Diterpenoids from Humirianthera ampla

Two diterpenoids, humirianthol and acrenol, as well as the known annonalide, were isolated from Humirianthera ampla. Humirianthol and acrenol were determined by 1D and 2D NMR spectroscopic techniques to be 3 beta,20:14 beta,16-diepoxy-3 alpha, 15 alpha-dihydroxy-7-pimaren-19,6 beta-olide and 3 beta,20-epoxy-3 alpha,15,16-trihydroxy-7-pimaren-19,6 beta-olide, respectively.     

Grayanane diterpenoids from the leaves of Craiobiodendron yunnanense

Ten new grayanane diterpenoids, craiobiotoxins I-VIII (1-8) and craiobiosides A (9) and B (10), and five known grayanane diterpenoids, grayanotoxin XVIII, lyoniol A, lyoniol B, pieristoxin H, and grayanoside B were isolated from the leaves of Craiobiodendron yunnanense (Ericaceae). The structures of 1-10 were elucidated by spectroscopic methods including various 2D NMR and X-ray crystal diffraction experiments. In biological testing of our isolates, craiobiotoxin III (3) and lyoniol B showed moderate antifeedant activity.     

Abietane diterpenoids from the roots of some Mexican Salvia species (Labiatae): chemical diversity, phytogeographical significance, and cytotoxic activity

From the roots of some Mexican Salvia species, classified in subgenus Jungia, several diterpenoids belonging to abietane (i.e., 3-7), salvifolane (9-->20,10-->6)-diabeoabietane) (i.e., 2), and totarane (i.e., 10) carbocyclic skeletons were isolated together with two 20-nor- and one 6,7-secoabietane derivatives, 1 and 9, and 8, respectively. While compounds 2-10 were previously known from different sources, compound 1 is a new 20-norabietane derivative, whose structure was deduced by spectroscopic means and confirmed by X-ray-diffraction analysis. The phytogeographical significance of the distribution of 20-norabietanic diterpenoids in the genus suggested an evolutionary link between the Chinese and New-World Salvias. Compounds 2 and 8 were tested for cell-growth inhibition activity against several human cancer cell lines and human normal lymphocytes, while 2 showed a moderate cytotoxic activity, 8 exhibited a moderate yet selective activity against leukemia cell line.     

Five diterpenoids (agallochins A-E) from the mangrove plant Excoecaria agallocha Linn

Chemical examination of the hexane extract of the roots of Excoecaria agallocha Linn collected from the Godavari estuary resulted in the isolation of altogether eleven diterpenoids of which five (1-5) are new. The structures of the new diterpenoids have been elucidated by a study of their physical and spectral (UV, IR, 1H, 13C, DEPT, 1H-1H COSY, NOESY, HMQC, HMBC and MASS) data as 3-oxo-ent-13epi-8(13)-epoxy-15-chloro-14-hydroxylabdane (1), ent-15-chloro-13,14-dihydroxylabd-8(9)-en-3-one (2), ent-15-chloro-labd-8(9)ene-3alpha,13,14-triol (3), ent-11beta-hydroxy-8(14),15-isopimaradien-3-one (4), 8,13-epoxy-3-nor-2,3-seco-14-epilabden-2,4-olide (5). The six known diterpenoids have been characterised respectively as ent-3-oxo-13-epi-manoyl oxide (6), ent-3beta-hydroxy-13-epi-manoyl oxide (7), (13R,14S)-ent-8alpha,13;14,15-diepoxy-13-epi-labdan-3-one (8), ent-16-hydroxy-3-oxo-13-epimanoyl oxide (9), ent-15-hydroxylabda-8(17),13E-dien-3-one (10), labda-8(17),13E-diene-3beta,15-diol (11) by a comparative study of their spectral data with the literature values.     

ent-Kaurene diterpenoids from Isodon oresbius

Three new ent-kaurene diterpenoids, oreskaurins A-C (1-3), together with ten known ent-kaurene diterpenoids, enmenin monoacetate (4), effusanin E (5), adenolin B (6), maoecrystal G (7), enmelol (8), trichokaurin (9), sodoponin (10), trichorabdal A (11), nodosin (12), enmein (13), and a flavonoid, vitexin (14), were isolated from Isodon oresbius. Their structures were determined by spectroscopic means. Compound 12 showed inhibitory activity toward K562 cells with IC(50)=1.43 microg/ml.     

