A Passiflora incarnata extract exerts multi-target effects on selected sleep-related receptors

Since ancient times, passionflower (Passiflora incarnata L.) is used to treat insomnia, nervousness, anxiety, and other neurological conditions, but the understanding of the underlying neurophysiological processes is largely limited to the involvement of the GABAergic system.

This work aims to elucidate the mechanism by which P. incarnata modulates selected sleep-promoting receptors and neurotransmitter pathways in the central nervous system.

We studied the effects of a standardized P. incarnata extract on selected sleep-promoting receptors and neurotransmitters using competitive binding and uptake assays in vitro.

The P. incarnata extract inhibited the binding of [³H]-DPCPX to the adenosine A₁, [¹²⁵I]-ZM 241385 to the adenosine A_2A, and [¹²⁵I]-LSD to the serotonin 5-HT_2A receptor, in a concentration-dependent manner, whereas the melatonin MT₁-and orexin OX₁-receptors were unaffected. The extract also inhibited [³H]-dopamine, [³H]-norepinephrine, and [³H]-serotonin uptake into rat cortical synaptosomes.

Hitherto undetermined active components of the P. incarnata extract inhibit monoamine uptake and show affinity to the adenosine A₁ and A_2A and the 5-HT_2A serotonin receptor. The results of this exploratory study support the longstanding use of P. incarnata to promote sleep.