Effects of the methoxy group in the side chain of debromoaplysiatoxin on its tumor-promoting and anti-proliferative activities

Debromoaplysiatoxin (DAT) is a tumor promoter isolated from sea hare and exhibits anti-proliferative activity against several cancer cell lines. To clarify key residues that are responsible for its tumor-promoting activity, we focused on the chiral methoxy group in the side chain, whose role had not yet been discussed or examined before. Demethoxy-DAT (8) was derived from DAT and we evaluated its tumor-promoting activity, anti-proliferative activity, and ability to bind to protein kinase C (PKC) isozymes. Compound 8 showed somewhat weaker tumor-promoting activity than that of DAT both in vitro and in vivo, but showed higher anti-proliferative activity against several cancer cell lines. Although the affinity to novel PKC isozymes of 8 was comparable to that of DAT, the affinity to conventional PKC isozymes decreased slightly. These results suggest that the methoxy group of DAT is one of the key residues critical for tumor-promoting activity but not for anti-proliferative activity. Since the methoxy group has little influence on the molecular hydrophobicity, this is the first report showing that structural factors other than hydrophobicity in the side chain of DAT affected its biological activities.     

Adipogenetic effects of retrofractamide A derivatives in 3T3-L1 cells

In a previous study, retrofractamide A from the fruit of Piper chaba was shown to promote adipogenesis in 3T3-L1 cells. In the present study, retrofractamide A and its derivatives were synthesized, and their adipogenetic effects in 3T3-L1 cells were examined. Among the tested compounds, an amide composed of 9-(3′,4′-methylenedioxyphenyl)-nona-2E,4E,8E-trienoic acid and an n-butyl or n-pentyl amine showed strongest activity. Moreover, the amide with the n-pentyl amine moiety significantly increased the uptake of 2-deoxyglucose into the cells, and also increased the mRNA levels of adiponectin, peroxisome proliferator-activated receptor γ2 (PPARγ2), glucose transporter 4 (GLUT4), fatty acid-binding protein (aP2), and CCAAT/enhancer-binding protein (C/EBP) α and β in a similar manner as the PPARγ agonist troglitazone, although it had less agonistic activity against PPARγ.     

CXCR4-derived synthetic peptides inducing anti-HIV-1 antibodies

Despite almost 30 years since the identification of the human immunodeficiency virus type I (HIV-1), development of effective AIDS vaccines has been hindered by the high mutability of HIV-1. The HIV-1 co-receptors CCR5 and CXCR4 are genetically stable, but viral proteins may mutate rapidly during the course of infection. CXCR4 is a seven transmembrane G protein-coupled receptor, possessing an N-terminal region (NT) and three extracellular loops (ECL1-3). Previous studies have shown that the CXCR4-ED-derived peptides inhibit the entry of HIV-1 by interacting with gp120, an HIV-1 envelope glycoprotein. In the present study, antigenicity of CXCR4-derived peptides has been investigated and the anti-HIV-1 effects of induced antisera have been assessed. It was found that CXCR4-ED-derived antigen molecules immunize mice, showing that the linear peptides have higher antigenicity than the cyclic peptides. The L1- and L2-induced antisera inhibited the HIV-1 entry significantly, while anti-N1 antibodies have no inhibitory activity. This study produced promising examples for the design of AIDS vaccines which target the human protein and can overcome mutability of HIV-1.     

Synthesis of l,7-Diphenyl-l,3-heptadien-5-one,One of the Components in the Fresh Catkin of Alnus pendula

Several microorganisms capable of utilizing 1-aminocyclopropane-1-carboxylate (ACPC) were isolated from soil. A bacterium which belongs to Pseudomonas accumulated cellular α-aminobutyrate with consumption of ACPC and cells incubated with ACPC medium had the activity deaminating the substrate to form α-ketobutyrate. An enzyme, ACPC deaminase, was highly purified and its molecular weight, substrate specificity and absorption spectrum were investigated. These results suggested that this enzyme was a pyridoxal 5′-phosphate enzyme which has the molecular weight of 104000 and high specificity for ACPC, Km= 1.5 mM. A yeast, Hansenula saturnus, is also capable of forming ACPC deaminase, which has a lower molecular weight, 69000, and higher Km value, 2.6 mM.     

Studies on the Conjugated Lipids

Acid hydrolysis of cytosinine gave each one mole of cytosine, levulinic acid, ammonia and carbon dioxide. Reduction of cytosinine with PtO₂ afforded a mixture of dihydrocytosinine, 3-amino-tetrahydropyran-2-carboxylic acid and cytosine. Ozonolysis of N,N’-diacetylcytosinine methyl ester, followed by oxidation with hydrogen peroxide and acid hydrolysis gave erythro-d-β-hydroxyaspartic acid. These data permitted the assignment of structure (I) for cytosinine. Acid hydrolysis of uracinine gave uracil instead of cytosine, therefore, the structure (II) could be assigned to uracinine. Some stereochemical features and mechanism of levulinic acid formation were discussed.     

Structure and Synthesis of a Minor Component in the Oxidation Products of Crude Natural Variotin Oxidized with Manganese Dioxide,and Its Reduction with Lithium Aluminum Tri-t-butoxy Hydride

The structure of a minor component in the oxidation products of crude natural variotin oxidized with manganese dioxide is elucidated. The synthesis of the investigated compound, N-(6-oxo-2,4-trans, tralls-heptadienoyl) 2-pyrrolidonide, and the reduction of the substance are also described.     

Syntheses of dl-N-Demethylvariotinyl 2-Pyrrolidonide (dl-Demethylvariotin), 2-Piperidonide,and ε-Caprolactamide

The syntheses of three dl-demethylvariotins are described.