New triterpene oligoglycosides from the Caribbean sponge Erylus formosus

Seven new triterpene glycosides, erylosides R₁ (1), T₁ (3), T₂ (4), T₃ (5), T₄ (6), T₅ (7), and T₆ (8) along with the known formoside (2) were isolated from the sponge Erylus formosus collected along the Caribbean coast of Mexico. Glycoside 1 was determined as a trisaccharide, glycoside 2 as a tetrasaccharide while glycosides 3–8 were hexasaccharide. Their carbohydrate chains were unprecedented and have never been found in oligosaccharides from other biological sources, except Erylus spp. Three carbohydrate chains in the glycosides 3 and 6, 4 and 7, 5 and 8 correspondingly are new. The glycosides 1–5 have penasterol as aglycone while glycosides 6–8 proved to be glycoconjugates of 24-methylene-14-carboxy-lanost-8(9)-en-3β-ol.     

Morpho-histochemical characterization of salivary gland cells of males of the tick <Emphasis Type="Italic">Rhipicephalus</Emphasis><Emphasis Type="Italic">sanguineus</Emphasis> (Acari: Ixodidae) at different feeding stages: description of new cell types

This study describes the changes undergone by cells of the salivary glands of unfed and feeding (at day two and four post-attachment) Rhipicephalus sanguineus males, as well as new cell types. In unfed males, types I and II acini are observed with cells “undifferentiated”, undefined 1 and 2 (the latter, with atypical granules), a, c1 and c3; type III is composed of cells d and e; and type IV present cells g. In males at day two post-attachment, type I acini exhibit the same morphology of unfed individuals. An increase in size is observed in types II, III, and IV, as cells are filled with secretion granules. Some granules are still undergoing maturation. In type II acinus, cells a, b and c1–c8 are observed. Cells c7 and c8 are described for the first time. Cells c7 are termed as such due to the addition of polysaccharides in the composition of the secretion granules (in unfed individuals, they are termed undefined 1). Type III acini exhibit cells d and e completely filled with granules, and in type IV, cells g contain granules in several stages of maturation. In males at day four post-attachment, type I acini do not exhibit changes. Granular acini exhibit cells with fewer secretion granules, which are already mature. In type II acini, cells a, b, c1–c5 are present, type III exhibit cells d and e, and type IV contain cells g with little or no secretion. This study shows that in the salivary glands of R. sanguineus males, cells a, c1, and c3 of type II acinus, and cells d and e of type III do not exhibit changes in granular content, remaining continuously active during the entire feeding period. This indicates that during the intervals among feeding stages, gland cells reacquire the same characteristics found in unfed individuals, suggesting that they undergo reprogramming to be active in the next cycle.     

New combinations and typifications in <Emphasis Type="Italic">Bistorta</Emphasis>, <Emphasis Type="Italic">Persicaria</Emphasis>, <Emphasis Type="Italic">Polygonum,</Emphasis> and <Emphasis Type="Italic">Rumex</Emphasis> (Polygonaceae)

New combinations are proposed in anticipation of the Polygonaceae treatment in the forthcoming volume of Intermountain Flora: Polygonum kelloggii var. esotericum, P. kelloggii var. watsonii , Rumex densiflorus var. pycnanthus , R. salicifolius var. utahensis, and R. occidentalis var. tomentellus. Typifications are proposed to facilitate ongoing studies in Polygonaceae and to maintain current usage.     

Synthesis and Biological Activity of Some Unsaturated 6-Azauracil Acyclonucleosides

A useful route is described for obtaining Z and E unsaturated alkylating agents 3 and 4. Coupling 6-azauracils 5 and 6 with unsaturated alkylating agent followed by the deprotection with H⁺ resin gave acyclonucleosides 11–14 in good overall yields. Unsaturated acyclonucleosides phosphonates 19 and 20 were prepared using potassium carbonate as base and 4-bromobut-2-enyl diethyl phosphonate 16 as the alkylating agent. The introduction of a propargyl group at the N-3 position of acyclonucleosides 7, 8, 17, 18, 19, and 20 was achieved using potassium carbonate in DMF.     

