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.     

Synthesis and evaluation of the anti-hepatitis B virus activity of 4′-Azido-thymidine analogs and 4′-Azido-2′-deoxy-5-methylcytidine analogs: structural insights for the development of a novel anti-HBV agent

Abstract

Hepatitis B virus (HBV) infection is a major worldwide health problem that requires the development of improved antiviral therapies. Here, a series of 4′-Azido-thymidine/4′-Azido-2′-deoxy-5-methylcytidine derivatives (6, 10–15) were synthesized, and their anti-HBV activities evaluated. Compounds 10–15 were synthesized via an S_NAr reaction of 18, in which the 4-position of the thymine moiety was activated as the 2,4,6-triisopropylbenzenesulfonate. Compounds 11–15 showed no antiviral activity. However, 4′-Azido thymidine (6) and 4′-Azido-2′-deoxy-5-methylcytidine (10) displayed significant anti-HBV activity (EC₅₀ = 0.63 and 5.99?µM, respectively) with no detectable cytotoxicity against MT-2 cells up to 100?µM.     

Two new anti-plasmodial flavonoid glycosides from Duranta repens

The CHCl₃-soluble fraction of the whole plant of Duranta repens showed anti-plasmodial activity against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum, with IC₅₀ values of 8.5?±?0.9 and 10.2?±?1.5?μg/mL, respectively. From this fraction, two new flavonoid glycosides, 7-O-α-d-glucopyranosyl-3,4′-dihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (1) and 7-O-α-d-glucopyranosyl(6′′′-p-hydroxcinnamoyl)-3,4′-dihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (2), along with five known flavonoids, 3,7,4′-trihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (3), 3,7-dihydroxy-3′-(4-hydroxy-3-methylbutyl)-5,6,4′-trimethoxyflavone (4), 5,7-dihydroxy-3′-(2-hydroxy-3-methyl-3-butenyl)-3,6,4′-trimethoxyflavone (5), 3,7-dihydroxy-3′-(2-hydroxy-3-methyl-3-buten-yl)-5,6,4′-trimethoxyflavone (6), and 7-O-α-d-glucopyranosyl-3,5-dihydroxy-3′-(4′′-acetoxy-3′′-methylbutyl)-6,4′-dimethoxyflavone (7), have been isolated as anti-plasmodial principles. Their structures were deduced by spectroscopic analysis including 1D and 2D NMR techniques. The compounds (1–7) showed potent anti-plasmodial activities against D6 and W2 strains of Plasmodium falciparum, with IC₅₀ values in the range of 5.2–13.5?μM and 5.9–13.1?μM, respectively.     

Nucleotides LXIV[1]: Synthesis,Hybridization and Enzymatic Degradation Studies of 2′-O-Methyl-Oligoribonucleotides and 2′-O-Methyl/Deoxy Gapmers

Abstract

2′-O-Methyloligoribonucleotides, deoxyoligonucleotides and 2′-O-methyl/ deoxy gapmers were synthesized using solid phase phosphoramidite chemistry employing the 2-(4-nitrophenyl)ethyl (npe) protection strategy. Melting temperatures of the synthesized oligonucleotides as well as their stability against degradation by several different nucleases were determined. 2′-O-Methyloligoribonucleotides showed the highest melting temperatures (T_m's) whereas 2′-O-methyl/deoxy gapmers revealed either slightly higher or surprizingly no thermal stabilities compared with their deoxy analogs when using selfcomplementary sequences. Gapmers with four 2′-O-methyl nucleotides on both ends showed about the same stability as all 2′-O-methyloligoribonucleotides against micrococal nuclease, nuclease S₁, and snake venom phosphodiesterase.     

Synthesis and Antiviral Activities of 5-Substituted 1-(2-Deoxy-2-C-methylene-4-thio-β-D-erythro-pentofuranosyl)uracilst†

Abstract

Various 5-substituted 1-(2-deoxy-2-C-methylene-4-thio-β-D-erythropentofuranosyl)uracils (4′-thioDMDUs) were synthesized from D-glucose via sila-Pummerer-type glycosylation. All of the β-anomers of 5-substituted 4′-thioDMDU, except the 5-hydroxyethyl derivative, showed potent anti-HSV-1 activity (ED₅₀ = 0.016–0.096 μg/mL). 5-Ethyl- and 5-iodo-4′-thioDMDUs were also active against HSV-2 (ED₅₀ = 0.17 and 0.86 μg/mL, respectively). 5-Bromovinyl-4′-thioDMDU was particularly active against VZV (ED₅₀ = 0.013 μg/mL).

