Xyloccensins Q-V, six new 8,9,30-phragmalin ortho ester antifeedants from the Chinese mangrove Xylocarpus granatum

Six new 8,9,30-phragmalin ortho esters, named xyloccensins Q-V (3-8), have been isolated from the stem bark of a Chinese mangrove Xylocarpus granatum, and their structures were elucidated on the basis of spectroscopic data and chemical means. The absolute stereochemistry of these compounds and xyloccensins O-P (1-2), revised as enantiomeric to all the phragmalins reported so far, was determined by application of the modified MTPA Mosher ester method and circular dichroism analysis. Both xyloccensins P and Q exhibited potent antifeedant activity against the third instar larvae of Mythimna separata (Walker) at a concentration of 500 ppm.     

Structures of new alkaloids sessilifoliamides A-D from Stemona sessilifolia

Four new Stemona alkaloids, sessilifoliamides A-D (1-4), were isolated from the roots of Stemona sessilifolia, along with five known alkaloids, stenine (5), 2-oxostenine (6), stemoninoamide (7), tuberostemonone (8), and neotuberostemonol (9). The structures and absolute configurations of the new alkaloids were determined by the spectral studies (HRMS, IR, ¹H, ¹³C, and 2D NMR), single-crystal X-ray analyses, and chemical correlations. The absolute configuration of 7 was also determined by the modified Mosher's method.     

The absolute configuration determination of naturally occurring diacetylenic spiroacetal enol ethers from Artemisia lactiflora

Six new naturally occurring diacetylenic spiroacetal enol ethers, Lactiflodiynes A-F (1-6), together with five known congeners (7-11), were isolated from the whole plant of Artemisia lactiflora (Compositae). The structures were elucidated by extensive spectroscopic methods, X-ray crystallography, chemical transformations, and CD. The absolute configuration of Lactiflodiyne A (1) was determined to be 2R, 5S, 6S, and 7R by an X-ray crystallographic diffraction experiment using Mo Kα radiation with the absolute parameter of 0.01(8). In combination with CD, the absolute configurations of compounds 2-11 were confirmed by chemical transformations using 1 as the starting material.     

Proanthocyanidin glycosides from the leaves of Quercus ilex L. (Fagaceae)

From the polar extracts of the leaves of Quercus ilex L., two new proanthocyanidin glycosides, namely afzelechin-(4α→8)-catechin-3-O-β-glucopyranoside (1) and afzelechin-(4α→8)-catechin-3-O-α-rhamnopyranoside (2), were isolated in addition to catechin (3), proanthocyanidin B₃ (4), prodelphinidin C (5), dehydrodicatechin A (6), quercetin (7) and six known flavonol glucosides with their acylated derivatives (8-13) and ellagic acid (14). The structures of all isolated compounds were established by spectroscopic means, mainly 1D and 2D NMR, as well as LC/MS and HR-MS spectrometric analyses. The absolute configuration of compound 1 was determined by CD measurements. The proanthocyanidin glycosides are especially interesting, as they possess the sugar in the upper unit of the dimer, which is rare for this type of compounds.     

New alkaloids sinomacutines A–E,and cephalonine-2-O-β-d-glucopyranoside from rhizomes of Sinomenium acutum

Phytochemical investigation on the rhizomes of Sinomenium acutum led to the isolation of new alkaloids sinomacutines A–E (1–5), and cephalonine-2-O-β-d-glucopyranoside (6), along with known tetrahydroisoquinoline alkaloids (7–9). Among them, sinomacutines A–C were new bistetrahydroisoquinoline alkaloids with morphinane–proaporphine and morphinane–benzyltetrahydroisoquinoline types, and coupled with unique C–CH₂–N unit. Their structures with absolute configuration were elucidated on the basis of 1D and 2D NMR, and ECD spectra analysis. The new compounds were evaluated for their anti-inflammatory and cytotoxic activities, and sallisonine B (2) showed moderate ability to inhibit NO production of LPS-stimulated RAW264.7 macrophages, as well as sallisonine A (1) showed weak inhibitory effects against five cancer cell lines.     

