Antibacterial activity of the root extracts of Garcinia Kola against MDR Staphylococcus aureus: an Invitro and in silico studies

Abstract

Abstract 
Multi Drug Resistance (MDR) Staphylococcus aureus is an important bacteria with clinical and economic implications. Plants including Garcinia kola provides bioactive principles with diverse structural and biological features. The n-butanol fraction of G. 
kola root extract recorded the highest activity against MDR staph aureus (18.50±0.41) compared to the chloroform (10.00±2.12) and methanol (8.16±0.62) extract, with no activity recorded with the n-hexane extract. Analysis of the n-butanol fraction on GC-MS 
recorded 14 phytoconstituents with varying structural composition; containing important scaffolds & motifs of benzoquinone, imidazo[1,2-a] pyridine, Chlorocarbazole and azetidine that present key pharmaceuticals as antibiotic for drug development. 
Further insilico molecular docking studies of these compounds on antibacterial drug target; Tyrosyl-tRNA synthetase (PDB 1JIJ) from MDR staph aureus was documented. Nine (9) compounds had good binding scores ranging from -4.63 to -7.08 kcal/mol; with 
3,8-di-tert-butyl-5,6-diphenyl-2,9-dithia-1-phosphabicyclo[4.3.0]nona-3,7-diene 1sulfide having the highest score. The compounds formed various bonding with the 1JIJ amino acid residues including H-bond, van der waal and π interactions. (S)-(-)-2
Azetidinecarboxlic acid and 2-Hydroxyethyl benzoate bind to the most active binding pocket (Drug score: 0.82 &0.72) while 9,9-dichloro-9-silafluorene tend to bind outside the active binding pocket. They also have good pharmacokinetic and toxicity profile. As a result of satisfactory in vitro and in silico experimental validation, these compounds are regarded as promising potential antibiotics against MDR Staphylococcus aureus.