Fig. 3. HPLC chromatogram of TLC purified metabolites. (A) Preparative HPLC analysis of TLC purified E. xiangfangensis cell-free extract. The chromatogram shows three active peaks, the inset picture in (A) is the agar overlay assay showing the anti-QS activity of three different fractions. (B) HPLC-chromatogram showing the single active peak of the purified fraction that demonstrated QS-inhibitory activity, the inset picture in (B) is the chromatogram showing the active peak of standard compound. LB broth and quercetin were used as negative and positive controls respectively.