Derivatives of methanopterin, a coenzyme involved in methanogenesis

Degradational studies of methanopterin, a coenzyme involved in methanogenesis, are reported. The results of these studies are in full accordance with the proposed structure of methanopterin as N-[1'-(2'-amino-4'-hydroxy-7' -methyl-6'-pteridinyl)ethyl]-4-[2', 3', 4', 5'-tetrahydroxypent-1'-yl(5'-1' )O-alpha-ribofuranosyl-5'-phosphoric acid] aniline in which the phosphate group is esterified with alpha-hydroxyglutaric acid. Acid hydrolysis of methanopterin cleaved the 5'----1' glycosidic bond and yielded a 'hydrolytic product' which was identified as N-[1'-(2'-amino-4'-hydroxy-7' -methyl-6'-pteridinyl)ethyl]-4-[2', 3', 4', 5'-tetrahydroxypent-1'-yl]aniline. Alkaline permanganate oxidation of methanopterin yielded 7-methylpterin-6-carboxylic acid. Catalytic (or enzymatic) hydrogenation of methanopterin gave a mixture of 6-ethyl-7-methyl-7,8-dihydropterin, 6-ethyl-7-methylpterin and a third compound, named methaniline which was identified as 4-[2', 3', 4', 5'-tetrahydroxypent-1'-yl(5'----1')O-alpha -ribofuranosyl-5'-phosphoric acid]aniline, in which the phosphate group is esterified with alpha-hydroxyglutaric acid. Methanosarcina barkeri contains a closely related coenzyme called sarcinapterin, which was identified as a L-glutamyl derivative of methanopterin, where the glutamate moiety is attached to the alpha-carboxylic acid group of the alpha-hydroxyglutaric acid moiety of methanopterin via an amide linkage.     

Iridoid glucosides and flavones from the aerial parts of Avicennia marina

Two new iridoid glucosides, namely, 2'-O-[(2E,4E)-5-phenylpenta-2,4-dienoyl]mussaenosidic acid (1; mussaenosidic acid = [1S-(1alpha,4aalpha,7alpha,7aalpha)]-1-(beta-D-glucopyranosyloxy)-1,4a,5,6,7,7a-hexahydro-7-hydroxy-7-methylcyclopenta[c]pyran-4-carboxylic acid) and 2'-O-(4-methoxycinnamoyl)mussaenosidic acid (2), were isolated from the aerial parts of the mangrove plant Avicennia marina. Beside that, one known iridoid glucoside, 2'-O-coumaroylmussaenosidic acid (3) and four known flavones (flavone = 2-phenyl-4H-1-benzopyran-4-one) including 4',5-dihydroxy-3',7-dimethoxyflavone (4), 4',5-dihydroxy-3',5',7-trimethoxyflavone (5), 4',5,7-trihydroxyflavone (6), and 3',4',5-trihydroxy-7-methoxyflavone (7) were also isolated and identified. The structures of these compounds were elucidated by NMR spectroscopy and by low- and high-resolution mass spectrometry. The chemotaxonomic significance of these findings was discussed. In addition, each isolated compound was evaluated for the ability of alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity.     

Degradation of the plant flavonoid phellamurin by Aspergillus niger.

We have previously described the structure of phellamurin, a plant flavonoid, as 3,4',5,7-tetrahydroxy-8-isoprenylflavanone-7-O-glucoside (17). Degradation of phellamurin by Aspergillus niger using modified Czapek-Dox medium as well as phellamurin or one of its degradation products as a sole carbon source, is reported here. Eleven compounds are identified from phellamurin degradation products. A. niger apparently decomposes phellamurin by first removing glucose with beta-glucosidase; neophellamuretin is the first degradation product. Fission of the heterocyclic ring of (5'-hydroxyisopropyl-4',5'-dihydrofurano)[2',3'-h]3,4',5-trihydroxyflavanone, which is obtained from neophellamuretin through a few alterations of the side chain, is followed by cleavage of a C--C bond between C=O and carbon at alpha-position and conversion of (5'-hydroxyisopropyl-4',5'-dihydrofurano)[2',3'-d]-2',4,6',alpha-tetrahydroxychalcone to rho-hydroxymandelic acid (B-ring) and 2,4,6-trihydroxy-5-carboxyphenylacetic acid (A-ring). It is suggested that rho-hydroxymandelic acid is oxidized to rho-hydroxybenzoic acid. 2,4,6-Trihydroxy-5-carboxyphenylacetic acid is metabolized to phloroglucinol carboxylic acid, which subsequently is decarboxylated to phloroglucinol. These results provided new information on the isoprene unit metabolism of the side chain of phellamurin and firmly established the degradation pathway of phellamurin by A. niger.     

