Magnolol and Honokiol: Two Natural Compounds with Similar Chemical Structure but Different Physicochemical and Stability Properties

Magnolia spp. extracts are known for their use in traditional Korean, Chinese, and Japanese medicine in the treatment of gastrointestinal disorders, anxiety, and allergies. Among their main components with pharmacological activity, the most relevant are magnolol and honokiol, which also show antitumoral activity. The objectives of this work were to study some physicochemical properties of both substances and their stability under different conditions of temperature, pH, and oxidation. Additionally, liposomes of honokiol (the least stable compound) were formulated and characterized. Both compounds showed pH-dependent solubility, with different solubility–pH profiles. Magnolol showed a lower …