Novel antibacterial diterpenoids from Larix chinensis Beissn

Two novel labdane-type diterpenoids, butanedioic acid mono[(13S)-13-hydroxylabda-8(17),14-dien-19-yl] ester (1) and butanedioic acid bis[(13S)-13-hydroxylabda-8(17),14-dien-19-yl] ester (2), along with the eleven known diterpenoids 3-13 and three other known compounds, were isolated from the bark of Larix chinensis. Their structures were elucidated both spectroscopically and chemically. The major diterpenoids 1-9, 11, and 13, as well as the very abundant phenolic compound 16, were subjected to antibacterial and cytotoxic bioassays. Compounds 7 and 9 showed remarkable in vitro inhibition of Staphylococcus aureus and S. epidermidis (MIC = 37-73 microM).     

Zierane sesquiterpene lactone,cembrane and fusicoccane diterpenoids,from the Tahitian liverwort Chandonanthus hirtellus

Cembrane-type diterpenoids, 13,18,20-epi-iso-chandonanthone (1) and (8E)-4α-acetoxy-12α,13α-epoxycembra-1(15),8-diene (2), two fusicoccane-type diterpenoids, fusicoauritone 6α-methyl ether (3) and 6β,10β-epoxy-5β-hydroxyfusicocc-2-ene (4) and a zierane sesquiterpene γ-lactone, chandolide (5) were isolated from the Tahitian liverwort Chandonanthus hirtellus (Web.) Mitt., together with eight known diterpenoids, chandonanthine (6), fusicogigantone A (7), fusicogigantone B (8), fusicogigantepoxide (9), anadensin (10), fusicoauritone (11), ent-verticillol (12) and ent-epi-verticillol (13). Their structures were established by a combination of extensive NMR spectroscopy and/or X-ray crystallographic analyses. Compounds 1, 5 and 10 showed weak cytotoxic activity against HL-60. Compound 3 also indicated weak cytotoxic activity against KB cell lines.     

abeo‐Taxane Diterpenoids from the Taiwanese Yew Taxus sumatrana

Chemical investigation of the acetonic extract of the leaves and twigs of Taxus sumatrana (Taxaceae) led to the isolation of four new taxane diterpene esters, taiwantaxins A–D ( 1 – 4 , resp.). Their structures were determined primarily on the basis of 1D‐ and 2D‐NMR techniques as well as MS. Compound 1 is a rearranged taxane diterpenoid possessing an opened oxetane ring moiety containing C(4), C(5), and C(20). The metabolites 2 and 3 belong to a 5/6/6 taxene system having a rare five‐membered γ‐lactone ring comprising C(8), C(9), C(10), and C(19). Compound 4 is an example of a taxane diterpene containing a 6/8/6 ring system with a tetrahydrofuran ring comprising C(2), C(3), C(4), and C(20). The 11(15→1)abeo‐taxane diterpenoids, taiwantaxins A–C ( 1 – 3 , resp.) are lacking an O‐bearing functionality at either C(13) or C(14). Compound 2 showed significant cytotoxic activity against human PC‐3 tumor cells.     

Anti-tumor promoting diterpenes from the stem bark of Thuja standishii (Cupressaceae).

Three new labdane-type diterpenoids, labda-8(17),13-dien-15,12R-olid-19-oic acid (1), 12S-hydroxylabda-8(17),13(16),14-trien-19-oic acid (2) and 13-ethoxylabda-8(17),11,14-trien-19-oic acid (3), along with known diterpenoids, trans-communic acid (4), totarol (5), 12-methoxyabieta-8,11,13-trien-11-ol (6), and 7 alpha,8 alpha-epoxy-6 alpha-hydroxyabieta-9(11),13-dien-12-one (7) were isolated from the stem bark of Thuja standishii. The structures of 1--3 were established by spectroscopic methods and chemical conversion. These compounds together with standishinal (8), 12-hydroxy-6,7-seco-abieta-8,11,13-trien-6,7-dial (9) and 6 alpha-hydroxysugiol (10) were tested for their inhibitory effects on Epstein--Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), as a test for potential cancer chemopreventive agents. Compound 10 showed strong inhibitory effect on EBV-EA induction (100% inhibition at 1000 mol ratio/TPA), and compounds 2 and 6 showed moderate inhibitory effects on EBV-EA induction. In addition, 15-oxolabda-8(17),11Z,13E-trien-19-oic acid (11) was found to exhibit the anti-tumor promoting activity in two-stage mouse skin carcinogenesis test using 7,12-dimethylbenz[a]anthracene and TPA.     