MOLECULAR AND PHARMACOLOGICAL CHARACTERISATION OF THE MSH-R ALLELES IN SWISS CATTLE BREEDS

ABSTRACT

The coat colour in mammals is determined by the relative amounts of eumelanin (black/brown) and phaeomelanin (red/yellow), produced in melanocytes, which are controlled by melanocyte stimulating hormone receptor (MSH-R). Melanocyte stimulating hormone receptor is activated by α-melanocyte-stimulating hormone (α-MSH). Stimulated MSH-R activates adenylyl cyclase (AC), thereby increasing the amount of cyclic AMP in the cell, which activates the enzyme tyrosinase resulting in eumelanin synthesis. In this study the complete coding sequences of five alleles of the MSH-R gene found in Holstein, Red Holstein, Simmental, and Brown Swiss cattle were cloned into a mammalian expression vector and transfected into human embryonic kidney (HEK) 293 cells. The expressed receptors were analyzed for their ability to increase intracellular cAMP in response to stimulation by α-MSH. The recessive red allele (e) found in Red Holstein and Simmental and the dominant black allele (E^D) found in Holstein were unresponsive to a wide range of α-MSH concentrations. Two alleles from Brown Swiss (E^d1, E^d2) and one allele found in the Simmental breed (e^f) responded to stimulation by α-MSH in a dose-dependent manner. When compared to E^d1 and E^d2, the cells transfected with the e^f MSH-R allele, however, reached the corresponding intracellular cAMP concentrations at a 10-fold higher concentration of α-MSH. In conjunction with the mode of inheritance of coat colour, the results indicate that the e MSH-R allele is a non-functional receptor, E^D is constitutively activated receptor, and E^d1 and E^d2 are hormonally activated receptors. The delay in e^f MSH-R response may explain the similarity between the e and e^f phenotypes.     

Evaluation of novel <Superscript>99m</Superscript>Tc(I)-labeled homobivalent α-melanocyte-stimulating hormone analogs for melanocortin-1 receptor targeting

Abstract  

Aiming to apply the multivalency concept to melanoma imaging, we have assessed the in vivo melanocortin type 1 receptor (MC1R)-targeting properties of ^99mTc(I)-labeled homobivalent peptide conjugates which contain copies of the α-melanocyte-stimulating hormone (α-MSH) analog [Ac-Nle⁴, Asp⁵, d-Phe⁷, Lys¹¹]α-MSH_4–11 separated by linkers of different length (L ² nine atoms and L ³ 14 atoms). The MC1R-binding affinity of L ² and L ³ is significantly higher than that of the monovalent conjugate L ¹ . Metallation of these conjugates yielded the complexes fac-[M(CO)₃(k³-L)]⁺ (M is ^99mTc/Re; 1/1a, L is L ¹ ; 2/2a, L is L ² ; 3/3a, L is L ³ ), with IC₅₀ values in the subnanomolar and nanomolar range. The MC1R-mediated internalization of 2 and 3 is higher than that of 1 in B16F1 melanoma cells. Biodistribution studies in melanoma-bearing mice have shown low nonspecific accumulation with a tumor uptake that correlates with IC₅₀ values. However, no correlation between tumor uptake and valency was found. Nevertheless, 2 displayed the highest tumor retention, and the best tumor to nontarget organ ratios.     

Conformational behaviours of 2-substituted cyclohexanones: a complete basis set,hybrid-DFT study and NBO interpretation

The generalised anomeric effect (GAE) and gauche effect (GE) associated with donor–acceptor delocalisations, dipole–dipole interactions and total steric exchange energies (TSEE) on the conformational properties of 2-methoxy- (1), 2-methylthio- (2), 2-methylseleno- (3), 2-fluoro- (4), 2-chloro- (5) and 2-bromocyclohexanone (6) have been studied by means of ab initio and hybrid density functional theory methods and natural bond orbital (NBO) analysis. All methods used showed that the axial conformation stability increased from 2-methoxy- (1) to 2-methylselenocyclohexanone (3) and also from 2-fluoro- (4) to 2-bromocyclohexanone (6), which is in agreement with reported NMR data. The results obtained by complete basis set 4 (CBS-4), B3LYP/6-311+G** and HF/6-311+G** levels for compounds 1, 5 and 6 are very similar, but the CBS-4 results for compound 4 are not in agreement with the reported experimental data (vapour phase). The NBO analysis showed that the GAE increases from compounds 1 to 3 and also from compounds 4 to 6. The low axial conformer populations of compounds 1 and 4 can be reasonably explained by their small GAE. GE does not have significant impact on the conformational behaviours of compounds 1–6 and GAE succeeds in accounting qualitatively for the increase in the axial preferences in both series of compounds. The results showed that the calculated Δ(TSEE_eq–ax) values decrease from compounds 4 to 6 which contradicts the suggested arguments in the literature about these compounds. On the other hand, the calculated differences between the dipole moment values of the axial and equatorial conformations, Δ(μ_eq ? μ_ax), increase from compounds 1 to 2, but decrease from compounds 2 to 3 and also decrease from compounds 4 to 6. The calculated GAE values are more significant for the explanation of the conformational preferences of compounds 1–6 than the dipole–dipole repulsion effects. The correlations between the GAE, GE, dipole–dipole interactions, Wiberg Bond Index, TSEE, donor and acceptor orbital energies and occupancies, structural parameters and conformational behaviour of compounds 1–6 have been investigated.     

