New erythroxane-type diterpenoids from Fagonia boveana (Hadidi) Hadidi & Graf

The aerial parts of Fagonia boveana afforded two new erythroxane-type diterpenes, 3beta,15,16-trihydroxy-erythrox-4(18)-ene (2) and 15,16-dihydroxy-cis-ent-erythrox-3-ene (fagonene) (3) together with two known ones; 16-O-acetylfagonone (1) and 7beta-hydroxy fagonene (8). Also a new guaiane sesquiterpene alcohol, 6,10-epoxy-4alpha-hydroxy guaiane type sesquiterpene (4) has been isolated. In addition three 8-methoxy flavonols, 8-methoxy-quercetin-3,7,3'-trimethyl ether (ternatin) (5), gossypetin, 3,8,3',4' tetramethyl ether (6) and herbacetin-3,8-dimethyl ether (7) were also isolated. The structures of the isolated compounds have been determined on the basis of spectroscopic evidences as well as physical and chemical correlation with known compounds. On performing different assays for biological activities, 6 displayed significant cytotoxic activity against KA3IT and NIH3T3 cell lines, 8 was the most active antiviral against Herpes simplex type 1 while 7 was the most active cancer-preventive agent using protein-tyrosine kinase inhibitory method.     

Enantiomeric Neolignans and a Sesquiterpene from Solanum erianthum and Their Absolute Configuration Assignment

One pair of new C‐8–C‐3′/C‐7–O–C‐4′ linked neolignan enantiomers ( 1a / 1b ) and one new guaiane sesquiterpene ( 2 ) first featuring the 1(2),9(10)‐conjugated double bond were isolated from the stems of Solanum erianthum (Solanceae). Their structures were characterized on the basis of extensive spectroscopic analyses, especially from their 2D nuclear magnetic resonance (NMR) spectra. The absolute configurations of 1a / 1b were rigorously elucidated by electronic circular dichroism (ECD) experiments combined with the reversed helicity rule for the 2,3‐dihydrobenzo[b]furan chromophore, and compound 2 is the first report on the sterochemical assignment of a guaiane sesquiterpene by using the allylic axial chirality rule for the conjugated diene chromophore in combination with the calculated ECD spectrum. Chirality 28:259–263, 2016. © 2016 Wiley Periodicals, Inc.     

Chemical constituents from Teucrium viscidum

A new guaiane sesquiterpenoid (1), two known guaiane sesquiterpenoids (2 and 3), and eleven known compounds (4–14), were isolated from Teucrium viscidum. Their structures were identified by spectroscopic analyses and by comparison of their spectral data with those reported in the literature. The absolute configuration of lipidiol (2) was determined by single-crystal X-ray diffraction analysis with Cu Kα radiation. Compounds 12 and 13 were isolated as natural products for the first time. All compounds were isolated from T. viscidum for the first time.     

Two new antibacterial sesquiterpenoids from Centipeda minima

Two new guaiane-type sesquiterpene lactones, compounds 1 and 2, along with three known guaianolide- or pseudoguaianolides, were isolated from Centipeda minima (whole plant). Their structures were identified by spectroscopic and mass-spectrometric analyses. The configuration at C5 of the guaiane framework of 1 was rationalized by quantum-mechanical calculations (Table 2). All compounds were found to be active against eight different microbial pathogens (Table 3), with MIC values in the range of 6.25-100 microg/ml.     

Sesquiterpenoid Compounds from Curcuma kwangsiensis

Two previously undescribed guaiane‐type sesquiterpenes ( 1 and 2 ), a pair of new salvialane‐type sesquiterpenes ( 3a and 3b ), together with 11 known compounds were isolated and purified from the rhizomes of Curcuma kwangsiensis. Their structures were elucidated by the extensive spectroscopic data (1D‐ and 2D‐NMR) analysis. All the isolated compounds were assessed for their anti‐neuroinflammatory activity by inhibiting the nitric oxide (NO) production in lipopolysaccharide (LPS)‐activated murine BV‐2 microglial cells in vitro assay, and the isolates 3 and 11 showed anti‐neuroinflammatory activity with IC₅₀ values of 1.85 and 20.05 μm , respectively.     

