Hydroxyframoside B, a Secoiridoid of Fraxinus rhynchophylla, Inhibits Adipocyte Differentiation in 3T3-L1 Cells

Abstract

Fraxinus rhynchophylla showed significant inhibitory activity on adipocyte differentiation in the 3T3-L1 preadipocyte cell line as assessed by measuring fat accumulation using Oil Red O staining. Further fractionation led to the isolation of two secoiridoids, oleuropein and hydroxyframoside B. Hydroxyframoside B significantly reduced fat accumulation and triglyceride content in differentiated 3T3-L1 cells without affecting cell viability, whereas oleuropein showed little effect. Further studies with interval treatment demonstrated that hydroxyframoside B exerted inhibitory activity on adipocyte differentiation when treated within 2 days (days 0–2) after differentiation induction. In addition, hydroxyframoside B significantly blocked the induction of adipogenic transcription factors such as C/EBPα, C/EBPβ, and PPARγ. Taken together, these results suggest that hydroxyframoside B inhibited early/middle stage of adipogenic differentiation, in part, via inhibition of C/EBPα, C/EBPβ, and PPARγ-dependent pathways.

Key words

Fraxinus rhynchophylla - Oleaceae - hydroxyframoside B - adipocyte differentiation - PPARγ - C/EBP - 3T3-L1

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