Advances on Semisynthesis, Total Synthesis, and Structure-Activity Relationships of Honokiol and Magnolol Derivatives.

Honokiol and magnolol (an isomer of honokiol) are small-molecule polyphenols isolated from the barks of Magnolia officinalis, which have been widely used in traditional Chinese and Japanese medicines. In the last decade, a variety of biological properties of honokiol and magnolol (e.g., anti-oxidativity, antitumor activity, anti-depressant activity, anti-inflammatory activity, neuroprotective activity, anti-diabetic activity, antiviral activity, and antimicrobial activity) have been reported. Meanwhile, certain mechanisms of action of some biological activities were also investigated. Moreover, many analogs of honokiol and magnolol were prepared by structural modification or total synthesis, and some exhibited very potent pharmacological activities with improved water solubility. Therefore, the present review will provide a systematic coverage on recent developments of honokiol and magnolol derivatives in regard to semisynthesis, total synthesis, and structure-activity relationships from 2000 up to now.