Anhydro Derivatives Research Articles

Preparation of 2,5-anhydro di-(hydrido) di-phosphate di-hydrate Mannitol (Glucitol) from Banana Fruit Yields a Possible Fructose 1,6 Bisphosphate Aldolase Inhibitor(s)

With previously unknown chemistry, 2,5-anhydro di-(hydrido)-di-phosphate-di-hydrate mannitol (glucitol) has (have) been prepared by H^- nucleophilic attack of neokestose-1,6-di-phosphate from commercial banana fruit. Negative ion mass spectrometry, Inductively Coupled Mass Spectrometry (ICP-MS), both ms and ms², has been used to characterize the product of this reaction. NaBH₄ in NH₄OH (pH 11.4, IN) for 18 hours was used to convert the 1,6-di-phospho neokestose to the 2,5 anhydro derivative(s). This molecule(s) are structural analogues of the known inhibitors of fructose-1,6 bisphosphate aldolase. The known inhibitors are 2,5 anhydro mannitol and 2,5 anhydro glucitol. They have K_is in the range of 10^-3 mM. It is expected that the di-(hydrido) di-phosphate di-hydrate 2,5 anhydro mannitol (glucitol), prepared here, may be tighter binding to fructose bisphosphate aldolase than the known non-phosphorylated inhibitors, because of their structural similarity to the substrate of the enzyme, fructose-1,6-bisphosphate. If the prepared molecule(s) bind to fbp aldolase, their preparation from inexpensive banana fruit would lead to an inexpensive method for treating fast growing cancer cells. The low cost of making the molecule(s) would allow access to cancer treatment by destitute or low income people.

Isolation and Structure Determination of Echinochrome A Oxidative Degradation Products.

Echinochrome A (Ech A, 1) is one of the main pigments of several sea urchin species and is registered in the Russian pharmacopeia as an active drug substance (Histochrome®), used in the fields of cardiology and ophthalmology. In this study, Ech A degradation products formed during oxidation by O2 in air-equilibrated aqueous solutions were identified, isolated, and structurally characterized. An HPLC method coupled with diode-array detection (DAD) and mass spectrometry (MS) was developed and validated to monitor the Ech A degradation process and identify the appearing compounds. Five primary oxidation products were detected and their structures were proposed on the basis of high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) as 7-ethyl-2,2,3,3,5,7,8-heptahydroxy-2,3-dihydro-1,4-naphthoquinone (2), 6-ethyl-5,7,8-trihydroxy-1,2,3,4-tetrahydronaphthalene-1,2,3,4-tetraone (3), 2,3-epoxy-7-ethyl-2,3-dihydro-2,3,5,6,8-pentahydroxy-1,4-naphthoquinone (4), 2,3,4,5,7-pentahydroxy-6-ethylinden-1-one (5), and 2,2,4,5,7-pentahydroxy-6-ethylindane-1,3-dione (6). Three novel oxidation products were isolated, and NMR and HR-ESI-MS methods were used to establish their structures as 4-ethyl-3,5,6-trihydroxy-2-oxalobenzoic acid (7), 4-ethyl-2-formyl-3,5,6-trihydroxybenzoic acid (8), and 4-ethyl-2,3,5-trihydroxybenzoic acid (9). The known compound 3-ethyl-2,5-dihydroxy-1,4-benzoquinone (10) was isolated along with products 7–9. Compound 7 turned out to be unstable; its anhydro derivative 11 was obtained in two crystal forms, the structure of which was elucidated using X-ray crystallography as 7-ethyl-5,6-dihydroxy-2,3-dioxo-2,3-dihydrobenzofuran-4-carboxylic acid and named echinolactone. The chemical mechanism of Ech A oxidative degradation is proposed. The in silico toxicity of Ech A and its degradation products 2 and 7–10 were predicted using the ProTox-II webserver. The predicted median lethal dose (LD50) value for product 2 was 221 mg/kg, and, for products 7–10, it appeared to be much lower (≥2000 mg/kg). For Ech A, the predicted toxicity and mutagenicity differed from our experimental data.

Antioxidant, Anti-Inflammatory, and Multidrug Resistance Modulation Activity of Silychristin Derivatives.

