Cytotoxic ent-kaurane diterpenoids from Isodon henryi

Five new ent-kaurane diterpenoids, isodonhenrins A-E (1-5), together with thirteen known ones were isolated from the aerial parts of Isodon henryi. Their structures were identified by means of extensive spectroscopic analysis, and the absolute configurations of 1 were determined by single-crystal X-ray diffraction. Most of the diterpenoids were evaluated for their cytotoxicity against HL-60, SMMC-7721, A-549, MCF-7, and SW480 cell lines. Compound 17 showed significant inhibitory effects on five cell lines, and compounds 6, 9, 10, 11, 12 and 16 exhibited selective activity.     

Neoclerodanes from Teucrium orientale

Two new neoclerodane diterpenoids, 6-deacetyl-teucrolivin A (5) and 8beta-hydroxy-teucrolivin B (6), were isolated from the aerial parts of Teucrium orientale, along with four already known neoclerodane diterpenoids, teucrolivin A (1), teucrolivin B (2), teucrolivin C (3) and teucrolivin H (4), previously isolated from Teucrium oliverianum. Their structures were elucidated on the basis of spectroscopic evidence and chemical transformations. Compounds 1-3 were assayed for antifeedant activity against Spodoptera littoralis, S. frugiperda and Heliocoverpa armigera. Teucrolivin A was the most potent of the three compounds tested.     

Cytotoxicity of labdane-type diterpenoids from Hedychium forrestii

Two new labdane-type diterpenoids, hedyforrestin D (1) and 15-ethoxy-hedyforrestin D (2), and three known compounds, yunnancoronarin A (4), B (3) and C (5) were isolated from the rhizomes of Hedychium forrestii. The structure of the new diterpenoids was established as 6beta,15xi-dihydroxylabda-8(17),11,13-trien-15,16-olide (1), and 6beta-hydroxy-15xi-ethoxylabda-8(17),11,13-trien-15,16-olide (2) on the basis of spectroscopic analyses. In addition, the isolated compounds were evaluated for their cytotoxicity against the lung adenocarcinoma cells A549 and leukemia cells K562 through 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assays. Of these, compounds 3 and 4 exhibited the most activity with IC(50) values of 0.92 and 2.20 microM, respectively, whereas 5 was inactive against A549 cells and 1 was inactive against both cell lines up to a concentration of 300.81 microM. This shows that both the hydroxy substitution and orientation of unsaturated lactone group in the five-membered ring of C-13 to C-16 seem to play an important role in the anti-tumor activities of human lung adenocarcinoma and leukemia.     

Junceols D-H, new polyoxygenated briaranes from sea whip gorgonian coral Junceella juncea (Ellisellidae)

Chemical investigations on the sea whip gorgonian coral Junceella juncea have led to the isolation of five new 8-hydroxybriarane diterpenoids, junceols D-H (1-5). The structures of briaranes 1-5 were determined on the basis of spectroscopic methods and the methylenecyclohexane rings were found to exist in boat form in these new diterpenoids. Junceols D (1) and F-H (3-5) exhibited cytotoxicity toward CCRF-CEM and DLD-1 tumor cells and junceols E-H (2-5) displayed weak inhibitory effects on superoxide anion generation by human neutrophils.     

Three new 18-oxygenated ent-kaurane diterpenoids from Isodon leucophyllus

Three new 18-oxygenated ent-kaurane diterpenoids, isoleuconins A-C (1-3) and ten known diterpenoids were isolated from the aerial parts of Isodon leucophyllus. The structures were elucidated by 1D and 2D NMR spectroscopic analysis. All of the compounds were evaluated for their cytotoxicity. Rabdokunmin A (13) showed significant cytotoxicity against HT-29 cells, with an IC50 value of 6.2 microM.     

Novel abietane diterpenoids and aromatic compounds from Cladonia rangiferina and their antimicrobial activity against antibiotics resistant bacteria

From Cladonia rangiferina were isolated two novel abietane diterpenoids, hanagokenols A (1) and B (2). Also in this investigation, four known abitetane diterpenoids (3-6), four known labdane diterpenoids (7-10), one known isopimarane diterpenoid (11), and six known aromatic compounds were isolated. These structures were elucidated primarily through extensive NMR experiments. Hanagokenol A (1) was a unique abietane diterpene having an ether linkage between C-6 and C-18 of sugiol. Hanagokenol B (2) is also a unique secoabietane diterpene, having gamma-lactone which occurred by cleavage and subsequently oxidation between C-6/C-7 of 12-hydroxydehydroabietinol. Furthermore, all the isolated compounds (1-17) were tested for the antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE).     

