2-(3-Hydroxy-2-oxoindolin-3-yl)-acetic acid is a naturally occurring organic acid containing an indole ring that is used in organic synthesis and biochemical research.
5-O-Methylnaringenin is a marker, reduced MS detection of 5-O-methylnaringenin indicated that nifedipine may preferably remove a proton from the 5-position OH group in the A ring of the flavonoid skeleton.