Synthesis and antimycobacterial activity of some N1-[1-[3-aryl-1-(pyridin-2-, 3-, or 4-yl)-3-oxo]propyl]-2- pyridinecarboxamidrazones

R. C, Chand K, Santos MA, Keri RS. Benzofuran: an emerging scaffold for antimicrobial agents

The present article systematically gives a comprehensive review of current development of benzofuran-based compounds as antimicrobial agents and the perspectives that they hold for future research.

Induced in-source fragmentation pattern of certain novel (1Z,2E)-N-(aryl)propanehydrazonoyl chlorides by electrospray mass spectrometry (ESI-MS/MS)

Background

Collision induced dissociation (CID) in the triple quadrupole mass spectrometer system (QQQ) typically yields more abundant fragment ions than those produced with resonance excitation in the presence of helium gas in the ion trap mass spectrometer system (IT). Detailed product ion spectra can be obtained from one stage MS² scan using the QQQ. In contrast, generating the same number of fragment ions in the ion trap requires multiple stages of fragmentation (MSⁿ) using CID via in-trap resonance excitation with the associated time penalties and drop in sensitivity.

Results

The use of in-source fragmentation with electrospray ionization (ESI) followed by product ion scan (MS²) in a triple quadrupole mass spectrometer system, was demonstrated. This process enhances the qualitative power of tandem mass spectrometry to simulate the MS³ of ion trap for a comprehensive study of fragmentation mechanisms. A five pharmacologically significant (1Z, 2E)-N-arylpropanehydrazonoyl chlorides (3a-e) were chosen as model compounds for this study. In this work, detailed fragmentation pathways were elucidated by further dissociation of each fragment ion in the ion spectrum, essentially, by incorporating fragmentor voltage induced dissociation (in-source fragmentation) and isolation of fragments in a quadrupole cell Q1. Subsequently, CID occurs in cell, Q2, and fragment ions are analyzed in Q3 operated in product ion mode this process can be referred to as pseudo-MS³ scan mode.

Conclusions

This approach allowed unambiguous assignment of all fragment ions using tandem mass spectrometer and provided adequate sensitivity and selectivity. It is beneficial for structure determination of unknown trace components. The data presented in this paper provide useful information on the effect of different substituents on the ionization/fragmentation processes and can be used in the characterization of this important class of compounds.

Stereoselective synthesis and antimicrobial activity of benzofuran-based (1E)-1-(piperidin-1-yl)-N2-arylamidrazones

The reaction of 2-oxo-N-arylpropanehydrazonoyl chlorides 3a-e with 3-methyl-2-benzofurancarboxylic acid hydrazide (7) furnished N-(aryl)propanehydrazonoyl chlorides 8a-e. X-Ray of 8c revealed the (1Z,2E) configuration of structure 8. Nucleophilic substitution reaction of 8a or 8d with piperidine resulted in the formation of 1-(piperidin-1-yl)-N(2)-arylamidrazones 9a, b. The X-ray diffraction of 9b showed its (1E,2E) configuration and it confirmed the stereoselectivity of the latter reaction. (1E,2Z,3E)-1-(Piperidin-1-yl)-1-(arylhydrazono)-2-[(3-methylbenzofuran-2-oyl)hydrazono]-4-arylbut-3-enes 11 were synthesized in stereoselective reaction from 8 or alternatively from 9. X-ray analysis of 11b showed a conversion of configuration respect to 8d or 9b. X-Ray analysis of 9b and 11b revealed the role of hydrogen interactions in the stereochemistry of their solid state structure. The in vitro antimicrobial activity of the newly synthesized compounds demonstrated an excellent growth inhibition of compounds 9 and 11 against clinically isolated strains of human fungal pathogens and exhibited a significant potency against gram-positive bacteria. Griseofulvin and Amoxicilline were used as references for antifungal and antibacterial screening. The effect of most potent antifungal compound 9b on morphological features of Aspergillus fumigatus and Candida albicans using image analyzer was studied. Furthermore, the effect of 9b on the ultra-structures of the latter fungi was occurred by transmission electron microscope.

Synthesis and antimycobacterial activity of [5-(pyridin-2-yl)-1,3,4-thiadiazol-2-ylthio]acetic acid arylidene-hydrazide derivatives

[5-(Pyridin-2-yl)-1,3,4-thiadiazol-2-ylthio]acetic acid arylidene-hydrazide derivatives were synthesized and tested for their in vitro antimycobacterial activity. Some compounds showed a feable activity against a strain of Mycobacterium tuberculosis and a strain of Mycobacterium avium.