Ligustolide A and B, two novel sesquiterpenes with rare skeletons and three 1,10-seco-guaianolide derivatives from Achillea ligustica

Achillea ligustica afforded two novel sesquiterpene lactones with rare 5/6/5 skeletons, three 1,10-seco-guaianolides and a chlorine-containing sesquiterpene lactone as well as six known compounds, including two monoterpenes, two guaianolides, one eudesmane and one secocaryophyllene derivative. The structures of the compounds were elucidated by extensive application of one- and two-dimensional NMR spectroscopy.     

Coriatone and corianlactone, two novel sesquiterpenes from Coriaria nepalensis

Both coriatone (1). a novel highly oxygenated picrotoxane-type sesquiterpene, and corianlactone (2). with an unprecedented sesquiterpene basic skeleton, named coriane, were isolated from Coriaria nepalensis Wall. The structures of 1 and 2 were determined by analysis of their two-dimensional NMR data, and the structure of 2 was confirmed by X-ray analysis. Compounds 1 and 2 showed no remarkable inhibitory activity toward K(562) cells. They are cytotoxic with IC(50) > 50 microg/mL (cis-platinim: IC(50) = 0.49 microg/mL).     

Daphnezomines P, Q, R and S, new alkaloids from Daphniphyllum humile

Four new alkaloids, daphnezomines P-S (1-4), have been isolated from the fruits of Daphniphyllum humile, and the structures and the stereochemistry were elucidated on the basis of spectroscopic data including 2D NMR and MS/MS spectra, and chemical correlations. Daphnezomines P (1) and Q (2) were the first Daphniphyllum alkaloids with an iridoid glycoside moiety.     

A new neolignan glycoside from Dolomiaea souliei

Abstract

One new neolignan glycoside, dolomiside A (1), together with 11 known phenylpropanoid glycosides were isolated from Dolomiaea souliei (Franch.) Shih. The structures of these isolates were determined by UV, CD, HR-ESI-TOFMS, 1D and 2D NMR analysis.     

Two novel sesquiterpenes from the roots of Taiwania cryptomerioides Hayata

Two novel 3,4-secocadinane and 4,5-seco-8(7→6)-abeoguaiane skeletons, namely taiwaninones A (1) and B (2), together with khusinodiol (3) and 4β,6β-dihydroxy-1α,5β(H)-guai-9-ene (4) were isolated from the roots of Taiwania cryptomerioides. Their structures were elucidated by the spectral methods. The biotransformations of 1 and 2 were proposed from 3 and 4, respectively.     

Swiemahogins A and B, two novel limonoids from Swietenia mahogani

Two novel limonoids, swiemahogins A (1) and B (2) isolated from the twigs and leaves of Swietenia mahogany, are the first examples of andirobin and phragmalin types of limonoids, of which the D-ring δ-lactone is demolished and a rare γ-lactone is fused to the C-ring at C-8 and C-14. Their structures were elucidated by extensive spectroscopic means, and that of 1 was confirmed by single-crystal X-ray diffraction.     

Acutaxylines A and B, two novel triterpenes from Dysoxylum acutangulum

Two novel triterpenes, acutaxylines A (1) and B (2) consisting of a cyclopentenone side chain at C-17 and an oxepan-2-ol, were isolated from the leaves of Dysoxylum acutangulum. The relative stereochemistry of 1 and 2 was determined by NOESY correlations. Acutaxyline B showed moderate cytotoxicity against human blood premyelocytic leukemia cells.     

Sulfur-containing sesquiterpenes from Thapsia villosa

Three new sesquiterpenoids bearing sulfurated ester groups have been isolated from the roots of Thapsia villosa L. Their structures have been elucidated by spectroscopic means. This is the first time that a methylthiopropionic acid ester is isolated from natural sources.     

Arabidopsides A and B, two new oxylipins from Arabidopsis thaliana

Two new oxylipins, arabidopsides A (1) and B (2), were isolated from the aerial parts of Arabidopsis thaliana, and their structures and absolute stereochemistries were elucidated by spectroscopic data and chemical means. Arabidopsides A (1) and B (2) were rare monogalactosyl diacylglycerides containing 12-oxophytodienoic acid and/or dinor-oxophytodienoic acid.     

Mekongenines A and B, two new alkaloids from Bousigonia mekongensis

Mekongenine A (1) possessing an unprecedented structure constituted from the union of a rare 2,7-seco eburnamine half and an aspidospermine alkaloid, together with a new bisindole alkaloid, mekongenine B (2), consisting of an eburnamine-aspidospermine type skeleton, was isolated from Bousigonia mekongensis. Their structures were elucidated by means of spectroscopic methods and those of 2 were further confirmed by X-ray diffraction. The absolute configurations of 1 and 2 were determined by comparison of quantum chemical TDDFT calculated and experimental ECD spectra. Mekongenines A (1) and B (2) exhibited cell growth inhibitory activities against various human cancer cell lines.     

