Figure 1 | British Journal of Cancer

Figure 1

From: Selective AKR1C3 inhibitors do not recapitulate the anti-leukaemic activities of the pan-AKR1C inhibitor medroxyprogesterone acetate

Figure 1

Identification of a novel tetracycline breakdown product. (A) A panel of 100 clinically licensed drugs (FMC100) at peak serum concentrations was screened for AKR1C-inhibitory activity against recombinant purified AKR1C proteins using the AKR1C-diaphorase assay. Data shown is mean fluorescence arbitrary units. Black bars indicate tetracycline and the dashed line represents level of inhibition by 5 μ M MPA. GC-MS and NMR were used to elucidate the structure of the novel tetracycline breakdown product 4-methyl,(didemethyl)-tetracycline (4-MDDT). (B) Structures and names of the parent tetracycline and novel tetracycline breakdown product. (C) The isoform specificity of HPLC-purified 4-MDDT was determined against recombinant AKR1C proteins using the AKR1C-daphorase assay (see Materials and Methods). (D) The IC50 of 4-MDDT for recombinant AKR1C3 protein was determined using the PQ assay (see Materials and Methods).

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