Synthesis of styrenes through the biocatalytic decarboxylation of trans-cinnamic acids by plant cell cultures.

A novel method for producing styrenes from trans-cinnamic acids was developed. When trans-cinnamic acid was incubated with plant cell cultures at room temperature, styrene was obtained. 4-Hydroxy-3-methoxystyrene (2a), 3-nitrostyrene (2f) and furan (2g) were synthesized quantitatively.

DELETEile chiral bidentate ligands derived from alpha-amino acids: synthetic applications and mechanistic considerations in the palladium-mediated asymmetric allylic substitutions.

A new class of chiral amidine-phosphine hybrid ligands 7a,b, which are readily accessible from the corresponding alpha-amino acids, were developed. A versatility for construction of new ligands is desirable, by which a variety of reactions and substrates become applicable. Indeed, a variety of modifications, such as exchange reactions to other amino groups in the amidine skeleton and the production of other types of ligands, are possible using the precursor compounds of 7a. Thus, novel chiral ligands 7c,d, 8, 11, and 13, which provide sterically and electronically different chiral circumstances, were prepared and used for the palladium-mediated asymmetric allylic substitutions of both acyclic and cyclic compounds. In these reactions, high levels of asymmetric induction were achieved for both substrates. A marked advancement of reactivity and enantioselectivity in palladium-catalyzed asymmetric allylations of 1,3-diphenylpropen-2-yl pivalate 14a was attained by examination of electronic substituent effects in a new series of chiral P-N and S-N hybrid ligands 8 and 11. Mechanistic views concerning the enantiodiscriminating step were demonstrated, in which a good correlation between a novel Pr/Mr concept and the absolute configuration of allylation products are discussed for the prediction of enantioselecting direction. The use of ketene silyl acetals as nucleophiles was investigated and compared with the corresponding harder anionic carbon nucleophiles. The former nucleophiles afforded higher enantioselectivity in asymmetric allylic transformations of 14a.

Lipid A and related compounds. XXXVII. Determination of favorable binding linkages of lipid A analog to antigen moiety for synthetic vaccines.

For the determination of favorable binding linkages of lipid A analog as a synthetic immunoadjuvant to the antigen moiety for synthetic vaccines, new N-acylated L-serine-containing D-glucosamine analogs (Type A, B, C) were synthesized and their mitogenicities were examined. Among chemically synthesized compounds (6-15, 30), compound 8 for Type B exhibited the most potent mitogenicity.

Synthesis of peptides mimicking chemokine receptor CCR5 and their inhibitory effects against HIV-1 infection.

Peptides mimicking chemokine receptor CCR5 were synthesized and their anti-HIV-1 activities evaluated. Prepared compounds, especially a sulfated derivatives, showed significant anti-HIV-1 activities. Furthermore, a hybrid molecule linked to an N-carbomethoxycarbonyl-prolyl-phenylalanine (CPF) moiety had a greater effect.

Prostanoids and related compounds. VII. Synthesis and inhibitory activity of 1-isoindolinone derivatives possessing inhibitory activity against thromboxane A2 analog (U-46619)-induced vasoconstriction.

We have synthesized a series of novel 1-isoindolinone derivatives, which inhibited the contraction of pig coronary artery induced by U-46619, a thromboxane A2 analog.

Synthesis of cancer peptide antigen-lipid A analog conjugates for synthetic vaccines.

Conjugates 6 and 7 of cancer peptide antigen with N-tetradecanoyl L-serine-beta-alanine-containing D-glucosamine derivative structurally related to lipid A as an immunoadjuvant were synthesized for the development of totally synthetic vaccines against cancers. The mitogenic activities of compounds 6 and 7 were stronger than that of lipid A analog 3.

Chemoenzymatic synthesis of an N-acetylneuraminic acid analogue having a carbamoylmethyl group at C-4 as an inhibitor of sialidase from influenza virus.

5,9-Diacetamido-2,6-anhydro-O-4-carbamoylmethyl-3,5,9-trideo xy-D-glycero- D-galacto-non-2-enonic acid (1) was synthesized via a key intemediate 2 through the Neu5Ac aldolase [E.C.4.1.3.3]-catalyzed aldol reaction of 2-acetamido-2,6-dideoxy-6-azido-D-glucose with sodium pyruvate operating under alkaline conditions (pH 10.5) in order to accelerate epimerization C-2 of N-acetyl-D-glucosamine (D-GlcNAc) derivatives. Compound 1 showed inhibitory activity against sialidase.

Synthesis of Tn, sialyl Tn and HIV-1-derived peptide antigen conjugates having a lipid A analog as an immunoadjuvant for synthetic vaccines.

