Undescribed C-Glycosylflavones from Corn Silk and Potential Anti-inflammatory Activity Evaluation of Isolates.

Phytochemical investigation of corn silk resulted in isolation and characterization of four flavone C-glycosides, chrysoeriol 6- C - β -oliopyranosyl-7- O - β -D-glucopyranoside (1: ), 3'-methoxycassiaoccidentalin A (2: ), chrysoeriol 6- C - β -boivinopyranosyl-7- O - β -D-glucopyranoside (3: ), and ax-4″-OH-3'-methoxymaysin (4: ), a triterpenoid, friedelin (5: ), two sterols, (22 E )-5 α ,8 α -epidioxyergosta-6,22-dien-3 β -ol (6: ) and 6 β -hydroxystigmasta-4,22-diene-3-one (7: ), and a mixture of β -sitosterol and stigmasterol. Compounds 1: and 2: were previously undescribed. Structure elucidation of the isolated compounds was attained using spectral data including 1D and 2D NMR and HRESIMS. Compounds1, 2, 5: , and 6: inhibited iNOS activity in LPS-induced macrophages and decreased nitrite levels by 68.64 ± 4.46, 65.67 ± 6.47, 88.50 ± 0.50, and 94.00 ± 4.00%, respectively, at 50 µM. Compound 5: also showed inhibition of NF- κ B (51.00 ± 1.50%). Compounds 1: and 2: induced NAG-1 activity in chondrocytes by 1.80 ± 0.05 and 2.00 ± 0.13 fold, respectively. The extract of corn silk, however, did not exhibit inhibition of iNOS or NF- κ B but induced NAG-1 by 1.80 ± 0.51 fold.