electronic spectra and magnetic susceptibility of these Ru(II)/(III) complexes suggest that they\nare of a low spin crystal field split, where the Ru(III) is a d5 and Ru(II) d6 low spin. These compounds were tested for antibacterial\nactivity on two bacterial species: Staphylococcus aureus (S. aureus) and Klebsiella pneumoniae (K. pneumoniae), as well as their\ndrug-resistant strains methicillin-resistant Staphylococcus aureus (MRSA) and multidrug resistant Klebsiella pneumoniae (MDR\nK. pneumoniae). All the compounds inhibited growth of the two non-drug-resistant bacteria and only one drug-resistant strain\nMRSA. However, only the ligands BUTand 2,2-dipyridylamine showed activity against MRSA, while all complexes did not show\nany antibacterial activity on MRSA. We observed large zones of inhibition for the Gram-positive S. aureus and MRSA bacteria,\ncompared to the Gram-negative K. pneumoniae bacteria. DNA cleavage studies with gel electrophoresis showed denatured\nbacterial DNA on the gel from all the complexes, with the exception of the ligand, suggesting DNA nuclease activity of the\ncomplexes in the bacterial DNA....
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