Secondary metabolites of the sponge-derived fungus Acremonium persicinum.

This study reports the isolation and characterization of six new acremine metabolites, 5-chloroacremine A (4), 5-chloroacremine H (5), and acremines O (6), P (7), Q (8), and R (9), together with the known acremines A (1), F (2), and N (3) from the fungus Acremonium persicinum cultured from the marine sponge Anomoianthella rubra. The relative configuration of acremine F (2) was determined by analyses of proton coupling constant values and NOESY data, and the absolute configuration confirmed as (1S, 4S, 6R) by X-ray crystallographic analysis of the borate ester derivative 15. Acremines O, P, and R were each shown to be of 8R configuration by ¹H NMR analyses of MPA esters. The relative configurations suggested for acremines P and Q were each deduced by molecular modeling together with NOESY and coupling constant data. The ³J(H-C) values in acremine P were measured using the pulse sequence EXSIDE, and the observed ³J(H8-C4) of 5.4 Hz and small ³J(H-C) values (<1.5 Hz) from H-8 to C-10 and C-11 were fully consistent with stereoisomer 7a. For acremine Q, NOESY data combined with molecular modeling established the preferred diastereomer 8a.

Oxidative processes in the Australian marine sponge Plakinastrella clathrata: isolation of plakortolides with oxidatively modified side chains.

Sixteen new cyclic peroxides (1-16) with a plakortolide skeleton and the methyl ester derivative of a didehydroplakinic acid (17) were isolated from the Australian sponge Plakinastrella clathrata Kirkpatrick, 1900. Structural elucidation and configurational assignments were based on spectroscopic analysis and comparison with data for previously isolated plakortolides and revealed both phenyl- and methyl-terminating side chains attached to the plakortolide core. Plakortoperoxides A-D (5-8) each contained a second 1,2-dioxine ring; a cis configuration for the side chain endoperoxide ring was determined by a low-temperature NMR study and by comparison of chemical shift values with those of reported compounds. An enantioselective HPLC study compared natural plakortoperoxide A with a synthetic sample prepared by cyclization of plakortolide P with singlet oxygen and revealed that the natural sample was a mixture of cis diastereomers at C-15/C18. Four other cyclic peroxides (9-12) possessed a C(9)-truncated side chain terminating in a formyl or carboxylic acid functionality, suggesting that these metabolites may have been formed by oxidative cleavage of the Δ(9,10) bond of diene-functionalized plakortolides. A final group of four metabolites (13-16) with hydroxy or the rare hydroperoxy functionality unexpectedly revealed a C(8) side chain, while the ester (17) represents further structural variation within the growing family of cyclic peroxy sponge metabolites.

Structure and bioactivity of steroidal saponins isolated from the roots of Chamaelirium luteum (false unicorn).

Phytochemical investigation of Chamaelirium luteum ("false unicorn") resulted in the isolation of 15 steroidal glycosides. Twelve of these (1, 2, 4-9, 11-13, and 15) are apparently unique to this species, and eight of these (6-9, 11-13, and 15) are previously unreported compounds; one (15) possesses a new steroidal aglycone. In addition, the absolute configuration of (23R,24S)-chiograsterol A (10) was defined, and its full spectroscopic characterization is reported for the first time. The structures and configurations of the saponins were determined using a combination of multistage mass spectrometry (MS(n)), 1D and 2D NMR experiments, and chemical degradation. The antiproliferative activity of nine compounds obtained in the present work, and eight related compounds generated in previous work, was compared in six human tumor cell lines, with aglycones 3 and 10 and related derivatives 16, 17, 19, and 20 all displaying significant antiproliferative activity.

Isolation of thuridillins D-F, diterpene metabolites from the Australian sacoglossan mollusk Thuridilla splendens; relative configuration of the epoxylactone ring.

This first chemical study of the sacoglossan mollusk Thuridilla splendens from Mooloolaba, South East Queensland, has resulted in the isolation of three new metabolites, thuridillins D-F (1-3), and one known metabolite, thuridillin A (4). Thuridillin D (1) was isolated by conventional flash chromatography on silica gel, while a mixture of thuridillins E (2) and F (3) was obtained by PTLC on AgNO(3)-impregnated silica gel. Thuridillins D-F were determined to be structurally related to thuridillin B (5); 1 possessed a hydroxy group at C-11, and 2 and 3 were Δ(10,11)- and Δ(11,12)-isomers, respectively. HSQC-HECADE NMR data, together with conformational analysis, NOESY experiments, and (1)H-(1)H coupling studies enabled assignment of the individual relative configurations of the epoxylactone, the 2,5-diacetoxy-2,5-dihydrofuran, and cyclohexyl moieties within thuridillin D (1).

