Enzymatic inhibitory activity of hydroxycinnamates (HCs): in silico studies

Diabetes is a worldwide health issue that has been expanding mainly in developed countries. It is characterized by abnormal levels of blood sugar due to several factors. The most common are resistance to insulin and the production of defective insulin which exerts little or no effect. Its most common symptoms include tissue damage to several systems due to elevated levels of blood sugar. One of the key enzymes in hydrocarbon metabolism is α-glucosidase (EC 3.2.1.20). It catalyzes the breakdown of complex carbohydrates into their respective monomers (glucose) which allows them to be absorbed. In this work, caffeoyl quinic acids and their metabolites were analyzed as potential inhibitors for α-glucosidase. The search for the best inhibitor was conducted using molecular docking. The affinity of each compound was compared to the inhibitor present in the crystal structure of the protein. As no inhibitor with a similar affinity was´found, a new approach was used, in situ drug design. It was not possible to achieve an inhibitor capable of competing with the one present in the crystal structure of the enzyme, which is also its current commercial inhibitor. It is possible to draw some conclusions as to which functional groups interact best with certain residues of the active site. This work was divided into three main sections. The first section, Diabetes, serves as an introduction to what is Diabetes, its symptoms and/or side effects and how caffeoyl quinic acids could be used as a treatment. The second section, Caffeoylquinic acids and their metabolites as inhibitors for Alfa-glucosidase, corresponds to the search through molecular docking of caffeoyl quinic acids as inhibitors for α-glucosidase and what was possible to draw from this search. The last section, In situ design of an inhibitor for α-glucosidase (EC 3.2.1.20), corresponds to the in situ drug design study and what it achieved. The representation of each of the molecules used as a ligand can be found in the Annexes.

Cell-responsive nanogels for anticancer drug delivery

One of the main goals in Nanomedicine is to create innovative drug delivery systems (DDS) capable of delivering drugs into a specific location with high efficiency. In the development of DDS, some essential properties are desired, such as biocompatibility and biodegradability. Furthermore, an ideal DDS should be able to deliver a drug in a controlled manner and minimize its side effects. These two objectives are still a challenge for researchers all around the world. Nanogels are an excellent vehicle to use in drug delivery and several other applications due to their biocompatibility. They are polymer-based networks, chemically or physically crosslinked, with at least 80-90% water in their composition. Their properties can be tuned, like the nanogel size, multifunctionality and degradability. Nanogels are capable of carrying in their interior bioactive molecules and deliver them into cells. The main objective of this project was to produce nanogels for the delivery of anticancer drugs with the ability of responding to existent stimuli inside cells (cellresponsiveness nanogels) and/or of controlled drug delivery. The nanogels were mainly based on alginate (AG), a natural biopolymer, and prepared using emulsion approaches. After their synthesis, they were used to encapsulate doxorubicin (Dox) which was chosen as a model drug. In the first part of the experimental work, disulfide-linked AG nanogels were prepared and, as expected, were redox-sensitive to a reducing environment like the intracellular medium. In the second part, AG nanogels crosslinked with both calcium ions and cationic poly(amidoamine) dendrimers were developed with improved sustained drug delivery. The prepared nanogels were characterized in terms of size, chemical composition, morphology, and drug delivery behavior (under redox/pH stimuli). The in vitro cytotoxicity of the nanogels was also tested against CAL-72 cells (an osteosarcoma cell line).