Hookerianolides A-C: three novel casbane-type diterpenoid lactones from Mallotus hookerianus

Three highly oxidized casbane-type diterpenoids with unique α,β-unsaturated γ-lactones, named Hookerianolides A (1), B (2), and C (3), were isolated from the methylene chloride extracts of Mallotus Hookerianus. Their structures were elucidated based on NMR spectroscopic data and chemical conversions. The stereochemistry was confirmed by combination of ROESY correlations and CD analyses.     

Thiamacrocyclic lactones: new Ag(I)-ionophores

The syntheses of novel adamantane thialactones 5-12 are reported, and the results of the heavy- and transition-metal cation extraction experiments are described. The results are compared with those obtained with similar thiamacrocyclic ligands that have flexible chains of methylene groups incorporated into the macrocyclic framework as in 13-20. The results show that most of the hosts studied are very good in complexing the Ag(+) ion. The formation of complexes has also been demonstrated using NMR titration experiments for macrocycles 13 and 14 with AgTFA. Introduction of a single polycyclic molecule into the 15- to 18-membered rings increases the rigidity and preorganizes the ligand for complexation. However, two adamantane molecules embedded in the ring usually diminish the complexing ability of the ligand, primarily due to sterical effects of the bulky adamantane moiety that obstructs formation of an optimal geometry for binding the desired metal ion. The structures of macrocycles 5, 7, 9, 11, and 19 were determined by X-ray structure analysis, and their conformational properties are discussed. In the solid state, 7, 11, and 19 are organized into tubular fashion using C-H...O interactions. Also, two silver complexes with thialactone 13, Ag13 and Ag(13)(2), were prepared and characterized. The structure analysis of Ag13 and Ag(13)(2) reveals the formation of mononuclear and binuclear species with silver in ambivalent, tetrahedral coordination via sulfur and oxygen from trifluoroacetate anion.     

Oxepinamides A-C and fumiquinazolines H--I: bioactive metabolites from a marine isolate of a fungus of the genus Acremonium

Three new oxepin-containing natural products (1-3) and two new fumiquinazoline metabolites (4-5) have been isolated from organic extracts of the culture broth and mycelia of an Acremonium sp., a fungus obtained from the surface of the Caribbean tunicate Ecteinascidia turbinata. The structures of the five compounds were determined through extensive analysis of 1D- and 2D-NMR data, and mass spectrometry. Compound 1 exhibited good anti-inflammatory activity in a topical RTX-induced mouse ear edema assay. Compounds 4 and 5 exhibited weak antifungal activity toward Candida albicans in a broth microdilution assay.     

Thiersinines A and B: novel antiinsectan indole diterpenoids from a new fungicolous Penicillium species (NRRL 28147)

[structure: see text] Two novel antiinsectan indole diterpenoids, thiersinines A (1) and B (2), along with seven known paxilline-type compounds, were isolated from organic extracts of a new Penicillium species (P. thiersii NRRL 28147). The structures of 1 and 2 were determined by analysis of 2D NMR data. Thiersinines A and B possess a unique spirocyclic subunit that is unprecedented in previously known compounds of this class. Both compounds exhibit potent activity against the fall armyworm (Spodoptera frugiperda).     

Three new friedelane lactones from the bark of gynocardia odorata (flacourtiaceae)

Three new triterpenes - odolactone, acetylodollactone and odollactone from the bark of Gynocardia odorata have been characterised as 3-keto, 3,α-O-acetyl and 3α(-hydroxyl derivatives of friedelan-26→12β-lactone respectively.     

Eucalyptals A-C with a new skeleton isolated from Eucalyptus globulus

Eucalyptals A-C (1-3) with a new skeleton of 3,5-diformyl-isopentyl phloroglucinol-coupled cadinane were isolated from the fruits of Eucalyptus globulus. Their structures were elucidated by spectroscopic analysis, and that of 1 was confirmed by single-crystal X-ray diffraction. The biosynthetic pathway of 1-3 was also postulated. Compounds 1-3 exhibited selective cytotoxicity against the HL-60 cell line.     

