Rhynchophylline Explained

Rhynchophylline is an alkaloid found in certain Uncaria species (Rubiaceae), notably Uncaria rhynchophylla^[1] and Uncaria tomentosa.^[2] It also occurs in the leaves of Mitragyna speciosa (kratom) and Mitragyna tubulosa,^[3] a tree native to Thailand. Chemically, it is related to the alkaloid mitragynine.

Rhynchophylline is a non-competitive NMDA antagonist (IC₅₀ = 43.2 μM) and a calcium channel blocker.^{[4] [5]}

Uncaria species have had a variety of uses in traditional herbal medicine, such as for lightheadedness, convulsions, numbness, and hypertension.^[6] These uses have been associated with the presence of rhynchophylline and have encouraged its investigation as a drug candidate for several cardiovascular and central nervous system diseases; however, few clinically relevant studies have been conducted.

See also

• Ibotenic acid
• Mitragynine pseudoindoxyl
• Proboscidea parviflora

Notes and References

1. Shi JS, Yu JX, Chen XP, Xu RX . Pharmacological Actions of Uncaria Alkaloids, Rhynchophylline and Isorhynchophylline . Acta Pharmacologica Sinica . 2003 . 24 . 2 . 97–101 . 12546715 .
2. Mohamed AF, Matsumoto K, Tabata K, Takayama H, Kitajima M, Watanabe H . Effects of Uncaria tomentosa Total Alkaloid and its Components on Experimental Amnesia in Mice: Elucidation Using the Passive Avoidance Test . Journal of Pharmacy and Pharmacology . 2000 . 52 . 12 . 1553–1561 . 10.1211/0022357001777612 . 11197086 . 40280160 . free .
3. Web site: Mitragyna Speciosa (Kratom) - World Roots .
4. Kang TH, Murakami Y, Matsumoto K, Takayama H, Kitajima M, Aimi N, Watanabe H . Rhynchophylline and Isorhynchophylline Inhibit NMDA Receptors Expressed in Xenopus Oocytes . European Journal of Pharmacology . 2002 . 455 . 1 . 27–34 . 10.1016/S0014-2999(02)02581-5 . 12433591 .
5. Kang TH, Murakami Y, Takayama H, Kitajima M, Aimi N, Watanabe H, Matsumoto K . Protective Effect of Rhynchophylline and Isorhynchophylline on in vitro Ischemia-Induced Neuronal Damage in the Hippocampus: Putative Neurotransmitter Receptors Involved in their Action . Life Sciences . 2004 . 76 . 3 . 331–343 . 10.1016/j.lfs.2004.08.012 . 15531384 .
6. Zhou J, Zhou S . Antihypertensive and neuroprotective activities of rhynchophylline: the role of rhynchophylline in neurotransmission and ion channel activity . Journal of Ethnopharmacology . 132 . 1 . 15–27 . 2010 . 20736055 . 10.1016/j.jep.2010.08.041 .