Secondary metabolites of Peucedanum tauricum fruits

From the essential oil of fruits of Peucedanum tauricum Bieb., two guaiane type sesquiterpene hydrocarbons guaia-1(10),11-diene (1) and guaia-9,11-diene (2) were identified. The structures of 1 and 2 were assigned by 1D and 2D NMR analysis. The relative configurations of the compounds were established by 2D-NOESY experiments while the absolute configurations were deduced through chemical correlations with (+)-gamma-gurjunene (9) and capillary GC analysis using modified cyclodextrins as the stationary phases. From the dichloromethane extract of the less volatile fraction of the fruits, coumarins, viz. peucedanin (3), oxypeucedanin hydrate (4) and officinalin isobutyrate (5) were isolated. Compound 5 was confirmed to be 6-carbomethoxy-7-isobutyroxycoumarin by its 1D and 2D NMR data as well as by conversion into officinalin (7) by alkaline hydrolysis. Peuruthenicin, a positional isomer of officinalin, is assigned structure 8 on spectral basis. Bergapten (6) was identified by its mass spectrum. This is the first report on the isolation of compounds 4 and 5 from P. tauricum.     

Five New Guaiane Sesquiterpenes from the Endophytic Fungus Xylaria sp. YM 311647 of Azadirachta indica

Five new guaiane sesquiterpenes, 1 – 5 , were isolated from the culture broth of the endophytic fungus Xylaria sp. YM 311647, isolated from Azadirachta indica A. Juss . The structures of these compounds were elucidated on the basis of spectroscopic analyses, and their inhibitory activities against five pathogenic fungi were evaluated. All guaiane sesquiterpenes showed moderate or weak antifungal activities in a broth microdilution assay.     

Novel Zierane‐ and Guaiane‐Type Sesquiterpenes from the Root of Melicope denhamii

Two novel zierane‐type sesquiterpenes, named melicodenones A and B ( 1 and 2 , resp.), and three new guaiane‐type sesquiterpenes, named melicodenones C–E ( 3 – 5 ), were isolated from the root of Melicope denhamii (Seem. ) T. G. Hartley together with zierone ( 6 ). Their structures were established by extensive NMR‐spectroscopic analyses. Compounds 1 – 6 were tested for cytotoxicity using human colon cancer DLD‐1 cells, and melicodenone A ( 1 ) was found to exhibit moderate activity.     

Isocedrene derivatives and other sesquiterpenes from moscharia pinnatifida

From the aerial parts of Moscharia pinnatifida nine further α-isocedrene, two guaiane, three cyperene and two nerolidol derivatives were isolated. The structures were elucidated by high field NMR studies. Chemotaxonomic aspects are discussed.     

Sesquiterpene derivatives from othonna and related species

The investigation of several South African representatives of the tribe Senecioneae afforded in addition to known compounds a caryophyllene and a bicyclogermacrene derivative, two furoeremophilanes, three bisabolone derivatives and a guaiane derivative.     

Guaiane sesquiterpene from Lactarius sanguifluus

The isolation of pigments from the fungus Lactarius sanguifluus and the determination of their structures is reported. The structure of a new compound with a guaiane skeleton has been elucidated by 2D NMR spectroscopy.     

Guaiane sesquiterpenes from Decachaeta scabrella

From the dichloromethane extract of leaves of Decachaeta scabrella, in addition to three known guaianolides and two flavonoids, a new guaianolide, 11α, 13-dihydroxerantholide, and two new guaiane acids, pechueloic acid and 11,13-dihydropechueloic acid, were characterized. The structures of the new compounds were determined by spectral and chemical methods.     

Terpenoids from Anthemis austriaca Jacq

The aerial parts of Anthemis austriaca Jacq. afforded five new sesquiterpene lactones (two of which are dimeric guaianolides) and three new guaiane type sesquiterpene acids In addition, seven known terpenoids were also found in the studied species. Their structures were elucidated by spectral methods.     

Guaiane sesquiterpene lactones from Salvia nubicola (Lamiaceae)

A new sesquiterpene lactone, nubiol (1), belonging to the guaiane class, along with a dimer, bisnubidiol (2), has been isolated from Salvia nubicola collected from Quetta, Pakistan. The structures of both metabolites were elucidated with the aid of spectroscopic techniques including 2D-NMR. Additionally, the structure of nubiol (1) was finally confirmed via the single crystal X-ray diffraction. Nubiol (1) was found moderately active against Pseudomonas aeruginosa.     

