Síntese e investigação de atividades biológicas de Diidro-Piran-2,4-Dionas

Abstract

This work presents synthesis of seven dihydro-pyran-2,4-diones and investigation of some of its biological activities (moluscicidal, antiulcer, antioxidant and anticholinesterasic). These compounds were prepared - in yields that had varied of moderate to good (50 - 85%) - through the aldol condensation of β-ketoester’s diânion with an aldehyde or a ketone, basic hydrolysis, followed of lactonization in acid medium. In the first investigation about its biological activities, dihydro-pyran-2,4-diones had been inactive on Biomphalaria glabrata adult, presenting active only on its egg masses. Studies about antiulcer activity were not satisfactory therefore results obtained for dihydro-pyran-2,4-diones were not significantly different of those observed in the control group. For determination of the antioxidant activity, the spectrophotometric assay with stable radical DPPH was chosen. The results obtained for dihydro-pyran-2,4-diones, in this assay, were similar to the observed ones for the positive control used, BHT, and show that these compounds constitute in a promising synthetic antioxidants. Results obtained still point with respect to a possible correlation between enol concentration in the equilibrium, and the capacity of reduction of free radical DPPH. It was verified that electron withdrawing groups increase the activity, whereas introduction of electron donators groups cause a reduction of the activity. When assays were extended for other acyclic 1,3-dicarbonilic compounds, was verified that these don’t present antioxidant activity on free radical DPPH. This fact indicates that conformation also can be decisive for manifestation of the studied activity. The inquiry of the anticholinesterasic activity not yet presented results conclusive, but the preliminary assays showed resulted sufficiently promising, with percentage of inhibition of the enzyme acetylcholinesterase between 50% - 60%.