Phosphorylation of alginate: synthesis, characterization, and evaluation of in vitro mineralization capacity.

Phosphorylation of alginate was achieved using a heterogeneous urea/phosphate reaction. The degree and stereoselectivity of phosphorylation as well as the effects on the physical properties of the polysaccharide were investigated by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies, inductively coupled plasma optical-emission spectroscopy (ICP-OES), and size exclusion chromatography (SEC). Multidimensional NMR studies of the phosporylated alginate revealed that phosphorylation of the M residues occurred predominantly at the C3 (equatorial) carbon of the polysaccharide ring. In addition, a more comprehensive assignment of the (1)H NMR spectrum of alginate, compared with those previously reported in the literature, is provided here. Hydrogel materials were formed from ionically cross-linked blends of phosphorylated alginate and alginate. These blended hydrogels showed an enhanced resistance to degradation by chelating agents compared with cross-linked alginate hydrogels and a reduction in their mineralization potential.

Selectively inducing the synthesis of a key structural exopolysaccharide in aerobic granules by enriching for Candidatus "Competibacter phosphatis".

A gel-forming exopolysaccharide was previously shown to play an important structural role in aerobic granules treating nutrient-rich industrial wastewater. To identify whether this exopolysaccharide performs a similar role in other granular biomass and if conditions favouring its production can be more precisely elucidated, extracellular polymeric substances (EPS) were extracted from granules grown under four different operating conditions. (1)H nuclear magnetic resonance (NMR) spectroscopy of their EPS indicated that the gel-forming exopolysaccharide was expressed in two granular sludges both enriched in Candidatus "Competibacter phosphatis". In contrast, it was not expressed in granules performing denitrification with methanol as a carbon source and nitrate as the electron acceptor or granules enriched in Candidatus "Accumulibacter phosphatis" performing enhanced biological phosphorus removal from synthetic wastewater. In one of the first two sludges, the exopolysaccharide contained in the seeding granular sludge continued to be a major component of the granule EPS while Competibacter was being enriched. In the second sludge, a floccular sludge not containing the gel-forming exopolysaccharide initially was also enriched for Competibacter. In this sludge, an increase in particle size was detected coinciding with a yield increase of EPS. NMR spectroscopy confirmed its yield increase to be attributable to the production of this structural gel-forming exopolysaccharide. The results show that (1) the particular gel-forming exopolysaccharide previously identified is not necessarily a key structural exopolysaccharide for all granule types, and (2) synthesis of this exopolysaccharide is induced under conditions favouring the selective enrichment of Competibacter. This indicates that Competibacter may be involved in its production.

Synergistic antimicrobial activity of galangal (Alpinia galanga), rosemary (Rosmarinus officinalis) and lemon iron bark (Eucalyptus staigerana) extracts.

BACKGROUND: In this study the synergistic antimicrobial activities of combinations of extracts from galangal (Alpinia galanga), rosemary (Rosmarinus officinalis) and lemon iron bark (Eucalyptus staigerana) were evaluated against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium and Clostridium perfringens. Chemical compositions of these extracts were also determined to provide further insight into antimicrobial constituents and their potential mechanisms of action. RESULTS: Combinations of galangal with either rosemary or lemon iron bark showed synergistic antimicrobial activity. Specifically, galangal and rosemary showed synergistic activity against S. aureus and L. monocytogenes only, while galangal and lemon iron bark showed synergistic activity against E. coli and S. typhimurium. Chemical compositions of the extracts were determined by gas chromatographic-mass spectrometric analysis. The major chemical components of the galangal and lemon iron bark extracts were 1'-acetoxy-chavicol acetate (1'ACA) (63.4%) and neral (15.6%), respectively, while 1,8-cineole (26.3%) and camphor (20.3%) were identified as major chemical components of the rosemary extract. CONCLUSION: The results of this study show that galangal, rosemary and lemon iron bark extracts contain components that may have different modes of antimicrobial action and combinations of these extracts may have potential as natural antimicrobials to preserve foods.

Structural determination of a key exopolysaccharide in mixed culture aerobic sludge granules using NMR spectroscopy.

