A cytotoxic diterpene from Alomia myriadenia

An extract of the aerial parts from Alomia myriadenia Schultz-Bip. ex Baker (Asteraceae) showed significant cytotoxicity against a panel of human cancer cell lines in a screening of extracts from Brazilian Atlantic Forest plant species. Employing a bioassay-linked HPLC-electrospray/MS method, followed by semi-preparative HPLC, the active component was isolated and characterized as a mixture of epimers of the labdane diterpene 12S,16-dihydroxy-ent-labda-7,13-dien-15,16-olide.     

ent-Beyerane diterpenoids from the heartwood of Excoecaria parvifolia

Chromatographic fractionations of the toluene extract of the heartwood of Excoecaria parvifolia collected in Australia resulted in the isolation of 12 beyerane diterpenes (1-12), and the triterpene, lupeol. Four of the isolated diterpenoids (5-7 and 12) have unusual structures: ent-3-oxa-beyer-15-en-2-one, (5); ent-15,16-epoxy-2-hydroxy-19-norbeyer-1,4-dien-3-one (6); methyl ent-2,4-seco-15,16-epoxy-4-oxo-3,19-dinorbeyer-15-en-2-oate (7); and ent-2,17-dihydroxy-19-norbeyer-1,4,15-trien-3-one (12). The structures were established by spectroscopic analyses, NMR data comparisons with similar diterpenes, and chemical correlations. All the diterpenes are assumed to have the same absolute configuration as the co-occurring (+)-stachenol (4). Diosphenol 2 and nor-lactone 5 exhibited significant potency in bioassays for cytotoxic activity against leukemia cells (L1210). Plausible biosynthetic pathways are proposed to explain the origin of the diterpene metabolites.     

Diterpenoids and triterpenoids from Euphorbia guyoniana

Two new compounds with tigliane and cycloartane skeletons: 4,12-dideoxy(4alpha)phorbol-13-hexadecanoate (1) and 24-methylenecycloartane-3,28-diol (2), respectively, in addition of four known diterpenoids and 13 triterpenoids: 3-benzoyloxy-5,15-diacetoxy-9,14-dioxojatropha-6(17),11-diene (4), ent-abieta-8(14),13(15)-dien-16,12-olide (5), ent-8alpha,14alpha-epoxyabieta-11,13(15)-dien-16,12-olide (6), ent-3-hydroxyatis-16(17)-ene-2,14-dione (7), 3beta-hydroxytaraxer-14-en-28-oic acid (8), beta-sitosteryl-3beta-glucopyranoside-6'-O-palmitate (9), multiflorenyl acetate (10), multiflorenyl palmitate (11), peplusol (12), 24-methylenecycloartanol (3), lanosterol (13), euferol (14), butyrospermol (15), cycloartenol (16), obtusifoliol (17), cycloeucalenol (18) and beta-sitosterol (19), were isolated from the roots of Euphorbia guyoniana. Their structures were established on the basis of physical and spectroscopic analysis, including 1D and 2D homo- and heteronuclear NMR experiments (COSY, HSQC, HMBC and NOESY) and by comparison with the literature data.     

ent-Clerodane diterpenes and other constituents from the liverwort Adelanthus lindenbergianus (Lehm.) Mitt

