P-menthane-based meroterpenoids with neuroprotective effects from the bark of Magnolia officinalis var. biloba

Seven undescribed meroterpenoids with different substituted types of p-menthane, named maglignans D-J (1-7), were obtained from the bark of Magnolia officinalis var. biloba. Maglignan D (1) was an un-usual meroterpenoid, featuring two p-menthane units with different substitution types were connected to two C6C3 fragments, respectively. Maglignans E-G (2-4) were characterized by a 6/5/6 or 6/6/6 tricyclic skeleton. The p-menthane in others connected to the magnolol through the ether or carbon -carbon single bonds directly. Spectroscopic techniques, NMR calculations with DP4+ analysis, and ECD calculations were used for the structure elucidation of these compounds. Moreover, maglignan E (2) showed significant neuroprotective effects on glutamic acid-induced cellular damage in cortical and hippocampal neurons.(c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

Seven undescribed meroterpenoids with diverse substitution types and structures were isolated from the bark of Magnolia officinalis var. biloba. The structures of these compounds were elucidated using various analytical techniques, and one of the compounds exhibited significant neuroprotective effects.