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.     

Celogentin K, a new cyclic peptide from the seeds of Celosia argentea and X-ray structure of moroidin

A new cyclic peptide with a 3-hydroxyoxindole ring, celogentin K (1), has been isolated from the seeds of Celosia argentea and the structure including its absolute stereochemistry was assigned by using extensive NMR, MS/MS, and CD spectra. The stereostructure of a known related bicyclic peptide, moroidin (2), was confirmed by a single crystal X-ray diffraction analysis.     

Celogentins A-C, new antimitotic bicyclic peptides from the seeds of Celosia argentea

Three new bicyclic peptides, celogentins A (1), B (2), and C (3), have been isolated together with a known-related peptide, moroidin (4), from the seeds of Celosia argentea, and their structures including absolute stereochemistry were determined by using extensive NMR methods and chemical means. Celogentins A (1), B (2), and C (3) inhibited the polymerization of tubulin, and celogentin C (3) was four times more potent than moroidin (4) in the inhibitory activity. Structure-activity relationship study using moroidin derivatives 5-7 and analogue 8 as well as celogentins A-C (1-3) and moroidin (4) indicates that the bicyclic ring system including unusual non-peptide connections among beta(s)-Leu, Trp, and His residues characteristic of celogentins and moroidin, with ring size and conformations suitable for interaction with tubulin would be important for their biological activity.     

New cytotoxic sesquiterpenes from the red algae Laurencia obtusa and Laurencia microcladia

Three new sesquiterpenes (1-3), along with five known (5-9), were isolated from the organic extract of the red alga Laurencia obtusa, collected from the coastal rocks of Serifos in the Aegean Sea. A new dimeric sesquiterpene of the cyclolaurane-type (4) along with four previously reported (7, 10-12) metabolites, were isolated from the extract of Laurencia microcladia, collected at Chios island in the North Aegean Sea. The structures and the relative stereochemistry of the compounds are proposed on the basis of their spectral data. The cytotoxicity of the isolated metabolites was evaluated against several cell lines including human tumor cell lines.     

A novel 3,8-seco-taxane metabolite from the seeds of the Chinese yew, Taxus mairei

The structure of a novel 3,8-seco-bicyclic taxanoid metabolite, isolated from the methanol extract of seeds of the Chinese yew, Taxus mairei, was established as (11αH)-3,8-seco-taxa-3E,7E,12(18)-triene-2α,6α,9β-triol (1) on the basis of spectral analysis including ¹H NMR, ¹³C NMR, HMQC, HMBC, NOESY and HR-FABMS.     

Four new minor alkaloids from the seeds of Strychnos nux-vomica

Four new minor alkaloids, stryvomicine A (1), deoxy-isostrychnine-chloromethochloride (2), β-colubrine-chloromethochloride (3) and α-colubrine-chloromethochloride (4) were isolated from the seeds of Strychnos nux-vomica. Stryvomicin A possesses an unprecedented 6/5/7/8/6/7/6 heptacyclic ring system, which is the first example of the linkage of the C3–O–C26–N4 bond in strychnan-type alkaloids. Compound 5 induced the occurrence of autophagy and might have potential implications in autophagy related diseases.     

Saikachinoside A, a novel 3-prenylated isoguanine glucoside from seeds of Gleditsia japonica

A new isoguanine glucoside designated saikachinoside A has been isolated from the seeds of Gleditsia japonica. The structure was determined as 7-β-d-glucopyranosyl-3-[(Z)-4-hydroxy-3-methyl-2-butenyl]isoguanine by interpretation of the spectroscopic data and was confirmed by X-ray crystallographic analysis. Saikachinoside A accelerated acetylcholinesterase 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.     

Pompanopeptins A and B, new cyclic peptides from the marine cyanobacterium Lyngbya confervoides

A new 3-amino-6-hydroxy-2-piperidone (Ahp) containing peptolide, pompanopeptin A (1), and a novel N-methyl-2-amino-6-(4′-hydroxyphenyl)hexanoic acid (N-Me-Ahpha) containing cyclic pentapeptide connected with a sixth amino acid residue via a rare ureido linkage, pompanopeptin B (2), were isolated from the marine cyanobacterium Lyngbya confervoides collected from the southeastern coast of Florida. Their planar structures were determined by a combination of NMR spectroscopic analysis and mass spectrometry. The absolute configurations were established using advanced Marfey's method and chiral HPLC analysis of the chemical degradation products. Compound 1 selectively inhibited trypsin over elastase and chymotrypsin, with an IC₅₀ value of 2.4 μM; selectivity is conferred by an arginine residue in the cyclic core.     

Pressurized fluid extraction of carotenoids from Haematococcus pluvialis and Dunaliella salina and kavalactones from Piper methysticum

Pressurized fluid extraction (PFE) was examined as an alternative technology for the extraction of carotenoids in the green algae Haematococcus pluvialis and Dunaliella salina and kavalactones in Piper methysticum. The extraction process was optimized by varying the key extraction factors of solvent, sample-solvent ratio, temperature, and time. The selectivity and efficiency of extraction parameters were determined with high performance liquid chromatography (LC) and LC-mass spectrometry (LC-MS). Results showed that PFE utilization of conventional solvents under controlled temperature and pressure in an oxygen and light-free environment could result in the use of less solvent in a shorter period of time. PFE showed higher or equal extraction efficiencies as compared with traditional solvent extractions while maintaining the integrity of chemical components. PFE showed high potential for extraction of natural products and nutraceuticals, particularly labile and light sensitive chemicals.     

