Four New Flavonoids with α‐Glucosidase Inhibitory Activities from Morus alba var. tatarica

Four new flavonoids, mortatarins A–D ( 1 – 4 , resp.), along with eight known flavonoids ( 5 – 12 ) were isolated from the root bark of Morus alba var. tatarica. Their structures were established on the basis of spectroscopic data analysis, and the absolute configuration of 4 was determined by analysis of its CD spectrum. All isolates were tested for inhibitory activities against α‐glucosidase. Compounds 4, 7 , and 8 exhibited a significant degree of inhibition with IC₅₀ values of 5.0±0.3, 7.5±0.5, and 5.9±0.2 μM , respectively.     

Syntheses,Receptor Bindings,in vitro and in vivo Stabilities and Biodistributions of DOTA‐Neurotensin(8–13) Derivatives Containing β‐Amino Acid Residues – A Lesson about the Importance of Animal Experiments

Neurotensin(8–13) (NTS(8–13)) analogs with C‐ and/or N‐terminal β‐amino acid residues and three DOTA derivatives thereof have been synthesized (i.e., 1 – 6 ). A virtual docking experiment showed almost perfect fit of one of the 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) derivatives, 6a , into a crystallographically identified receptor NTSR1 (Fig. 1). The affinities for the receptors of the NTS analogs and derivatives are low, when determined with cell‐membrane homogenates, while, with NTSR1‐exhibiting cancer tissues, affinities in the single‐digit nanomolar range can be observed (Table 2). Most of the β‐amino acid‐containing NTS(8–13) analogs (Table 1 and Fig. 2), including the ⁶⁸Ga complexes of the DOTA‐substituted ones ( 6 ; Figs. 2 and 5), are stable for ca. 1 h in human serum and plasma, and in murine plasma. The biodistributions of two ⁶⁸Ga complexes (of 6a and 6b ) in HT29 tumor‐bearing nude mice, in the absence and in the presence of a blocking compound, after 10, 30, and 60 min (Figs. 3 and 4) lead to the conclusion that the amount of specifically bound radioligand is rather low. This was confirmed by PET‐imaging experiments with the tumor‐bearing mice (Fig. 6). Comparison of the in vitro plasma stability (after 1 h) with the ex vivo blood content (after 10–15 min) of the two ⁶⁸Ga complexes shows that they are rapidly cleaved in the animals (Fig. 5).     

Novel Zierane‐ and Guaiane‐Type Sesquiterpenes from the Root of Melicope denhamii

Two novel zierane‐type sesquiterpenes, named melicodenones A and B ( 1 and 2 , resp.), and three new guaiane‐type sesquiterpenes, named melicodenones C–E ( 3 – 5 ), were isolated from the root of Melicope denhamii (Seem. ) T. G. Hartley together with zierone ( 6 ). Their structures were established by extensive NMR‐spectroscopic analyses. Compounds 1 – 6 were tested for cytotoxicity using human colon cancer DLD‐1 cells, and melicodenone A ( 1 ) was found to exhibit moderate activity.     

Pierisformotoxins A – D,Polyesterified Grayanane Diterpenoids from Pieris formosa and Their cAMP‐Decreasing Activities

Four highly acylated diterpenoids, designated as pierisformotoxins A–D ( 1 – 4 , resp.), along with 26 known compounds, were isolated from the flowers of Pieris formosa. Among them, pierisformotoxins A and B ( 1 and 2 , resp.) were new highly acylated grayanane diterpenoids, of which the five‐membered ring A has undergone an oxidative cleavage between C(3) and C(4), followed by lactonization, to give rise to a five‐membered lactone ring between C(3) and C(5), differing from the previously reported grayanane diterpenoids with a 5/7/6/5 ring system. Results of the cAMP‐regulation‐activity assay showed that pierisformotoxin C ( 3 ) at 10 μM (inhibitory ratio (IR): 10.1%) or 2 μM (9.8%), and pierisformotoxin B ( 2 ) at 50 μM (13.9%) significantly decreased the cAMP level in N1E‐115 neuroblastoma cells (p<0.05).     

