(2R,7R,12S)-12,17-diamino-2,7-bis(4-aminobutyl)-17-imino-4,9-dioxo-5,10-dioxa-3,8,16-triazaheptadec-1-yl hydrogen carbonate AIDS-188832 AIDS188832 L-ArgCar-D-LysCar-D-LysCar