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Dendrimers are nanosized, symmetrical molecules in which a small atom or group of atoms is surrounded by the symmetric branches known as dendrons. The structure of dendrimers possesses the greatest impact on their physical and chemical properties. They grow outwards from the core-shell which further reacts with monomers having one reactive or two dormant molecules. Dendrimers’ unique characteristics such as hyperbranching, well-defined spherical structure, and high compatibility with the biological systems are responsible for their wide range of applications including medical and biomedical areas. Particularly, the dendrimers’ three-dimensional structure can incorporate a wide variety of drugs to form biologically active drug conjugates. In this review, we focus on the synthesis, mechanism of drug encapsulations in dendrimers, and their wide applications in drug delivery.

Galal Elgemeie,1 Farag Altalbawy,2,3 Mohammed Alfaidi,3 Rania Azab,2,4 Atef Hassan5 1Department of Chemistry, Faculty of Science, Helwan University, Helwan, 2National Institute of Laser Enhanced Sciences (NILES), Cairo University, Giza, Egypt; 3Department of Biological Sciences, University College of Duba, Tabuk University, Tabuk, 4Department of Biological Sciences, Faculty of Science, Al-Baha University, Al-Baha, Saudi Arabia; 5Department of Mycology and Mycotoxins, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt Abstract: The present research describes the synthesis of novel 5-benzoyl-N-substituted-amino- and 5-benzoyl-N-sulfonylamino-4-alkylsulfanyl-2-pyridones 5a–c and 6a–c via the reaction of 2-benzoyl-3,3-bis(alkylthio)acrylonitriles 2a–c with N-cyanoacetohydrazide 3 and cyanoaceto-N-phenylsulfonylhydrazide 4, respectively. Also, the reactivity of the compounds 5a–c toward hydrazine hydrate to give product 1H-pyrazolo[4,3-c]pyridine derivative 7 was studied. Inaddition, the reactivity of the 2a–c toward 1-cyanoacetyl-4 arylidenesemicarbazides 8a–c afforded3,5-dihydro[1,2,4]triazolo[1,5-a]pyridine-6-carbonitrile derivatives (12–14)a–c, which reacted with hydrazine hydrate to give 3H-pyrazolo[4,3-c][1,2,4]triazolo[1,5-a]pyridine-6-carbonitrile derivatives 15a–c. The structures of the new products were characterized based on 1H nuclear magnetic resonance, 13C nuclear magnetic resonance, infrared, mass-spectroscopy, and elemental analyses. The products were screened in vitro for their antibacterial and antifungal activity properties. Keywords: amino-2-pyridones, N-cyanoacetohydrazide, cyanoaceto-N-phenylsulfonylhydrazide, 2-benzoyl-3,3-bis(alkylthio)acrylonitriles, 5-benzoyl-N-sulfonylamino-4-alkylsulfanyl-2-pyridones, 5-benzoyl-N-substituted-amino-4-alkylsulfanyl-2 pyridones, antimicrobial activity