reviewed by Ezequiel Perez-Inestrosa and Donald A. Tomalia) 2,2-Bis(azidomethyl)propionic acid was prepared in four steps and 85% yield from the commercially available 2,2-bis(hydroxymethyl) propionic acid and used as the starting building block for the divergent, convergent, and double-stage convergent-divergent iterative methods for the synthesis of dendrimers and dendrons containing ethylenediamine (EDA), piperazine (PPZ), and methyl 2,2-bis(aminomethyl)propionate (COOMe) cores. These cores have the same multiplicity but different conformations. A diversity of synthetic methods were used for the synthesis of dendrimers and dendrons. Regardless of the method used, a self-interruption of the synthesis was observed at generation 4 for the dendrimer with an EDA core and at generation 5 for the one with a PPZ core, whereas for the COOMe core, self-interruption was observed at generation 6 dendron, which is equivalent to generation 5 dendrimer. Molecular modeling and molecular-dynamics simulations demonstrated that the observed self-interruption is determined by the backfolding of the azide groups at the periphery of the dendrimer. The latter conformation inhibits completely the heterogeneous hydrogenation of the azide groups catalyzed by 10% Pd/carbon as well as homogeneous hydrogenation by the Staudinger method. These self-terminated polyamide dendrimers are enzymatically and hydrolytically stable and also exhibit antimicrobial activity. Thus, these nanoscale constructs open avenues for biomedical applications.dendrons | ethylenediamine core | piperazine core | antimicrobials | nanomedicine
Mimusops elengi is an ornamental plant, famous for its fragrant flowers. Its bark and fruit are astringent in nature. The different parts of the plants are frequently used in medicine. The extracts of fruits, bark and leaves were studied presently. The extract of fruit and bark confirmed the presence of both hydrolysable and condensed tannins. The crude and purified fractions of the fruit and bark was subjected to the antioxidant and antifungal activity by using simple Thiocyanate and agar diffusion method respectively. The tannins present in the fruit especially shows marvelous antioxidant activity which was not reported before.
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