Multistalides A and B, two novel sesquiterpenoid dimers from Chloranthus multistachys

Two novel sesquiterpenoid dimers, multistalides A and B (1-2), were isolated from the whole plant of Chloranthus multistachys. Their structures were established on the basis of spectroscopic analysis, and the absolute configuration of 1-2 was determined by CD exciton chirality method.     

Rubiyunnanins A and B, two novel cyclic hexapeptides from Rubia yunnanensis

Two novel cyclic hexapeptides, named rubiyunnanins A (1) and B (2), were isolated from the roots of Rubia yunnanensis (Franch.) Diels. Their structures were elucidated extensively by spectroscopic analysis and theoretical computation. Possible biosynthetic pathways for RAs, 1, and 2 were proposed. Compound 2 showed moderate cytotoxicities against 11 cancer cell lines and inhibited nitric oxide (NO) production in LPS and IFN-γ-induced RAW 264.7 murine macrophages.     

Malayanines A and B, two novel limonoids from Chisocheton erythrocarpus Hiern

Two structurally interesting novel limonoids, malayanine A and malayanine B, were isolated from the bark of Chisocheton erythrocarpus Hiern. The structures were fully characterized through spectroscopic methods.     

Aminocadambines A and B, two novel indole alkaloids from Neolamarckia cadamba

Two novel monoterpenoid indole alkaloids, aminocadambines A (1) and B (2), characterized by tetrahydrofuran and 1,2,3,4-tetrahydropyridine rings, were isolated from the leaves of Neolamarckia cadamba. Their structures were elucidated on the basis of spectroscopic and computational methods. The absolute configuration of 1 was established by CD analysis. A plausible biosynthetic pathway for 1 and 2 is proposed.     

Daedaleanols A and B,two new sesquiterpenes from cultures of the basidiomycete Daedalea incana

Two new sesquiterpenes, daedaleanols A (1) and B (2), together with three known sesquiterpenes (3–5), were isolated from cultures of the basidiomycete Daedalea incana. Their structures were elucidated on the basis of extensive spectroscopic means. All compounds were tested for their cytotoxicities against three human cancer cell lines.     

Nukiangendines A and B,two novel 13,14-seco-abietanes from Abies nukiangensis

From Abies nukiangensis, two novel 13,14-seco-abietane diterpenes, nukiangendines A (1) and B (2) were isolated. Their relative structures were determined by extensive NMR and HRMS spectroscopic analysis. The absolute configuration of 1 was established by ECD calculations. Compound 1 showed significant anti-hepatitis C virus (HCV) effects.     

Cytotoxic cuparene sesquiterpenes from Laurencia microcladia

Three new cuparene sesquiterpenes 1-3 were isolated from the organic extract of the red alga Laurencia microcladia, collected at Chios island in the North Aegean Sea, Greece. The structures and the relative stereochemistry of the compounds are proposed on the basis of their spectral data. Metabolite 2 shows an unprecedented (for the cuparene class of sesquiterpenes) migration of the C-1 methyl group. All metabolites 1-3 were found to exhibit significant cytotoxic activity against two lung cancer cell lines.     

A novel chlorinated norsesquiterpenoid and two related new metabolites from the soft coral Paralemnalia thyrsoides

A structurally unique chlorinated norsesquiterpenoid, paralemnolin A (1), along with two new metabolites, paralemnolin B (2) and C (3), have been isolated from the soft coral Paralemnalia thyrsoides. Their structures were determined by extensive spectroscopic analyses. Single-crystal X-ray diffraction analysis of 1 further establish the absolute stereochemistry of 1.     

Natural anti-HIV agents. Part 3: Litseaverticillols A-H, novel sesquiterpenes from Litsea verticillata

Bioassay directed-fractionation led to the identification of litseaverticillols A-H (1-8) from the leaves and twigs of Litsea verticillata Hance. These new sesquiterpenes possess a unique skeleton that was recently designated as ‘litseane’. The structures of these compounds were determined by spectroscopic means including 1D and 2D NMR data. Structural configurations were determined by ROESY experiments. Mosher ester reactions and optical rotation measurements established the sesquiterpenes 1-8 as racemates. Isolates 1-8 inhibited HIV-1 replication in HOG.R5 cells with IC₅₀ values ranging from 2 to 15 μg/ml (8-58 μM) while affecting the growth of HOG.R5 at concentrations 2-3-fold higher. Based on this data, structure-activity relationships can be discerned, suggesting compounds of this class are good candidates for analog production.