Antioxidative acylphloroglucinols from the roots of Lysidice rhodostegia

Four new acylphloroglucinols, lysidicins I and J (1 and 2), and lysidisides V and W (3 and 4), were isolated from the roots of Lysidice rhodostegia. Among them, compound 1 is a novel acylphloroglucinol, and compound 2 is the first naturally occurring acylphloroglucinol derivative with an uncommon spiro(benzofuran-[2H]pyran) skeleton. Their structures were elucidated by spectroscopic and chemical methods. The absolute configuration of 1 was assigned by employing dimolybdenum tetraacetate-induced CD spectrum method, and that of 2 was determined by analysis of their experimental and theoretically calculated CD spectra. Compounds 3 and 4 exhibited potent antioxidative activity with IC₅₀ values of 3.29 and 3.39 μM, respectively.     

New polyesters from Talaromyces flavus

Six new polyesters, talapolyesters A–F (1–4, 14, and 16), together with 11 known ones 15G256ν (5), 15G256ν-me (6), 15G256π (7), 15G256β-2 (8), 15G256α-2 (9), 15G256α-2-me (10), 15G256ι (11), 15G256β (12), 15G256α (13), 15G256α-1 (15), and 15G256ω (17), were isolated from the wetland soil-derived fungus Talaromyces flavus BYD07-13, and their structures were determined by NMR and MS spectroscopic data. Among them, 1–4 and 16 were assembled in a different manner from that of the known 256 polyesters. All the polyesters are composed of (R)-2,4-dihydroxy-6-(2-hydroxypropyl)benzoic acid and (R)-3-hydroxybutyric acid/(S)-3,4-dihydroxybutyric acid residues. The absolute configurations of the residues were determined by alkaline hydrolysis. The cytotoxicity against five tumor cell lines of these compounds was examined, and a tight structure–activity relationship is proposed.     

Daphniglaucins D-H, J, and K, new alkaloids from Daphniphyllum glaucescens

Five new fused-hexacyclic alkaloids, daphniglaucins D (1), E (2), F (3), G (4), and H (5), and two new yuzurimine-type alkaloids, daphniglaucins J (6) and K (7), have been isolated from the leaves of Daphniphyllum glaucescens, and the structures and relative stereochemistry were elucidated on the basis of spectroscopic data and chemical means.     

Cytotoxic dimeric sesquiterpenoids from Curcuma parviflora: isolation of three new parviflorenes and absolute stereochemistry of parviflorenes A, B, D, F, and G

Three novel dimeric sesquiterpenoids, named parviflorenes G-I (1-3), have been isolated from Curcuma parviflora (Zingiberaceae), and their structures were elucidated by means of spectroscopic studies. Absolute stereochemistry of parviflorene G (1) as well as previously isolated related compounds, parviflorenes A (4), B (5), D (6), and F (7), was revealed by CD spectral data and chemical means. Parviflorenes G (1) and I (3) were cytotoxic against HeLa cells, while parviflorenes A (4) and F (7) were cytotoxic against all tested tumor cell lines in the human cancer cell line panel assay.     

Pseudopterosins P-V, new compounds from the gorgonian octocoral Pseudopterogorgia elisabethae from Providencia island, Colombian Caribbean

Seven new diterpene glycosides, pseudopterosins P (1), Q (2), R (3), S (4), T (5), U (6) and V (7) along with two known compounds PsG and PsK have been isolated from the methanol/dichloromethane extract of the gorgonian octocoral Pseudopterogorgia elisabethae collected off Providencia Island, Colombian Caribbean. The structures of the new metabolites, including their relative and absolute configuration, were established by MS and NMR spectroscopic studies as well as their conversion to known compounds.     

Eight novel serine proteases inhibitors from a water bloom of the cyanobacterium Microcystis sp.

