Evaluation of the Potential of Brazilian Propolis against UV-Induced Oxidative Stress

Abstract

This study investigated the potential use of topically and orally administered propolis extracts to prevent UV irradiation-induced oxidative stress in skin. The results illustrated that green propolis extract (GPE) contained greater amounts of polyphenols, coumaric acid, drupanin, baccharin and artepillin C than did brown propolis extract (BPE). GPE showed higher antioxidant activity than BPE when the IC(50) (concentration that caused 50% inhibition) values were compared. Interesting, the oral treatment of hairless mice demonstrated a recovery of 30.0% for GPE and 22.8% for BPE with respect to UV irradiation-induced GSH depletion. The topical pretreatment of animals with both propolis extract solutions recovered around 14.0% of the depleted GSH. However, the employed treatments did not inhibit the increase of cutaneous proteinase secretion/activity caused by irradiation. These findings indicate that despite differences in composition and antioxidant properties, GPE and BPE both successfully prevent UV-induced GSH depletion in vivo and are both promising antioxidant systems against oxidative stress in skin. Based on these findings, complementary studies should be performed to enhance our understanding of the protective effects of propolis extracts in skin.

Figure 1

Chromatograms of BPE (a) and GPE (b). 1: p-coumaric acid, 2: drupanin, 3: artepillin C, and 4: baccharin.

Figure 2

In vivo protective effect as assessed by the GSH depletion assay. G1 = nonirradiated control, G2 = irradiated control, G3 = GPE, and G4 = BPE. (a) Topical treatment and (b) Oral treatment. Bars represent means ± SE of three replicates. Statistical analysis was performed using the Student's t-test. *P < 0.05 compared to the nonirradiated control and **P < 0.05 compared to the irradiated control.

Figure 3

Hypothetical diagram of UV irradiation-induced skin damages and intervention of propolis extract. Degenerative processes related to UV irradiation skin exposure are largely mediated by the overproduction of reactive oxygen species (ROS) and by the impairment of antioxidant systems. Thus, the ROS not eliminated by the biological system can cause cellular damage and biochemical alterations, such as oxidation of proteins and lipids, inflammation, damage to DNA, and activation and inactivation of enzymes. These biochemical alterations generate clinical signals as photoaging, local and systemic immunosuppression, and skin cancer. We showed that propolis extract may interfere in the overproduction of ROS and in the UV irradiation-induced GSH depletion. Then, the present study suggests the potential applicability of propolis extracts against UV-induced skin damages.