Synthesis of 1′-Deoxypsicofuranosyl-deoxynucleosides as Potential Anti-HIV Agents

Abstract

Various routes to the targets 1, 2, 3, 1-deoxy-psicofuranosyl nucleoside analogues related to anti-HIV agents, are reported. Two routes afforded their 6′-benzylated derivatives 9, 10 and 15. Only the epoxide 12 and deoxynucleosides 19 and 22 were able to be deprotected leading in the first case to 16 and its ring opening derivative 17 and in the second case to 20 and to the target 3.     

Thiosugar Nucleosides. Synthesis and Biological Activity of 1,3,4‐Thiadiazole,Thiazoline and Thiourea Derivatives of 5‐Thio‐d‐Glucose

New acylated 5‐thio‐β‐d‐glucopyranosylimino‐disusbstituted 1,3,4‐thiadiazols 8, and 11 were prepared, via spontaneous rearrangements, by cycloaddition of the glycosyl isothiocyanate 2 with the reactive intermediates 1‐aza‐2‐azoniaallene hexachloroantimonates 4 and 6, respectively. Reaction of 2 with aminoacetone or chloroethylamine afforded the acylated 5‐thio‐β‐d‐glucopyranosyl‐4‐imidazoline‐2‐thione nucleoside 16 and glucopyranosylamino‐2‐thiazoline derivative 18, respectively. Deblocking of 8, 11, 17 and 19 furnished the free nucleoside analogues 9, 12, 18 and 20, respectively. Analogously, treatment of 2 with chloroethylamine in the 1:2 ratio afforded the thioureylendisaccharide 21. No in vitro antiviral activity against HIV‐1, HIV‐2, human cytomegallovirus (HMCV), has been found for the new synthesized compounds.     

SYNTHESIS OF 4-ACYL-1H-1,2,3-TRIAZOLIC NUCLEOSIDES

Two simple regiospecific methodologies based on triazolic ring construction in the course of synthesis were applied for the synthesis of 1,2,3-triazolic nucleoside analogues. The cycloaddition reactions between diazomalonaldehyde and appropriate glycosylamine derivatives were rather effective, producing the desired nucleosides 11, 17 and 24. Diazotization of enamines 21a and 21b led to the corresponding triazolic ribonucleoside derivatives 22a and 22b, in good yields. Deprotection reaction of 22a, 22b and 24 was easily achieved by Lewis acid catalysis, producing the corresponding ribonucleosides 23a, 23b and 25.     

A Practical and Stereospecific Approach to the Synthesis of 3′-Deoxy-2′,3′-didehydrothymidine (D4T)

Abstract

Starting with D-glucose, 5-t-butyldimethylsilyl-3-deoxy-D-arabinose (5) was prepared. Condensation of 5 with cyanamide followed by reaction of the resulting oxazoline 6 with methyl-2-formylpropionate furnished the anhydronucleoside 7. t-Butoxide elimination of 7 gave the target compound in moderate yields due to concomitant 1′,2′-double bond formation. However, phenylselenolate and phenylthiolate opened 7 regiospecifically to the corresponding seleno and thio compounds, 10 and 11, respectively. Oxidative elimination of 10 and the pivaloyl derivative 12 gave 5′-t-butyldimethylsilyl (8) and 5′-pivaloyl (13) D₄T in excellent yield.     

Nutrient turnover studies in alpine ecosystems

Summary Two plant communities, both dominated by Carex sempervirens but growing at different altitudes of the Northern Calcareous Alp region (IS: 600 m; KS: 1200 m) and one Carex ferruginea — dominated community (KC: 1200 m) are compared as to changes in dry matter, nitrogen, phosphorus, and potassium content of living and dead overground and underground phytomass.The soils of the montanic sites KS and KC are better provided with water and the three nutrients than that of the prealpine site IS. KC has the highest potassium content in the soil and in the phytomass.The dry matter increase (g/m²) of the living overground phytomass during the growing season is about 200 in IS, 360 in KS, and 340 in KC with maxima of 365 in IS, 550 in KS and 375 in KC.The increase of dead overground phytomass is highest in KS, indicating that the total annual overground production exceeds the mere increase in living parts. Furthermore, there is an increase of underground phytomass in KS and KC. The average ratio of total underground/living overground phytomass is 4.6 in IS, 3.7 in KS, but 7.5 in KC.The annual fluctuation of nitrogen (g/m²) in the living overground phytomass increases from 2.5 in IS to 3.8 in KS and to 5.9 in KC. For KS and KC these values approach the nitrogen mineralization values of the soils observed during the growing season. There is an obvious increase of nitrogen in the underground phytomass of KS and KC toward the end of the growing season. It is concluded that in KC, there is a more pronounced annual oscillation of nitrogen between overground and underground phytomass, which is not observed in IS, and which in KS is intermediate.     