Eleven ent-clerodanes, 13-hydroxy-cis-ent-cleroda-3,14-diene, 15-hydroxy-cis-ent-cleroda-3,13(E)-diene, 1beta,12:15,16-diepoxy-cis-ent-cleroda-13(16),14-dien-18alpha,6alpha-olide, 8beta,12:15, 16-diepoxy-cis-ent-cleroda-13(16),14-dien-18alpha,6alpha-olide, 1beta,16:15,16-diepoxy-cis-ent-cleroda-12,14-dien-18alpha,6alpha-olide, 7beta,12:8beta,12-diepoxy-15-hydroxy-cis-ent-cleroda-13-en-16,15:18alpha,6alpha-diolide, 7beta,12:8beta,12-diepoxy-16-hydroxy-cis-ent-cleroda-13-en-15,16:18alpha,6alpha-diolide, 1alpha-acetoxy-8beta,12-epoxy-15-hydroxy-cis-ent-cleroda-13-en-16,15:18alpha,6alpha-diolide, 1beta,12-epoxy-16-hydroxy-cis-ent-cleroda-13-en-15,16:18alpha,6alpha-diolide, 8beta,12-epoxy-15-hydroxy-trans-cleroda-13-en-16,15:18alpha,6alpha-diolide, 8beta,12-epoxy-16-hydroxy-trans-cleroda-13-en-15,16:18alpha,6alpha-diolide along with the known clerodane diterpenes anastreptin and orcadensin have been isolated from the liverwort Adelanthus lindenbergianus (Lehm.) Mitt. Furthermore, three eudesmane sesquiterpenes together with the known (-)-1beta,10-epoxyaristolan, 3,4-seco-4(23),20(29)-lupadien-3,28-dicarboxylic acid dimethyl ester and two acetophenone derivatives were identified by spectroscopic methods, essentially MS and NMR experiments.     

Antibacterial diterpenes and their fatty acid conjugates from rice leaves

Six structurally oryzalide-related compounds, oryzadione (1), 2, 3, 4, 5 and 6, were isolated from a neutral fraction of the extract of healthy leaves using a bacterial leaf blight-resistant cultivar of a rice plant, "Norin-27", as a group of antimicrobial substances. Their structures were determined by spectroscopic studies to be kaurane analogues and kaurane analogues conjugated with fatty acids, i.e., 1: ent-15,16-epoxy-kauran-2,3-dione (enol form: ent-15,16-epoxy-2-hydroxy-kauran-1-en-3-one), 2: ent-15,16-epoxy-3beta-hydroxy-kauran-2-one, 3: ent-15,16-epoxy-3-oxa-kauran-2-one, 4: ent-15,16-epoxy-3beta-myristoyloxy-kauran-2-one, 5: ent-15,16-epoxy-3alpha-palmitoyloxy-kauran-2-one, and 6: ent-15,16-epoxy-2beta-palmitoyloxy-kauran-2-one.     

neo-Clerodane diterpenoids from Baccharis flabellata

Three diterpenoid derivatives were isolated from the acetone extract of Baccharis flabellata. Their structures were elucidated as 2,19;15,16-diepoxy-neo-clerodan-3,13(16),14-trien-18-oic acid, 15,16-epoxy-5,10-seco-clerodan-1(10),2,4,13(16),14-pentaen-18,19-olide and 15,16-epoxy-neo-clerodan-1,3,13(16),14-tetraen-18,19-olide through spectroscopic analyses.     

Guaianolide sesquiterpenes from Pulicaria crispa (Forssk.) Oliv

A phytochemical study of the asteraceous herb Pulicaria crispa (Forssk.) Oliv. resulted in the characterisation of three guaianolide sesquiterpenes, 2alpha,4alpha-dihydroxy-7alphaH,8alphaH,10alphaH-guaia-1(5),11(13)-dien-8beta,12-olide (1), 1alpha,2alpha-epoxy-4beta-hydroxy-5alphaH,7alphaH,8alphaH,10alphaH-guaia-11(13)-en-8beta,12-olide (2) and 5,10-epi-2,3-dihydroaromatin (3). The structures were assigned on the basis of extensive 1 and 2D NMR experiments. Compound 3 exhibited weak antimycobacterial activity against Mycobacterium phlei with a minimum inhibitory concentration of 0.52 mM and cytotoxicity (IC50 of 5.8+/-0.2 microM) in a human bladder carcinoma cell line, EJ-138.     

Neo-clerodane diterpenoids from Teucrium oxylepis subsp. Marianum

Two new neo-clerodane diterpenoids have been isolated from the aerial parts of Teucrium oxylepis subsp. marianum. Their structures, 4,18;15,16-diepoxy-6β,12S-dihydroxy-neo-clerado-13(16),14-dien-20,19-olide (teucroxylepin) and 12S-acetoxy-6β,18; 15,16-diepoxy-4,6-dihydroxy-neo-cleroda-13(16),14-dien-20,19-olide (12-O-acetylteugnaphalodin), were established by chemical and spectroscopic means. In addition, 10 already known neo-clerodane diterpenoids were also isolated from the same source.     