Silychristin A is the second most abundant compound of silymarin. Silymarin complex was previously described as an antioxidant with multidrug resistance modulation activity. Here, the results of a classical biochemical antioxidant assay (ORAC) were compared with a cellular assay evaluating the antioxidant capacity of pure silychristin A and its derivatives (anhydrosilychristin, isosilychristin and 2,3-dehydrosilychristin A). All the tested compounds acted as antioxidants within the cells, but 2,3-dehydro- and anhydro derivatives were almost twice as potent as the other tested compounds. Similar results were obtained in LPS-stimulated macrophages, where 2,3-dehydro- and anhydrosilychristin inhibited NO production nearly twice as efficiently as silychristin A. The inhibition of P-glycoprotein (P-gp) was determined in vitro, and the respective sensitization of doxorubicin-resistant ovarian carcinoma overproducing P-gp was detected. Despite the fact that the inhibition of P-gp was demonstrated in a concentration-dependent manner for each tested compound, the sensitization of the resistant cell line was observed predominantly for silychristin A and 2,3-dehydrosilychristin A. However, anhydrosilychristin and isosilychristin affected the expression of both the P-gp (ABCB1) and ABCG2 genes. This is the first report showing that silychristin A and its 2,3-dehydro-derivative modulate multidrug resistance by the direct inhibition of P-gp, in contrast to anhydrosilychristin and isosilychristin modulating multidrug resistance by downregulating the expression of the dominant transmembrane efflux pumps.

Synthesis and properties of 2′,3′-anhydro derivatives of (2′-5′)-oligoadenylates containing modified heterobases

New analogs of natural (2′-5′)-oligoadenylates containing ribavirin or BAP-riboside fragments in addition to adenine 2′,3′-anhydronucleoside units were obtained. The synthesized compounds were highly stable to enzymatic hydrolysis by snake venom phosphodiesterase. It was shown that ribavirin-containing (2′-5′)-oligonucleotides could be used for elimination of pathogenic raspberry ringspot virus in culture in vitro of microrunners of black current and cherry.

New C-aryl alditols from Diels-Alder adducts of sugar nitroalkenes

Nitro-, 2-amino- and 2-acetamido-1-(penta-O-acetylpentitol-1´-yl)benzenes were prepared using previously reported Diels-Alder cycloadducts obtained from sugar-derived nitroalkenes with D-galacto and D-manno configurations as starting materials. Deacetylation and oxidative cleavage of the sugar side-chain of nitrobenzene pentitol peracetates yielded nitrobenzaldehydes. From 2-nitro-1-(D-galacto-pentitol-1´-yl)benzene also 1´,4´- and 2´,5´-anhydro derivatives were synthesized.

7,8-dihydro analogs of ecdysteroids

Reactions of 20-hydroxyecdysone, its diacetonide, and 24,25(25,26)-anhydro derivative with lithium tetrahydridoaluminate gave the corresponding 6α- and 6β-epimeric alcohols and 7,8-dihydro analogs.

Functional Screening of Serine Protease Inhibitors in the Medical Leech Hirudo medicinalis Monitored by Intensity Fading MALDI-TOF MS

The blood-feeding invertebrates are a rich biological source of drugs and lead compounds to treat cardiovascular diseases because they have evolved highly efficient mechanisms to feed on their hosts by blocking blood coagulation. In this work, we focused our attention on the leech Hirudo medicinalis. We performed, by "intensity fading" MALDI-TOF mass spectrometry, a comprehensive detection and functional analysis of pre-existent peptides and small proteins with the capability of binding to trypsin-like proteases related to blood coagulation. Combining "intensity fading MS" and off-line LC prefractionation allowed us to detect more than 75 molecules present in the leech extract that interact specifically with a trypsin-like protease over a sample profile of nearly 2,000 different peptides/proteins in the 2-20-kDa range. Moreover we resolved 232 individual components from the complex mixture, 13 of which have high sequence homology with previously described serine protease inhibitors. Our findings indicate that such extracts are much more complex than expected. Additionally, intensity fading MS, when complemented with LC separation strategies, seems to be a useful tool to investigate complex biological samples, establishing a new bridge between profiling, functional peptidomics, and subsequent drug discovery.

