3-D Cryptand Like Normal and Doubly N-Confused Calixbenzophyrins: Synthesis and Structural Studies

The three-dimensional (3-D) cryptand-like normal and doubly-N-confused calixbenzophyrins embedded with phenyl rings in the macrocyclic skeleton are successfully synthesized from single starting materials. These structural isomers are characterized by spectral studies and unambiguously confirmed by crystal analyses.

PtCl2 mediated peripheral transformation of carbatriphyrin(3.1.1) into a meso-fused β-β' dimer and its monomer analogue

An unprecedented formation of a meso-fused β-β' carbaporphyrin dimer and its monomer with a keto group was described. These analogues were synthesized from carbatriphyrin(3.1.1.) by a metal assisted strategy using PtCl2 salt in a single step without any prefunctionalized precursors. Upon dimerization, the monomeric ligand with a dianionic core is transformed into a dimeric structure with unique trianionic cores.

Rhodium(III) and Iridium(III) Bipyricorrole Complexes: Syntheses, Structures, and Properties

Rhodium(III) and iridium(III) bipyricorrole complexes have been unprecedentedly reported. Single-crystal X-ray diffraction studies unambiguously evinced the molecular structures of metal complexes in octahedral geometry. The monoanionic platform of bipyricorrole effectively stabilizes metal ions in their higher oxidation states. It is worth mentioning that the fluorescence quantum yield of the rhodium(III) complex is 3-fold higher than that of free-base bipyricorrole.

Precursor-directed combinatorial biosynthesis of cephalosporin analogue by endolithic actinobacterium Streptomyces sp. AL51 by utilizing thiophene derivative

Natural products or their derivatives provide a reliable resource for new drugs. The multi-step chemical reaction to produce new drug is not only expensive but also release pollutants. The precursor-based combinatorial biosynthesis (PCB) is, however, a better option to produce novel natural products with potential pharmaceutical applications. The present work is an attempt to synthesize an antibacterial compound by transforming thiophene precursor using endolithic Streptomyces sp. AL51. The Streptomyces sp. AL51 was isolated from a granite rock sample collected from Mylliem, Meghalaya, India. The isolate was identified as Streptomyces sp. based on its cultural, morphological, biochemical and molecular characteristics. The bioactive compound CAx1 was extracted from the fermentation broth. The compound was characterized by bioactivity-guided fractionation and identified by infrared, UV-visible, nuclear magnetic resonance and mass spectrometry data and identified as 7-[1-(thiophene-5-yl)-1-formamido]-3-propylenyl-3-cephem-4-carboxylic acid with molecular formula C₁₅H₁₄N₂O₄S₂. The purified compound showed considerable in vitro antibacterial activity against both Gram-positive and Gram-negative bacteria showing its broad spectrum property. The obtained results provide promising baseline information for the potential use of endolithic actinobacterium for semisynthetic drug discovery. This is the first report on PCB of broad range antibacterial compound by endolithic Streptomyces strain.

Structure elucidation and in silico docking studies of a novel furopyrimidine antibiotics synthesized by endolithic bacterium Actinomadura sp. AL2

On screening of endolithic actinobacteria from a granite rock sample of Meghalaya for antibacterial compound, a novel antibacterial compound CCp1 was isolated from the fermentation broth of Actinomadura sp. AL2. On purification of the compound based on chromatographic techniques followed by characterization with FT-IR, UV-visible, ¹H NMR, ¹³C NMR and mass spectrometry, the molecular formula of the compound was generated as C₂₀H₁₇N₃O₂, a furopyrimidine derivative. In vitro antibacterial activity of the compound was evaluated against both Gram positive and negative bacteria by agar well diffusion assay. The compound had lowest MIC (2.00 µg/ml) for Bacillus subtilis and highest MIC (> 64 µg/ml) for Staphylococcus epidermidis and Pseudomonas aeruginosa. The study revealed that the compound has potential antibacterial activity. The mode of action of the antibacterial compound was evaluated through in silico studies for its ability to bind DNA gyrase, 30S RNA molecules, OmpF porins and N-Acetylglucosamine-1-phosphate uridyltransferase (GlmU). The antibacterial compound demonstrated more favorable docking with DNA gyrase, 30S RNA molecules and OmpF porins than GlmU which support the antibacterial compound CCp1 can be as a promising broad spectrum antibiotic agent with "multitarget" characteristics.

Microbial inhibitory properties and stability of topotecan hydrochloride injection

The viability of five microorganisms in topotecan 1 mg/mL (as the hydrochloride salt) in sterile water and the stability of the drug were studied. Duplicate portions of topotecan 1 mg/mL were inoculated with Escherichia coli. The process was repeated for Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and Aspergillus niger. Samples were removed from each solution initially and after 6, 16, and 24 hours and 3, 7, 14, 21, and 28 days of incubation at 20-25 degrees C. To test stability, vials of reconstituted topotecan hydrochloride injection were stored at each of three temperatures--5, 25, and 30 degrees C--and other vials were used for time zero analysis. For each temperature, vials were removed at 1, 7, and 14 days and the remaining vials at 28 days for analysis by high-performance liquid chromatography and for visual and pH assessment. P. aeruginosa, S. aureus, and E. coli lost viability at 16 hours, 24 hours, and 28 days, respectively. C. albicans and A. niger did not lose viability, but their numbers did not grow. No differences in color or clarity were observed, and pH was constant. In all solutions, the topotecan concentration was > 98% of the initial concentration. Topotecan 1 mg/mL in sterile water stored at 20-25 degrees C for up t 28 days did not support growth of the five microorganisms studied; in solutions stored at 5, 25, or 30 degrees C for up to 28 days, topotecan 1 mg/mL remained stable.

Aqueous stability of SB 210661: kinetics and primary degradation mechanisms of an N-hydroxyurea-containing 5-lipoxygenase inhibitor

SB 210661, (S)-N-hydroxy-N-[2,3-dihydro-6-(2,6-difluorophenylmethoxy)-3-benzo furanyl]urea, is a potent and selective inhibitor of 5-lipoxygenase. Its aqueous stability was primarily evaluated to support development of analytical methods and formulations. The results also add to the growing database on the stability of N-hydroxyurea compounds. Comparison of the stability of SB 210661 with that of two other N-hydroxyurea-containing compounds, zileuton and Abbott-79175, supported a common primary degradative pathway at pH > 5 and different degradative pathways at pH < 5. The pathway at pH > 5 is consistent with the hydrolysis of the N-hydroxyurea group, whereas for SB 210661, the pathway at pH < 5 is consistent with specific acid-catalysed nucleophilic displacement of the N-hydroxyurea group by water.