Drimane Sesquiterpenoids from the Aspergillus oryzae QXPC‐4

Three new drimane sesquiterpenoids, astellolides C–E ( 1 – 3 , resp.), four new drimane sesquiterpenoid p‐hydroxybenzoates, astellolides F–I ( 4 – 7 , resp.), together with two known compounds astellolides A and B ( 8 and 9 , resp.), have been isolated from the liquid culture of Aspergillus oryzae (strain No. QXPC‐4). Their structures were established by comprehensive analysis of spectroscopic data. The relative and absolute configurations were determined on the basis of NOESY and CD data, together with single‐crystal X‐ray diffraction analyses of compounds 1 – 3 . The metabolites were evaluated for their cytotoxic activities, however, no compounds showed a significant cytotoxicity against the tested cell lines at a concentration of 20 μM .     

Organocatalyzed Domino Synthesis of New Thiazole‐Based Decahydroacridine‐1,8‐diones and Dihydropyrido[2,3‐d : 6,5‐d′]‐ dipyrimidines in Water as Antimicrobial Agents

Organopromoter, 2‐aminoethanesulfonic acid was used to catalyze the synthesis of a series of structurally intriguing new hybrids thiazolyl acridine‐1,8(2H,5H)‐diones and dihydropyrido[2,3‐d : 6,5‐d′]dipyrimidine‐2,4,6,8(1H,3H,5H,7H)‐tetraones for the first time. 2‐Aminoethanesulfonic acid is a biobased organopromoter, used to generate four new bonds for the synthesis of new coupled thiazole‐based decahydroacridine‐1,8‐diones. Superior green credentials, operational simplicity, easy work‐up and recyclability of the catalyst are the key strengths of this method. The broad substrate scope, mild reaction conditions, short reaction time, cost effectiveness, high atom economy and good to excellent yields make the present method a distinct improvement over existing methods. Spectral (IR, ¹H‐NMR,¹³C‐NMR, Mass) data and elemental analyses confirmed the structures of the titled products. A series of thiazolyl acridine‐1,8(2H,5H)‐diones and dihydropyrido[2,3‐d : 6,5‐d′]dipyrimidine‐2,4,6,8(1H,3H,5H,7H)‐tetraones were screened for their antimicrobial activity against four bacterial and three fungal strains.     

Preparative isolation and purification of four flavonoids from the petals of nelumbo nucifera by high‐speed counter‐current chromatography

Introduction – Flavonoids, the primary constituents of the petals of Nelumbo nucifera, are known to have antioxidant properties and antibacterial bioactivities. However, efficient methods for the preparative isolation and purification of flavonoids from this plant are not currently available. Objective – To develop an efficient method for the preparative isolation and purification of flavonoids from the petals of N. nucifera by high‐speed counter‐current chromatography (HSCCC). Methodology – Following an initial clean‐up step on a polyamide column, HSCCC was utilised to separate and purify flavonoids. Purities and identities of the isolated compounds were established by HPLC‐PAD, ESI‐MS, ¹H‐NMR and ¹³C‐NMR. Results – The separation was performed using a two‐phase solvent system composed of ethyl acetate–methanol–water–acetic acid (4 : 1 : 5 : 0.1, by volume), in which the upper phase was used as the stationary phase and the lower phase was used as the mobile phase at a flow‐rate of 1.0 mL/min in the head‐to‐tail elution mode. Ultimately, 5.0 mg syringetin‐3‐O‐β‐d‐glucoside, 6.5 mg quercetin‐3‐O‐β‐d‐glucoside, 12.8 mg isorhamnetin‐3‐O‐β‐d‐glucoside and 32.5 mg kaempferol‐3‐O‐β‐d‐glucoside were obtained from 125 mg crude sample. Conclusion – The combination of HSCCC with a polyamide column is an efficient method for the preparative separation and purification of flavonoids from the petals of N. nucifera. Copyright © 2009 John Wiley & Sons, Ltd.     

Cytotoxic ent‐Kaurane Diterpenoids from Isodon nervosus

Four new ent‐kaurane diterpenoids, rabdonervosins G–J ( 1 – 4 , resp.), were isolated from the leaves and stems of Isodon nervosus. Their structures were elucidated by extensive spectroscopic analyses, including 1D‐, 2D‐NMR and HR mass spectra. Compound 2 showed potent cytotoxicity against the HepG2 and PC‐9/ZD cell lines with IC₅₀ values of 2.36 and 6.07 μM , respectively, and compound 3 exhibited cytotoxicity against the HepG2 and CNE2 cell lines with IC₅₀ values of 8.64 and 9.77 μM , respectively.     

