SYNTHESIS OF SOME ACYCLONUCLEOSIDES α-(PYRAZOLO[3,4-d]PYRIMIDIN-4-YLTHIO)-ALKYLAMIDES

The synthesis of some acyclic α-(pyrazolo[3,4-d]pyrimidin-4-ylthio)alkylamide nucleosides is described.     

PARALLEL DNA CONTAINING PYRAZOLO[3,4-D]PYRIMIDINE ANALOGUES OF ISOGUANINE

The phosphoramidites of 8-aza-7-deaza-2′-deoxyisoguanosine (1a) and its bromo derivative 1b as well as of 6-aza-2′-deoxyisocytidine and its 5-methyl derivative (3a,b) were synthesized. Parallel-stranded duplexes containing the nucleosides 1a,b show a significantly enhanced duplex stability compared to those containing 2′-deoxyisoguanosine.     

SYNTHESIS OF OLIGONUCLEOSIDE BORANOPHOSPHATES VIA AN H-PHOSPHONATE METHOD WITHOUT NUCLEOBASE PROTECTION

Short oligonucleoside boranophosphates containing all four nucleosides were synthesized on solid support using base-unprotected nucleoside H-phosphonate monomers. This strategy avoided irreversible base modifications during the boronation procedure. Structures of the boranophosphate oligomers were confirmed by ¹H, ³¹P, ¹⁰B NMR and MS analysis as well as by enzymatic hydrolysis.     

EVALUATION OF AN EFFECTIVE METHOD TO ESTIMATE AGE OF CAPE FUR SEALS USING GROUND TOOTH SECTIONS

Teeth of known-age Cape fur seals Arctocephalus pusillus pusillus were used to validate age estimated from ground sections. In the canines, dentine growth layer groups (GLGs) reflected age accurately but no reliable readings could be obtained from GLGs in the cementum. Upper canines were the most suitable for age estimation. By contrast, in the postcanines where the cementum is thicker, only GLGs in the cementum could be used for age determination, but not with the same accuracy as for dentine in the canines. Therefore, it is recommended that GLGs in the dentine be used to determine age in the Cape fur seal. However, pulp cavities in canines closed at about 13 yr and consequently GLGs in the cementum of the postcanines should be used where the pulp cavities of canines are closed. Accurate estimation of age is not possible from the dentine of older animals.     

蓝藻的一种人工转化系统研究

本研究用溶菌酶处理ＳｙｎｅｃｈｏｃｏｃｃｕｓＰＣＣ６３０１细胞诱导人工感受态,并用外源质粒ｐＢＲ３２５转化受体细胞表达氯霉素抗性,转化频率接近５×１０￣（－５）转化子／细胞。用转化子ＤＮＡ再进行次级转化,转化频率可达５×１０￣（－４）转化子／细胞。这比以前的研究者对同种藻株,用克隆的ＤＮＡ、通过生理感受态进行转化得到的转化频率要高。ＤＮＡ电泳、次级转化和斑点杂交证明外源质粒通过单交换已经整合到了受体细胞染色体上。这些结果表明,人工转化系统是有效的,并具有可重复性。对于影响转化的一些条件,如ＤＮＡ与细胞保温时间、藻龄、光照或黑暗培养,也同时进行了研究。     

MORPHOLOGICAL AND PHYSIOLOGICAL CHARACTERISTICS OF AN ACHLOROPHYLLOUS MUTANT SOYBEAN VARIETY SUSTAINED TO MATURATION VIA GRAFTING

An achlorophyllous lethal-yellow (LY) soybean mutant was demonstrated to be capable of survival when provided with a suitable carbon source. In this study the carbon source was a normally pigmented soybean plant to which the LY was grafted. When grafted to a green plant the LY grew to maturity and produced viable seeds. Under moderate to high light intensities the LY leaves possessed virtually no chlorophyll; however, under low levels of continuous illumination the chlorophyll content of LY leaves increased greatly and these leaves were then capable of limited photosynthetic activity. Under the low-light conditions, LY plants could survive, independent of grafting, for several weeks. A major genetic difference in the LY when compared to its chlorophyllous counterparts appears to be a tendency for rapid chlorophyll degradation rather than inability to synthesize it.     