Degradation of the plant flavonoid phellamurin by Aspergillus niger.

We have previously described the structure of phellamurin, a plant flavonoid, as 3,4',5,7-tetrahydroxy-8-isoprenylflavanone-7-O-glucoside (17). Degradation of phellamurin by Aspergillus niger using modified Czapek-Dox medium as well as phellamurin or one of its degradation products as a sole carbon source, is reported here. Eleven compounds are identified from phellamurin degradation products. A. niger apparently decomposes phellamurin by first removing glucose with beta-glucosidase; neophellamuretin is the first degradation product. Fission of the heterocyclic ring of (5'-hydroxyisopropyl-4',5'-dihydrofurano)[2',3'-h]3,4',5-trihydroxyflavanone, which is obtained from neophellamuretin through a few alterations of the side chain, is followed by cleavage of a C--C bond between C=O and carbon at alpha-position and conversion of (5'-hydroxyisopropyl-4',5'-dihydrofurano)[2',3'-d]-2',4,6',alpha-tetrahydroxychalcone to rho-hydroxymandelic acid (B-ring) and 2,4,6-trihydroxy-5-carboxyphenylacetic acid (A-ring). It is suggested that rho-hydroxymandelic acid is oxidized to rho-hydroxybenzoic acid. 2,4,6-Trihydroxy-5-carboxyphenylacetic acid is metabolized to phloroglucinol carboxylic acid, which subsequently is decarboxylated to phloroglucinol. These results provided new information on the isoprene unit metabolism of the side chain of phellamurin and firmly established the degradation pathway of phellamurin by A. niger.     

地菍的化学成分(英文)

为了研究野牡丹科药用植物地菍(Melastoma dodecandrum)的化学成分,采用柱层析方法分离鉴定了15个化合物,通过波谱分析及对比文献等方法鉴定为4-O-β-D-吡喃葡萄糖基-3,3',4'-三甲氧基鞣花酸(1),槲皮素3-O-刺槐二糖苷(2),8-C-吡喃葡萄糖基-5,7,3',4'-四羟基黄酮(3),3-O-β-D-吡喃葡萄糖基-4',5,7-三羟基黄酮(4),6-C-吡喃葡萄糖基-4',5,7-三羟基黄酮(5),3-hydroxy-22(29)-hopen-23-oic acid(6),2,3-dihydroxy-9(11)-fernen-23-oic acid(7),3β-sitosterol laminaribioside(8),姜糖酯B(9),3-O-β-D-galactopyranoside-glycerol1-alkanoates(10),胡萝卜苷(11),β-谷甾醇(12),二十八烷醇(13),二十四烷酸(14)以及三十四烷(15)化合物结构。所有化合物均为首次从该植物中分离得到。     

Structural characterization of tatiopterin, a novel pterin isolated from Methanogenium tationis

Cofactor extracts of Methanogenium tationis were screened for the presence of pterin-derivatives. Methanopterin, sarcinapterin and 7-methylpterin were absent, while 2-amino-4-hydroxy-pteridine and another blue fluorescent compound with a pterin spectrum were detected. The latter pterin was purified by ion exchange and reversed-phase column chromatography. The structure of this compound was elucidated by combining spectrophotometry, amino acid analysis and 1H-NMR spectroscopy. The pterin, which we named tatiopterin, was identified as an aspartyl derivative of sarcinapterin with a 7-proton instead of a 7-methyl group in the pterin moiety. The IUPAC name is: N-[-1'-(2'-amino-4'-hydroxy-7'-proton-6'-pteridinyl)ethyl]-4- [2',3',4',5'-tetrahydroxypent-1'-yl(5'----1')O-alpha- ribofuranosyl-5'-phosphoric acid]aniline, in which the phosphate group is esterified with alpha-hydroxyglutarylglutamylaspartic acid.     