Abietane diterpenes from the cones of Cedrus atlantica

Five new abietanes, three of them isolated as the corresponding acetate derivatives, i.e., 9alpha,13alpha-epidioxiabiet-8(14)-en-18-ol, 7alpha,18-diacetoxy, 9beta,13beta-epidioxiabiet-8(14)-ene, 7alpha,18-diacetoxyabiet-8(14)-en-13beta-ol, 7alpha,18-diacetoxy-13beta-methoxyabiet-8(14)-ene, and 13beta-hydroxyabiet-8(14)-en-7-one, were isolated from the neutral part of the hexane extract of the cones of Cedrus atlantica collected in Middle Atlas, Morocco. The structures of these compounds were established by spectroscopic techniques, including 2D NMR spectra, and in the case of 1, by chemical correlation. The cytotoxicity of these abietane diterpenoids was tested against five cell lines.     

Cytotoxic abietane-type diterpenoids from twigs and leaves of Croton laevigatus

Seven new abietane-type diterpenoids, crotolaevigatones A–G (1–7), one new aromatic compound, hexyl Z-ferulate (8), along with three known diterpenoids (9–11) and one known aromatic ester, hexyl E-ferulate (12), were obtained from the twigs and leaves of Croton laevigatus. The structures of all isolated compounds were established on the basis of extensive NMR and MS spectroscopic analyses. Compounds 2 and 7 exhibited weak anti-proliferative activity against the A549 and MDA-MB-231 cancer cells, while compound 10 selectively showed significant inhibitory activity against the A549 cancer cells.     

Terpenoids from the liverwort Blepharostoma trichophyllum

Blepharostol, a new sesquiterpenoid alcohol with a rearranged drimane skeleton and five new ent-labdane diterpenoids, ent-labda-13(16),14-diene-8alpha-ol, ent-labda-13(16),14-diene-1beta,8alpha-diol, ent-labda-13(16),14-diene-8alpha,9beta-diol, ent-labda-13(16),14-diene-1beta,8alpha,9beta-triol and ent-8alpha,9beta-dihydroxylabda-13(16),14-dien-1-one, have been isolated from the liverwort Blepharostoma trichophyllum. Their structures have been assigned on the basis of their spectroscopic properties.     

Cassane-Type Diterpenoids from the Seeds of Caesalpinia bonduc (L.) Roxb.

Ten new cassane-type diterpenoids were isolated from the seeds of Caesalpinia bonduc (L.) Roxb., including 6α-hydroxycaesalpinin P ( 1 ), 14-epi-caesalpinin E1 ( 2 ), 6-deacetylcaesalmin Z ( 3 ), 14-epi-caesalmin Z ( 4 ), caesalpinolides I ( 5 ), K ( 6 ), L ( 7 ), M ( 9 ) and N ( 10 ), and 14-epi-neocaesalpin L ( 8 ). Their planar structures and absolute configurations were fully determined by comprehensive spectroscopic methods, including 2D NMR and electronic circular dichroism spectra. Compounds 1 – 4 are tetracyclic cassane diterpenoids possessing a furan ring, and compounds 5 – 10 are tetracyclic cassane diterpenoids possessing a fused butenolide moiety. The anti-inflammatory and cytotoxic activities of the isolates were evaluated, while none of them showed obvious effects. The current study identified ten new cassane-type diterpenoids from the seeds of C. bonduc (L.) Roxb., which enriched the chemical diversity of the titled herbal medicine.     

Kaurane and abietane diterpenoids from Tripterygium doianum (Celastraceae)

Extraction of Tripterygium doianum (Celastraceae) afforded five new diterpenoids and 11 known diterpenoids belonging to the ent-kaurane and abietane families. Their structures were established based on spectroscopic studies. The isolated compounds showed moderate cytotoxicity against human tumor cell assays.     

Cytotoxic macrocyclic diterpenoids from Jatropha multifida

Nine new macrocyclic diterpenoids (1–9), jatromultones A-I, along with eight known analogues (10–17) were isolated from the trunks of Jatropha multifida. The structures of the new compounds, including their absolute configurations, were elucidated by combination of spectroscopic analysis, single crystal X-ray diffraction, Rh₂(OCOCF₃)₄-induced CD method, and chemical correlations. All compounds were screened for the cytotoxicity against five cancer cell lines, including one drug-resistant cell line, and seven compounds exhibited significant activity with IC₅₀ values less than 10 μM. Compound 4 with IC₅₀ values ranging from 2.69 to 6.44 μM toward all cell lines was selected for further mechanistic study, which showed that 4 could arrest cell cycle at G2/M phase and induce apoptosis. The brief structure-activity relationships (SARs) of these macrocyclic diterpenoids were also discussed.     