Syntheses of s-Triazolo [4,3-a] Pyrimidine Derivatives

The metabolism in rats of dihydrocapsaicin, a pungent principle of hot pepper, was investigated in vivo and in vitro by thin-layer chromatography, high-performance liquid chromatography and combined gas chromatography-mass spectrometry. Within 48 hr of oral administration of dihydrocapsaicin (20 mg/kg body weight) to male adult rats, unchanged dihydrocapsaicin and eight of its metabolites were identified in urine; i.e., dihydrocapsaicin (8.7% of total dose), vanillylamine (4.7%), vanillin (4.6%), vanillyl alcohol (37.6%) and vanillic acid (19.2%) as free forms and/or their glucuronides. The proportions of free and glucuronide metabolites in urine were 14.5% and 60.5% of the total dose. Part of the unchanged dihydrocapsaicin (10% of total dose) was excreted into the feces within 48 hr. Cell-free extracts of rat liver catalyzed the hydrolysis of dihydrocapsaicin to vanillylamine and 8-methyl nonanoic acid. The former compound was further transformed to vanillin in situ. Dihydrocapsaicin-hydrolyzing enzyme activity was found in various organs of rat. The activity was located mainly in the liver. On the basis of the present data, the metabolic pathway of dihydrocapsaicin in rats was proposed.     

EXISTENCE OF AN ENDOGENOUS INHIBITOR OF DNA SYNTHESIS IN RABBIT SMALL INTESTINE SPECIFICALLY EFFECTIVE ON CELL PROLIFERATION IN ADULT MOUSE INTESTINE

Aqueous extracts from rabbit organs were prepared by homogenization and centrifugation at 105,000 g . After precipitation with ammonium sulphate, the 0–50 fraction was separated by ultrafiltration through Amicon XM 100 and XM 300 membranes yielding two filtrate fractions (U₁ and U₂) and one retentate fraction (U₃). Only U₁ and U₃ inhibited thymidine incorporation into DNA. After a single injection of U₁ from rabbit small intestine, the uptake of tritiated thymidine was decreased in mouse jejunal and colonic DNA. This effect, totally reversible after 7 hr, was found in neither the kidney nor the testis. The U₁ fractions of colon and non-digestive organs (kidney, testis) were found not to exert a significant inhibition on thymidine incorporation into intestinal DNA in vivo. The U₃ fraction from rabbit small intestine also decreased the uptake of tritiated thymidine in mouse jejunal and colonic DNA in vivo. However, this inhibition was irreversible and not tissue-specific. Slowing of cell migration was also noticed in the jejunum of mice injected with U₁ or U₃, as ascertained radioautographically by determining the position of the leading edge of the labelled cells in U₁- or U₃-injected mice compared with controls. A decrease of mitotic activity in U₁- and U₃-injected mice was recorded 8·5 hr after a single injection of small intestinal fractions. Our results suggest that U₁ and U₃ from rabbit small intestine contain one or more substances which may act on the G₁—S transition of the cell cycle in the mouse intestine. However, only the effect of U₁ is reversible and tissue specific. Our data suggest the existence of a factor, having a low molecular weight, which regulates intestinal cell proliferation.     

BINDING OF [3H]KAINIC ACID, AN ANALOGUE OF l-GLUTAMATE, TO BRAIN MEMBRANES

—The specific binding of [³H]kainic acid to synaptic membranes from rat brain was saturable with a dissociation constant of about 60 nm . The apparent maximal number of binding sites was about 1 pmol/mg protein. The most effective displacer of specific [³H]kainic acid binding was quisqualic acid, a powerful excitant which is structurally similar to l -glutamate. However, quisqualic acid was one-third as potent a displacer as kainic acid itself. l -Glutamate was the next potent in displacing [³H]kainic acid binding, but also was less effective (1/25) than kainic acid itself. All other compounds including suspected neurotransmitters were at least an order of magnitude lower in potency compared to l -glutamate. When various tissues and brain regions were tested for specific [³H]kainic acid binding, we found the specified binding was localized to grey matter in the brain. In studies of subcellular fractionation of the brain, we found that crude synaptosomal membrane preparations were most enriched in specific [³H]kainic acid binding. Specific [³H]kainic acid binding in various regions of the rat brain varied 5- to 6-fold.     