Inhibitory Effects of Maleimide Derivatives from the Mycelia of the Fungus Antrodia cinnamomea BCRC 36799 on Nitric Oxide Production in Lipopolysaccharide (LPS)‐Activated RAW264.7 Macrophages

Four new maleimide derivatives, antrocinnamomins E–H ( 1 – 4 , resp.), together with (3S,4R)‐1‐hydroxy‐3‐(4‐hydroxyphenyl)‐4‐(2‐methylpropyl)pyrrolidine‐2,5‐dione ( 5 ) and ergosterol were isolated from the mycelia of Antrodia cinnamomea BCRC 36799. The structures were elucidated by 1D‐ and 2D‐NMR spectroscopy, and mass spectrometry. Compounds 1 – 5 were evaluated for their inhibitory effects on nitric oxide (NO) production by macrophages. Compounds 2 and 4 showed stronger inhibition of NO production than the positive control quercetin.     

Crassocolides G–M,Cembranoids from the Formosan Soft Coral Sarcophyton crassocaule

Seven new polyoxygenated cembranoids possessing an α‐methylene‐γ‐lactone group, crassocolides G–M ( 1 – 7 , resp.), have been isolated from the AcOEt extract of the Formosan soft coral Sarcophyton crassocaule. The structures of compounds 1 – 7 were established by detailed spectroscopic analyses, including 2D‐NMR spectroscopy (¹H,¹H‐COSY, HMQC, HMBC, and NOESY), while the absolute configuration of 1 was determined using a modified reaction of Mosher's method. The cytotoxicity of compounds 1 – 7 against a limited panel of cancer cell lines was also determined.     

Synthesis,Characterization, and Anti‐Amoebic Activity of N‐(Pyrimidin‐2‐yl)benzenesulfonamide Derivatives

A new series of N‐(pyrimidin‐2‐yl)benzenesulfonamide derivatives, 3a – 3i and 4a – 4i , was synthesized from pyrimidin‐2‐amines, 2a – 2i , with the aim to explore their effects on in vitro growth of Entamoeba histolytica. The chemical structures of the compounds were elucidated by elemental analysis, FT‐IR, ¹H‐ and ¹³C‐NMR, and ESI mass‐spectral data. In vitro anti‐amoebic activity was evaluated against HM1 : IMSS strain of Entamoeba histolytica. The IC₅₀ values were calculated by using the double dilution method. The results were compared with the IC₅₀ value of the standard drug ‘metronidazole’. The selected compounds were tested for their cytotoxic activities by cell‐viability assay using H9C2 cardiac myoblasts cell line, and the results indicated that all the compounds displayed remarkable >80% viabilities to a concentration of 100 μg/ml.     

Antibacterial Activity of Enrofloxacin and Ciprofloxacin Derivatives of β‐Octaarginine

β³‐Octaarginine chains were attached to the functional groups NH and CO₂H of the antibacterial fluoroquinolones ciprofloxacin (→ 1 ) and enrofloxacin (→ 2 ), respectively, in order to find out whether the activity increases by attachment of the polycationic, cell‐penetrating peptide (CPP) moiety. For comparison, simple amides, 3 – 5 , of the two antimicrobial compounds and β³‐octaarginine amide ( βR₈ ) were included in the antibacterial susceptibility tests to clarify the impact of chemical modification on the microbiological activity of either scaffold (Table).     

Production of 3‐Fucosyllactose in Engineered Escherichia coli with α‐1,3‐Fucosyltransferase from Helicobacter pylori

3‐Fucosyllactose (3‐FL), one of the major oligosaccharides in human breast milk, is produced in engineered Escherichia coli. In order to search for a good α‐1,3‐fucosyltransferase, three bacterial α‐1,3‐fucosyltransferases are expressed in engineered E. coli deficient in β‐galactosidase activity and expressing the essential enzymes for the production of guanosine 5′‐diphosphate‐l ‐fucose, the donor of fucose for 3‐FL biosynthesis. Among the three enzymes tested, the fucT gene from Helicobacter pylori National Collection of Type Cultures 11637 gives the best 3‐FL production in a simple batch fermentation process using glycerol as a carbon source and lactose as an acceptor. In order to use glucose as a carbon source, the chromosomal ptsG gene, considered the main regulator of the glucose repression mechanism, is disrupted. The resulting E. coli strain of ?LP‐YA+FT shows a much lower performance of 3‐FL production (4.50 g L^?1) than the ?L‐YA+FT strain grown in a glycerol medium (10.7 g L^?1), suggesting that glycerol is a better carbon source than glucose. Finally, the engineered E. coli ?LW‐YA+FT expressing the essential genes for 3‐FL production and blocking the colanic acid biosynthetic pathway (?wcaJ) exhibits the highest concentration (11.5 g L^?1), yield (0.39 mol mol^?1), and productivity (0.22 g L^?1 h) of 3‐FL in glycerol‐limited fed‐batch fermentation.     