Nuclear magnetic resonance (NMR) techniques were used to elucidate the structure of an exopolysaccharide material previously revealed to be important in formation of aerobic granules. The 1D NMR spectral data acquired showed that this gel-forming polysaccharide was a major component of granular EPS, while 1D and 2D NMR spectra showed it consisted of eight sugar residues. These were assigned as α-galactose, α-rhamnose, 2-acetoamido-2-deoxy-α-galactopyranuronic acid, ß-mannose, ß-galactose, ß-glucuronate, ß-glucosamine, and N-acetyl ß-galactosamine. With the exception of 2-acetoamido-2-deoxy-α-galactopyranuronic acid, a highly unusual sugar, their presence was confirmed with high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Carbon and proton shifts were assigned for each sugar. Heteronuclear multiple bond correlation (HMBC) and nuclear Overhauser enhancement spectroscopy (NOESY) were used to identify linkage sites between individual sugar residues. This gel-forming exopolysaccharide appeared to be a highly complex single heteropolysaccharide with a repeat sequence of α-galactose, ß-mannose, ß-glucosamine, N-acetyl-ß-galactosamine, and 2-acetoamido-2-deoxy-α-galactopyranuronic acid. It has a disaccharide branch of ß-galactose and ß-glucuronic acid attached to 2-acetoamido-2-deoxy-α-galactopyranuronic acid and an α-rhamnose branch attached to α-galactose.

Lignans and Triterpenes from the Bark of Durio carinatus and Durio oxleyanus.

Investigation of chemical constituents from the bark of Durio carinatus has led to the isolation of three lignans, boehmenan X (1), threo-carolignan X (2), and erythro-carolignan X (3), together with the three known lignans boehmenan, threo-carolignan E, and erythro-carolignan E. The bark of D. oxleyanus yielded two new lignan ethers, threo-carolignan Y (4) and erythro-carolignan Y (5), together with compounds 1, 3, and boehmenan. J-Based configurational analysis and NOE measurements were used to explore conformational issues for the lignan diastereomers, while CD measurements supported an 8'S configuration for the various lignans. The triterpenes 3ß-O-cis-caffeoylbetulinic acid and 3ß-O-trans-caffeoylbetulinic acid were also characterized from D. carinatus.

Bifunctional Succinylated ε-Polylysine-Coated Mesoporous Silica Nanoparticles for pH-Responsive and Intracellular Drug Delivery Targeting the Colon.

Conventional oral drug formulations for colonic diseases require the administration of high doses of drug to achieve effective drug concentrations at the target site. However, this exposes patients to serious systemic toxicity in order to achieve efficacy. To overcome this problem, an oral drug delivery system was developed by loading a large amount (ca. 34% w/w) of prednisolone into 3-aminopropyl-functionalized mesoporous silica nanoparticles (MCM-NH2) and targeting prednisolone release to the colon by coating the nanoparticle with succinylated ε-polylysine (SPL). We demonstrate for the first time the pH-responsive ability of SPL as a "nanogate" to selectively release prednisolone in the pH conditions of the colon (pH 5.5-7.4) but not in the more acidic conditions of the stomach (pH 1.9) or small intestine (pH 5.0). In addition to targeting drug delivery to the colon, we explored whether the nanoparticles could deliver cargo intracellularly to immune cells (RAW 264.7 macrophages) and intestinal epithelial cells (LS 174T and Caco-2 adenocarcinoma cell lines). To trace uptake, MCM-NH2 were loaded with a cell membrane-impermeable dye, sulforhodamine B. The SPL-coated nanoparticles were able to deliver the dye intracellularly to RAW 264.7 macrophages and the intestinal epithelial cancer cells, which offers a highly promising and novel drug delivery system for diseases of the colon such as inflammatory bowel disease and colorectal cancer.

A diverse suite of spiroacetals, including a novel branched representative, is released by female Bactrocera tryoni (Queensland fruit fly).

A remarkably diverse suite of spiroacetals including a novel member of the rare, branched chain class has been identified in the glandular secretions of Bactrocera tryoni, the most destructive horticultural pest in Australia.

4,6,8,10,16-penta- and 4,6,8,10,16,18-hexamethyldocosanes from the cane beetle antitrogusparvulus--cuticular hydrocarbons with unprecedented structure and stereochemistry.

The major cuticular hydrocarbons from the cane beetle species Antitrogus parvulus were deduced to be 4,6,8,10,16,18-hexa- and 4,6,8,10,16-pentamethyldocosanes 2 and 3, respectively. Isomers of 2,4,6,8-tetramethylundecanal 27, 36, and 37, derived from 2,4,6-trimethylphenol, were coupled with the phosphoranes 28 and 29 to furnish alkenes and, by reduction, diastereomers of 2 and 3. Chromatographic and spectroscopic comparisons confirmed 2 as either 6a or 6b and 3 as either 34a or 34b. [structure: see text]

Cyclodextrin-crosslinked poly(acrylic acid): Synthesis, physicochemical characterization and controlled release of diflunisal and fluconazole from hydrogels.

