No, I don't know. 
( No ( , ( I ( ( ( do n't ) know ) . ) ) ) )
(ROOT (S (INTJ (UH No)) (, ,) (NP (PRP I)) (VP (VBP do) (RB n't) (VP (VB know))) (. .)))
I don't know what she said, no.
( ( ( ( I ( ( do n't ) ( know ( what ( she said ) ) ) ) ) , ) no ) . )
(ROOT (S (S (NP (PRP I)) (VP (VBP do) (RB n't) (VP (VB know) (SBAR (WHNP (WP what)) (S (NP (PRP she)) (VP (VBD said))))))) (, ,) (FRAG (INTJ (UH no))) (. .)))