Eight new secondary metabolites, micropeptin MM836 (1), micropeptin MM850 (2), micropeptin MM916 (3), micropeptin MM932 (4), micropeptin MM978 (5), anabaenopeptin MM823 (6), anabaenopeptin MM850 (7), and anabaenopeptin MM913 (8), as well as the known anabaenopeptin B (9) were isolated from the hydrophilic extract of the cyanobacterium Microcystis sp. that was collected from a fishpond in Kibbutz Ma’agan Michael, Israel, in September 2006. The structure of the pure natural products was established by spectroscopic methods including 1D and 2D NMR, UV, and MS techniques. The absolute configuration of the chiral centers of the compounds was determined using Marfey’s method. The inhibitory activity of the compounds was determined against the serine proteases, trypsin, chymotrypsin, thrombin and elastase.     

Euryjanicins E–G,poly-phenylalanine,and poly-proline cyclic heptapeptides from the Caribbean sponge Prosuberites laughlini

A new investigation of the active sponge extracts of Prosuberites laughlini collected off the West coast of Puerto Rico has yielded three new cyclic heptapeptides, namely euryjanicins E (1)–G (3), containing multiple phenylalanine and proline residues. In CDCl₃ solution, each euryjanicin F (2) and G (3) exists as an inseparable complex mixture of conformational isomers. The molecular structures of 1–3 were elucidated by a combination of chemical degradation, extensive ESI-MS/MSⁿ analyses, and 2D NMR methods. The elucidation of the absolute configuration was achieved by HPLC following analysis of the acid hydrolysates after derivatization with Marfey's reagent. When assayed against the National Cancer Institute 60 tumor cell line panel, the new cyclic peptides did not display significant in vitro cytotoxicity.     

Fluevirines A–D,four new securinega-type alkaloids from Flueggea virosa

Four new securinega-type alkaloids, fluevirines A–D (1–4), along with ten known ones, were isolated from the twigs and leaves of Flueggea virosa. The structures of the new ones were elucidated by means of spectroscopic methods, and their absolute configurations were assigned by CD spectra. Among them, fluevirine A (1) was a novel C,C-linked dimeric indolizidine alkaloid and showed weak antimicrobial activity against Staphylococcus aureus.     

New diterpenes of the pseudopterane class from two closely related Pseudopterogorgia species: isolation, structural elucidation, and biological evaluation

Parallel chemical investigations of the hexane and chloroform extracts of the sea plumes Pseudopterogorgia bipinnata and Pseudopterogorgia kallos has led to the discovery of seven new diterpenoids of the pseudopterane class, namely, kallolide D (2), kallolide C acetate (3), kallolide E (4), kallolide F (5), kallolide G (6), kallolide H (7), and kallolide I (8), in addition to nine previously described compounds of the pseudopterane and gersolane families of diterpenes. The chemical structures of the new metabolites were established by 1D and 2D NMR, IR, UV, HRMS, and, in some instances, by single-crystal X-ray crystallographic analyses. Biological screening of these metabolites revealed significant anti-parasitic activity albeit marginal anti-tubercular activity.     

Tabularisins A-D, phragmalin ortho esters with new skeleton isolated from the seeds of Chukrasia tabularis

Tabularisins A-D (1-4), a new class of phragmalins incorporating a cyclopropanyl ring, were isolated from Chukrasia tabularis. Compounds 1 and 2 are also the first examples of phragmalins with an 8,9,11-ortho ester. The structures of 1 and 3 were confirmed by single crystal X-ray studies. The absolute configuration of 2 was determined by CD exciton chirality method on its benzoate (2a), and those of 1, 3, and 4 were proposed by correlating with 2 chemically and biogenetically.     