Synthesis of some newer derivatives of substituted quinazolinonyl-2-oxo/thiobarbituric acid as potent anticonvulsant agents

5-[1'-[3"-Aminoacetyl-2"-methyl-6",8"-dihalosubstitutedquinazolin-4"(3"H)-onyl]-thiosemicarbazido]-2-oxo/thiobarbituric acids 3a-3h and 5-[2'-amino-5'-[3"-aminomethylene-2"-methyl-6",8"-dihalosubstitutedquinazolin-4"(3"H)-onyl]-1',3',4'-thiadiazol-2'-yl]-2-oxo/thiobarbituric acid 5a-5h were prepared by incorporating 1-[3'-aminoacetyl-2'-methyl-6",8"-dihalosubstituted-quinazolin-4'(3'H)-onyl]-thiosemicarbazides 2a-2d and 2-amino-5-[3'-aminomethylene-2'-methyl-6',8'-dihalosubstituted-quinazolin-4'(3'H)-onyl]-1,3,4-thiadiazoles 4a-4 h respectively at 5(th) position of 2-oxo/thiobarbituric acids (via Mannich reaction). All the newly synthesized compounds were screened for their anti-convulsant activity in MES and PTZ models and were compared with standard drugs phenytoin sodium and sodium valproate. Interestingly, these compounds were found to be devoid of sedative and hypnotic activities when tested. Out of the compounds studied, the most active compound 5h, that is 5-[2'-amino-5'-[3"-aminomethylene-2"-methyl-6",8"-dibromoquinazolin-4"(3"H)-onyl]-1',3',4'-thiadiazol-2'-yl]-2-thiobarbituric acid showed activity (90%) more potent than the standard drug.     

Selective deprotection of 2',6'-di-O-benzyl-2,3:5,6:3',4'-tri-O-isopropylidenelactose dimethyl acetal

The reactivity order of O-deisopropylidenation of the three isopropylidene protecting groups of 2',6'-di-O-benzyl-2,3:5,6:3',4'-tri-O-isopropylidenelactose dimethyl acetal (2) with various reagents was established. The 5,6-acetal group was, although to a limited extent, more reactive as compared with the 3',4' group, while the 2,3-O-isopropylidene group was definitely less reactive. Conditions were determined for the direct preparation of the 5,6,3',4'-tetraol 5 (60% aqueous acetic acid, room temperature, 48 h, 73% yield) and the 5,6-diol 4 (propylene glycol and p-toluenesulphonic acid in dichloromethane, 46% yield). The diacetonated derivative 3, formally arising from a selective 3',4'-O-deisopropylidenation, was obtained in high yield (90%) through a selective acetonation with 2-methoxypropene of the tetraol 5.     

Metabolism of myricetin and related compounds in the rat. Metabolite formation in vivo and by the intestinal microflora in vitro

1. The metabolism of a group of polyphenols related in structure to myricetin (3,5,7,3',4',5'-hexahydroxyflavone), including myricetin, myricitrin, 3,4,5-trihydroxyphenylacetic acid, delphinidin, robinetin, tricetin, tricin, malvin and 5,7-dihydroxy-3',4',5'-trimethoxyflavone, has been studied both in vivo after oral administration to the rat and in vitro in cultures of micro-organisms derived from the intestine of the rat. 2. It was shown that the rat intestinal microflora are able to degrade compounds of this group to the ring-fission products observed in urine after oral administration of the specific flavonoid. 3. All flavones and flavonols possessing free 5- and 7-hydroxyl groups in the A ring and a free 4'-hydroxyl group in the B ring gave rise to ring-fission products that included 3',5'-dihydroxyphenylacyl derivatives. 4. The metabolites 3,5-dihydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, 3,5-dihydroxyphenylpropionic acid and 3-hydroxyphenylpropionic acid were isolated and identified by chromatographic and spectral methods. 5. On anaerobic incubation in a thioglycollate medium it was shown that intestinal micro-organisms can effect cleavage of glycosidic bonds, ring fission of certain flavonoid molecules showing 3',4',5'-trihydroxyphenyl substitution and dehydroxylation of certain flavonoid metabolites. 6. The urinary excretion of the metabolites 3,5-dihydroxyphenylacetic acid and 3-hydroxyphenylacetic acid was completely abolished when neomycin-treated rats were used.     

