Anti-neuroinflammatory oleanane-type triterpenoids from the seeds of Quercus serrata Thunb.

Chinese oak (Quercus serrata Thunb.) is widely distributed throughout China and plays an important role as a building material. Its seeds (acorns) have served as a traditional herbal medicine in East Asia. Eighteen oleanane-type triterpenoids, including seven previously undescribed (1, 2, and 4-8) and eleven known triterpenoids, were isolated and identified from acorns. Their structures were elucidated using various spectroscopic and chemical methods. All isolated triterpenoids were screened for anti-neuroinflammatory effects by measuring their abilities to inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)-induced BV-2 microglial cells, and most of the triterpenoids exhibited obvious anti-neuroinflammatory activity. Among them, Compounds 1 and 5 exhibited the strongest NO inhibitory activity, reduced the expression of inflammatory cytokines (iNOS, COX-2, and TNF-alpha), and blocked the nuclear translocation of NF-kappa B.