Própolis: um agente antioxidante neutralizador de radicais livres e redutor do estresse oxidativo

Abstract

The aim of the present study was to evaluate the effects of the antioxidant property present in propolis on oxidative stress and reactive oxygen species. We prepared this dissertation as two articles (1st - systematic review and 2nd - in vitro study). The systematic review evaluated the relevance of propolis administration on the oxidative parameters of diabetes mellitus (DM) induced in animal models. There was great heterogeneity regarding the origin of the studies and propolis used, showing a significant increase in the number of DM cases around the world and the search for new molecules with antidiabetic potential. The administration of propolis induced the restoration of the endogenous antioxidant defenses of the treated animals, a process accompanied by an increase in insulin secretion, a reduction in glycemic levels and lipid peroxidation. All the biochemical/physiological results got were because of the reduction of reactive oxygen species and increase in plasma levels of antioxidant enzymes, demonstrating that propolis has a beneficial effect on induced diabetes in animals, without presenting toxicity and providing parameters for its use in humans, alone or in association with reference drugs. In the in vitro study, we evaluated the antioxidant activity in two formulations based on green propolis from the south of Minas Gerais. From a sample of this propolis, we developed two formulations at 11% (w/v), such as 1) hydroethanolic extract (EEP) and 2) aqueous mucoadhesive gel (MuAd-P) to be compared. First, the chemical profile of green propolis was determined by RP-HPLC, and the cinnamic acid derivative - artepelin C - was the major compound identified. Then, the phenolic and flavonoid total contents and antioxidant activity of both formulations were determined. EEP and MuAd-P differed statistically (p<0.05) in their phenolic and flavonoid total contents, a result possibly influenced by the linseed oil polyphenols present only in the MuAd-P gel. In the DPPH, ABTS •+ and FRAP assays, there were no statistically significant differences between the formulations (p>0.05) and both showed strong reducing activity. With the results got, it was possible to determine that EEP and MuAd-P have strong antioxidant activity and that the pharmacotechnical processes used in the production of mucoadhesive did not change their ability to neutralize free radicals. We concluded that the antioxidant property of propolis reduces oxidative stress, restoring enzymatic parameters combined with a strong neutralizing effect on reactive oxygen species. We also highlight the strong antioxidant activity observed in green propolis from the south of Minas Gerais, both as ethanolic extract and as mucoadhesive gel.