Constituents and bioactivity of the tubers of Euphorbia sessiliflora

The diterpene ent-12-hydroxy-12[R]-abieta-8(14),13(15)-dien-16,12-olide was isolated from the tubers of Euphorbia sessiliflora Roxb., together with four known ent-abietadienolides, four known cycloartane triterpenes and ellagic acid-beta-D-glucopyranoside. Two of these metabolates displayed moderate antibacterial activities.     

Cytotoxic sesquiterpenes from Ligularia platyglossa

Four sesquiterpene lactones including an eremophilenolide dimer, named as biligulaplenolide, 1, 8beta-hydroxy-1-oxo-(14alpha,15alpha eremophil-7(11),9(10)-dien-12,8alpha-olide, 2, 1-hydroxy-2-oxo-(14alpha,15alpha eremophil-1(10),7(11),8(9)-trien-12,8-olide, 3, 4alpha,8beta,9alpha-trihydroxy- 5alphaEta-7(11)-eudesmen-12,8alpha-olide, 4, along with two known ones, 10alpha-hydroxy-1-oxo-eremophil-7(11),8(9)-dien-12,8-olide, 5, and furanoeremophil-1(10)-ene-2,9-dione, 6, were isolated from the underground organs of Ligularia platyglossa (Franch.) Hand.-Mazz. Their structures were elucidated by spectroscopic methods including single-crystal X-ray diffraction analysis (2 and 3). Their in vitro cytotoxicities against seven cancer cell lines (BGC-823, A549, HL-60, B16, SMMC-7721, BEL7402, Hela) were evaluated. Compounds 2, 3, 5 showed cytotoxic activities on HL-60 cancer cells with IC50 in the range of 24.0 to 51.1 microM, whereas compound 3 exhibited only weak cytotoxic activity against the B16, BEL7402 and Hela cancer cells. Flow cytometric analysis indicated that compound 3 induces Hela cells to apoptotic death after 48 h treatment with 0.38 mM of this compound.     

Labdane diterpenoids from Aframomum sceptrum: NMR study and antiparasitic activities

Two novel labdane diterpenoids, 15ξ-methoxy-labdan-8(17),11(E),13(14)-trien-15,16-olide (1) and 12(S)-hydroxy-15ξ-methoxy-labdan-8(17),13(14)-dien-15,16-olide (2) were isolated from the rhizomes of Aframomum sceptrum K. Schum (Zingiberaceae). Their structures were established on the basis of their spectroscopic data. Stigmast-4-en-6β-ol-3-one and caryophylene oxide were also obtained. In vitro trypanocidal and leishmanicidal activities of labdanes 1 and 2 were evaluated. Compound 2 exhibited activity similar to that of reference drugs against Leishmania donovani.     

Cytotoxic and apoptosis-inducing effect of ent-15-oxo-kaur-16-en-19-oic acid, a derivative of grandiflorolic acid from Espeletia schultzii

ent-Kaurenic acid and many natural derivatives of this diterpene are known to have interesting biological properties. ent-15-Oxo-kaur-16-en-19-oic acid can be easily obtained from grandiflorolic acid which was first isolated from Espeletia grandiflora. The present work describes the proapoptotic effect of ent-15-oxo-kaur-16-en-19-oic acid on the human prostate carcinoma epithelial cell line PC-3 as evidenced by the changes in the expression level of proteins associated with the execution and regulation of apoptosis. Cell viability was affected upon exposure to the compound, the IC(50) were determined as 3.7 microg/ml, which is 4 times lower than that corresponding to a primary cell culture of fibroblasts (14.8 microg/mL). Through Western blot analysis, active forms of caspace-3 associated with the specific proteolysis of Poly(ADP-ribose) polymerase (PARP) were detected. Reduced levels of the antiapoptotic protein Bcl-2, as well as the appearance of internucleosomal DNA fragmentation, were also demonstrated. Thus, ent-15-oxo-kaur-16-en-19-oic acid may be a promising lead compound for new chemopreventive strategies, alone or in combination with traditional chemotherapy agents to overcome drug resistance in tumoral cells.     