Synthesis and bioactivities of nitronyl nitroxide and RGD containing pseudopeptides

1-(1',3'-dioxyl-4',4',5',5'-tetramethyldihydroimidazol-2'-yl)-phenyl-4-yloxylacetic acid (3), and 1-(1',3'-dioxyl-4',4',5',5'-tetramethyldihydroimidazol-2'-yl)-phenyl-4-yloxylacetyl-RGDS (13), -RGDV (14), -RGDF (15) were synthesized. The ESR measurement gave the same spectroscopy for 3 and 13-15. The NO scavenging tests in vitro, anti-platelet aggregation tests in vitro and the anti-thrombosis assay in vivo indicated that introducing 3 into the N-terminal of RGDS, RGDV and RGDF the corresponding bioactivities for both of 3 and RGD peptides can be remained completely. The present combinations provided a beneficial strategy for simultaneous scavenging NO and anti-thrombosis, and for the use of spin label of RGD peptides in the conformational researches.     

Microbial hydroxylation of (+/-)- and (-)-(2Z,4E)-5-(1',2'-epoxy-2',6',6'-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid into (+/-)- and (-)-xanthoxin acid by Cunninghamella echinulata

Microbial hydroxylation of (+/-)-(2Z,4E)-5-(1',2'-epoxy-2',6',6'-trimethylcyclohexyl)-3-methyl-2,4-pentadienoic acid (3a) with Cercospora cruenta, a fungus producing (+)-abscisic acid, gave a four-stereoisomeric mixture consisting of (+)- and (-)-xanthoxin acid (4a), and (+)- and (-)-epi-xanthoxin acid (5a) by an HPLC analysis with a chiral column. Screening of the microorganisms capable of oxidizing (+/-)-3a showed that Cunninghamella echinulata stereoselectively oxidized (+/-)-3a to xanthoxin acid (4a) with the some degree of enantioselectivity as (-)-3a to (-)-4a.     

Properties of a cyclic 3'5'-nucleotide phosphodiesterase from Vigna mungo

Cyclic AMP phosphodiesterase (PDE) partially purified from roots of Vigna mungo exhibited optimum activity at pH 5.5 to 6.0 and maximum enzyme activity at 50 degrees C. Levels of PDE activity in roots remained relatively constant from the first to the eleventh day after germination; on the twelfth day there was a 400% increase in PDE activity. The enzyme was stable for at least 48 hours at 28 degrees C, retaining 92% of its original activity. Plant growth hormones including gibberellic acid, indoleacetic acid and kinetin at 1.0 and 10.0 microM concentrations did not have any significant effect on enzyme activity. Nucleotides tested including cyclic 2'3' AMP, cyclic 2'3' GMP completely abolished enzyme activity at 1.0mM while cyclic 3'5' GMP, cyclic 3'5' GMP, 2'deoxy 5' ATP, 2'deoxy 5'GTP and 5'ADP were also inhibitory to the enzyme. The enzyme was stimulated by Mg2+, Fe2+ and NH4+ while Cu2+ and Fe3+ were inhibitory. Theophylline, caffeine, phosphate, pyrophosphate and EDTA were inhibitory to the enzyme.     

Elucidation of the structure of methanopterin, a coenzyme from Methanobacterium thermoautotrophicum, using two-dimensional nuclear-magnetic-resonance techniques

Methanopterin is a coenzyme involved in methanogenesis. From 2 kg wet cells of Methanobacterium thermoautotrophicum about 35 mumol methanopterin were isolated. The structure of this compound was elucidated by various two-dimensional nuclear-magnetic-resonance techniques. Methanopterin was identified as N-[1'-(2"-amino-4"-hydroxy-7" - methyl-6"- pteridinyl) ethyl]-4-[2',3',4',5'- tetrahydroxypent-1'- yl (5' leads to 1") O-alpha-ribofuranosyl-5"-phosphoric acid] aniline, in which the phosphate group is esterified with alpha-hydroxyglutaric acid. The molecular formula of the sodium salt of methanopterin at pH 7.0 is C30H38O16N6PNa3 X chiH2O (chi is about 4). The anhydrous sodium salt of methanopterin has a molecular mass of 838.60 Da and the molar absorption coefficient at 342 nm is 7.4 mM-1 cm-1 at pH 7.0.     