Novel Regioselective Formation of S- and N-Hydroxyl-Alkyls of 5-(3-Chlorobenzo[b]Thien-2-yl)-3-Mercapto-4H-1,2,4-Triazole and A Facile Synthesis of Triazolo-Thiazoles and Thiazolo-Triazoles. Role of Catalyst and Microwave

Regioselective alkylation of 5-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole (1) with hydroxy alkylating agents 2, 3, 13, and the 2,3-O-isopropylidene-1-O-(p-tolylsulfonyl)-glycerol (10) afforded the corresponding S-alkylated derivatives 6, 7, 11, and 14 under both conventional and microwave irradiation conditions; bentonite as a solid support gave better results, with no change in regioselectivity. A facile intramolecular dehydrative ring closure of 6, 7, 11, and 14 using K₂CO₃ in DMF afforded the corresponding fused triazolo-thiazines and thiazolo-triazole 17–19. The isopropylidenes and acetyl derivatives of the products were prepared.     

Chemical constituents isolated from Polygala japonica leaves and their inhibitory effect on nitric oxide production in vitro

A methanolic extract of dried leaves of Polygala japonica Houtt (Polygalaceae) significantly attenuated nitric oxide production in lipopolysaccharide-simulated BV2 microglia. Five anthraquinones chrysophanol (1), emodin (2), aloe-emodin (3), emodin 8-O-β-D-glucopyranoside (4) and trihydroxy anthraquinone (5), and four flavonoids kaempferol (6), chrysoeriol (7), kaempferol 3-gentiobioside (8) and isorhamnetin (9) were isolated from the methanolic extract using bioactivity-guided fractionation. Among them, compounds 1–4, 6 and 7 showed significant inhibitory effect on lipopolysaccharide-induced nitric oxide production in BV2 microglia at the concentrations ranging from 1.0 to 100.0 μM.     

Conferin,potent antioxidant and anti-inflammatory isoflavone from Caragana conferta Benth

Conferin (1), a new isoflavone, has been isolated from the ethyl acetate soluble fraction of Caragana conferta Benth. along with seven known compounds, namely biochanin A (2), p-hydroxybenzoic acid (3), 3,5- dimethoxybenzoic acid (4), ursolic acid (5), erythrodiol (6), pinoresinol (7), and syringresinol (8), reported for the first time from this species. The structure of the new isoflavone was deduced on the basis of spectroscopic studies. Compounds 1 and 2 were investigated for biological activities and showed significant anti-inflammatory activity in carrageenan induced paw edema of rats. Evaluation of antioxidant activity by the radical scavenging method indicated that compound 1 is a potent antioxidant while 2 is moderately active. It was also shown that the reducing capability of compound 2 was remarkably increased in a concentration dependent manner as compared to 1. Compound 1 showed moderate inhibitory activity against the enzyme lipoxygenase, while 2 showed weak activity.     

Studies on the Later Stage of the Biosynthesis of Pleuromutilin

Mutilin (4) and deoxy analogues 2 and 3 are biosynthetic precursors of pleuromutilin (1) in the later stage of biosynthesis. Precursors 2 and 3 are required for studies on the oxygenation steps in biosynthesis, and were synthesized from readily available 1 via 4 by deoxygenation of the hydroxy groups. Feeding experiments with the ²H-labeled precursors confirmed their microbial conversion into 1.     

<Emphasis Type="Italic">Alansmia</Emphasis>, a new genus of grammitid ferns (Polypodiaceae) segregated from <Emphasis Type="Italic">Terpsichore</Emphasis>

