Convenient and Efficient Syntheses of Peptide Nucleic Acid Purine Monomers

Currently, peptide nucleic acids (PNAs) play an important role as therapeutic agents, molecular tools for diagnosis and detection of genetic diseases as well as in biosensor probes. This research aims to optimize the synthesis of aeg- and γ-(S)-Me PNA monomers based on L-Ala, intended for oligomerization according to the Boc protocol. The monomers were obtained through the condensation of the corresponding pseudopeptides with carboxymethyl purine nucleic bases. During the work, the optimization of benzyloxycarbonyl- N6-adenine-9-yl-acetic acid and benzyloxycarbonyl-N2-guanine-9-ylacetic acid was carried out. The synthesis of benzyloxycarbonyl-N6-adenine-9-yl-acetic acid was conducted in three stages based on adenine with an overall yield of 22%. At the same time, the conditions for effective recrystallization of the mixture after alkylation of benzyloxycarbonyl-N6-adenine with ethyl bromoacetic acid ether have been developed to isolate the desired N9-regioisomer. Also, the optimization of a known method for producing benzyloxycarbonyl-N2-guanine-9-ylacetic acid from 2-amino-6-chloropurine was carried out. The total yield of the five-stage scheme was 55%. Condensation of aeg- and γ-(S)-Me pseudopeptides with benzyloxycarbonyl-N6-adenine-9-yl-acetic acid and benzyloxycarbonyl-N2-guanine-9-yl-acetic acid was performed by the standard carbodiimide method, DCC/HOBt in DMF followed by the removal of C-terminal methyl protective group by alkaline hydrolysis. The structure of the new compounds obtained was confirmed by spectral analysis methods. This work provides simple and optimized methods for obtaining protected carboxymethyl purine bases and increasing the efficiency of the synthesis and synthesized purine PNA monomers in an acceptable yield.

Application of Pyrazole Derivatives As New Substitutes of Auxin IAA To Regulate Morphometric and Biochemical Parameters of Wheat (Triticum Aestivum L.) Seedlings

The regulating activity of new synthetic low molecular weight heterocyclic compounds, pyrazole derivatives on morphometric, and biochemical parameters of wheat (Triticum aestivum L.) seedlings was studied. The synthetic compounds used at the concentration 10-8M revealed auxin-like stimulating effect on morphometric parameters of 6th-week-old wheat seedlings, which were increased on average: to 31 - 54 % – for total number of roots, to 39 – 104 % – for full length of sources, to 53 - 66 % – for length of the longest root as compared with similar parameters of the wheat seedlings grown in the distilled water (control) or water solution of auxin IAA (1H-Indol-3-ylacetic acid). The synthetic compounds used at the concentration 10-8M revealed cytokinin-like stimulating effect on biochemical parameters of 6th-week-old wheat seedlings. The content of photosynthetic pigments in the leaves of the wheat seedlings grown in the water solution of the pyrazole derivatives used at the concentration 10-8M increased on average: to 15-34 % – for content of chlorophyll a, to 10-61 % – for content of chlorophyll b, to 16–34 % – for content of chlorophylls a+b, to 14–28 % – for content of carotenoids, as compared with similar indices of the wheat seedlings grown in the distilled water (control) or water solution of auxin IAA. The practical application of pyrazole derivatives to regulate morphometric and biochemical parameters of wheat seedlings was proposed.

Influence of counterions on the conformation of conjugated polyelectrolytes: the case of poly(thiophen-3-ylacetic acid)

Binding of large hydrophobic counterions to poly(thiophen-3-ylacetate) provokes the conformational change of this conjugated polyelectrolyte.

Salt-specific effects observed in calorimetric studies of alkali and tetraalkylammonium salt solutions of poly(thiophen-3-ylacetic acid)

Differences in hydration of counterions are blamed for strong salt-specific effects produced upon dilution and mixing of poly(thiophene-3-ylacetic acid) salts with simple salts.