Conformations of peptides containing a chiral cyclic α, α‐disubstituted α‐amino acid within the sequence of Aib residues

A single chiral cyclic α,α‐disubstituted amino acid, (3S,4S)‐1‐amino‐(3,4‐dimethoxy)cyclopentanecarboxylic acid [(S,S)‐Ac₅c^dOM], was placed at the N‐terminal or C‐terminal positions of achiral α‐aminoisobutyric acid (Aib) peptide segments. The IR and ¹H NMR spectra indicated that the dominant conformations of two peptides Cbz‐[(S,S)‐Ac₅c^dOM]‐(Aib)₄‐OEt ( 1) and Cbz‐(Aib)₄‐[(S,S)‐Ac₅c^dOM]‐OMe (2) in solution were helical structures. X‐ray crystallographic analysis of 1 and 2 revealed that a left‐handed (M) 3₁₀‐helical structure was present in 1 and that a right‐handed (P) 3₁₀‐helical structure was present in 2 in their crystalline states. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

Determination of the Absolute Configuration of Two Pairs of C‐8 − C‐9′ Linked Neolignan Enantiomers

Two pairs of new neolignan enantiomers, (±)‐torreyayunan A ( 1a / 1b ) and (±)‐torreyayunan B ( 2a / 2b ), featuring a rare C‐8 ? C‐9′ linked skeleton, were isolated from leaves and twigs of Torreya yunnanensis. Their absolute configuration involving two chiral centers was determined by combined spectral and Density Functional Theory (DFT) calculation. This is the first report of the absolute configuration of this group of neolignans. Chirality 26:825–828, 2014. © 2014 Wiley Periodicals, Inc.     

Cytotoxic (9βH)‐Pimarane and (9βH)‐17‐Norpimarane Diterpenes from the Tuber of Icacina trichantha

Three (9βH)‐pimaranes, 1, 2 , and 3 , and two (9βH)‐17‐norpimaranes, 4 and 5 , belonging to a rare compound class in nature, were obtained from the tubers of Icacina trichantha for the first time. Compound 1 is a new natural product, and 2 – 5 have been previously reported. The structures were elucidated based on NMR and MS data, and optical rotation values. The absolute configurations of (9βH)‐pimaranes were unambiguously established based on X‐ray crystallographic analysis. Full NMR signal assignments for the known compounds 2, 4 , and 5 , which were not available in previous publications, are also reported. All five isolates displayed cytotoxic activities on MDA‐MB‐435 cells (IC₅₀ 0.66–6.44 μM ), while 2, 3 , and 4 also exhibited cytotoxicities on HT‐29 cells (IC₅₀ 3.00–4.94 μM ).     

11α‐Ethoxy‐β‐boswellic Acid and Nizwanone,a New Boswellic Acid Derivative and a New Triterpene,Respectively, from Boswellia sacra

A new boswellic acid derivative, 11α‐ethoxy‐β‐boswellic acid (EBA; 1 ) and a new ursane‐type triterpene, named nizwanone ( 2 ), were isolated from Omani frankincense Boswellia sacra Flueck . together with two known compounds papyriogenin B and rigidenol. The structures of 1 and 2 were elucidated by detailed spectroscopic analysis using ¹H‐ and ¹³C‐NMR, ¹H,¹H‐COSY, HMQC, HMBC, and HR‐EI‐MS techniques. The relative configurations of 1 and 2 were assigned by comparative analysis of the NMR spectral data with those of known analogs together with NOESY experiments. Structures of known compounds were identified by comparison with the reported data.     