Antifouling activity of simple synthetic diterpenoids against larvae of the barnacle Balanus albicostatus Pilsbry

Five new pimarane diterpenoids 1-5 were synthesized using ent-8(14)-pimarene-15R,16-diol as starting material. The structures were elucidated by means of extensive NMR and MS analysis. The antifouling activity against larval settlement of the barnacle Balanus albicostatus were evaluated using capsaicin as a positive control. Compounds 1-3 and 5 showed more potent antifouling activity than capsaicin. Compound 5, which exhibited almost the same antifouling activity as starting material, showed better stability than starting material. These compounds all showed antifouling activity in a non-toxic way against larval settlement of the barnacle B. albicostatus. Analysis of structure-activity relationships (SAR) demonstrated that the substituents on the C-15 and C-16 position of pimarane diterpenoid were responsible for the antifouling activity.     

Three new podocarpane-type diterpenoids from callus of Securinega suffruticosa

Three new podocarpane-type diterpenoids, 3beta,12-dihydroxy-13-methyl-6,8,11,13-podocarpatetraen (1), 3beta,12-dihydroxy-13-methyl-5,8,11,13-podocarpatetraen-7-one (2), and 1-(7-hydroxy-2,6-dimethyl-1-naphthyl)-4-methyl-3-pentanone (3) (20(10-->5)-abeo-4,5-seco-5(10),6,8,11,13-podocarpapentaen-3-one) were isolated from callus of Securinega suffruticosa. The structures were elucidated by spectroscopic methods. Compounds 1, 2, and 3 showed cytotoxic activity against five human cancer cell lines (A549, BEL 7402, BGC-823, HCT-8, A2780).     

Two New Abietane Diterpenoids from the Stems of Clerodendrum kaichianum P. S. Hsu

Two new abietane diterpenoids, named 17‐hydroxyteuvincenone G ( 1 ) and 17‐hydroxyteuvincen‐5(6)‐enone G ( 2 ), together with four known diterpenoids, were isolated from the stems of Clerodendrum kaichianum P. S. Hsu . Their structures were elucidated by extensive NMR and MS analyses, and by comparison with literature data. The new compounds showed significant cytotoxicities against the HL‐60 and A‐549 tumor cell lines.     

Dichotellides A-E, five new iodine-containing briarane type diterpenoids from Dichotella gemmacea

Five new briarane type diterpenoids, dichotellides A−E (1−5), were isolated from the South China Sea gorgonian Dichotella gemmacea together with four known analogues (6−9). Compounds 1−5 represent the first examples of iodine-containing briarane type diterpenoids from nature. The structures of these diterpenoids were elucidated by spectroscopic analysis, including 1D, 2D-NMR, and HRESIMS, and the absolute configuration of 1 was further confirmed by single crystal X-ray diffraction analysis. All the isolates were evaluated for cytotoxicity activity against four human tumor cell lines, and only 3 exhibited marginal activity against SW1990 (human pancreatic cancer).     

Ent-kaurane diterpenoids from Isodon rubescens var. lushanensis

Four new ent-kaurane diterpenoids lushanrubescensins F-I (1-4), together with 11 known ones, lasiodonin (5), oridonin (6), ponicidin (7), isodonoiol (8), isodonal (9), rabdosin B (10), rabdoternins A and B (11 and 12), enmenol (13), epinodosin (14), and inflexusin (15), were isolated from Isodon rubescens var. lushanensis, and the structures were elucidated by spectroscopic analysis. The inhibitory effect against the K562, Bcap37, BGC823, BIU87, CA, CNE, and Hela cell lines of compounds 3 and 5-10 were evaluated.     

Diterpenoids from the gum resin of Boswellia carterii and their biological activities

Seven new diterpenoids, classified as three cembrane-type diterpenoids boscartins I-K (1–3) and four prenylaromadendrane-type diterpenoids boscartols K-N (4–7), respectively, along with nine known diterpenoids, were isolated from the gum resin of Boswellia carterii. Their structure elucidations were achieved by spectroscopic examination. All isolates were evaluated for anti-inflammatory activity against nitric oxide (NO) production and antiproliferative activity against MCF-7 human breast cancer cell in vitro. 4 and 5 exhibited potent inhibitory effects on NO production (IC₅₀ of 2.22 and 1.10?μM, respectively), with 11 showing moderate inhibition (IC₅₀ of 8.63?μM), and 12 and 15 demonstrated moderate antiproliferative effects against MCF-7?cell (IC₅₀ of 9.5, and 6.3?μM, respectively).     

New labdane-type diterpenoids from Leonurus heterophyllus SW

Five new natural labdane-type diterpenoids (5-9), designated leoheteronins A-E, together with four known diterpenoids (1-4), two phytosterols as a mixture of beta-sitosterol and stigmasterol, and the flavone genkwanin (10) were isolated from the aerial parts of Leonurus heterophyllus SW. (Lamiaceae) collected in northern Vietnam. Compound 1 was isolated for the first time from a Leonurus species, and 10 is considered to be a chemotaxonomic marker of the Leonurus genus. Their structures were determined using spectroscopic analyses.     

