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. 2013 Apr 8;8(4):e60770. doi: 10.1371/journal.pone.0060770

Figure 2. Inhibition of E. coli topoisomerase I relaxation activity by lichen extracts and fractions.

Figure 2

(a) Secondary assay of natural product hits from HTS using negatively supercoiled DNA plasmid substrate. Lane 1: no enzyme. Relaxation activity of 10 ng of E. coli topoisomerase I was assayed in the presence of DMSO (lane 2) or 80 µg/mL of natural product extracts hits (lane 3–12). Extracts PL2050/C13 and PL2050/D12 prepared from lichen Hypotrachyna sp. samples were present in lanes 7 and 8 respectively. (b) Assay of HP20ss fractionated extracts of lichen Hypotrachynasp. samples. Lane 1: no enzyme control. Lane 2: Enzyme with DMSO control. Lanes 3–20: serial 4-fold dilutions (12, 3, 0.75 µg/mL) of unfractionated total extract (lanes 3–5), Fraction 1 (lanes 6–8), Fraction 2 (lanes 9–11), Fraction 3 (lanes 12–14), Fraction 4 (lanes 15–17), Fraction 5 (lanes 18–20). S: supercoiled plasmid DNA substrate. N: nicked plasmid DNA. Ro: Relaxed closed plasmid DNA. PR: partially relaxed plasmid DNA.