2-(Hexopyranosyloxy)-1a-(hydroxymethyl)-1a,1b,2,5a,6,6a-hexahydrooxireno[2',3':4,5]cyclopenta[1,2-c]pyran-6-yl 3-hydroxy-4-methoxybenzoate 6-Isovanillylcatalpol AIDS-138439 AIDS138439 NSC645270