Nortriterpenoids from Schisandra chinensis and their absolute configurational assignments by electronic circular dichroism study

Twelve new nortriterpenoids, namely wuweizidilactones J–P (1–7), schindilactones I–K (8–10), preschisanartanin N (11), and schisdilactone J (12), as well as 23 known analogues, were isolated from the leaves and stems of Schisandra chinensis. The absolute configurations of 1 and 11 were established by calculated electronic circular dichroism (ECD) spectra and that of 7 was confirmed by single-crystal X-ray diffraction. The absolute configurations of 2–6, 8, and 9 were determined by an empirical comparison of their experimental ECD spectra with that of 1. It is the first time that the ECD spectra of 18(13→14)-abeo-schiartane-, 18-norschiartane-, and schisanartane-type nortriterpenoids possessing an α,β-unsaturated-γ-lactone moiety are presented, this method providing an alternative means of obtaining absolute configurational assignments for these types of nortriterpenoids. All isolates were evaluated for their anti-acetylcholinesterase and anti-butyrylcholinesterase activities, and compounds 8, 13, 23, and 31 show anti-acetylcholinesterase activity at concentrations of 50 μM, with 12.7, 10.7, 16.6, and 32.1% inhibition, respectively.     

New phlegmarane-type, cernuane-type, and quinolizidine alkaloids from two species of Lycopodium

Two new phlegmarane-type alkaloids, cermizines A (1) and B (2), three new quinolizidine alkaloids, cermizine C (3) and senepodines G (4) and H (5), and a new C₁₆N₂ type alkaloid consisting of a quinolizidine and a piperidine ring, cermizine D (6), as well as two new cernuane-type alkaloids, cernuine N-oxide (7) and lycocernuine N-oxide (8), have been isolated together with cernuine (9) and lycocernuine (10) from the club moss Lycopodium cernuum and L. chinense. The relative stereochemistry of 1-4 and 6, and the absolute stereochemistry of 5, 7, and 8 were elucidated by combination of NOESY correlations, modified Mosher's method, chemical transformations, and computational methods. Cermizine D (6) might be a biosynthetic intermediate of cernuane-type alkaloids such as 7-10.     

New pyridoacridine alkaloids from the purple morph of the ascidian Cystodytes dellechiajei

Two new pyridoacridine alkaloids, 13-didemethylaminocycloshermilamine D (1) and demethyldeoxyamphimedine (2), were isolated from the purple chromotype of the Western Mediterranean ascidian Cystodytes dellechiajei. This morph also contained the known shermilamine B (3), kuanoniamine D (4), N-deacetylshermilamine B (5), N-deacetylkuanoniamine D (6), styelsamines C (7), and D (8). The structures of new compounds were elucidated on the basis of spectroscopic data. A hypothetic biosynthetic pathway from the tetracyclic styelsamine D (8) was proposed for both compounds 1 and 2 and their antimicrobial potential was evaluated.     

The structures of three new shishididemniols from a tunicate of the family Didemnidae

Three new serinolipid derivatives, shishididemniols C (1), D (2), and E (3), were isolated as antibacterial constituents of a tunicate of the family Didemnidae. Their planar structures were elucidated by interpretation of NMR and MS data, whereas the absolute stereochemistry was determined by chemical conversions. Shishididemniols C (3), D (4), and E (5) exhibited antibacterial activity against the fish pathogenic bacterium Vibrio anguillarum.     

Crucigasterins A-E, antimicrobial amino alcohols from the Mediterranean colonial ascidian Pseudodistoma crucigaster

Five new unsaturated 2-amino-3-alcohols, crucigasterins A-E (2-6), were isolated together with known related compound 7 from the Mediterranean ascidian Pseudodistoma crucigaster and characterised as diacetyl derivatives (2a-6a) by spectroscopic methods. The threo-relative configuration of the amino alcohol portion was inferred by NOE analysis of the oxazolidinone derivative of crucigasterin A (2) as well as by ¹³C NMR comparison with synthetic threo and erythro model compounds. The co-occurring metabolites were assumed to have the same relative configuration as 2 by comparison of the diagnostic carbon value of C-1. The absolute stereochemistry of compound 7 that had not been previously reported was determined by applying the modified Mosher’s method on the corresponding N-acetyl derivative. The same absolute configuration was suggested for the other co-occurring crucigasterins by biogenetic considerations. Antibacterial and antifungal activities of selected crucigasterins were also evaluated.