Antitumor Cembrane Diterpenoids from the South China Sea Soft Coral Lobophytum sp.

Two new highly functionalized cembrane diterpenoids named ximaolobophytolides A ( 1 ) and B ( 2 ) as minor components, together with seven related known compounds ( 3 – 9 ), have been isolated and identified from the Ximao soft coral Lobophytum sp. They were characterized by the presence of an α-methylene-γ-lactone moiety. Based on the comprehensive analyses of 1D and 2D NMR spectroscopic data, the absolute configurations of these two new compounds were elucidated by the combination of quantum mechanical (QM)-NMR and time-dependent density functional theory/electronic circular dichroism (TDDFT-ECD) calculation approaches. In the anti-tumor bioassays, compounds 3 – 9 showed moderate to significant inhibitory effects (IC₅₀ values ranging from 29.66 to 0.39 μM) against the proliferations of five tumor cells HEL, A549, H1975, MDA-MB-231, and H1299. It might be worthy to point out that compounds 4 , 7 , and 8 exhibited better anti-tumor activities than that of the positive control Doxorubicin.     

Diterpenoids and a Diarylheptanoid from Hedychium coronarium with Significant Anti‐Angiogenic and Cytotoxic Activities

Two new labdane diterpenoids, namely hedycoronals A and B ( 1 and 2 , resp.), were isolated from the rhizomes of Hedychium coronarium, together with eight known diterpenoids, 4 – 11 , and a known diarylheptanoid, 3 . The structures of 1 and 2 were established by detailed interpretation of their 1D‐ and 2D‐NMR spectra and HR‐ESI‐MS data. Inhibitory activities against human umbilical vein endothelial cells (HUMECs) proliferation and cytotoxic activities against four cancer cell lines were assessed for all the isolates. Most of these metabolites showed moderate or potent cytotoxic activities against four cancer cell lines. Moreover, compounds 3 and 8 exhibited promising inhibitory activities against HUMECs with the IC₅₀ values of 6.4 to 3.3 μM .     

Novel diterpenoids with potent inhibitory activity against endothelium cell HMEC and cytotoxic activities from a well-known TCM plant Daphne genkwa

Twelve highly oxygenated novel daphnane-type diterpenoids genkwanines A-L (1-12), together with four known diterpenes (13-16), were isolated from the bud of Daphne genkwa, a well-known traditional Chinese medicine (TCM). The new structures were elucidated on the basis of spectral methods, especially 2D NMR spectra (HMQC, HMBC, NOESY). Inhibitory activity against endothelium cell HMEC proliferation and cytotoxic activities against two tumor cell lines were assessed for all the compounds 1-16, and found to be significant and structure related. A number of compounds showed very potent cytotoxic activities against two tumor cell lines at the IC50 levels of 0.15-8.40 microM, and most interestingly, five of the compounds 4, 8, 10, 13, and 14 exhibited strong activity to inhibit the endothelium cell HMEC at the IC50 levels of 2.90-15.0 microM.     

Five labdane diterpenoids from the seeds of Aframomum zambesiacum

Five labdane diterpenoids, (3-5), zambesiacolactone A (7) and zambesiacolactone B (8), were isolated from the seeds of Aframomum zambesiacum (Baker) K. Schum., along with five known labdanes and a linear sesquiterpene, nerolidol. Their structures were elucidated by spectroscopic analysis. Their antiplasmodial activity was evaluated in vitro against Plasmodium falciparum. Compound 3 was the most active with an IC(50) value of 4.97 microM.     

Bioactive briarane diterpenoids from the South China Sea gorgonian Dichotella gemmacea

Six new briarane diterpenoids, gemmacolides T-Y (1-6), were isolated together with three known analogs, juncenolide J (7), praelolide (8), and junceellolide C (9), from the South China Sea gorgonian Dichotella gemmacea. The structures of the new compounds were elucidated by detailed spectroscopic analysis and comparison with reported data. The absolute configuration was suggested based on biosynthetic considerations. In an in vitro bioassay, compounds 3 and 6 showed potent growth inhibition towards tumor cell lines of A549 and MG63, being stronger than the positive control of adriamycin. These compounds also exhibited weak antimicrobial activity against the bacterium Escherichia coli and the fungi Microbotryum violaceum and Septoria tritici.