Anti-allergic Inflammatory Triterpenoids Isolated from the Spikes of Prunella vulgaris.

Twelve known triterpenoids (1-12) and two steroids (13 and 14) have been isolated from the spike of the plant Prunella vulgaris. Among them, 2α,3α,23-trihydroxyursa-12,20(30)-dien-28-oic acid (10) was isolated for the first time from this plant. All isolates were evaluated for their inhibitory effect on the gene expression of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and release of histamine in human mast cells. β-Amyrin (5), 10, and euscaphic acid (12) showed suppression of histamine release with percentage inhibitions of 46.7, 57.9, and 54.2%, respectively. In addition, 5 and 10 showed strong inhibition of TNF-α and IL-6 in the test for pro-inflammatory cytokines. Our results suggest that compounds 5 and 10 largely contribute to the anti-allergic inflammatory effect of P. vulgaris.