SYNTHESIS AND ANTI-HIV ACTIVITY OF [D4U]-[TROVIRDINE ANALOGUE] AND [D4T]-[TROVIRDINE ANALOGUE] HETERODIMERS AS INHIBITORS OF HIV-1 REVERSE TRANSCRIPTASE

ABSTRACT

A series of eleven heterodimers containing both a nucleoside analogue (d4U, d4T) and a non-nucleoside type inhibitor (Trovirdine analogue) were synthesized and evaluated for their ability to inhibit HIV replication. Unfortunately, the (N-3)d4U-Trovirdine conjugates (9a–e) and (N-3)d4T-Trovirdine conjugates (10a–f) were found to be inactive suggesting that the two individual inhibitor compounds do not bind simultaneously in their respective sites.     

EFFICIENT SYNTHESIS OF FUSED ISOTHIAZOLO C-NUCLEOSIDES. III. SYNTHESIS OF 7-SUBSTITUTED ISOTHIAZOLO[4,5-d]PYRIMIDINE C-NUCLEOSIDES*

The Divakar-Reese procedure has been successfully applied for transforming 7-oxo-isothiazolo[4,5-d]pyrimidine C-nucleosides (4a,b, 5a,b, 6a) via 1,2,4-triazol-1-yl intermediates (7a,b, 8a,b) into various 7-substituted C-nucle- osides 15a,b, 16a,b, 17a, 18a, 19a,b, 20a,b; their subsequent deprotection provides novel types of unusual C-glycosides 22b, 23a, 24a,b, 25b, 26b.

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BINDING OF [99mTc]CHONDROITIN SULFATE TO SCAVENGER RECEPTORS ON HUMAN CHONDROCYTES AS COMPARED TO BINDING OF OXIDIZED [125I]LDL ON HUMAN MACROPHAGES

ABSTRACT

Chondroitin sulfate (CS) used for treatment of osteoarthritis exerts distinct effects on human articular chondrocytes in vitro. We performed a binding analysis with ^99mTc-labeled CS (Condrosulf, a commercial CS preparation containing calcium stearate) and cultured human chondrocytes in order to evaluate the presence of specific receptors. Saturation binding at 37°C for 2?h revealed the presence of high-affinity binding sites for CS with a K_d of 2.3 × 10^?9?mol/L and a B_max of 5.0 × 10⁸. Extensive dialysis of Chondrosulf led to a decrease of the binding affinity by 52.5 ± 19.5% and of the number of CS binding sites/cell by 62.0 ± 14.0%, demonstrating that the additive present in the Condrosulf preparation enhances CS binding. The nature of the binding site is not yet known but evidence exists in the literature that the scavenger receptor CD36, thoroughly investigated on macrophages, is also found on chondrocytes and might be involved in CS binding. Therefore, we undertook a comparative binding study with human monocytes and labelled LDL and oxidized LDL, the latter being a postulated atherogenic agent in atherosclerosis. For [¹²⁵I]-LDL binding we found a K_d of 0.45 × 10^?8?mol/L and a B_max of 0.14 × 10⁶ on quiescent monocytes and for [¹²⁵I]-(ox)LDL binding a K_d of 1.8 × 10^?8?mol/L and a B_max of 1.3 × 10⁶ using LPS-activated monocytes. These data are comparable to the binding affinity found for lipoprotein–proteoglycan-complexes and hence are an indication but not a proof that CD36 is involved in CS binding to human chondrocytes.     

AN EFFICIENT PROCESS FOR THE SYNTHESIS OF CYCLIC HPMPC

1-[((S)-2-Hydroxy-2-oxo-1,4,2-dioxaphosphorinan-5-yl)methyl] cytosine (cyc-lic HPMPC) was readily synthesized in gram to multi-kilogram quantities by treating a DMF suspension of HPMPC with four molar equivalents of ethyl chloroformate. This dehydrative intramolecular cyclization process typically afforded cHPMPC in 94% isolated yield and high purity. Benign by-products and solvents were easily removed.     

