Secondary metabolites from the liverwort Jamesoniella colorata

Six new labdane type diterpenoids, three seco-clerodane diterpenoids, jamesoniellide I, along with the two new jamesoniellides K and L, the sesquiterpene waitziacuminone and a new chlorinated bisbibenzyl, 6,6',10,10',12,12'-hexachloroisoperrottetin A, have been isolated from the liverwort Jamesoniella colorata. Their structures were elucidated by NMR spectroscopy. The absolute configuration of 3-oxo-labda-8(17),13(16),14-triene (1) was established by CD spectroscopy.     

Minor labdane diterpenes from Marrubium thessalum

Five new labdane diterpenes, thessalines A, B, and D, 14β-hydroxythessaline A, and 14β-hydroxythessaline B (1-5, resp.) were isolated from the aerial parts of Marrubium thessalum, along with the known labdane diterpene deacetylvitexilactone (6) and the methoxylated flavones 4',7-dimethylapigenin and salvigenin. (3S,5R)-Loliolide was also found in the same source. Their structures were established by 1D- and 2D-NMR (COSY, HSQC, HMBC, NOESY, and ROESY) and MS analyses. The plant produces a great variety of labdane-type diterpenes, with variations in functionalities, particularly in the side chain. Their structures could be of chemotaxonomic significance for the genus Marrubium.     

Clerodane and labdane diterpenoids from Nuxia sphaerocephala

Seven diterpenoids including four clerodane and three labdane derivatives, (13S)-ent-7beta-hydroxy-3-cleroden-15-oic acid (1), ent-7beta-hydroxy-2-oxo-3-cleroden-15-oic acid (2), ent-2,7-dioxo-3-clero-den-15-oic acid (3), ent-18-(E)-caffeoyloxy-7beta-hydroxy-3-cleroden-15-oic acid (4) (13S)-ent-18-(E)-coumaroyloxy-8(17)-labden-15-oic acid (5), ent-18-(E)-caffeoyloxy-8(17)-labden-15-oic acid (6), ent-15-(E)-caffeoyloxy-8(17)-labden-18-oic acid (7), have been isolated from an ethyl acetate extract of the leaves of Nuxia sphaerocephala, together with 17 known compounds. 3-Oxolup-20(29)-en-30-al (3-oxolupenal) (8) and 3beta-hydroxylup-20(29)-en-30-al (3beta-hydroxy-lupenal) (9) showed the best inhibitory activity against Plasmodium falciparum with the IC(50) values between 1.55 and 4.67 microg/ml in vitro, respectively. The structure and the relative stereochemistry of the compounds were established on the basis of their spectroscopic properties. The absolute configuration at C-13 of 1 and 5 was determined by the PGME amide procedure.     

Two new labdane diterpenoids and one new β-lactam from the aerial parts of Roylea cinerea

Two new labdane diterpenoids cinereanoid C (1), cinereanoid D (2), a new β-lactam, cinerealactam E (3) as well as six known flavonoid glycosides (4–9) were isolated from the aerial parts of Roylea cinerea (Lamiaceae). The structures of (1–9) were all determined by MS, IR and NMR spectroscopy. The structure of cinereanoid D (2) was further proven by single crystal X-ray diffraction. Six known flavonoid glycosides (4–9) were also isolated for the first time from this plant. 2, 5, 6 and 7 were found to significantly inhibit the ATP binding of a tumour growth-promoting heat shock protein, Hsp90.     

Terpenoids and sterols from Saussurea cauloptera

A total of 27 natural products were isolated from Saussurea cauloptera, including two new eudesmane-type sesquiterpenoids, the gerin derivatives 2 and 3, and one new ent-labdane diterpenoid, compound 9. The known compounds included six sesquiterpenoids, eleven triterpenoids, six sterols, and one lignan. Their structures were elucidated on the basis of extensive spectroscopic and mass-spectrometric analyses, as well as by X-ray crystallography in the case of gerin (1). The structurally related compounds 1-4 were found to exhibit strong inhibitory activities against human gastric carcinoma (SGC-7901) cells.     

Labdane and norlabdane diterpenoids from the aerial parts of Leonurus japonicus

A new labdane diterpenoid, leojaponicin (1), a novel norlabdane, methyl 15,16-dinor-7-oxolabda-8-ene-14-oate (2), along with four known labdanes, hispanone (3), leoheteronins A (4) and B (5), 15-methoxyleoheteronin B (6), and three norlabdanes, 14,15,16-trinor-7-oxolabda-8-ene-13-oic acid (7), methyl 14,15,16-trinor-7-oxolabda-8-ene-13-oate (8), 14,15-dinor-8-labdene-7,13-dione (9), and a steroid, stigmast-4-ene-3-one (10), were isolated from a hexane extract of Leonurus japonicus. Their structures were determined using spectroscopic methods, mainly 1-D and 2-D NMR. Compounds 7 and 8 were previously semisynthesized but are reported here for the first time as naturally occurring compounds. In addition, α-glucosidase inhibitory activity of the isolated compounds was evaluated and compound 6 exhibited the strongest effect with IC₅₀ value of 26.7 μM (compared with the positive control acarbose, IC₅₀ = 214.5 μM).     

Labdane diterpenes from Leonurus japonicus leaves

Three labdane diterpenes 15,16-epoxy-6-hydroxylabda-5,8,13(16),14-tretraen-7-one (leojaponin), (9alpha,13S);15,16-diepoxy-7beta-hydroxylabd-14-en-6-one (13-epi-preleoheterin), and (9alpha,13R);15,16-diepoxy-6beta-hydroxylabd-14-en-7-one (iso-preleoheterin) were isolated from the leaves of Leonurus japonicus, in addition to the previously reported preleoheterin. The structure elucidations were made based on analysis of their spectroscopic data.