Malettinin A: a new antifungal tropolone from an unidentified fungal colonist of Hypoxylon stromata (NRRL 29110)

Malettinin A (1) has been isolated from cultures of an unidentified fungus encountered as a colonist of Hypoxylon stromata. The structure of 1 was proposed by analysis of NMR and MS data, and confirmed by X-ray diffraction analysis of a methanol adduct. Malettinin A shows significant activity in assays against Aspergillus flavus.     

Bisrubescensins A-C: three new dimeric ent-kauranoids isolated from isodon rubescens

[reaction: see text] A phytochemical study of the secondary metabolites produced by the species of Isodon rubescens has led to the isolation of three new dimeric ent-kauranoids and two known ones. The most important of these compounds are bisrubescensin A (1), which contains an unprecedented C(23) ent-kaurane unit, and bisrubescensin C (3), which is the precursor of bisrubescensin B (2) from the viewpoint of biosynthesis. Their structures were determined on the basis of extensive spectroscopic analysis and chemical evidence.     

Sesquiterpene lactones from Crepis cameroonica (Asteraceae)

In addition to one known compound, 3beta,8alpha-dihydroxyguaian-4(15),10(14),11(13)-trien-6,12 olide (8-desacylcynaropicrin) (3), two new sesquiterpene lactones have been isolated from the aerial parts of Crepis cameroonica. By means of spectroscopic analysis, the structures and relative configurations of the new compounds were established as 3beta,9beta-dihydroxyguaian-4(15),10(14),11(13)-trien-6,12 olide (1) and 8alpha-hydroxy-4alpha(13),11beta(15)-tetrahydrozaluzanin C (2). The in vitro antimicrobial spectrum of pure compounds and crude extracts are also reported.     

Synthesis of new derivatives of carbo(hetero)cyclospirobutanoic lactones

The diethyl esters of 2-oxo-1-oxaspiro[4,4]nonan-3,4-dicarboxylic, 2-oxo-1-oxaspiro[4,5]decan-3,4-dicarboxylic and 7,7-di-methyl-1,8-dioxaspiro-[4,5]decan-3,4-dicarboxylic acids (la-c) are transformed by hydrochloric acid into 2-oxo-1-oxa-spiro[4,4]nonan-, 2-oxo-1-oxaspiro-[4,5]decan-, and 7,7-dimethyl-1,8-dioxaspiro[4,5]decan-4-carboxylic acids (Ila-c), which are converted into the acyl chlorides IIIa-c, and the latter into the chloromethyl ketones IVa-c. Reaction of the acyl chlorides of IIa and IIb with thiosemicarbazide gives the acid thiosemicarbazides Va and Vb, which form the triazoles VIa and VIb in potassium hydroxide solution, and the thiadiazoles VIIa an VIIb in sulfuric acid. Reaction of the chloromethyl ketones IVa-c with formamide gives the imidazoles VIIIa-c. The diesters Ia-creatwithbenzylamine to form the N-benzylimides IXa-c.     

Glaucolide-A and -B,new germacranolide-type sesquiterpene lactones from Vernonia (compositae)

The structures of two new germacranolides, glaucolide-A (1a) and -B (1b), isolated from more than 25 species of Vernonia from the Western Hemisphere, have been established by a series of chemical transformations, and spectral and X-ray crystallographic studies.     

Biyoulactones A-C, new pentacyclic meroterpenoids from Hypericum chinense

Three novel pentacyclic meroterpenoids with a unique dilactone structure containing C-C bonded bi- and tricyclic γ-lactone moieties, biyoulactones A-C (1-3), were isolated from the roots of Hypericum chinense, and their structures were elucidated on the basis of spectroscopic data. The relative and absolute stereochemistry of 1 was assigned by a combination of NOESY and a single crystal X-ray diffraction analysis.     

New Scabimycins A-C Isolated from Streptomyces acidiscabies (Lu19992)

Peptide natural products displaying a wide range of biological activities have become important drug candidates over the years. Microorganisms have been a powerful source of such bioactive peptides, and Streptomyces have yielded many novel natural products thus far. In an effort to uncover such new, meaningful compounds, the metabolome of Streptomyces acidiscabies was analyzed thoroughly. Three new compounds, scabimycins A–C (1–3), were discovered, and their chemical structures were elucidated by NMR spectroscopy. The relative and absolute configurations were determined using ROESY NMR experiments and advanced Marfey’s method.     