Neo-clerodane diterpenoids from Teucrium salviastrum

From the aerial parts of Teucrium salviastrum six new neo-clerodane diterpenoids, teusalvins A–F, have been isolated, together with the previously known diterpenes teucvidin teucroxide. The structures of teusalvins A [15,16-epoxy-2,6-diketo-neo- cleroda-13(16),14-dien-20,12S-olide-18R19-hemiacetal], B [15,16-epoxy-2β-hydroxy-6-keto-neo-cleroda-13(16),14-dien-20,12S-olide-18R,19-hemiacetal], C [15,16-epoxy-6β,18,19-trihydroxy-neo-cleroda- 3,13(16),14-trien-20,12R-olide], D [15,16-epoxy-2β,6β,18,19-tetrahydroxy-neo-cleroda-3,13(16),14-trien-20,12S-olide], E [15,16-epoxy-2β,6β,12S,18-tetrahydroxy-neo-cleroda-3,13(16),14-trien-20,19-olide] and F [15,16; 19,2α-diepoxy-6β,8-dihydroxy-neo-cleroda-3,13(16),14-trien-20,12S-olide] were established mainly by spectroscopic means and, in the case of teusalvin F, by X-ray diffraction.     

Cytotoxic clerodane diterpenes from Glossocarya calcicola

Three clerodane diterpenes were isolated and identified from leaf extract of Glossocarya calcicola. Compound has been characterised as (rel)-10betaH-trans-12xi-(2-methylbut-2(E)-enoyl)-1beta-(isobutanoyl)-6alpha,13xi-dihydroxyclerodan-4(20),8(18)-dien-7,15-dione-15,16-oxide, to which we have assigned the trivial name calcicolin-A. The other two compounds had the same skeletal structure and C-12 substituent but in compound, the C-1 esterifying group becomes 2-methylbut-2(E)-enoic acid and in it becomes 2-methylbutanoic acid. Although anti-insect activity was not observed for G. calcicola, cytotoxicity against insect and human carcinoma cell lines was detected.     

Neo-clerodane diterpenoids and phenylethanoid glycosides from Teucrium chamaedrys L

A neo-clerodane type diterpenoid, 12(S)-15,16-epoxy-19-hydroxy-neo-cleroda-13(16),14-dien-18,6alpha:20,12-diolide, and two phenylethanoid glycosides, teucrioside-3(IIII)-O-methylether and teucrioside-3(IIII),4(IIII)-O-dimethylether were isolated from the aerial parts of Teucrium chamaedrys. Their structures were identified on the basis of extensive NMR spectra, LC-ESIMS analysis, and molecular modeling studies.     

Microbial transformation of deoxyandrographolide and their inhibitory activity on LPS-induced NO production in RAW 264.7 macrophages

A series of analogues of deoxyandrographolide (1) transformed by Cunninghamella blakesleana AS 3.2004 were isolated and identified by spectral methods including 2D NMR. Among them, 3-oxo-17,19-dihydroxy-7,13-ent-labdadien-15,16-olide (9), 3-oxo-19-hydroxy-1,13-ent-labdadien-15,16-olide (16), 3-oxo-1β-hydroxy-14-deoxy-andrographolide (17) and 3-oxo-2β-hydroxy-14-deoxyandrographolide (18) are new compounds. And their structure-activity relationships (SAR) of inhibitory activity on LPS-induced NO production in RAW 264.7 macrophage cells were also discussed.     