Alansmia, a new genus of grammitid ferns is described and combinations are made for the 26 species known to belong to it. Alansmia is supported by five morphological synapomorphies: setae present on the rhizomes, cells of the rhizome scales turgid, both surfaces of the rhizome scales ciliate, laminae membranaceous, and sporangial capsules setose. Other diagnostic characters include pendent fronds with indeterminate growth, concolorous, orange to castaneous rhizome scales with ciliate or sometimes glandular margins, hydathodes often cretaceous, and setae simple, paired or stellate. The group also exhibits the uncommon characteristic of producing both trilete and apparently monolete spores, sometimes on the same plant. New combinations are made for Alansmia alfaroi, A. bradeana, A. canescens, A. concinna, A. contacta, A. cultrata, A. dependens, A. diaphana, A. elastica, A. glandulifera, A. heteromorpha, A. immixta, A. kirkii, A. lanigera, A. laxa, A. longa, A. monosora, A. reclinata, A. semilunaris, A. senilis, A. smithii, A. spathulata, A. stella var. stella, A. stella var. flava, A. turrialbae, A. variabilis, A. xanthotrichia. Lectotypifications are made for Alansmia concina, A. variabilis, Polypodium ciliare, P. flexile, and P. ovalescens. The genus is named in honor of pteridologist Alan R. Smith.     

Inhibition and inactivation of equine aromatase by steroidal and non-steroid al compounds. A comparison with human aromatase inhibition

Abstract

In order to approach the detailed structure-function relationships of aromatase, we studied the inhibitory and inactivatory potencies of several steroidal androstenedione analogues (1: 4-hydroxyandrostenedione, 2: 4-acetoxyandrostenedione and 3: 7α-(4'-amino)phenylthio-4-androstene-3, 17-dione) and non-steroidal imidazole derivatives (4: ketoconazole, 5: miconazole and 6: fadrozole) on equine aromatase in placental microsomes, a well established mammalian model. Human placental microsomes and the purified enzyme from equine testis were also used to compare inhibition by 1 and 2. In equine microsomes, all compounds tested exhibited a competitive inhibition, with K_i values of 4.1, 26 and 1.8 nM for 1, 2 and 3, and of 2400, 1.4 and 4 nM for 4, 5, and 6, respectively. The K_m for androstenedione, the substrate mainly used in these studies, was 1.8 ± 0.13 nM. The three non-steroidal derivatives did not inactivate equine aromatase, but 1 and 2 acted as comparable inactivators to a much higher degree than 3. Compound 1 inhibited in a similar manner (89–94%) purified or equine and human microsomal aromatases, whereas 2 inhibited microsomal aromatase more efficiently in the horse than in man (92% and 33% inhibition, respectively). There was only a 40% inhibition with 2 on the purified equine enzyme, which is no more in the natural membrane environment. The comparisons between equine and human microsomal aromatases allow precise functional and structural differences to be observed with these enzymes.     

A Short High Yielding Synthesis of the Potent Anti-VZV Carbocyclic Nucleoside Analogue Carba-BVDU

Abstract

A short high yielding synthesis of the potent anti-varicella-zoster virus (VZV) carbocyclic nucleoside analogue carba-BVDU 1 starting from aminodiol 2 is described. Reaction of 2 with acyl carbamate 3 and subsequent ring closure under acidic conditions afforded 5-ethyl-2′-deoxy-4′a-carbauridine 5. In situ acetylation of 5 afforded 3′,5′-di-O-acetyl-5-ethyl-2′-deoxy-4′a-carbauridine 6 in 78% overall yield from 2. Radical bromination of 6 with either bromine or NBS and subsequent treatment with triethylamine gave an efficient conversion to 3′,5′-di-O-acetyl-5-(E)-(2-bromovinyl)-2′-deoxy-4′a-carbauridine 7. Deacetylation of 7 afforded 1 in an overall 45–53% yield from 2.     

Nucleosides and Nucleotides. 125. Synthesis and Biological Evaluation of 2′,3′-Dideoxy-3′-fluoro-2′-methylidene Pyrimidine Nucleosides

Abstract

Reaction of 2′-deoxy-2′-methylidene-5′-O-trityluridine (1) with diethylamino-sulfur trifluoride (DAST) in CH₂Cl₂ resulted in the formation of a mixture of (3′R)-2′,3′-dideoxy-3′-fluoro-2′-methylidene derivative 3 and 2′,3′-didehydro-2′,3′-dideoxy-2′-fluoromethyl derivative 4 (3:4 = 1:1.5) in 65% yield. A similar treatment of 1-(2-deoxy-2-methylidene-5-O-trityl-β-D-threo-pentofuranosyl)uracil (19) with DAST in CH₂Cl₂ afforded (3′S)-2′,3′-dideoxy-3′-fluoro-2′-methylidene derivatives 20 and 4 in 38% and 17% yields respectively. Transformation of the uracil nucleosides 4, 12, and 20 into cytosines followed by deprotection furnished the corresponding cytidine derivatives 29, 18, and 25, respectively. The corresponding thymidine congener 27 was also synthesized in a similar manner. All of the newly synthesized nucleosides were evaluated for their inhibitory activities against HIV and for their antiproliferative activities against L1210 and KB cells.