The Effects of Euterpe oleracea Mart. (Açaí) Extract on the Survival of Random-Pattern Skin Flaps in Rats

Purpose: Flap necrosis remains a major complication of reconstructive surgery. Euterpe oleracea Mart., popularly known as "açaí," is cultivated in the Amazon region of Brazil. It contains hydroxybenzoic acids, antioxidant polyphenolics, flavan-3-ols, and anthocyanins. Açaí exhibits anti-inflammatory action through the inhibition of cyclooxygenases 1 and 2¹, vasodilation, inhibition of nitric oxide production, inducible nitric oxide synthase activity and expression, and antioxidant properties². Current study demonstrates that polyphenolics increase cutaneous angiogenesis³. This study evaluated whether açaí could improve the survival of random-pattern skin flaps in an experimental rat model.

Methods: Thirty male Sprague-Dawley rats were randomly divided into two groups: the açaí treatment group(n=15), and the control group(n=15). In açaí and control groups, 3x9cm dorsal skin flaps including the panniculus carnosus were elevated and sutured back into place. To block the new blood supply from the bed, a silicone sheet was placed under the flaps⁴. In açaí treatment group, 100 mg/kg/day of açaí stone extract⁵ was administered in drinking water for 7 days. Control group received saline. Seven days post-procedure, flap survival was measured and histologic specimens were harvested from the flap midline. Histologic examination, inflammatory mediator detection, and immunohistochemical analysis were performed.

Results: The percentage of flap survival was higher in açaí treatment group(80.21±9.05%) than in control group(60.08±8.53%)(P<0.05). Açaí treatment group had more VEGF-positive cells than control group on immunohistochemistry(138.13±26.93/HPF vs. 85.20±19.05/HPF, respectively; P<0.05). CD31-positive microvascular densities were significantly higher in açaí treatment group than in control group(30.67±4.62/HPF vs. 15.33±5.25/HPF, respectively; P<0.05). Anti-a-smooth muscle actin antibody expression was also significantly higher in açaí treatment group than in control group(16.47±4.32/HPF vs. 7.40±2.69/HPF, respectively; P<0.05). Western blot analysis of the expression of anti-VEGF in lysates revealed significantly greater VEGF protein expression in açaí treatment group compared with control group(1.11±0.17 vs. 0.39±0.09, respectively; P<0.05).

Conclusion: This study found that açaí intake increased neovascularization and mitigated tissue damage and inflammatory responses; açaí treatment was also associated with a higher percentage of random-pattern skin flap area survival.

Fig. 1. The caudally based random pattern skin flap(3 x 9 cm) was elevated on the dorsum of rat.

Fig. 2. Açaí stone extract increases the expression of VEGF determined by Western blot analysis in  flap midline specimens from Sprague-Dawley rats. Results are represented as mean±SEM; n=10 for each group, *P<0.05