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| Author(s): |
Daniel Xavier Andreguetti
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ) |
| Defense date: | 2010-12-06 |
| Examining board members: |
Pio Colepicolo Neto;
Guilherme Luiz Indig;
Ana Paula de Melo Loureiro
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| Advisor: | Pio Colepicolo Neto |
| Abstract | |
Mycosporines are substances belonging to a group of compounds naturally found in algae and fungi, which are used by these organisms as a defense mechanism. They are potent chemical blockers of ultraviolet radiation (UV), acting mainly in the spectral range of UVA, with maximum absorption ranging from 300 to 360 nm, depending on its structural composition. Chemically, they are characterized by a cyclohexenone or cyclohexenimine chromophore conjugated with the nitrogen substituent of an amino acid or an amino alcohol. Some mycosporines present a moderate antioxidant activity; in this case, they can act as natural antioxidants in marine organisms. Our synthesis was based on green chemistry principles and avoided the use of organic solvents and the production of toxic intermediates. The reactions involving a cyclic diketone and different amino acids were tested by different clean methods. Eleven mycosporines analogues were obtained. Nine of them had their pharmacological and toxicological potential evaluated. In order to verify the pharmacological potential of molecules, we determined the UV absorption spectrum of each mycosporine analogue. In addition, we evaluated their antioxidant activity by DPPH and superoxide radical scavenging potential methods. The compounds spectra show an absorption maximum ranging from 255 to 309 nm for different compounds. In the DPPH assay, two compounds reached the IC50 at concentrations of 1.597 e 1.387 mM. In the superoxide scavenging assay, all compounds tested reached the IC50 at concentrations ranging from 0.204 to 1.164 mM. The cytotoxic potential of these molecules was tested in cell cultures (3T3 fibroblasts) through the incorporation of different concentrations of the analogues and checking cell viability by MTT reduction method. The phototoxic test was conducted similarly, but adding the exposure of cells to UV radiation after addition of mycosporines analogues. The results showed that none of the compounds can be considered cytotoxic, but one of the compounds is activated by exposure to UVA radiation, becoming phototoxic. (AU) | |