A honokiol-enriched Magnolia officinalis Rehder & E.H. Wilson. bark extract alleviates neuropathic pain by inhibiting neuroinflammation

Neuropathic pain is a chronic condition that influence patient’s quality of life [1]. Current therapies are characterized by several side effects, which limits their prolonged used. Magnolia officinalis Rehder & E.H. Wilson bark extracts have been extensively used in traditional medicine. Its main constituent, honokiol, is an effective modulator of cannabinoid receptors [2]. In this work we evaluated the effect of a honokiol-enriched M. officinalis bark extract (MOE) in a mice model of peripheral neuropathy, investigating the mechanism of action in the spinal cord tissue. MOE 30 mg/kg reduced mechanical allodynia and thermal hyperalgesia 45 min after oral administration, without affecting locomotor activity and cognitive function. The anti-hyperalgesic effect was completely prevented by the co-administration with a CB1 antagonist (AM251). MOE reduced the inflammatory factors in spinal cord tissue of animal with neuropathy, compared to the control group and that these effects were completely reverted by AM251. These results highlight that M. officinalis could be considered a possible candidate for the management of neuropathic pain through the regulation of cannabinoid receptors, and encourage the search for honokiol structural analogs to be investigated as novel potential drugs against neuroinflammation