     

Synthesis of 1-β-L-Arabinofuranosylcytosine (β-L-Ara-C) and 2′-Deoxy-2′-methylene-β-L-cytidine (β-L-DMDC) as Potential Antineoplastic Agents

Abstract

1-β-L-Arabinofuranosylcytosine (β-L-Ara-C, 7) and 2′-deoxy-2′-methylene-β-L-cytidine (β-L-DMDC, 14) have been synthesized via a multi-step synthesis from L-arabinose. These compounds were tested in vitro against L1210, P388, Sarcoma 180, and CEM cells, and found not to be active at a concentration up to 100 μM. β-L-Ara-C and β-L-DMDC were also tested against HSV-1 and HSV-2 and yielded ID₅₀ values of 100 μM.     

Synthetic Nucleosides and Nucleotides. XXX.1 Synthesis and Antiviral Activity of 3′-Azido, 2′,3′-Unsaturated and 2′,3′-Dideoxy Derivatives of E-5-Styryl-2′-Deoxyuridine on Human Immunodeficiency Virus

Abstract

Some new 3′-azido, 2′,3′-unsaturated and 2′,3′-dideoxy 5-styryl analogs of deoxyuridine-related compounds have been synthesized and evaluated against human immunodeficiency virus in vitro. Among these compounds, 3′-azido-2′,3′-dideoxy-5-E-styryluridine (6) and 2′,3′-dideoxy-E-5-styryluridine (9) were found to be active, with ED₅₀ values of 5 and 10 μg/ml respectively.     

Synthesis of 3′,5′-Dithymidylyl-α-hydroxyphosphonate Dimer Building Blocks for Oligonucleotide Synthesis—A New Pro-oliguncleotide

Abstract

The synthesis of the dimer building blocks 1 and 2 and their introduction into (T)₁₅-oligonucleotides is described. The stability against 3′-exonuclease digestion (SVP) as well as the hybridization properties (T_m values) were examined.     

Inhibition of Cytidine Deaminase by Derivatives of 1-(β-D-Ribofuranosyl)-Dihydropyrimidin-2-One (Zebularine)

Abstract

The 2′-deoxy and ara derivatives of 1-β-(D-ribofuranosyl)-1,2-dihydropyrimidin-2-one (zebularine) were synthesized by improved routes and tested for their inhibitory properties against cytidine deaminase. It was shown that the K_i′s of both compounds were comparable to that of the parent zebularine in inhibition studies with purified enzyme. In contrast to zebularine, 2′-deoxy and ara zebularine showed only nominal cytotoxicity against MOLT-4 and L1210 cells in vitro. A model compound for the inhibition of deoxycytidylate deaminase, 2′-deoxyzebularine 5′-monophosphate (6), was also prepared.     

Further in vitro biological activity evaluation of amino-, thio- and ester-derivatives of avarol

Abstract

The acetylcholinesterase inhibitory and/or antitumour activities of amino-, thio- and ester-derivatives of avarol selected were evaluated for the first time at in vitro conditions. Avarol-3′,4′-dithioglycol (1) and avarol-4′-(3)mercaptopropionic acid (3) were shown to be the best inhibitors of the enzyme tested (0.50?µg and IC₅₀ 0.05?mM and 0.50?µg and IC₅₀ 0.12?mM, respectively), while 4′-tryptamine-avarone (9) and avarol-3′-(3)mercaptopropionic acid (2) exhibited the highest cytotoxicity against the human breast T-47D cancer cell line (IC₅₀ 0.66?µg/mL and 1.25?µg/mL, respectively). According to experimental data obtained, the sesquiterpenoid hydroquinone structure of bioactive avarol derivatives may inspire development of new pharmacologically useful substances to be used in the treatment of Alzheimer's disease and/or human breast tumour.     

Effect of the structure of dietary epoxylignan on its cytotoxic activity: relationship between the structure and the activity of 7,7′-epoxylignan and the introduction of apoptosis by caspase 3/7

We compared the cytotoxic activities of dietary epoxylignans and their stereoisomers and found (?)-verrucosin, which is (7S,7′R,8R,8′R)-7,7′-epoxylignan, to be the most cytotoxic epoxylignan against HeLa cells (IC₅₀ = 6.6 μM). On the other hand, the activity was about a factor of 10 less against HL-60. In this research on the relationship between the structure and cytotoxic activity of (?)-verrucosin 13, the 7-(4-methoxyphenyl)-7′-(3,4-dimethoxyphenyl) derivative 60, for which the activity (IC₅₀ = 2.4 μM) is three times greater than (?)-verrucosin 13, was discovered. The induction of apoptosis by caspase 3/7 was observed upon treatment with the (?)-verrucosin derivative.     