Conjugates (3-5) of Tn, sialyl Tn and HIV-1-derived peptide antigen with a N-tetradecanoyl L-serine-beta-alanine-containing D-glucosamine derivative, structurally related to lipid A, as an immunoadjuvant for the development of totally synthetic vaccines against cancers or HIV were synthesized. The mitogenic activity of compounds 3, 4 and 5 was stronger than that of lipid A analogs (1, 2).

Synthesis of dipeptide-type human immunodeficiency virus (HIV) protease inhibitors with a binding unit to gp120.

Some dipeptide-type human immunodeficiency virus (HIV) protease inhibitors derived from KNI-102, with a N-carbomethoxycarbonylprolyl-phenylalanine benzyl ester (CPF) moiety as a binding site to gp120, were synthesized. Compounds 11a showed 7--100 times higher HIV protease-inhibitory activity (11a; IC50 = 0.90 microgram/ml, 1.1 microM) than the standard compound 3 or 4 (3; IC50 = 3.7 micrograms/ml, 7.7 microM, 4; IC50 = 75 micrograms/ml, 155 microM). Generally, the compounds substituted at the o-position of the phenoxyacetyl group 7a, 11a, 16a and 21a showed several times higher inhibitory activity than 3.

Syntheses of HIV-protease inhibitors having a peptide moiety which binds to GP120.

Some HIV-protease inhibitor derivatives having an N-carbomethoxycarbonyl-prolyl-phenylalanine benzyl ester (CPF) moiety as a binding site to gp120 were designed and synthesized. Almost all the compounds bearing CPF on the phenoxyacetyl group showed protease-inhibitory activity. Compounds 25a and 25b, which have the CPF moiety at the ortho- and meta-positions of the phenoxyacetyl group, respectively, had anti-HIV activity, although the others showed only protease-inhibitory activity. These results suggest that 25b binds to gp120 and inhibits HIV protease.

Synthesis of Tn and sialyl Tn antigen-lipid A analog conjugates for synthetic vaccines.

Conjugates of Tn and sialyl Tn antigen with N-teradecanoyl L-seryl-beta-alanine-containing D-glucosamine derivatives structurally related to lipid A as an immunoadjuvant were synthesized for the development of totally synthetic vaccines against cancers or HIV.

Structural characterization of lipid A obtained from Pantoea agglomerans lipopolysaccharide.

Lipopolysaccharide isolated from Pantoea agglomerans showed higher priming and triggering activities for macrophages in terms of tumor necrosis factor production than other lipopolysaccharides. To identify the difference in biological activities of lipopolysaccharide of Pantoea agglomerans from other lipopolysaccharides on the basis of structure, we determined the structure of the lipid A part, which is the biological center of lipopolysaccharides, by quantitative analysis, nuclear magnetic resonance spectroscopy and mass spectrometry. Lipopolysaccharide of Pantoea agglomerans is constructed with at least two kinds of lipid A of different levels of acylation. One is of the same type as that of Escherichia coli with hexa-acyl lipid A and the other is the Salmonella minnesota type with hepta-acyl lipid A.

Synthesis of N-acetylglucosaminyl- and N-acetylgalactosaminylceramides as cerebroside analogs and their anti-human immunodeficiency virus type 1 activities.

Monoglycosylceramide derivatives containing mimicks of ceramide were synthesized as cerebroside analogs from D-glucosamine or D-galactosamine derivatives and N-benzyloxycarbonyl-L-serine myristylamide by using trimethylsilyl trifluoromethanesulfonate (TMSOTf) as a promoter. The synthesized sulfate glycolipids show moderate anti-HIV-1 activities.

Lipid A and related compounds. XXX. Synthesis of biologically active N,N'-diacyl chitobiose derivatives structurally related to lipid A.

Two new glycolipids, which mimic lipid A disaccharide, were synthesized from N,N'-diacylchitobiose via a key intermediate (2). They showed mitogenicity and nitric oxide (NO) productivity.

Antibody-producing effects in mice by synthetic immunoactive lipopeptides with the conjugated amino acid sequence of gp120 in human immunodeficiency virus.

