Chemical characterization of balloon flower (Platycodon grandiflorum) sprout extracts and their regulation of inflammatory activity in lipopolysaccharide‐stimulated RAW 264.7 murine macrophage cells

The balloon flower (BF) is a potent natural source of phytochemical compounds and is associated with our health. The sprouting process is accompanied by significant changes in phytochemical compounds in comparison with their original plants. Even though many studies are conducted with BF, there are not yet reports of BF sprouts. In the present study, we determined the chemical composition and biological activity of BF sprouts that had been cultivated for 50 days. Kaempferol‐3‐O‐galactoside and 1‐O‐caffeoylquinic acid were identified as major components of whole BF sprouts. The leaves/stems of the sprouts had higher total phenolic and flavonoid contents and lower IC(50) values in DPPH(•) and ABTS(•+) scavenging assays than whole sprouts or roots. The roots of the sprouts had the highest polygalacin D content (1.44 mg/g). We also determined the effects of different parts of BF sprouts on RAW 264.7 macrophage cells. When these cells were stimulated with lipopolysaccharide (LPS), their nitrite and pro‐inflammatory cytokine production increased. BF sprouts suppressed the LPS‐induced production of nitrite, tumor necrosis factor‐α, and interleukin‐6 in a concentration‐dependent manner without causing any cytotoxic effects. Nitrite and pro‐inflammatory cytokine production were significantly inhibited by the roots and leaves/stems, respectively. The inhibitory effects of BF sprouts on LPS‐stimulated inflammatory responses in RAW 264.7 macrophage cells were associated with suppressed NF‐κB activation. These findings suggest that BF sprouts could be a valuable source of bioactive compounds and exert anti‐inflammatory effects due to their polygalacin D, deapi‐platycodin D(3,) and polyphenol content.