Preliminary reportAnti-inflammatory effects of phenolic extracts from strawberry and mulberry fruits on cytokine secretion profiles using mouse primary splenocytes and peritoneal macrophages

- Phenolic extracts from strawberry (ES) and mulberry (EM) fruit juice were isolated.
- Individual phenolics including four flavonoid components were analyzed.
- ES was rich in p-coumaric acid, morin and quercetin.
- EM was rich in p-coumaric acid, rutin and quercetin.
- Both ES and EM had anti-inflammatory effects on splenocytes in vitro.

This study isolated phenolic-rich extracts from strawberry (ES) and mulberry (EM) fruit juice using 70% ethanol, analyzed the individual phenolics including four flavonoid components using HPLC and assessed their cytokine secretion regulatory activities using murine primary splenocytes and peritoneal macrophages. The results showed that EM was rich in p-coumaric acid (20798 ± 719 μg/g dry weight), rutin (1992 ± 26 μg/g dry weight) and quercetin (81 ± 5 μg/g dry weight), but ES was relatively rich in p-coumaric acid (7475 ± 1219 μg/g dry weight), morin (101 ± 68 μg/g dry weight) and quercetin (72 ± 42 μg/g dry weight). ES and EM administration significantly decreased splenocytes' (IFN-γ + IL-2 + IL-12)/IL-10 (Th1/Th2) cytokine secretion ratios in the absence or presence of lipopolysaccharide (LPS) and TNF-α/IL-10 (pro-/anti-inflammatory) cytokine secretion ratios in the presence of LPS in dose-dependent manners. Our results suggest that ES and EM that are rich in p-coumaric acid, rutin, morin or quercetin, may have strong immunomodulatory effects on splenocytes, via decreasing Th1/Th2 and pro-/anti-inflammatory cytokine secretion ratios.

HPLC chromatograms including the standards of phenolic acid (p-coumaric acid) and flavonoids (rutin, morin, quercetin, and isorhamnetin) (A), ES (B), and EM (C). ES, phenolic-rich extract from strawberry juice; EM, phenolic-rich extract from mulberry juice.