Chemical-Enzymatic Synthesis of 3′-Amino-2′, 3′-dideoxy-β-D-ribofuranosides of Natural Heterocyclic Bases and Their 5′-Monophosphates

Abstract

Treatment of O², 3′-anhydro-5′-O-trityl derivatives of thymidine (1) and 2′-deoxyuridine (2) with lithium azide in dimethylformamide at 150 °C resulted in the formation of the corresponding isomeric 3′-azido-2′, 3′-dideoxy-5′-O-trityl-β-D-ribofuranosyl N¹- (the major products) and N³-nucleosides (3/4 and 5/6). 3′-Amino-2′, 3′-dideoxy-β-D-ribofuranosides of thymidine [Thd(3′NH₂)], uridine [dUrd(3′NH₂)], and cytidine [dCyd(3′NH₂)] were synthesized from the corresponding 3′-azido derivatives. The Thd(3′NH₂) and dUrd(3′NH₂) were used as donors of carbohydrate moiety in the reaction of enzymatic transglycosylation of adenine and guanine to afford dAdo(3′NH₂) and dGuo(3′NH₂). The substrate activity of dN(3′NH₂) vs. nucleoside phosphotransferase of the whole cells of Erwinia herbicola was studied.     

Efficient Electrophilic Fluorination for the Synthesis of Novel 2′-Fluoro-3′-Methyl-5′-Deoxyphosphonic Acid Apiosyl Nucleoside Analogues

Novel 5′-deoxyapiosyl purine phosphonic acid analogues with a 2′-electropositive moiety, such as, a fluorine atom were designed and synthesized from commercially available hydroxylacetone. Condensation of a glycosyl donor 10 with purines under Vorbruggen conditions and cross-metathesis give the desired nucleoside phosphonic acid analogues 14, 17, 21, and 24. The synthesized nucleoside analogues were subjected to antiviral screening against HIV-1, and the adenine analogue 17 exhibited weak in vitro anti-HIV-1 activity (EC₅₀ = 26.6 μM)     

Synthesis of Bis(Aziridinyl) Phosphinic Amide Derivatives of Thymidine as Potential Anticancer Agents

Abstract

3′- and 5′-Bis(aziridinyl)phosphinic amide derivatives of thymidine have been synthesized as potential anticancer agents from 3′-amino-3′-deoxythymidine and 5′-amino-5′-deoxythymidine, respectively. The aziridine-containing compounds were tested for their cytotoxic action in vitro against the L1210 leukemia; the 3′-bis(aziridinyl)phosphinic amide derivative was found to be about 11-times more active than its 5′-counterpart in inhibiting the replication of these leukemic cells, with ED₅₀ values of 0.6 and 7 μM, respectively, being obtained.     

Analogues of Uridinediphosphatehexoses. A New Type of Protein Glycosylation Inhibitors That Show Antiviral Activity

Abstract

A series of analogues of UDP-Glc and UDP-GlcNAc prepared by reaction of protected hexoses with ClSO₂NCO and 2′3′-O-isopropylideneuridine, inhibited glycosylation of proteins in HSV-1 infected HeLa cells and were active against several enveloped viruses.     

Compounds with neuroprotective activity from the medicinal plant Machilus thunbergii

The dichloromethane fraction of the bark of Machilus thunbergii Sieb. et Zucc. (Lauraceae) significantly protected primary cultures of rat cortical cells exposed to the excitotoxic amino acid, L-glutamate. Through the activity-guided isolation from the CH₂Cl₂ fraction, (+)-9′-hydroxygalbelgin (1), isogalcatin B (2), (7S,8S,8′R)-3′,4′-dimethoxy-3,4,-methylenedioxylignan-7-ol (3), 1-hydroxy-7-hydroxymethyl-6-methoxyxanthone (4), 5,7-dimethoxy-3′,4′-methylenedioxyflavan-3-ol (5), (+)-(3S,4S,6R)-3,6-dihydroxypiperitone (6), protocatechuic acid methyl ester (7) and tyrosol (8) were obtained. All of them had significant neuroprotective activities against glutamate-induced neurotoxicity in primary cultures of rat cortical cells at concentrations ranging from 0.1 μM to 10.0 μM and were comparable to MK-801, a well-known inhibitor of glutamate receptor.     