Synthesis of 3',5'-cyclic diguanylic acid (cdiGMP) using 1-(4-chlorophenyl)-4-ethoxypiperidin-4-yl as a protecting group for 2'-hydroxy functions of ribonucleosides

We herein report a convenient synthesis of 3',5'-cyclic diguanylic acid via the modified H-phosphonate approach. The 1-(4-chlorophenyl)-4-ethoxypiperidin-4-yl (Cpep) group was used as protecting group for the 2'-hydroxy functions of ribonucleosides. Complete unblocking of the fully protected 3',5'-cyclic diguanylic acid gave cdiGMP as a homogeneous compound in an excellent yield.     

4-Coumarate:coenzyme A ligase has the catalytic capacity to synthesize and reuse various (di)adenosine polyphosphates

4-Coumarate:coenzyme A ligase (4CL) is known to activate cinnamic acid derivatives to their corresponding coenzyme A esters. As a new type of 4CL-catalyzed reaction, we observed the synthesis of various mono- and diadenosine polyphosphates. Both the native 4CL2 isoform from Arabidopsis (At4CL2 wild type) and the At4CL2 gain of function mutant M293P/K320L, which exhibits the capacity to use a broader range of phenolic substrates, catalyzed the synthesis of adenosine 5'-tetraphosphate (p(4)A) and adenosine 5'-pentaphosphate when incubated with MgATP(-2) and tripolyphosphate or tetrapolyphosphate (P(4)), respectively. Diadenosine 5',5',-P(1),P(4)-tetraphosphate represented the main product when the enzymes were supplied with only MgATP(2-). The At4CL2 mutant M293P/K320L was studied in more detail and was also found to catalyze the synthesis of additional dinucleoside polyphosphates such as diadenosine 5',5'-P(1),P(5)-pentaphosphate and dAp(4)dA from the appropriate substrates, p(4)A and dATP, respectively. Formation of Ap(3)A from ATP and ADP was not observed with either At4CL2 variant. In all cases analyzed, (di)adenosine polyphosphate synthesis was either strictly dependent on or strongly stimulated by the presence of a cognate cinnamic acid derivative. The At4CL2 mutant enzyme K540L carrying a point mutation in the catalytic center that is critical for adenylate intermediate formation was inactive in both p(4)A and diadenosine 5',5',-P(1),P(4)-tetraphosphate synthesis. These results indicate that the cinnamoyl-adenylate intermediate synthesized by At4CL2 not only functions as an intermediate in coenzyme A ester formation but can also act as a cocatalytic AMP-donor in (di)adenosine polyphosphate synthesis.     

Synthesis of 1-(3',4',5'-trimethoxy) phenyl naphtho[2,1b]furan as a novel anticancer agent

3',4',5'-Trimethoxy benzoyl-naphthalene 2-O-acetic acid (5) underwent base catalysed intramolecular condensation to yield exclusively 1-(3',4',5'-trimethoxy) phenyl naphtho[2,1-b]furan 8. The cyclised product 8 has been characterised by spectroscopy. The product 8 showed significant anticancer activity against human cancer cell lines COLO320DM (colon), CaCO2 (colon) and WRL68 (liver) at 0.7, 0.65 and 0.50 microg/ml concentrations, respectively, in the in vitro MTT assay.     

粗糙肉齿菌子实体化学成分研究

利用硅胶柱层析、RP-8层析及Sephadex LH-20分离的方法,从高等真菌粗糙肉齿菌(Sarcodon scabrosus)干燥子实体的甲醇提取物中分离并鉴定了8个化合物,经现代光谱技术鉴定分别为苯甲酸(1)、麦角甾-5,7,22-三烯-3β-醇(2)、2',3'-二乙酰基-3,4,5',6',4″-五羟基-对联三苯(3)和1-乙基-β-D-吡喃葡萄糖苷(4)、对羟基苯甲酸(5)、丁二酸(6)、腺嘌呤(7)、腺嘌呤核苷(8).以上化合物均为首次从粗糙肉齿菌中获得.     

