In the previous paper, we reported two new metabolites of IAA named zeanoside A and B from immature sweet corn (Zea mays L.) kernels, their structures having been elucidated as the 7-O-β-D-glucopyranoside of 3,7-dihydroxy-2-indolinone-3-acetic acid and the 8-O-β-D-glucopyranoside of 2-quinolone-4-carboxylic acid by chemical studies and spectral data. Further investigation of this kernel resulted in the isolation of a new stereoisomer of zeanoside A. In this paper, we describe the isolation and structural elucidation of this new compound named zeanoside C. Zeanoside C was isolated from dent corn (cv. Pioneer) kernels via processes including grinding with concentrated HCl in n-butanol, filtration, centrifugation, extraction with saturated aqueous sodium bicarbonate, column chromatography (charcoal, Amberlite IRA-400), repeated paper chromatography, and HPLC. Acid hydrolysis of zeanoside C yielded zeanic acid and glucose, confirmed by PPC and GC. Its structure was elucidated by spectral data (UV, IR, MS, ¹H NMR, ¹³C NMR), showing the sugar moiety was β-D-glucopyranosyl and the aglycon was 3,7-dihydroxy-2-indolinone-3-acetic acid. Zeanoside C was determined to be 7-O-β-D-glucopyranosyl 3,7-dihydroxy-2-indolinone-3-acetic acid, a stereoisomer of zeanoside A at the C3 position. HPLC analysis revealed all tested corn cultivars (dent and sweet corn) contained zeanoside A, B, and C with different concentrations.