Bioactivity-Guided Extract Optimization of <i>Osmanthus fragrans</i> var. <i>aurantiacus</i> Leaves and Anti-Inflammatory Activities of Phillyrin
2021
Hwa-Young Song | Da-Eun Jeong | Mina Lee
The aim of this study was to identify the optimal extraction conditions for leaves of <i>Osmanthus fragrans</i> var. <i>aurantiacus</i>. Inhibitory effects of various extracts on NO production were compared. Antioxidant evaluations for total phenol and flavonoid contents were carried out using various extracts of <i>O. fragrans</i> var. <i>aurantiacus</i> leaves obtained under optimal extraction conditions that showed the greatest effect on NO production. The optimal method for extracting <i>O. fragrans</i> var. <i>aurantiacus</i> leaves resulted in an extract named OP OFLE. OP OFLE showed DPPH and ABTS radical scavenging activities in a concentration-dependent manner. Phillyrin (PH) was isolated as a major compound from OP OFLE by HPLC/DAD analysis. OP OFLE and PH reduced inducible nitric oxide (iNOS) and cyclooxygenase (COX)-2 protein expression and downregulated proinflammatory cytokines such as interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α in LPS-stimulated RAW 264.7 and HT-29 cells. To determine the signal pathway involved in the inhibition of NO production, a Western blot analysis was performed. Results showed that OP OFLE decreased phosphorylation of extracellular regulated kinase (pERK) 1/2 and the expression of nuclear factor-kappa B (NF-κB). Our results suggest that extracts of <i>O. fragrans</i> var. <i>aurantiacus</i> leaves and its major components have biological activities such as antioxidative and anti-inflammatory properties.
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