Vulgarisins B–D,three novel diterpenoids with a rare skeleton isolated from Prunella vulgaris Linn

Three new diterpenoids, vulgarisins B–D (1–3), have been isolated from a medicinal plant Prunella vulgaris Linn. These diterpenoids contain a rare 5/6/4/5 fused tetracyclic ring skeleton. Their structures were determined through the analysis of spectroscopic data, and the absolute configuration were further confirmed by single crystal X-ray diffraction as well as CD analysis. All the compounds were evaluated for their cytotoxicity activity, vulgarisins B (1) and C (2) demonstrated modest cytotoxicity activity against human lung carcinoma A549 cell line.     

Spongolactams, farnesyl transferase inhibitors from a marine sponge: isolation through an LC/MS-guided assay, structures, and semisyntheses

Novel nitrogenous diterpenoids, spongolactams A-C (1-3), were isolated as trace components of an Okinawan marine sponge, Spongia sp., by an LC/MS-guided assay for farnesyl transferase (FTase) inhibitors. Their structures were elucidated by spectroscopic analyses. To evaluate their structures and biological activity, the metabolites were semisynthesized from the known furanoditerpene 5, obtained from the same sponge. Three related compounds 4, 13, and 16 were also semisynthesized. The IC50 values against FTase for 1-3 were 23, 130, and >260 microM, respectively, while the IC50 values against a human tumor cell line were 2.0, 3.5, and 20 microM, respectively. The structure-activity relationships within the six compounds suggest some positive correlation between FTase inhibitory and cytotoxic activities.     

Two new diterpenoids from Plectranthus nummularius Briq

Two new antioxidative diterpenoids, plectranthol A (3)[19-O-(3,4-dihydroxybenzoyl)-11,12-dihydroxy-20(10-->5)-abeo-abieta-1(10),6,8,11,13-tetraene] and plectranthol B (4)[12-O-(3-methyl-2-butenoyl)-19-O-(3,4-dihydroxybenzoyl)-11-hydroxyabieta-8,11,13-trienel along with two known diterpenoids, parvifloron E (1) and F (2) were isolated from the leaves of Plectranthus nummularius Briq. Antioxidative activities of the compounds were measured by the alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) method.     

Two new diterpenoids from the buds of Wikstroemia chamaedaphne

Two new diterpenoids, wikstroelide Q (1) and prostratin Q (5), together with three known diterpenoids, pimelea factors P? (2), P? (3), and prostratin (4), and five known lignans, (+)-epipioresinol (6), (+)-isolariciresinol (7), (?)-lariciresinol (8), (+)-epi-sesaminone (9), and prestegane B (10), were isolated from the buds of Wikstroemia chamaedaphne Meissn. Their structures were elucidated by a combination of spectroscopic analyses. Compounds 1–10 were evaluated for their cytotoxicities against HL-60, SMMC-7721, A549, MCF-7, SW480, and BEAS-2B cell lines in vitro.     

Sabiperones A-F, new diterpenoids from Juniperus sabina

Six new diterpenoids, sabiperones A-F (1-6) have been isolated from the aerial part of Juniperus sabina. Their structures were elucidated by spectroscopic methods including 2D NMR techniques. Sabiperone F showed moderate cell growth inhibitory activities against five human cancer cell lines.     

A hexacyclic ent-trachylobane diterpenoid possessing an oxetane ring from Mitrephora glabra

[chemical reaction: see text]. Three new ent-trachylobane diterpenoids (1-3) were isolated and structures elucidated from Mitrephora glabra Scheff. (Annonaceae). Mitrephorone A (1) possesses a hexacyclic ring system with adjacent ketone moieties and an oxetane ring, both of which are unprecedented among trachylobanes. All compounds were evaluated for cytotoxicity against a panel of cancer cells, where 1 displayed the most potent and broadest activity, and against a battery of antimicrobial assays, where all compounds were approximately equipotent.     

A novel 18-norclerodane diterpenoid from the roots of Tinospora sagittata var. yunnanensis

A novel 18-nor-clerodane diterpenoid named sagitone (1) was isolated from the 95% ethanol extract of dry roots of Tinospora sagittata var. yunnanensis together with the five known diterpenoids columbin (2), palmatoside C (3), fibleucin (4), tinophylloloside (5) and epitinophylloloside (6). The structure of the new compound 1 was determined based on MS, IR, 1D and 2D NMR spectral data. The compounds 1-6 did not show significant cytotoxic activity against cancer cell lines K562 and HL-60.