New ent-kauranes from the fruits of Annona glabra and their inhibitory nitric oxide production in LPS-stimulated RAW264.7 macrophages.

Three new ent-kaurane diterpenoids, 7β,16α,17-trihydroxy-ent-kauran-19-oic acid (1), 7β,17-dihydroxy-16α-ent-kauran-19-oic acid 19-O-β-d-glucopyranoside ester (2), 7β,17-dihydroxy-ent-kaur-15-en-19-oic acid 19-O-β-d-glucopyranoside ester (3) along with five known compounds, paniculoside IV (4), 16α,17-dihydroxy-ent-kaurane (5), 16β,17-dihydroxy-ent-kaurane (6), 16β,17-dihydroxy-ent-kauran-19-al (7), and 16β,17-dihydroxy-ent-kauran-19-oic acid (8) were isolated from the fruits of Annona glabra. Their chemical structures were elucidated by physical and chemical methods. All compounds were evaluated for inhibitory activity against nitric oxide (NO) production in LPS-stimulated RAW 264.7 macrophages. As the results, compound 3 showed potent inhibitory LPS-stimulated NO production in RAW 264.7 macrophages with the IC50 value of 0.01±0.01μM; compounds 1 and 7 showed significant inhibitory NO production with the IC50 values of 0.39±0.12μM and 0.32±0.04μM, respectively.