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Figure 2 A2-4-2-4 purification. (A) HPLC analysis showed many compounds in the A2 fraction. (B) The A2-4 fraction was further separated into seven fractions, A2-4-1 to A2-4-7. Among them, A2-4-2 showed the highest AHF attenuation activity. (C) A representative UV absorbance graph during the preparative HPLC for A2-4-2 revealed that the A2-4-2 fraction contains four UV absorbance peaks which are significantly overlapped. Although extreme care was taken to separate the compounds into the final four fractions, named A2-4-2-1 to A2-4-2-4, the NMR analysis eventually showed impurities in A2-4-2-4 (see Figure 3).