ABSTRACT

Syzygium aromaticum, a popular ethanomedicinal herb, possesses quorum quenching and inhibition of virulence factors of Pseudomonas aeruginosa. The objective of the present study was to partially purify and study quorum sensing inhibition of S.aromaticum methanolic extract using in vitro and in silico docking studies. S. aromaticum was extracted with methanol using Soxhlet apparatus and was subjected to TLC-bioautography using Chromobacterium violaceum as reporter strain. The TLC purified fraction was subjected to biofilm inhibition on P. aeruginosa and GC-MS analysis. The identified compounds from GC-MS were docked with LasI and EsaI proteins. TLC-bioautography analysis showed clear zone of inhibition at the bioactive fraction (Rf =0.78) and also exhibited dose dependent (50- 200 ?g/mL) biofilm inhibition on P. aeruginosa. GC-MS analysis of active fraction revealed six major compounds viz. 4-hydroxy-3-methoxy-benzaldehyde, 1-phenoxy ethanol, eugenol, chavicol, p-hydroxyacetophenone and 4-azido-phenol that may account for the antibiofilm activity. These compounds were studied for their in silico binding patterns with quorum sensing regulated proteins, LasI and EsaI. Among all, chavicol formed three hydrogen bonds with LasI (-6.20 kcal/mol) and three hydrogen bonds with EsaI (-4.36 kcal/mol), indicating best interaction with targeted protein binding sites. The current study demonstrated that the bioactive fraction has the ability of quorum quenching which is supported by in silico analysis and might leads to in vivo establishment in future. Keywords: Syzygium aromaticum, in silico, TLC-bioautography, LasI, EsaI

https://ijbpas.com/pdf/2018/March/1519918456MS IJBPAS 2018 4385.pdf

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