Dehydroleucodine and dehydroparishin-B inhibit proliferation and motility of B16 melanoma cells

Dehydroleucodine, a known sesquiterpene lactone, and dehydroparishin-B, a new guaiane type sesquiterpene acid, were isolated from aerial parts of Artemisia douglasiana by chloroform extraction. We identified dehydroparishin-B as (7R)-2-oxo-guaia-1(10),3(4),5(6),11(13)-tetraen-12-oic acid by MS and NMR methods. We demonstrated that both dehydroparishin-B and dehydroleucodine blocked cell proliferation of B16 melanoma cells, but not normal murine Melan-A melanocytes, in a dose-dependent manner without affecting cell viability. We also found that both dehydroparishin-B and dehydroleucodine inhibited migration of B16 melanoma cells. These results suggest that dehydroleucodine and dehydroparishin-B could represent potential candidates for the treatment of metastatic melanomas.     

Cytotoxic hydroazulene diterpenes from the brown alga Dictyota dichotoma

Two new hydroazulenoid (prenyl guaiane) diterpenes, dictyone acetate (2) and 3,4-epoxy 13-hydroxy pachydictyol A (4) were isolated from the petroleum ether fraction of the alcoholic extract of the brown alga, Dictyota dichotoma (Hudson) Lamouroux, which was collected from the Red Sea coasts at Hurgada, Egypt, together with three known ones, pachydictyol A (1), dictyone (3) and 11-hydroxypachydictyol A (dictyol E) (5). In addition, the steroidal compound, stigmasta-5,(E)-24(28)-dien-3-beta-ol (fucosterol) (6) was also isolated. The structures of the isolated compounds have been determined on the basis of spectroscopic evidences as well as physical and chemical correlation with known compounds. Compounds 1, 2, 3 and 5 showed moderate cytotoxic activity.     

Japonicones A–D,bioactive dimeric sesquiterpenes from Inula japonica Thunb.

Four new dimeric sesquiterpene lactones japonicones A?D (1?4), comprised by eudesmane and guaiane sesquiterpenes, were isolated from the aerial part of Inula japonica Thunb. The structures and stereochemistry of 1?4 were elucidated by use of 2D NMR spectroscopic techniques, X-ray crystallography and modified Mosher method. Japonicone A (1) showed the most potent cytotoxicities against four tumor cell lines, A549, LOVO, CEM and MDA-MB-435.     

Diterpene content of the alga Dictyota ciliolata from a Moroccan lagoon

Analysis of the secondary metabolites content of the brown alga Dictyota ciliolata, collected from Oualidia lagoon (Morocco), revealed the presence of xenicane and guaiane homologous diterpenes. Two new xenicanes, 1 and 2, co-occurring with the known dictyodial, dictyol C and dictyol H, have been isolated and characterized by spectral methods, mainly by NMR techniques. Compound 2 displayed mild antifungal activity against Candida albicans.     

Partial Purification and Some Properties of Two Novel Deoxyribonucleases from Bacillus subtilis

Optically active guaiane dienes, 3 and 4, related to sclerosporene 2 were synthesized from (—)-carvone and (—)-α-santonin. The mass spectra of 3 and 4 were not identical with that of natural sclerosporene.     

Sesquiterpene Lactones with COX‐2 Inhibition Activity from Artemisia lavandulaefolia

Two new sesquiterpene lactones, artelavanolides A ( 1 ) and B ( 2 ), and four known sesquiterpene lactones ( 3 – 6 ) were isolated from the leaves of Artemisia lavandulaefolia. Their structures were elucidated based on the analysis of spectroscopic data (1D, 2D‐NMR and HR‐ESI‐MS). The absolute configuration of 1 was determined by the analysis of single‐crystal X‐ray diffraction data. Artelavanolide A ( 1 ) is a rare sesquiterpene lactone possessing an unusual skeleton with the linkage of Me(14)–C(1) that is probably formed through a rearrangement of the guaiane‐type sesquiterpenoids. Artelavanolide B ( 2 ) is a new highly unsaturated guaianolide. Compounds 1 – 6 were tested for activities on the inhibition of COX‐2 enzyme in vitro. All of compounds exhibited inhibitory activity against COX‐2 with IC₅₀ values ranging from 43.29 to 287.07 μm compared with the positive control, celecoxib (IC₅₀ = 18.10 μm ). Among them, 3 showed the best COX‐2 inhibitory activity with an IC₅₀ value of 43.29 μm .