Açai palm fruit (Euterpe oleracea Mart.) pulp improves survival of flies on a high fat diet

Abstract

Reducing oxidative damage is thought to be an effective aging intervention. Açai, a fruit indigenous to the Amazon, is rich in phytochemicals that possesses high anti-oxidant activities, and has anti-inflammatory, anti-cancer and anti-cardiovascular disease properties. However, little is known about its potential anti-aging properties especially at the organismal level. Here we evaluated the effect of açai pulp on modulating lifespan in Drosophila melanogaster. We found that açai supplementation at 2% in the food increased the lifespan of female flies fed a high fat diet compared to the non-supplemented control. We measured transcript changes induced by açai for age-related genes. Although transcript levels of most genes tested were not altered, açai increased the transcript level of l(2)efl, a small heat-shock-related protein, and two detoxification genes, GstD1 and MtnA, while decreasing the transcript level of phosphoenolpyruvate carboxykinase (Pepck), a key gene involved in gluconeogenesis. Furthermore, açai increased the lifespan of oxidative stressed females caused by sod1 RNAi. This suggests that açai improves survival of flies fed a high fat diet through activation of stress response pathways and suppression of Pepck expression. Açai has the potential to antagonize the detrimental effect of fat in the diet and alleviate oxidative stress in aging.

Fig. 1

Effect of açai supplementation on the lifespan of males (A) and females (B). Lifespan curves of flies fed a standard diet supplemented with various amount of açai are shown in the graph. The concentrations of açai and mean lifespan of flies in parenthesis are listed beside the lifespan curves. d refers to days for lifespan. The number of flies in each experiment is listed in Table 1.

Fig. 2

Effect of fat and açai supplementation on the lifespan of females. (A) Lifespan curves of female flies fed a normal diet, a high fat diet and a high fat diet supplemented with 2% açai from experiment #1 are shown in the graph. (B) Food intake in 24 hours for females on the high fat diet control and the high fat diet supplemented with 2% açai from one experiment is shown (n=4). The similar results on food intake were observed from the other repeated experiment (data not shown). (C) Lifespan curves of female flies fed the high fat diet and the high fat supplemented with 0.5%, 1% and 2% açai from experiment #2 are shown. (D) Lifespan curves of male flies fed the high fat diet and the high fat supplemented with 0.5%, 1% and 2% açai are shown. The mean lifespan in days are listed in parenthesis. The number of flies in each experiment is listed in Table 1. ***p<0.001 by ANOVA after the Bonferroni adjustment for multiple comparisons.

Fig. 3

Effect of açai supplementation on gene expression. (A) Head-specific expression levels of 12 genes were measured for females fed a normal diet (N), a high fat diet (F) and a high fat diet supplemented with 2% açai (F+ açai) (n=3). Full description of these genes and the primers for qPCR is presented in Table 1. (B) Body-specific expression levels of Sir2, dFoxo, and Pepck were measured for females fed a normal diet, a high fat diet and a high fat diet supplemented with 2% açai (n=3). (C) Head-specific expression levels of six putative JNK target genes were measured for females fed the high fat diet (F) and the high fat diet supplemented with 2% açai (F+ açai) (n=3). ***p<0.05; **p<0.01; ***p<0.001.

Fig. 4

Effect of açai pulp supplementation on the lifespan of oxidative stressed female. (A) Western blot analysis of expression of SOD1 protein in the control (da-Gal4/+) and sod1 RNAi (da-Gal4/UAS-sod1IR) flies. (B) Lifespan curves of sod1 RNAi females fed the normal SY diet and the SY diet supplemented with 2% açai from experimental #2 are shown in the graph. Açai supplementation was initiated at adult age of 3 days old in experiment #2. (C) Lifespan curves of sod1 RNAi males fed the normal SY diet and the SY diet supplemented with 2% açai from experimental #2 are shown in the graph. Açai supplementation was initiated at adult age of 3 days old in experiment #2. The mean lifespan in days are listed in parenthesis. ** p<0.01;***p<0.001.