Evaluation of the stability of chlortetracycline in granular premixes by monitoring its conversion into degradation products

A methodology for the evaluation of the stability of chlortetracycline (CTC) in granular premixes is described. This methodology is based on the monitoring of the conversion of CTC into its degradation products by an improved gradient liquid chromatography (LC) method, based on one previously described by our laboratory. Sample preparation involves the extraction of CTC and its degradation products prior to LC analysis, using acidified methanol as extraction solvent. The gradient elution LC method proved to be very sensitive, especially towards the late eluting anhydro derivatives. The use of a Hypersil C8 BDS, 5 μm, 250 mm × 4.6 mm i.d. column is recommended since this column allowed a complete separation of the different impurities from each other and from the main component CTC. The applicability of this approach was demonstrated by the analysis of stability samples.

Sucrose esterification under Mitsunobu conditions: evidence for the formation of 6- O-acyl-3′,6′-anhydrosucrose besides mono and diesters of fatty acids

A series of sucrose monoesters and homogeneous or mixed diesters, which have various chain lengths and saturation levels, were prepared under Mitsunobu conditions with good regioselectivity. Among the anhydro derivatives arising from competitive intramolecular etherification, 3′,6′-anhydrosucrose 6- O-monoesters, which have never been reported, were identified.

Semi-synthesis, topoisomerase I and kinases inhibitory properties, and antiproliferative activities of new rebeccamycin derivatives

In the course of structure–activity relationship studies, new rebeccamycin derivatives substituted in 3,9-positions on the indolocarbazole framework, and a 2′,3′-anhydro derivative were prepared by semi-synthesis from rebeccamycin. The antiproliferative activities against nine tumor cell lines were determined and the effect on the cell cycle of murine leukemia L1210 cells was examined. Their DNA binding properties and inhibitory properties toward topoisomerase I and three kinases PKCζ, CDK1/cyclin B, CDK5/p25 and a phosphatase cdc25A were evaluated. The 3,9-dihydroxy derivative is the most efficient compound of this series toward CDK1/cyclin B and CDK5/p25. It is also characterized as a DNA binding topoisomerase I poison. Its broad spectrum of molecular activities likely accounts for its cytotoxic potential. This compound which displays a tumor cell line-selectivity may represent a new lead for subsequent drug design in this series of glycosylated indolocarbazoles.

Ring‐Opening Reactions of Iminosugar‐Derived Aziridines: Application to the General Synthesis of α‐1‐C‐Substituted Derivatives of Fagomine.

AbstractFor Abstract see ChemInform Abstract in Full Text.

β-Keto-ester chemistry and ketolides. synthesis and antibacterial activity of 2-halogeno, 2-methyl and 2,3 enol-ether ketolides

The effect of 2,3 modifications on the antibacterial activity of ketolides was evaluated by introducing substituents in position 2 and converting the C-1, C-2, C-3 β-keto-ester into stable 2,3 enol-ether or 2,3 anhydro derivatives. Introduction of a fluorine in C-2 is beneficial with regard to the overall antibacterial spectrum whereas the enol-ether and 2,3 unsaturated compounds, as well as the bulky gem dimethyl or 2-chloro derivatives, are less active particularly against erythromycin resistant strains. A 2-fluoro ketolide derivative demonstrates good antibacterial activity and in vivo efficacy against multi-resistant Streptococcus pneumoniae. Compared to azithromycin against Haemophilus influenzae, this compound is equivalent in vitro and slightly more active in vivo. These results demonstrate that within the ketolide class, to retain good antibacterial activity, position 2 needs to remain tetrahedral and tolerates only very small substituents such as fluorine.

Evaluation of (1R,2R)-1-(5'-methylfur-3'-yl)propane-1,2,3-triol, a sphydrofuran derivative isolated from a Streptomyces species, as an anti-herpesvirus drug.