Isolation and characterization of α‐(1→3)‐glucan‐degrading bacteria from the gut of Diaperis boleti feeding on Laetiporus sulphureus

Bacteria degrading α‐(1→3)‐glucan were sought in the gut of fungivorous insects feeding on fruiting bodies of a polypore fungus Laetiporus sulphureus, which are rich in this polymer. One isolate, from Diaperis boleti, was selected in an enrichment culture in the glucan‐containing medium. The bacterium was identified as Paenibacillus sp. based on the results of the ribosomal DNA analysis. The Paenibacillus showed enzyme activity of 4.97 mU/cm³ and effectively degraded fungal α‐(1→3)‐glucan, releasing nigerooligosaccharides and a trace amount of glucose. This strain is the first reported α‐(1→3)‐glucan‐degrading microorganism in the gut microbiome of insects inhabiting fruiting bodies of polypore fungi.     

Interaction of β3/β2‐Peptides,Consisting of Val‐Ala‐Leu Segments,with POPC Giant Unilamellar Vesicles (GUVs) and White Blood Cancer Cells (U937) – A New Type of Cell‐Penetrating Peptides,and a Surprising Chain‐Length Dependence of Their Vesicle‐ and Cell‐Lysing Activity

Many years ago, β²/β³‐peptides, consisting of alternatively arranged β²‐ and β³h‐amino‐acid residues, have been found to undergo folding to a unique type of helix, the 10/12‐helix, and to exhibit non‐polar, lipophilic properties (Helv. Chim. Acta 1997 , 80, 2033). We have now synthesized such ‘mixed’ hexa‐, nona‐, dodeca‐, and octadecapeptides, consisting of Val‐Ala‐Leu triads, with N‐terminal fluorescein (FAM) labels, i.e., 1 – 4 , and studied their interactions with POPC (=1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine) giant unilamellar vesicles (GUVs) and with human white blood cancer cells U937. The methods used were microfluidic technology, fluorescence correlation spectroscopy (FCS), a flow‐cytometry assay, a membrane‐toxicity assay with the dehydrogenase G6PDH as enzymatic reporter, and visual microscopy observations. All β³/β²‐peptide derivatives penetrate the GUVs and/or the cells. As shown with the isomeric β³/β²‐, β³‐, and β²‐nonamers, 2, 5 , and 6 , respectively, the derivatives 5 and 6 consisting exclusively of β³‐ or β²‐amino‐acid residues, respectively, interact neither with the vesicles nor with the cells. Depending on the method of investigation and on the pretreatment of the cells, the β³/β²‐nonamer and/or the β³/β²‐dodecamer derivative, 2 and/or 3 , respectively, cause a surprising disintegration or lysis of the GUVs and cells, comparable with the action of tensides, viral fusion peptides, and host‐defense antimicrobial peptides. Possible sources of the chain‐length‐dependent destructive potential of the β³/β²‐nona‐ and β³/β²‐dodecapeptide derivatives, and a possible relationship with the phosphate‐to‐phosphate and hydrocarbon thicknesses of GUVs, and eukaryotic cells are discussed. Further investigations with other types of GUVs and of eukaryotic or prokaryotic cells will be necessary to elucidate the mechanism(s) of interaction of ‘mixed’ β³/β²‐peptides with membranes and to evaluate possible biomedical applications.     

Antituberculosis Agents and an Inhibitor of the para‐Aminobenzoic Acid Biosynthetic Pathway from Hydnocarpus anthelminthica Seeds

Investigation on the extracts of Hydnocarpus anthelminthica seeds led to the isolation of three new compounds, anthelminthicins A–C ( 1 – 3 , resp.), and two known ones, namely chaulmoogric acid ( 4 ) and ethyl chaulmoograte ( 5 ). Their structures were determined mainly by using spectroscopic techniques. The absolute configuration at the cyclopentenyl moiety of compound 2 was rationalized by quantum calculations. Base hydrolysis, followed by optical‐rotation comparison, allowed assignment of the configuration of chaulmoogric‐acid moiety of compounds 3 and 5 . Biological assays revealed that compounds 1 – 5 significantly inhibit Mycobacterium tuberculosis (MTB) growth with MIC values of 5.54, 16.70, 4.38, 9.82, and 16.80 μM , respectively. Compound 3 was found to inhibit the pathway between chorismate and para‐aminobenzoic acid (pAba) with a MIC value of 11.3 μM , representing a new example of pAba inhibitor isolated from a natural source. All compounds were not toxic to Candida albicans SC5314 at a concentration up to 100 μM .