Antioxidant active ingredients from the seeds of Dimocarpus longan Lour.

The seeds of Dimocarpus longan Lour. are rich in bioactive compounds, notably polyphenols, flavonoids, and sesquiterpenoids, which have demonstrated antioxidant, antitumor, and antifungal activities. Phytochemical investigation of the seeds led to the isolation of thirteen compounds (1-13), comprising six previously undescribed structures (1-6) and seven known analogues (7-13). The structures of the new compounds were elucidated through comprehensive spectroscopic analysis, including 1D/2D NMR, HR-ESI-MS, UV, ECD, and optical rotation. All isolated compounds were evaluated for their protective effects against hydrogen peroxide-induced oxidative stress in BV-2 microglial cells. Among them, compounds 2, 3, 7, 11, and 12 exhibited significant antioxidant activity. These findings underscore the potential of Dimocarpus longan seeds as a valuable source of bioactive agents for medicinal and functional food applications.