DPPH radical scavengers from dried leaves of oregano (Origanum vulgare)

1,1-Dipehnyl-2-picrylhydrazyl (DPPH) radical scavenging activities were found in the extract of dried leaves of oregano (Origanum vulgare). The water-soluble active ingredients were isolated, and their structures were determined to be 4'-O-beta-D-glucopyranosyl-3',4'-dihydroxybenzyl protocatechuate and 4'-O-beta-D-glucopyranosyl-3',4'-dihydroxybenzyl 4-O-methylprotocatechuate by (1)H-, (13)C-NMR, DEPT, HMQC, and HMBC spectral analyses, and by NOE experiments. The DPPH radical scavenging activities of these compounds were compared with those of rutin, quercetin and rosmarinic acid at a concentration of 2 x 10(-5) M. The scavenging activity of 4'-O-beta-D-glucopyranosyl-3',4'-dihydroxybenzyl protocatechuate was almost the same as that of quercetin and rosmarinic acid, but that of 4'-O-beta-D-glucopyranosyl-3',4'-dihydroxybennzyl 4-O-methylprotocatechuate was less than that of quercetin, rosmarinic acid and 4'-O-beta-D-glucopyranosyl-3',4'-dihydroxybenzyl protocatechuate. The amount of 4'-O-beta-D-glucopyranosyl-3',4'-dihydroxybenzyl protocatechuate was estimated to be 3.8 mg/1 g of dried leaves by an HPLC analysis.     

Prolyl endopeptidase inhibitors from Syzygium samarangense (Blume) Merr. & L. M. Perry

Compounds isolated from the hexane extract of the leaves of Syzygium samarangense (Blume) Merr. & L. M. Perry were tested for inhibitory activity against the following serine proteases: trypsin, thrombin and prolyl endopeptidase. The compounds were identified as an intractable mixture of alpha-carotene and beta-carotene (1), lupeol (2), betulin (3), epi-betulinic acid (4), 2',4'-dihydroxy-6'-methoxy-3'-methylchalcone (5), 2'-hydroxy-4',6'-dimethoxy-3'-methylchalcone (6), 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (7), 2',4'-dihydroxy-6'-methoxy-3'-methyldihydrochalcone (8) and 7-hydroxy-5-methoxy-6,8-dimethylflavanone (9). Hydrogenation of compounds 5, 6 and 7 yielded compound 8, 2'-hydroxy-4',6'-dimethoxy-3'-methyldihydrochalcone (10) and 2',4'-dihydroxy-6'-methoxy-3',5'-dimethyldihydrochalcone (11), respectively. The hydrogenated products of compounds 6 and 7 were also tested for enzyme inhibitory activity. In addition, beta-sitosterol (12) and beta-D-sitosterylglucoside (13) were also isolated. This is the first report of the isolation of compounds 1-6, 8 and 13 from this plant. Compounds 3-8 and 10 exhibited significant and selective inhibition against prolyl endopeptidase among three serine proteases. This is the first report of this kind of activity for all these compounds.     

Synthesis and properties of 3'-amino-2',4'-BNA, a bridged nucleic acid with a N3'-->P5' phosphoramidate linkage

The synthesis and properties of a bridged nucleic acid analogue containing a N3'-->P5' phosphoramidate linkage, 3'-amino-2',4'-BNA, is described. A heterodimer containing a 3'-amino-2',4'-BNA thymine monomer, and thymine and methylcytosine monomers of 3'-amino-2',4'-BNA and their 5'-phosphoramidites, were synthesized efficiently. The dimer and monomers were incorporated into oligonucleotides by conventional 3'-->5' assembly, and 5'-->3' reverse assembly phosphoramidite protocols, respectively. Compared to a natural DNA oligonucleotide, modified oligonucleotides containing the 3'-amino-2',4'-BNA residue formed highly stable duplexes and triplexes with single-stranded DNA (ssDNA), single-stranded RNA (ssRNA), and double-stranded DNA (dsDNA) targets, with the average increase in melting temperature (T(m)) against ssDNA, ssRNA and dsDNA being +2.7 to +4.0 degrees C, +5.0 to +7.0 degrees C, and +5.0 to +11.0 degrees C, respectively. These increases are comparable to those observed for 2',4'-BNA-modified oligonucleotides. In addition, an oligonucleotide modified with a single 3'-amino-2',4'-BNA thymine residue showed extraordinarily high resistance to nuclease degradation, much higher than that of 2',4'-BNA and substantially higher even than that of 3'-amino-DNA and phosphorothioate oligonucleotides. The above properties indicate that 3'-amino-2',4'-BNA has significant potential for antisense and antigene applications.