Two new sesquiterpene lactones from Ixeris chinensis

Phytochemical investigation of Ixeris chinensis NAKAI (Asteraceae) has resulted in the isolation of a new guaianolide-type sesquiterpene lactone, ixerochinolide (1) as well as the related glucoside, ixerochinoside (2). In addition, the known guaianolides, 8beta-hydroxy-3-oxo-guaia-4(15),10(14),11(13)-trien-1alpha,5alpha,6beta,7alphaH-12,6-olide (8beta-hydroxydehydrozaluzanin), 8beta,15-dihydroxy-2-oxo-guaia-1(10),3,11(13)-trien-5alpha,6beta,7alphaH-12,6-olide (lactucin), 3beta,8alpha,10alpha-trihydroxy-guaia-4(15),11(13)-dien-1alpha,5alpha,6beta,7alphaH-12,6-olide (10alpha-hydroxy-10,14-dihydro-desacylcynaropicrin) and 3beta-D-glucopyranosyloxy-8beta-(p-hydroxyphenylacetyloxy)-guaia-4(15),10(14),11(13)-trien-1alpha,5alpha,6beta,7alphaH-12,6-olide (8-epicrepioside) were identified. The structures were determined on the basis of spectral analyses, especially 1- and 2D NMR. Compound 1 exhibited significant cytotoxicity against human PC-3 tumor cells.     

Two new withanolide lactones from flos daturae

Chemical investigation of the 50% ethanol eluate fraction from a macroporous resin of flowers of Datura metel L. collected in the Jiangsu Province of China resulted in the isolation of two new withanolides, baimantuoluoline G (1) and baimantuoluoside H (2). Their structures were elucidated as (12β,6β,22R)-1,10-seco-6,12,27-trihydroxy-26-oxo-witha-3,5,24-trienolide-1-oic acid-ε-lactone (1) and (5β,6α,12β,22R)-5,6,12,27-tetra-hydroxy-1,26-dioxo-witha-2,24-dienolide-27-O-β-glucopyranoside (2) on the basis of extensive spectroscopic analysis (1D, 2D-NMR and HRESIMS) and chemical studies.     

Two new sesquiterpene lactones from Ixeris sonchifolia

The structures of two new sesquiterpene lactones, 11,13beta-dihydroixerin Z (1) and Ixerin Z2 (2) isolated from Ixeris sonchifolia were determined to be 3-hydroxy-1(10),3-guaiadiene-12,6-olide-2-one-3-O-beta-D-glucopyranoside and 1(10),3,11 (13)-guaiatriene-12,6-olide-2-one-3-O-[6'-(4"-hydroxybenzyl lactyl)]-beta-D-glucopyranoside, respectively on the basis of detailed spectral analysis.     

Structure of new sesquiterpene lactones from Inula germanica

Chemistry of Natural Compounds - It has been established that the substance isolated previously fromInula germanica L. is a mixture of two new sesquiterpene lactones: germanin A and germanin B. On...     

Structure of new sesquiterpene lactones from Inula germanica

Summary It has been established that the substance isolated previously fromInula germanica L. is a mixture of two new sesquiterpene lactones: germanin A and germanin B.On the basis of chemical reactions and a study of IR, UV, NMR, and mass spectra, structures (I) and (XVI), respectively, are proposed for germanin A and germanin B.All-Union Scientific-Research Institute of Medicinal Plants. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 578–589, September–October, 1974.     

Robustolides A-C, three new briarane-type diterpenoids from the female gorgonian coral Ellisella robusta (Ellisellidae)

Three new briarane-type diterpenoids, designated as robustolides A-C (1-3), were obtained from the female gorgonian coral Ellisella robusta. The structures of briaranes 1-3 were elucidated by the interpretation of spectral data analysis and the structure of 1 was further confirmed by a single-crystal X-ray diffraction analysis. Briaranes 1 and 2 were found to show weak activity against the bacteria Pseudomonas aeruginosa and Staphylococcus aureus.     

Sesquiterpene lactones of new stereostructural types from laser trilobum

The newly established structures of sesquiterpene lactones from Laser trilobum showed that these lactones belong among the stereostructural types of germacranolides, guaianolides, eudesmanolides and elemanolides.