(1R,2R)-1-(5'-Methylfur-3'-yl)propane-1,2,3-triol (MFPT), a stable anhydro derivative of sphydrofuran, was obtained from the culture broth of STREPTOMYCES: sp. strain FV60 as an inhibitor of herpes simplex virus type 1 (HSV-1). The compound showed antiherpetic activity with a 50% inhibitory concentration of 1.2 IM in an in vitro assay system. Although the binding of virus to host cells was not inhibited, the penetration of virus into cells was moderately blocked by MFPT. Some of the viruses, once they had penetrated cells, failed to form plaques in the presence of MFPT. When added to the late stages of HSV-1 replication, MFPT also inhibited virus production. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis of isotope-labelled HSV-specific proteins revealed that a protein or proteins with reduced molecular weight (about 120 kDa) was clearly detected in cells treated with MFPT. Western blot analysis with antibodies against three HSV-specific glycoproteins (gB, gC and gD) showed a significant difference in gC synthesis between untreated and MFPT-treated cells. Release of progeny viruses was suppressed by MFPT. Syncytium formation by HSV-1 strain HF was inhibited and small plaques with rounded cells were formed in MFPT-treated cell cultures. When wild-type HSV-1 was serially propagated under the selective pressure of MFPT, resistant virus emerged. MFPT-resistant progeny were accompanied by the formation of plaques with rounded cells. These results, taken together, suggest that MFPT might act by limiting the maturation of HSV-specific glycoproteins, particularly of HSV-1 gC.

Enzymatic Synthesis of a Branched-Chain Hexulose: 5-Deoxy-5-C-hydroxymethyl-β-L-xylo-hex-2-ulopyranose

The coupling of dihydroxyacetone phosphate with 3-hydroxy-2-(hydroxymethyl)propanal (1) in the presence of rabbit muscle aldolase afforded a branched-chain hexulose phosphate isolated in 64% yield as the barium salt 3.The parent, dephosphorylated sugar 4 was converted to its anhydro derivative 8 and glycoside 9.

Phenylsulfonyl-methylenation of aldonolactones

The low temperature addition of dilithiomethylphenyl sulfone to 2,3-O-isopropylidene-D-erythronolactone, and to 5-O-(tert-butyldimethylsilyl)-2,3-O-isopropylidene-D-ribofuranolactone gives the lactols 2 and 3a, respectively. Dehydration of lactol 2 in the presence of boron trifluoride etherate produces tetrahydrofuranylidene sulfones 5 and 6 in good yields. The reaction of lactol 3a under the same reaction conditions proceeds with formation of the 1′,5′-anhydro derivative 7 via competing intramolecular substitution.

Atmospheric pressure chemical ionization tandem mass spectra of α- and β-aspartame

Atmospheric pressure chemical ionization tandem mass spectrometry was used to study the gas-phase reactions of protonated α- and β-aspartame. The results show that under collision-induced dissociation conditions, these ions undergo dehydration to form anhydro derivatives in addition to carbon–carbon bond cleavages. The fragment ions formed from these dissociation pathways can be used to distinguish the two isomers. Specifically, ions at m/z 175 and 88 are unique to protonated α-aspartame whereas ions at m/z 249, 189 and 74 are unique to protonated β-aspartame. © 1998 John Wiley & Sons, Ltd.

Synthesis of sugar-modified 2,6-diaminopurine and guanine nucleosides from guanosine via transformations of 2-aminoadenosine and enzymatic deamination with adenosine deaminase

Treatment of 2,6-diaminopurine riboside (2-aminoadenosine) with α-acetoxyisobutyryl bromide in acetonitrile gave mixtures of the trans 2′,3′-bromohydrin acetates 2. Treatment of 2 with zinc–copper couple effected reductive elimination, and deprotection gave 2,6-diamino-9-(2,3-dideoxy-β-D-erythro-pent-2-enofuranosyl)purine (3a). Treatment of 2 with Dowex 1 × 2 (OH−) resin in methanol gave the 2′,3′-anhydro derivative 4. Stannyl radical-mediated hydrogenolysis of 2 and deprotection gave the 2′-deoxy 6a and 3′-deoxy 7a nucleosides. Treatment of the 3′,5′-O-(tetraisopropyldisiloxanyl) derivative (5a) with trifluoromethanesulfonyl chloride – 4-(dimethylamino)pyridine gave 2′-triflate 5c. Displacement with lithium azide–dimethylformamide and deprotection gave the arabino 2′-azido derivative 8a, which was reduced to give 2,6-diamino-9-(2-amino-2-deoxy-β-D-arabinofuranosyl)purine (8b). Sugar-modified 2,6-diaminopurine nucleosides were treated with adenosine deaminase to give the corresponding guanine analogues. Keywords: adenosine deaminase, 2,6-diaminopurine nucleosides, deoxygenation, guanine nucleosides, nucleosides.