AN ATTEMPT TO DETECT UTILIZATION OF DNA BREAKDOWN PRODUCTS FROM THE TAPETUM FOR DNA SYNTHESIS IN THE MICROSPORES OF LILIUM LONGIFLORUM

Takats , Stephen T. (Brookhaven Natl. Lab., Upton, N. Y.) An attempt to detect utilization of DNA breakdown products from the tapetum for DNA synthesis in the microspores of Lilium longiflorum. Amer. Jour. Bot. 49(7): 748–758. Illus. 1962.—The tapetum in anthers of Lilium longiflorum encloses the developing microspores and when it degenerates is a possible source of precursor material for DNA⁴ synthesis in the microspores. To check this, time-course experiments were carried out tracing the fate of label introduced into the tapetal DNA. H³-thymidine was given in vivo to anthers during late pachytene of meiosis, when the tapetum can be selectively labelled. Growth was then followed by sampling anthers until the tapetum degenerated and the microspores synthesized DNA and divided. Autoradiographs indicated that the label in tapetal nuclei was lost shortly before DNA synthesis in the microspores. The microspore walls were transiently labelled, but the microspore nuclei did not incorporate a detectable amount of label. The results are discussed in the light of related biochemical findings, and are explained on the basis of: (1) complete catabolism of tapetal DNA (or tapetal thymine); and (2) the existence of a non-tapetal pool of precursors.     

SYNTHESIS OF MODIFIED NUCLEOSIDE 5′-TRIPHOSPHATES FOR IN VITRO SELECTION OF CATALYTIC NUCLEIC ACIDS [1]

2′-Modified pyrimidine nucleoside 5′-triphosphates comprising amino, imidazole and carboxylate functionality attached to the 5-position of the base were synthesized. Two different phosphorylation methods were used to optimize the yields of these highly modified triphosphates.     

AN IMPROVED SYNTHESIS OF 9-[2-(DIETHOXYPHOSPHONOMETHOXY)ETHYL]ADENINE AND ITS ANALOGUES WITH OTHER PURINE BASES UTILIZING THE MITSUNOBU REACTION

Abstract

Unprotected adenine, 6-chloropurine, 2.6-diaminopurine. and 2-amino-6-chluropurine have been directly coupled with 2-(diethoxyphosphonomethoxy)ethanol under Mitsunobu reaction conditions to provide acyclic phosphonate nucleotide analogues which are intermediates for antiviral agents such as PMEA.     

Kinase inhibitions in pyrido[4,3-h] and [3,4-g]quinazolines: Synthesis,SAR and molecular modeling studies

New pyrido[3,4-g]quinazoline derivatives were prepared and evaluated for their inhibitory potency toward 5 protein kinases (CLK1, DYRK1A, GSK3, CDK5, CK1). A related pyrido[4,3-h]quinazoline scaffold with an angular structure was also synthesized and its potency against the same protein kinase panel was compared to the analogous pyrido[3,4-g]quinazoline. Best results were obtained for 10-nitropyrido[3,4-g]quinazoline 4 toward CLK1 with nanomolar activities.     

Synthesis and in vitro anti-hepatitis B virus activity of 6H-[1]benzothiopyrano[4,3-b]quinolin-9-ols

A series of novel 6H-[1]benzothiopyrano[4,3-b]quinoline derivatives were prepared and evaluated for their anti-hepatitis B virus (HBV) activity and cytotoxicity in human hepatoblastoma-derived liver Hep-G2 cells. Compounds 10g, 10h, 10j, 10l and 10o were found to be potent anti-HBV compounds with IC₅₀ values less than 50 μM. The most promising compound was 10l, with an IC₅₀ value of 14.7 μM and a SI value of 12.4. This is the first report of the anti-HBV effects of 6H-[1]benzothiopyrano[4,3-b] quinolin-9-ols.