Conessine is a steroidal alkaloid found in a number of plant species from the family Apocynaceae, including Holarrhena floribunda,[1] Holarrhena antidysenterica[2] and Funtumia elastica.

[3] It acts as a histamine antagonist, selective for the H3 subtype (with an affinity of pKi = 8.27; Ki = ~5 nM).

[4] It was also found to have long CNS clearance times, high blood–brain barrier penetration and high affinity for the adrenergic receptors.

[5] This pharmacology-related article is a stub.

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