Labdane-type diterpenoids from the rhizomes of Hedychium coronarium inhibit lipopolysaccharide-stimulated production of pro-inflammatory cytokines in bone marrow-derived dendritic cells

The rhizomes of Hedychium coronarium have been used for the treatment of inflammation, skin diseases, headache, and sharp pain due to rheumatism in traditional medicine. From this plant, two new labdanes, 15-methoxylabda-8(17),11E,13-trien-16,15-olide (1) and 16-methoxylabda-8(17),11E,13-trien-15,16-olide (3), named hedycoronens A and B, as well as four known, labda-8(17),11,13-trien-16,15-olide (2), 16-hydroxylabda-8(17),11,13-trien-15,16-olide (4), coronarin A (5), and corronarin E (6) were isolated. Their chemical structures were elucidated by mass, 1D- and 2D-nuclear magnetic resonance (NMR) spectroscopy. They were evaluated for inhibitory effects on the lipopolysaccharide (LPS)-stimulated production of pro-inflammatory cytokines in bone marrow-derived dendritic cells. Among of them, compounds 1-3 were potent inhibitors of LPS-stimulated interleukin-6 (IL-6) and IL-12 p40, with IC(50) ranging from 4.1±0.2 to 9.1±0.3 μM. Compounds 1 and 3 showed moderate inhibitory activity on the tumor necrosis factor-α (TNF-α) production with IC(50) values of 46.0±1.3 and 12.7±0.3 μM. The remains of compounds showed inactivity. These results warrant further studies concerning the potential anti-inflammatory benefits of labdane-diterpenes from H. coronarium.