1 H - NMR ( DMSO - d 6 ) δ 8 . 91 ( t , 1 H - NH , J = 6 . 4 Hz ) , 8 . 44 ( s , 1 H ) , 7 . 75 ( s , 1 H ) , 7 . 61 ( d , 1 H , J = 8 . 0 Hz ) , 7 . 36 ( d , 1 H , J = 7 . 6 Hz ) , 7 . 13 ( t , 1 H , J = 4 . 0 Hz ) , 5 . 81 ( d , 1 H , J = 6 . 8 Hz ) , 5 . 47 ( d , 1 H - OH , J = 6 . 8 Hz ) , 5 . 23 ( d , 1 H - OH , J = 4 . 0 Hz ) , 4 . 72 ( dd , 1 H , J = 6 . 4 , 10 . 8 Hz ) , 4 . 61 ( d , 1 H , J = 6 . 0 Hz ) , 4 . 34 ( dd , 1 H , J = 3 . 6 , 9 . 2 Hz ) , 3 . 81 ( dd , 1 H , J = 1 . 2 , 9 . 2 Hz ) ;