New sialic acids from biological sources identified by a comprehensive and sensitive approach: liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) of SIA quinoxalinones.

Sialic acids are a family of 9-carbon carboxylated sugars, where different substitutions of the backbone define over 30 members. Biological roles of these substitutions have been missed until recently because of their low abundance and lability to conventional isolation/purification methods. This new approach characterizes sialic acids using electrospray ionization-mass spectrometry (ESI-MS) to monitor the HPLC separation of their DMB (1,2-diamino-4,5-methylenedioxy-benzene) derivatives (quinoxalinones). A combination of retention times and spectra characteristics allows definition of the type and position of the various substituents. This approach requires no previous purification, involving a simple derivatization reaction followed by direct injection on the microbore HPLC column. A complete spectrum, including molecular ions and CAD fragments of a sialic acid quinoxalinone, is obtained by injecting 10-20 pmol of the compound. Individual quinoxalinones can be purified by regular RP-HPLC and analyzed by direct-injection ESI-MS or LSIMS. Using this approach, we identified 28 different sialic acids, including the following new species: Neu5Gc9Lt (BSM), anhydro derivatives of Neu5Ac other than the 4,8-anhydro (horse serum hydrolyzates), KDN5(7)Ac and KDN5(7),9Ac2 (amphibian Pleurodeles waltl), four isomers of Neu5Gc8MexAc and three anhydro derivatives of Neu5Gc8Me (glycolipids of the starfish Pisaster brevispinus), and Neu5Ac8S (in addition to Neu5Gc8S, in the glycolipids of the sea urchin Lovenia cordiformis). Results show the usefulness of LC-ESI-MS to study sialic acid diversity, and identification of small amounts of unexpected sialic acids or new members of their family.

A highly diastereoselective synthesis of 4-octulose and 2-deoxy-4-octulose from a d-fructose derivative

Bishydroxylation of methyl (Z)-2,3- dideoxy-4,5:6,7- di-O- isopropylidene-β- d -arabino- oct-2-ene-4-ulo-4,8-pyranosonate 1 with osmium tetraoxide proceeded with extremed high diastereoselectivity to give only methyl 4,5:6,7- di-O- isopropylidene-β- d -arabino- l -erythro- oct-4-ulo-4,8- pyranosonate 2. Configurations of the new stereogenic centers (C-2,3) in 2 were determined by degradation of the C-5,6,7,8 fragment to the well-known methyl 2,3,4- tri-O- methyl- d-(+)-erythronate 7. Transformation of 2 into the required d -arabino- l -erythro- oct-4-ulosa 10, was achieved by a methodology that implied, protection to 8, reduction of the ester group in 8 to a hydroxymethyl group in 9, and finally deprotection to the free d -arabino- l -erythro- oct-4-ulosa 10. On the other hand, epoxidation reaction on (E)-2,3- dideoxy-4,5:6,7-di-O- isopropylidene-β- d -arabino- oct-2-ene-4-ulo- 4,8-pyranose 11 afforded only the corresponding 2,3- anhydro derivative 12 with β- d -arabino- d -threo configuration, as could be demonstrated by degradation to ( S)-1,2,4-trimetoxybutane 16, which synthesis is reported herein.

Synthesis of 2,2′-Anhydro Nucleosides with a Modified Sugar Side-Chain

Abstract 2,2′-Anhydro-1-(5,6-di-O-benzoyl-β-D-altrofuranosyl)thymine 6 and uracil derivative 7 are prepared by transformation of the corresponding 5′,6′-di-O-benzoyl-3′-O-mesyl-β-D-glucofuranosyl nucleosides 4 and 5 into the 2,2′-anhydro derivatives 6 and 7 using DBU.