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Conessine is a naturally occurring steroid alkaloid found in a number of plant species from the Apocynaceae family, which have been used in traditional herbal medicine as a treatment for amoebic dysentery. In a radioligand-based high-throughput screen, conessine demonstrated high affinity for both rat and human histamine H3 receptors (K_is = 5.2 and 24.5 nM, respectively) and high selectivity against histamine receptors H1, H2, and H4. Though conessine potently blocks H3 agonist-stimulated GTPγS binding in cell- and tissue-based functional assays and efficiently crosses the blood-brain barrier, it has a poor rate of CNS clearance.

antiamebic, antibacterial, antineoplastic, anesthetic (local)

Conessine is a steroidal dibasic alkaloid with a rigid steroid-based skeleton. Conessine is a potent and selective histamine H3 receptor antagonist.

ChEBI: A steroid alkaloid that is con-5-enine substituted by a N,N-dimethylamino group at position 3. It has been isolated from the plant species of the family Apocynaceae.

Potent and selective histamine H 3 receptor antagonist (pK i values are 7.61 and 8.27 at rat and human H 3 receptors respectively). A steroidal alkaloid that displays in vitro antiplasmodial activity (IC 50 = 1.04 μ M). Also has high affinity for α 2C adrenoceptors (pK i = 7.98).

It crystallises from acetone, sublimes at 95o/0.01mm and boils at 0.1mm with bath temperature at 220o. The dihydrochloride has m >340o (browns at 235o and decomposes at 338-240o) and has [] D +9.3o (c 2, H2O). [Marshall & Johnson J Am Chem Soc 84 1458 1962, Beilstein 22 III/IV 4382.]

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