Synephrine Inhibits Oxidative Stress and H₂O₂-Induced Premature Senescence

Area of Science:

• Biochemistry
• Cell Biology
• Antioxidant Research

Background:

• Synephrine from Citrus aurantium possesses known lipolytic, anti-inflammatory, and vasoconstrictive properties.
• Its antioxidant capacity and effects on cellular senescence were previously unclear.
• Oxidative stress from agents like hydrogen peroxide (H₂O₂) is a known inducer of stress-induced premature senescence (SIPS).

Purpose of the Study:

• To investigate the antioxidant activity of synephrine.
• To determine if synephrine can prevent H₂O₂-induced premature senescence in human WI-38 cells.
• To elucidate the molecular mechanisms underlying synephrine's potential anti-senescence effects.

Main Methods:

• Electron spin resonance spectroscopy was used to assess radical scavenging activity.
• WI-38 cells were treated with H₂O₂ to induce oxidative stress and premature senescence.
• Synephrine's effects on reactive oxygen species (ROS) levels, lipid peroxidation, DNA damage, mitochondrial function, and key senescence markers (p53, p21, p16INK4A) were evaluated.

Main Results:

• Synephrine demonstrated significant scavenging of hydroxyl and superoxide anion radicals.
• It effectively reduced H₂O₂-induced ROS levels, lipid peroxidation, and oxidative DNA damage in WI-38 cells.
• Synephrine inhibited mitochondrial dysfunction and suppressed the activation of p53-p21 and p16INK4A-pRB pathways, thereby preventing SIPS.

Conclusions:

• Synephrine exhibits potent antioxidant properties.
• It protects against H₂O₂-induced oxidative stress and mitochondrial dysfunction.
• Synephrine effectively suppresses premature senescence by inhibiting key cell cycle regulatory pathways.