Indicaxanthin from Opuntia Ficus Indica crosses the blood-brain barrier and modulates neuronal bioelectric activity in rat hippocampus at dietary-consistent amounts.
J Agric Food Chem. 2015 Jul 31. Epub 2015 Jul 31. PMID: 26227670
Indicaxanthin is a bioactive and bioavailable betalain pigment from the Opuntia ficus indica fruits. In this in vivo study, kinetic measurements showed that indicaxanthin is revealed in the rat brain within 1h from oral administration of 2µmol/kg, an amount compatible with a dietary consumption of cactus pear fruits in humans. A peak (20 ± 2.4 ng indicaxanthin per whole brain) was measured after 2.5 h, thereafter the molecule disappeared with first order kinetics within 4 h. The potential of indicaxanthin to affect neural activities was in vivo investigated by a microiontophoretic approach. Indicaxanthin, administered in a range between 0.085 ng and 0.34 ng per neuron, dose-dependently modulated the rate of discharge of spontaneously active neurons of the hippocampus, with reduction of the discharge and related changes of latency and duration of the effect. Indicaxanthin (0.34 ng/neuron) showed inhibitory effects on glutamate-induced excitation, indicating activity at the level of glutamatergic synapses. A molecular target of indicaxanthin is suggested by in silico molecular modeling of indicaxanthin with N-methyl-D-aspartate receptor (NMDAR), the most represented of the glutamate receptor family in hippocampus. Therefore at nutritionally compatible amounts indicaxanthin i) crosses the rat BBB and accumulates in brain; ii) can affect the bioelectric activity of hippocampal neurons locally treated with amounts comparable with those measured in the brain and iii) modulates glutamate-induced neuronal excitation. The potential of dietary indicaxanthin as a natural neuromodulatory agent deserves further mechanistic and neurophysiologic investigation.