Synthesis and Biological Activities of Sugar-Modified 2-(p-n-Butylanilino)-2′-deoxyadenosine Analogues

Abstract

Several sugar-modified 2-(p-n-butylanilino)-2′-deoxyadenosine analogues, including arabino and 2′(R)-azido-2′-deoxy analogues and their 5′-triphosphates were synthesized. These nucleosides thus obtained exhibited moderate cytotoxicity against P-388 leukemic cells in culture (IC₅₀ = 13–24 μ). In contrast to above results, the 5′-triphosphates have been shown to exert strong and selective inhibitory effects on mammalian DNA polymerase α (Ki= 0.02–0.04 μ).     

Relationship Between Conformation and Antiviral Activity-III. 3′-Azidothymidine (AZT) and 3′-Azido-2′, 3′-dideoxy-5-hydroxymethyluridine

Abstract

3′-Azido-2′,3′-dideoxy-5-hydroxymethyluridine (AZHMddUrd) was synthesized to improve the potency of 5-hydroxymethyl-2′-deoxyuridine (HMdUrd) against human immunodeficiency virus (HIV). AZHMddUrd was a very poor inhibitor of HIV replication (ED₅₀ >200 μM) and was also nontoxic up to 400 μM (highest concentration tested) to HT4-6C (HeLa CD₄) cells. AZT was phosphorylated by human cellular thymidine kinase. In contrast, AZHMddUrd and HMdUrd were poor substrates for the kinase. The relationship between molecular conformation and antiretroviral activity for 3′-azidothymidine (AZT), HMdUrd and AZHMddUrd is discussed.     

Synthesis and Antiretroviral Activity of Novel 4′-Fluoro-5′-Deoxyphosphonic Acid Carbocyclic Nucleoside Analogs

Novel 5′-deoxycarbocyclic purine phosphonic acid analogs with the 4′-electropositive moiety, fluorine were designed, and synthesized from glyceraldehyde. The cyclopentenol intermediate, 9, was successfully synthesized by the ring-closing metathesis of divinyl 8. The condensation reaction of cyclopentanol 15 with purine bases under Mitsunobu conditions successfully afforded the desired phosphonate analogs. The synthesized nucleoside phosphonic acid analogs, 19, 22, 26, and 29, were subjected to antiviral screening against human immunodeficiency virus (HIV)-1. Guanine phosphonic acid analog 29 showed significant anti-HIV activity (EC₅₀ = 10.3 μM).     

Antioxidant and α-Amylase Inhibitory Compounds from Aerial Parts of Varthemia iphionoides Boiss

Various extracts of aerial parts of Varthemia (Varthemia iphionoides Boiss) were investigated for radical-scavenging activity, antioxidative activity, and porcine pancreas α-amylase inhibitory activity. The ethanol and water extracts showed a pronounced 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, with inhibition of about 90% at a concentration of 100 μg/ml, and α-amylase inhibitory activity of about 70% at a concentration of 200 μg/ml by the 2-chloro-4-nitrophenyl α-maltotrioside (CNP-G₃) degradation method. The ethanol extract was purified by column chromatography to give seven 3-methoxyflavones (1–7) and eudesmane sesquiterpene, selina-4,11(13)-dien-3-on-12-oic acid (8). The structures of these compounds were established by NMR, MS, and UV spectroscopy. Of 3-methoxyflavones, 5,7,4′-trihydroxy-3,6-dimethoxyflavone (1), 5,7,4′-trihydroxy-3,3′-dimethoxyflavone (2), and 5,4′-dihydroxy-3,7,3′-trimethoxyflavone (3,7,3′-tri-O-methyl-quercetin) (7) exhibited pronounced radical-scavenging activity. The antioxidative activity in the linoleic acid system was considerable in compounds 1, 2, and 5,4′-dihydroxy-3,6,7-trimethoxyflavone (4). Compounds 1, 2, 4, 5 (5,7,4′-trihydroxy-3-methoxyflavone), and 6 (5,4′-dihydroxy-3,7-dimethoxyflavone) showed markedly high inhibitory activity against porcine pancreas α-amylase. Eudesmane sesquiterpene did not show any activity.