4-[5-Hydroxy-4-methylene-7-(sulfomethyl)-3,4-dihydro-2H-chromen-2-yl]-2-[5-hydroxy-4-methylene-7-(sulfomethyl)-2-(4-sulfophenyl)-3,4-dihydro-2H-chromen-6-yl]benzenesulfonic acid AIDS-155598 AIDS155598 Robustaflavone Tetrasulfate K-salt