To induce peptide-specific antibodies in mice, as a model for vaccination against human immunodeficiency virus (HIV), lipopeptide analogs conjugated with three repeating units (KAB-112; designated as gp120-peptide) of a part (Gly-Pro-Gly-Arg-Ala-Phe) of the amino acid sequences of the V3 loop region in gp120 of HIV were synthesized. The mitogenicity, production of nitric oxide (NO) and induction of peptide-specific antibodies in mice by synthetic lipopeptides were examined. Compounds, KAB-8 (diacylglycerol-tetrapeptide having a part of the amino acid sequence in Escherichia coli), KAB-116 (diacylglycerol-cysteine), KAB-117 (diacylglycerol with gp120-peptide) and KAB-121 (KAB-8 with gp120-peptide) were capable of increasing significantly the incorporation of [3H]thymidine into splenocytes of C3H/He mice at concentrations ranging from 12.5 to 100 microM, but KAB-112 (gp120-peptide) and KAB-115 (monoacylglycerol with gp120-peptide) did not show such activity. The compounds, KAB-8, KAB-117 and 121, exhibited NO production in murine macrophages. When 50 nmol of these compounds was administered intraperitoneally into BALB/c mice on days 0, 16 and 46, the peptide-specific antibody titers in their sera produced by each compound were determined with ELISA. The sera of KAB-117 and KAB-121, which were obtained on days 14, 30, 42, 57 and 70, had a higher titer than that of KAB-112 and KAB-115, suggesting that the diacylglycerol derivative enhance the production of the peptide-specific antibodies.

Comparison of the biological activity of synthetic N-acylated asparagine or serine linked monosaccharide lipid A analogs.

The mitogenicity, lethal toxicity, induction of tumor necrosis factor (TNF), production of nitric oxide (NO) and antitumor activity against Meth A fibrosarcoma by chemically synthesized N-acylated asparagine-linked (A-701, A-702 and A-703) or N-acylated serine-linked (A-607) nonphosphorylated acylglucosamine and 4-0-phosphorylated acylglucosamine (A-103) derived lipid A analogs were determined. compound A-607 (with tetradecanoyl and (R)-3-tetradecanoyloxytetradecanoyl at the C-2 and C-3 positions) induced a significant incorporation of 3H-thymidine into splenocytes of C3H/He mice at concentrations ranging from 3.13 to 50 microM, but the mitogenic activity of A-701 (2-N-acetylglucosamine), A-702 (tetradecanoyl at the C-2), and A-703 (with (R)-tetradecanoyloxytetradecanoyl and tetradecanoyl at the C-2 and C-3) was very weak. The lethality of A-703 and A-103 (with (R)-3-tetradecanoyloxytetradecanoyl at the C-2 and C-3) was weaker than that of A-607 at doses of 300 and 750 nmol/kg in C57BL/6 mice loaded with D-galactosamine. Peritoneal macrophages, stimulated with A-701-A-703, caused production of TNF which induce L929 cell lysis in vitro, and A-703 showed a high production of TNF. The compounds, except for A-607, exhibited little NO production by macrophages, but did induce the NO production in the presence of interferon gamma. Induction of TNF and NO inducible activity by A-703 was lower than that of A-607. A-703, A-607 and A-103 showed antitumor activity against Meth A fibrosarcoma in BALB/c mice. When A-703 or A-103 with muramyl dipeptide was administered, A-703 failed to show combined effects, but A-103 did. We concluded from these findings that the biological potency of asparagine compounds appears to be placed between serine- and amino-free compounds.

Chemoenzymatic synthesis of neuraminic acid analogs structurally varied at C-5 and C-9 as potential inhibitors of the sialidase from influenza virus.

The 9-amino or 9-N-acyl-5-trifluoroacetyl methyl alpha-ketosides (1a-c) and their 2,3-didehydro analogs (2a-c) have been synthesized through Neu5Ac aldolase-catalyzed aldol reaction of 6-azido-2-benzyloxycarbonylamino-2-deoxy-D-mannose with sodium pyruvate. The six compounds were investigated as inhibitors of sialidase from influenza virus. Compound 2b, a 2,3-didehydro type, showed the most potent inhibitory activity (IC50 > 7.8 microM) against the enzyme, whereas, compounds 1a-c as the methyl alpha-glycosides were found to be practically inactive (IC50 > 100 microM).

Synthesis of ganglioside GM3 and GM4 analogs having mimics of ceramide moieties and their binding activities with influenza virus A.

Ganglioside GM4 (1) and GM3 (2) analogs, which contain mimics of the ceramide moieties of gangliosides, were synthesized. The syntheses of 1 and 2 feature stereoselective glycosylation of methyl (phenyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-beta-D- galacto-2-nonulopyranosid)onate (10) as the sialosyl donor with suitably protected galactose and lactose acceptors catalyzed by N-bromosuccinimide (NBS), iodine, and tetrabutylammonium trifluoromethanesulfonate (TBAOTf) as the glycosyl promoter in acetonitrile under kinetically controlled conditions. Compound 2 exhibited binding activity towards influenza virus A.