A pair of unique sesquiterpene-chalcone conjugates isolated from the seeds of Alpinia katsumadai

Sumadains A (1) and B (2), a pair of unique isomeric sesquiterpene-chalcone conjugates with unprecedented skeletons, were isolated from the seeds of Alpinia katsumadai. Their structures and relative configurations were established by NMR spectroscopy and X-ray crystallography.     

Infectopyrone, a potential mycotoxin from Alternaria infectoria

A new metabolite, infectopyrone (1), has been isolated from the filamentous fungus Alternaria infectoria. The structure of 1 was elucidated by analysis of 2D NMR spectroscopic data. Compound 1 is an α-pyrone resembling known toxins, and is a useful phenotaxonomic marker for the A. infectoria species-group. Infectopyrone (1) was also produced by species within Stemphyllium and Ulocladium, and found in mouldy food.     

New constituents from Mikania laevigata Shultz Bip. ex Baker

A new phenylpropanoid and two new diterpenes were isolated from the leaves of the plant Mikania laevigata Shultz Bip. ex Baker. The structures of these compounds were established by 1D- and 2D-nuclear magnetic resonance spectroscopic techniques and mass spectrometry data. Taraxerol, lupeol, coumarin, syringaldehyde, trans-melilotoside, cis-melilotoside, adenosine, patuletin 3-O-β-d-glucopyranoside, kaempferol 3-O-β-d-glucopyranoside, quercetin 3-O-β-d-glucopyranoside, methyl 3,5-di-O-caffeoyl quinate, and 3,3′,5-trihydroxy-4′,6,7-trimethoxyflavone were isolated too. In addition, the compounds dihydrocoumarin, spathulenol, caryophyllene oxide, kaurenoic acid, beyerenoic acid, and lupeol acetate were identified by GC-MS.     

Emervaridione and varioxiranediol, two new metabolites from the endophytic fungus, Emericella variecolor

Two new compounds, emervaridione and varioxiranediol, together with the three known compounds, stellatic acid, ergosterol and dihydroterrein, were isolated from the endophytic fungus, Emericella variecolor. The structures of emervaridione and varioxiranediol were established from spectroscopic and X-ray crystallographic analysis.     

New briaranes from the octocorals Briareum excavatum (Briareidae) and Junceella fragilis (Ellisellidae)

Six 12-hydroxybriaranes, including four new diterpenoids, briaexcavatins I-L (1-4), and two known metabolites, excavatolides C (5) and E (6), have been isolated from the cultured scleraxonia Briareum excavatum. In addition, the gorgonian coral Junceella fragilis yielded a new chlorinated briarane, fragilide C (10). The structures of above compounds were determined by spectroscopic methods and the structures of 5 and 6 were further confirmed by X-ray data analysis for the first time. The absolute configuration of 6 was elucidated by chemical conversion. Some of these briaranes have displayed inhibitory effects on superoxide anion generation by human neutrophils.     

Ashitabaol A, a new antioxidative sesquiterpenoid from seeds of Angelica keiskei

A new sesquiterpenoid designated ashitabaol A was isolated from seeds of Angelica keiskei. The structure was determined by interpretation of spectroscopic data and was confirmed by X-ray crystallographic analysis. Ashitabaol A exhibited free radical scavenging activity.     

Biopreparation of an anti-inflammatory agent,diarctigenin, from arctiin isolated from Arctium lappa by Rhizoctonia solani AG-4

In the preliminary screening for the plant-derived pesticides against Rhizoctonia solani Kühn AG-4 (RS AG-4), the indicator compounds arctiin (1) and arctigenin (2) in methanol extracts of Arctium lappa L. were consumed and transformed to other compounds. Thus, in the present study RS AG-4 was used as a biocatalyst and the biotransformation of arctiin (1) was investigated. Conversion of arctiin (1) to arctigenin (2) was achieved by the enzymatic hydrolysis of sugar moiety. In addition, an anti-inflammatory lignan dimer reported from the Arctium species, diarctigenin (3) was afforded in good yields. The HPLC monitoring of the biotransformation process indicated the possible mechanism. It would be an excellent method to produce a large scale of diarctigenin (3) for the successive medicinal examinations.     

Calyciphyllines H-M, new Daphniphyllum alkaloids from Daphniphyllum calycinum

Six new Daphniphyllum alkaloids, calyciphyllines H-M (1-6), were isolated from the leaves and stems of Daphniphyllum calycinum (Daphniphyllaceae). The structures and relative stereochemistry of 1-6 were elucidated on the basis of spectroscopic data, and the absolute stereochemistry of 3 was assigned by PGME method.     

New sesquiterpenes from the red alga Laurencia microcladia

Three new aromatic sesquiterpenes (1, 2, and 4), one new dimeric sesquiterpene of the cyclolaurane-type (3), one sesquiterpene alcohol of bisabolene type (8) along with three previously reported metabolites (5-7), were isolated from the organic extracts of Laurencia microcladia, collected from the Chios island in the North Aegean Sea. The structures of the new natural products, as well as their relative stereochemistries, were established by means of spectral data analyses, including 2D experiments. The cytotoxicity of the isolated metabolites was evaluated against five human tumor cell lines.     

New pyrrolidine alkaloids from the roots of Pandanus amaryllifolius

Four new alkaloids, pandamarilactonines-E, -F, and -F-N-oxide consisting of a pyrrolidine moiety and two α-methyl-γ-lactone residues, and pandamarilactonine-G, possessing a pyrrolidinone function, were isolated from the roots of Pandanus amaryllifolius. Their structures were determined based on spectroscopic analyses and chemical syntheses.