Table 3 Summary of the studies examining the effect of flavonoid-rich foods (gingko biloba, green teas, blueberry, promegranate juice) and pure flavonoids ((-) epicatechin, Quercetin, Rutin. EGCG, catechin) on neuro-cognitive ability in rodents

Ginkgo Biloba

 20, 30 and 50 mg/kg bw 1 h before the test trial

RAM: reference and working memory task

Effects of GBE mainly contributable to cholinergic activity and partly due to a histaminergic mechanism

[231]

 10; 20; 40 mg/kg bw of GBE per day in the interval between training and testing (17 days)

RAM: olton task and delayed non-matching to sample; MWM: classic task and probe trials

No effects in short-term and long term memory. Possible contribution to acquisition of the DNMS in RAM

[183]

 10 mg/kg bw per day for 28 days prior to and throughout the testing

MWM: classic task and probe trials (5 min and 2 weeks later), reversal learning paradigm

No effect on task acquisition or long-term retention. Effect on ST retention for animals trained in massed trials. GBE enhanced reversal learning in massed and spaced trained animals.

[94]

 30 and 60 mg/kg bw per day for 30 days (during training and testing)

MWM: Classic task and reversal learning paradigm

Egb 761 enhanced learning in the classic task in aged rats (60 mg/kg) and in the repeated reversal task (30 and 60 mg/kg). Enhanced LTP in CA1 in supplemented animals

[219]

 CL:50 mg/kg bw 30 min before testing and after testing. DNMS:100 and 200 mg/kg immediately before the pre-delay sub-session

RAM: Delayed non-matching to sample and continuous learning task

Pre-session administration resulted in faster continuous maze learning. Dose-related decrease in errors in delayed non-match task

[227]

 100 mg/kg bw per day for 21 days

MWM: classic task and probe trial (24 h); object recognition test (non-spatial memory)

Egb 761 improved spatial and non-spatial memory in control rats. Preventive doses of Egb 761 normalised non-spatial cognitive deficits and improved spatial memory in rats chronically stressed or corticosterone treated

[218]

Pomegranate juice

 5 ml of juice per day for 6 months and a half

MWM: classic task and probe trials (2 days)

Supplemented mice learned MWM task faster and had significantly less accumulation of soluble AB42 and amyloid deposition in the hippocampus. Potential effect of PJ in AD should be considered.

[87]

Green tea

 Green tea catechins (PE) mixed in water at concentrations of 1 and 5 g/l for 26 weeks

RAM: working and reference memory task

Administration of PE had improved reference and working memory and conducted to lower plasma concentrations of lipid peroxides (LPO) and greater plasma ferric-reducing anti-oxidation power. Lower hippocampal ROS concentrations in treated rats was also observed.

[85]

 Tea polyphenol (TP)- 0,2%(w/w) for 7 weeks

Passive avoidance learning; Y-maze: continuous alternation task

Chronic administration of TP improved cognitive performance and inhibited acetylcholinesterase (AChE) activity in scopolamine-induced amnesic mice

[108]

Blueberry

 2%(m/m) blueberry incorporated in the food for 8 weeks before testing

MWM:classic task and probe trials (during acquisition)

Blueberry supplemented rats showed the greatest increases in GTPase activity, Ca2+ recovery and dopamina release, as well as improved spatial memory.

[102]

 2%(m/m) blueberry incorporated in the food for 8 weeks before testing

RAWM: Working and reference memory task and reversal learning paradigm

Improvement in LT reference memory correlated with significant increase in the levels of IGF-1, IGF-1R and ERK activation (hippocampal plasticity)

[189]

 2%(m/m) blueberry incorporated in the food for 10 weeks before, during and after testing

MWM: working memory task, reversal learning paradigm

There was no significant improvement in spatial memory. Anthocyanins were found in the cerebellum, cortex and hippocampus

[9]

 3,2 mg/kg/day of anthocyanins administered in blueberry powder dissolved in water for 4 weeks before training

Inhibitory fear conditioning learning: Short- and Long-term memory tasks. RAM: working and reference memory task

Improvement in ST spatial memory and ST inhibitory fear conditioning memory. Positive effect in locomotion

[162]

 2%(m/m) blueberry incorporated in the food for 12 weeks during testing

X maze: Delayed non-matching to sample

Improvement in spatial working memory in aged animals (performance comparable to young animals), associated with increases in BDNF synthesis, via ERK/CREB pathway

[224]

Epicatechin

 2,5 mg/day/rat for 2 weeks before testing

MWM: Classic task and probe trials (24 h, 1 and 2 weeks after acquisition)

Effect of diet on retention after 24 h and 1 week, especially in combination with exercise. Increased angiogenesis and neuronal spine density in DG

[214]

Quercetin, Rutin. EGCG, catechin

 EGCG- 50 mg/kg; catechin- 200 mg/kg, rutin- 50 mg/kg, quercetin-50 mg/kg- 30 min before the first and second arterial occlusions

RAM: Olton task

Both rutin and quercetin improved spatial memory impairment and neuronal death in the hippocampal CA1 area.

[159]