The aim of this work was to develop mucoadhesive hydrogels with variable drug delivery properties by crosslinking poly(acrylic acid) (PAA) with cyclodextrins (CDs). CD-PAA polymers with high CD content and good inter-batch reproducibility were synthesized by activating PAA with SOCl2, then reacting PAA chloride with CD in the presence of 4-dimethylaminopyridine at 50°C. Manipulation of the synthesis conditions affected the physicochemical character of the CD-PAA polymers and hydrogels in terms of CD content, the average number of ester bonds to an individual CD, viscosity, and the association and release of model drugs. Inclusion complexation of diflunisal (DIF) and fluconazole (FLZ) with CD-PAA hydrogels was assessed by (19)F NMR spectroscopy and association constants (Kas) for DIF were in the range 220-486M(-1) with ßCD-PAA and 1327-6055M(-1) with hydroxypropyl-ßCD-PAA. For FLZ the Ka range was 34-171M(-1) with hydroxypropyl-ßCD-PAA. The hydrogels were found to release both drugs by means of Fickian diffusion as the predominant mechanism. A slight trend toward negative correlation was found between the Ka and Higuchi kH values for DIF. These results highlight the potential of CD-PAA hydrogels to control the release of model drugs through inclusion complexation.

Complete (1)H and (13)C assignments of the four major saponins from Dioscorea villosa (wild yam).

Complete (1)H and (13)C spectral assignments for the four major steroidal saponins isolated by methanolic extraction of the roots of Dioscorea villosa, collected in North Carolina, United States (in summer and autumn), are presented in this paper. The structures were determined by a combination of (1)H, (13)C and 2D NMR techniques and were found to be ((3beta,25R)-26-(beta-D-glucopyranosyloxy)-22-methoxyfurost-5-en-3-yl-O-beta-D-glucopyranosyl-(1 --> 3)-O-beta-D-glucopyranosyl-(1 --> 4)-O-[alpha-L-rhamnopyranosyl-(1 --> 2)]-beta-D-glucopyranoside (1) (or methyl parvifloside), ((3beta,25R)-26-(beta-D-glucopyranosyloxy)-22 methoxyfurost-5-en-3-yl-O-alpha-L-rhamnopyranosyl-(1 --> 2)-O-[beta-D-gluco- pyranosyl-(1 --> 4)]-beta-D-glucopyranoside (2) (or methyl protodeltonin), (3beta,25R)-spirost-5-en-3-yl-O-beta-D-glucopy ranosyl-(1 --> 3)-O-beta-D-glucopyranosyl-(1 --> 4)-O-[alpha-L-rhamnopyranosyl-(1 --> 2)]-beta-D-glucopyranoside (3) (or Zingiberensis saponin I) and (3beta,25R)-spirost-5-en-3-yl-O-alpha-L-rhamnopyranosyl-(1 --> 2)-O-[beta-Ds-glucopyranosyl -(1 --> 4)]-beta-D-glucopyranoside (4) (or deltonin).

Synthesis and absolute configuration of a constitutionally-new [5.6] spiroacetal from B. tryoni (Queensland fruit fly).

A novel spiroacetal, (2S,6R,8S)-2-methyl-8-ethyl-1,7-dioxaspiro[5.6]dodecane (1), has been identified from the volatile secretions of female B. tryoni by mass spectral analysis and synthesis of an authentic, enantioenriched sample.

Novel cuticular hydrocarbons from the cane beetle Antitrogus parvulus--4,6,8,10,16-penta- and 4,6,8,10,16,18-hexamethyldocosanes-unprecedented anti-anti-anti-stereochemistry in the 4,6,8,10-methyltetrad.

The major cuticular hydrocarbons from the cane beetle species Antitrogus parvulus are 4,6,8,10,16-penta- and 4,6,8,10,16,18-hexamethyldocosanes, 1 and 2, respectively. Stereoisomers of 2,4,6,8-tetramethylundecanal of established relative stereochemistry were derived from 2,4,6-trimethylphenol and were then coupled with appropriate methyl-substituted phosphoranes 62 and 25 to furnish alkenes, which on reduction provided diastereomers of 1 and 2, respectively. Capillary gas chromatography, mass spectrometry, and high resolution 13C NMR spectroscopy confirmed 1 as either 84a or 84b and 2 as either 15a or 15b. The novelty of these structures and their relative stereochemistry is briefly related to polyketide assembly.