An in vitro screening method for DNA cytosine-C5-methylase inhibitor

A specific inhibitor of DNA cytosine C5-methylases would be useful for studying genomic imprinting, X-chromosome inactivation, carcinogenesis, and regulation of tissue-specific gene expression, for these physiological phenomena appears to be regulated through DNA methylation in promoter sequences. This paper reports a novel convenient in vitro assay method for screening DNA cytosine C5-methylase inhibitor. Our method uses a commercially available Hae III methylase (cytosine C5 methylase), its corresponding Hae III endonuclease, and lambda DNA as their substrate.     

Effect of water-soluble polymers on fusion of egg yolk and soybean phospholipid liposomes

The efficiencies of polyelectrolytes, i.e., polycations and polyanions, and several kinds of water-soluble polymers as fusogens on soybean phospholipid liposome (SL) and egg yolk phospholipid liposome (EL) were investigated by the fluorescence quenching method. There were optimal concentrations for the induction of fusion in every system. Polycations induced fusion of liposomes at very low concentration in comparison with other polymers. Poly(carboxylic acid)s induced fusion at relatively high concentration. A strong acidic polyanion with high molecular weight also induced fusion of liposomes. The induction efficiency of poly(ethylene glycol) on fusion was higher than other nonionic polymers. The efficiency of fusion of EL was lower than that of SL in all systems because of the higher stability of EL membrane. It was found that electrostatic interactions, hydrogen bonding and/or hydrophobic interaction between these water-soluble polymers and liposomal membranes played an important role on aggregation and fusion of liposomes.     

Structure-activity relationships of alpha-human atrial natriuretic peptide (alpha-hANP) analogs: role of charged groups in alpha-hANP.

To determine whether the addition of a methylene unit in the side chain of the Asp or Arg residue in alpha-human atrial natriuretic peptide (alpha-hANP) influences its biological activity, analogs of alpha-hANP, [Glu13]-alpha-hANP (7-28) (1), [Aad13]-alpha-hANP (7-28) (2), and [Harn]-alpha-hANP(7-28) (where n is any possible combination of 11, 14 and 27) (3-9), where the original Asp or Arg residue was replaced by a homo-amino acid, were synthesized by the solid-phase synthesis method. All the analogs were evaluated for their receptor binding, cyclic guanosine monophosphate (cGMP) accumulation activity in rat vascular smooth muscle cells (VSMC), and for vasorelaxant activity employing rat aorta. 1 and 2 were 0.9 and 0.03 times as potent as alpha-hANP (7-28), respectively, in binding. Har-containing analogs (3-9) were as potent as alpha-hANP (7-28) in binding. Among the Har-containing analogs, [Har11,14]-alpha-hANP (7-28) (6) and [Har11,27]-alpha-hANP (7-28) (7) were remarkably vasorelaxant active, being 4.2 and 5.3 times potent than alpha-hANP (7-28), respectively, in spite of relatively lower cGMP accumulation activity in the case of 7. The roles of the chargeable amino acid residues in biological activity are discussed.     

Structure elucidation and synthesis of lycoposerramine-B, a novel oxime-containing Lycopodium alkaloid from Lycopodium serratum Thunb

A new alkaloid, lycoposerramine-B (1), containing an oxime function, was isolated from the club moss Lycopodium serratum Thunb. The structure of 1 was elucidated by spectroscopic analysis, including J-resolved HMBC spectroscopy, and confirmed by its synthesis from the known alkaloid, serratinine (3).     

Isolation, structure elucidation, and total synthesis of two new Chimonanthus alkaloids, chimonamidine and chimonanthidine

Two new tryptamine-related alkaloids, chimonamidine and chimonanthidine, were isolated from the seeds of Chimonanthus praecox Link. and their structures including absolute configuration were elucidated by spectroscopic analysis and biomimetic total synthesis from tryptamine.     

Polymerization of 3,4-dihydro-2H-carboxyaldehyde (acrolein dimer). Part II. Copolymerization with isocyanates

Copolymers of 3,4-dihydro-2H-pyran-2-carboxyaldehyde (acrolein dimer) with phenyl isocyanate were obtained under several conditions. Infrared and NMR analyses showed that the isocyanate always reacted with acrolein dimer forming urethane linkages, not block units of isocyanate. An alternating copolymer was obtained from the copolymerization in the presence of anionic catalysts such as butyllithium at room temperature, irrespective of the monomer ratios employed. The isocyanate content in the copolymer prepared with an Al(C₂H₅)₂Cl catalyst was increased by elevating polymerization temperature. The copolymerizability of aldehydes with the isocyanate depends upon the polarity of aldehyde group.     

First total synthesis of trimeric indole alkaloid, psychotrimine

The first total synthesis of (+/-)-psychotrimine, a novel trimeric indole alkaloid isolated from Psychotria rostrata, was achieved. In the total synthesis, the copper-mediated intramolecular and intermolecular aminations of halobenzenes, which respectively contributed to the construction of a pyrrolidinoindoline core and the installation of a third tryptamine unit, were used as key steps.     

Pyrene aromatic arrays on RNA duplexes as helical templates

RNA oligomers having multiple (2 to 4) pyrenylmethyl substituents at the 2'-O-sugar residues were synthesized. UV-melting studies showed that the pyrene-modified RNAs could form duplexes with complementary RNA sequences without loss of thermal stability. Absorption, fluorescence, and circular dichroism (CD) spectra revealed that the incorporated pyrenes projected toward the outside of A-form RNA duplexes and assembled in helical aromatic arrays along the minor grooves of the RNA duplexes. Results of computer simulations agreed with the assembled structures of the pyrenes. The helical pyrene arrays exhibited remarkably strong excimer fluorescence, which was dependent on the sequence contexts of RNA duplexes.