Carvalho, Maria de FátimaGrosso, ClaraFerraz, RicardoSalgado, Bárbara Inês dos Santos2025-02-192025-02-192024-11-192024-11-19http://hdl.handle.net/10400.22/29589Alzheimer’s disease remains as the most common cause of dementia, accountig for an estimated 60% to 80% of total cases. However, effective treatment for this neurodegenerative disease has yet to be found. Bactéria from the phylum Actinomycetota, known as actinobacteria, are a group of gram-positive bactéria with highly promising biotechnological potential, being responsibel for the production of a large number of antibiotics and other clinically importante molecules. Terrestrial Actinomycetota are extensively explored, but marine environments are yet poorly investigated in terms of these valuable microbials resources. In this work, the crude extracts from various strains of actinobacteria previously isolated from marine macroalgae and deep-sea samples were obtained. These extracts were screened for their anti-Alzheimer potential by testing enzymes involved in the pathogenesis of Alzheimer’s disease, namely acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) (1,2). The percentagem of inhibition of these enzymes was evaluated by performing an adapted protocolo f Elman’s colirimetric method (3). After performing the assays above, a selected group of the actinobacteria strains demonstrated some degree of inhibition of AChE and BuChE at a concentration of 2mg/ml in each well. Besides AChE and BuChE inhibition, their inhibitory potential against tyrosinase was also evaluated, showing that the extratcs had a high percentagem of inhibition of this enzyme (above 60%). The antioxidante activity was also assessed against superoxide anion radical, and only one strain (S_113_5) showed some degree of scavening (53,7%). Lastly, their cytotoxic effects were tested on both neuroblastoma cells (SH-SY5Y), and healthy fibroblasts (3T3-L1) and being possible to see some cytotoxicity on the neuroblastoma cell line not on the fibroblasts, suggesting a selective effet that doesn’t harm the healthy cells. These results suggested a putative anticancer potential and additionaly extracts were tested in the cancer cell line RKO. Results indicat that all extracts showed some level of cytotoxicity against RKO cells, indicating potential anti-cancer activity. Taking into account the results obtained, this study shows that actinobacteria can be a source of nw therapies for tackling Alzheimer’s disease.engActinomycetotaAlzheimer´s diseaseMacroalgaeDeep-seaAcetylcholinesteraseButyrylcholinesteraseTyrosinasemaster thesis203852761