Effect of Nutrients and Phytochemical Compounds of Solanum melongena (Eggplants) on Cognitive Protection in Rats

Abstract

Many factors among which life style and oxidative stress are implicated in the incidence of neurodegenerative diseases. One of the ways to prevent neurodegeneration is to supply the body with antioxidant molecules derived from food. The aim of this study is to evaluate the nutritional value and neuroprotective activities of eggplants on cognitive impaired rat model. Powder was made with the white and purple Solanum melongena and the nutritional value of each was determined. Total phenolic and flavonoid content, antioxidant activity by DPPH scavenging and reducing iron tests, were determined from aqueous, ethanolic and hydroethanolic fruit extracts. The powder and the most active extract of Solanum melongena were used to determine neuroprotective activity in rats. Male wistar rats were divided into 7 groups of 6 each. Morris water maze and radial maze tests were performed at the end of the experiment to assess behaviour in rats. After 28 days, the rats were sacrificed and biochemical investigations such as protein content, reduced glutathione, catalase activity, malondiadehyde and acetylcholinesterase activity were evaluated in brain homogenates. The purple Solamun melongena showed the highest ash (6.06%), calcium (10.50 mg/100 g of desiccated foods), phosphorus (25.75 mg/100 g of desiccated foods), potassium (218.00 mg/100 g of desiccated foods) and zinc (0.18 mg/100 g of desiccated foods) content. On the other hand, white Solanum melongena showed the highest fiber (3.61%) and iron (0.36 mg/100 g of desiccated foods) content. The greatest phenolic content (69.90 mg GAE /g) and flavonoid content (31.54 mg CATE / g) was observed with the purple Solanum melongena. It also presented the best scavenging DPPH activity (EC 50 = 41.91 μg/ml). The group Sm400 showed the best memory learning activity with radial maze tests (0.66 n/min), a significant decrease of malondialdehyde (15.26 µmole/g), acetylcholinesterase activity (0.13 nmol/min/mg protein) and an increase of protein content (43.71µmole/g) (P<0.05). The group Sm10% showed the best memory capacity radial maze tests (0.73 n/min), the lowest malondialdehyde level and acetylcholinesterase activity (12.45 µmole/g and 0.11nmol/min/mg protein respectively) (P<0.05). Purple Solanum melongena could be used to protect neuron functions.