Neuroprotective Triterpenoids from Mastic Gum ( <i>Pistacia lentiscus</i> L.)

Mastic gum, the resin of Pistacia lentiscus L., is rich in triterpenoids that have been associated with antioxidant activity. Given the central role of oxidative stress in neurodegenerative diseases, we investigated the phytochemical composition and neuroprotective potential of mastic gum collected from the Karaburun Peninsula (Türkiye). Phytochemical investigation led to the isolation of 12 triterpenoids, including one new compound (11) and a previously reported compound (9) whose 2- and 3-D structures were fully established for the first time. The new triterpenoid was characterized as 3,4-seco-isomasticadienonic acid (11), representing the first 3,4-seco structure reported from mastic gum, while the structure of 9 was confirmed as 17(S)-28-norolean-17-ol-12-ene-3-one (9) by the aid of X-ray crystallography. The neuroprotective activity of the isolates was evaluated in in vitro models of oxidative stress using differentiated and undifferentiated SH-SY5Y cells treated with H2O2. Compounds 9 and 5 (oleanolic acid) significantly protected SH-SY5Y cells against H2O2-induced cytotoxicity. These results suggest that certain triterpenoids from mastic gum may act as natural neuroprotective agents and potential functional food ingredients for oxidative stress-related disorders.