Antialgal furano-diterpenes from Potamogeton natans L

Six furano-ent-labdanes, 19-acetoxy-15,16-epoxy-8(17),13(16),14-ent-labdatrien-20-al, 15,16-epoxy-12-oxo-8(17),13(16),14-ent-labdatrien-20,19-olide, 12(S)-hydroxy-15,16-epoxy-8(17),13(16),14-ent-labdatrien-20,19-olide, 10alpha,19-dihydroxy-15,16-epoxy-8(17),13(16),14-nor-ent-labdatriene, 19,20-dihydroxy-15,16-epoxy-8(17),13(16),14-ent-labdatriene, 15,16-epoxy-12-oxo-8(17),13(16),14-ent-labdatrien-19,20-olide, were isolated, together with the known potamogetonin, from the aquatic plant Potamogeton natans. Their structures were determined on the basis of their chemical and spectral data. The compounds showed in vitro phytotoxicity against Raphidocelis subcapitata, a microalga used in aquatic tests.     

Volatile components from European liverworts Marsupella emarginata,M. aquatica and M. alpina

The hydrodistillation products of the liverworts Marsupella emarginata, M. aquatica and M. alpina were investigated by spectroscopic methods. A number of new compounds could be isolated by preparative gas chromatography (GC) and identified by spectroscopic techniques including GC-mass spectrometry, NMR and chemical correlations in conjunction with enantioselective GC. From M. emarginata, in addition to many known compounds, the sesquiterpene hydrocarbon (-)-7-epi-eremophila-1(10),8,11-triene (1) and the sesquiterpene derivatives (-)-4-epi-marsupellol (2), (-)-marsupellol acetate (18), (-)-4-epi-marsupellol acetate (4), (+)-5-hydroxymarsupellol acetate (5) and (-)-9-acetoxygymnomitr-8(12)-ene (24) could be identified. In M. aquatica the sesquiterpene hydrocarbons (-)-myltayl-8(12)-ene (7), ent-(+)-amorpha-4,11-diene (8), (-)-amorpha-4,7(11)-diene (9), the sesquiterpene alcohol (+)-9-hydroxyselina-4,11-diene (10) and (-)-2-acetoxyamorpha-4,7(11)-diene (11) were identified. In M. alpina (-)-trans-selina-4(15),11-dien-5-ol (12), (+)-8,9-epoxyselina-4,11-diene (13) and (+)-cis-selina-4(15),11-dien-5-ol (14) were found as new natural products.     

ent-Labdane diterpenes from the aquatic plant Potamogeton pectinatus

Four new ent-labdane diterpenes were isolated from the freshwater aquatic plant Potamogeton pectinatus, together with two known furano-ent-labdanes. The new compounds were assigned the structures methyl-15,16-epoxy-12(R)-acetoxy- 8(17), 13(16),14-ent-labdatrien-19-oate,15,16-epoxy-12(R)-acetoxy-8(17), 13(16),14-ent-labdatrien-19-oic acid, 8(17),13-ent-labdadien-15 --> 16-lactone-19-oic acid and 16-hydroxy-8(17),13-ent-labdadien-15,16-olid-19-oic acid by spectroscopic means. Some of these labdanes showed a strong algicidal activity against Raphidocelis subcapitata.     

Identification of the polar constituents of Potamogeton species by HPLC-UV with post-column derivatization, HPLC-MSn and HPLC-NMR, and isolation of a new ent-labdane diglycoside

The polar extracts of Potamogeton pectinatus, P. lucens, P. perfoliatus and P. crispus (Potamogetonaceae) were analyzed by HPLC-UV-MS and their chromatographic profiles were very similar. The polar constituents of P. pectinatus were more exhaustively investigated by HPLC-UV with post-column derivatization, HPLC-MS(n) and HPLC-NMR, which allowed the on-line identification of various known flavones (dereplication). One of these compounds, luteolin 3'-O-glucoside, has never been characterized in the Potamogeton genus. The HPLC-UV-MS and HPLC-NMR analyses revealed also the presence of ent-labdane diterpene glycosides in the polar extracts of P. pectinatus and P. lucens and led to the isolation of a new ent-labdane diglycoside from P. pectinatus, beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-15,16-epoxy-12-oxo-8(17),13(16),14-ent-labdatrien-19-oate.