Hogantharanni Govender

Title : Synthesis and antibacterial activity of quinoline tetrazolo phenylhydrazine hybrids

Abstract:

The aim of the study was to investigate the antibacterial activity of a synthesised library of new tetrazolo phenylhydrazone derivatives of quinoline.

A small library of fifteen quinoline tetrazolo phenylhydrazones were synthesised in a four-step reaction, which involved the formation of 2-chloroquinoline-3-carbaldehydes, adding a tetrazolo ring onto the quinoline and forming phenylhydrazones at the 3-carbaldehyde (Scheme 1 ). The synthesised compounds were tested for the antibacterial activity against two Gram +ve bacteria (Staphylococcus aureus and methicillin resistant S. aureus, MRSA)) and four Gram -ve bacteria (Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli and Salmonella typhimurium.

The final compounds were prepared in yields ranging from 55 to 96%.  The synthesised compounds were characterised by extensive 2D-NMR spectroscopy and confirmed by High resolution mass spectrometry.  Compounds with a 2-phenylhydrazone moiety showed moderate activity against all bacterial strains tested against with MBC values in the range of 3.26-31.22 mM.

Only tetrazolo quinoline phenylhydrazones that had a 2-fluorophenylhydrazone moiety was active against the bacterial strains tested.  Activity was lost with a phenylhydrazone group and a 4-phenylhydrazone group. 
The best substituents at C-6 on the quinoline scaffold were H, Br and Cl.

Audience Take Away:

• The information will help the audience to identify compounds that could be developed further into antibiotics.
• It would help them to determine whether these compounds could be hits for future generation antibiotics.  
• Yes, antibacterial testing was done and the information could be useful for the pharmaceutical sector (teaching or industry). 
• Yes. It is hypothesized that joining other pharmacologically active scaffolds to this quinoline framework will result in bioactive molecules with enhanced activity compared to the quinolone core framework or molecules with fewer side effects than known drugs. 
• It will provide new information to assist in a design problem. 

Biography:

Dr. Govender joined the University of Durban-Westville, South Africa, as a research assistant in Natural products in 1991. She studied honours in chemistry at the University of Durban Westville, South Africa, whilst being employed as a laboratory technician at the institution, and graduated with her BSc Honours degree in 2001.  In 2003 she was employed as an associate lecturer. She then achieved her MSc (analytical chemistry ) in 2011 at the new merged institution, University of KwaZulu-Natal.   In 2018 she graduated with her PhD degree in chemistry (Organic synthetic chemistry) and was promoted to Lecturer. She is currently co-supervising students in analytical chemistry as well as in organic synthetic chemistry and is also the sole supervisor for an MSc project in organic synthetic chemistry (including antibacterial and anti-cancer activity).   Her PhD has produced two publications and the third paper is yet to be published.