Chemical Properties
Light yellow to yellow solid
Definition
ChEBI: Icariin is a member of the class of flavonols that is kaempferol which is substituted at position 8 by a 3-methylbut-2-en-1-yl group and in which the hydroxy groups at positions 3, 4', and 7 have been converted to the corresponding 6-deoxy-alpha-L-mannopyranoside, methyl ether, and beta-D-glucopyranoside, respectively. A phoshphodiesterase-5 inhibitor, it is obtained from several species of plants in the genus Epimedium and is thought to be the main active ingredient of the Chinese herbal medicine Herba Epimedii (yinyanghuo). It has a role as a bone density conservation agent, a phytoestrogen, an EC 3.1.4.35 (3',5'-cyclic-GMP phosphodiesterase) inhibitor and an antioxidant. It is a glycosyloxyflavone and a member of flavonols.
General Description
Icariin is a prenylated flavonol and the major bioactive compound found in Epimedium herb.
Biological Activity
icariin exhibits inhibitory effects on cgmp-specific phosphodiesterase pde5 and camp-specific phosphodiesterase pde4 activities. phosphodiesterase (pde) is a crucial regulator of camp/pka signaling. pdes are encoded by 21 genes which can be sdivided into 11 families according to the substrate specificities and subcellular localization. pdes are widely expressed in neurons. pde5 has been implicated in regulating some physiological processes such as smooth muscle relaxation and neuronal survival. pde4 has been associated with the darpp-32 signaling pathway and dopaminergic neurotransmission [1].
Biochem/physiol Actions
Icariin is a potent neuroprotective agent in neurodegenerative disorders and other disorders affecting the nervous system. It elicits anti-aging properties in unfertilized oocytes against age-related damage. Icariin exerts anti-inflammatory and antifibrotic properties aiding protection in chronic kidney disease (CKD)-associated renal fibrosis in mouse model. It also serves as an excellent antidiabetic and anti-atherosclerotic agent. Icariin is an excellent anti-cancer agent.
Mechanism of action
Icariin is known as an indicative constituent of the Epimedium genus, which has been commonly used in Chinese herbal medicine to enhance treat impotence and improve sexual function, as well as for several other indications for over 2000 years. Icariside II is a intestinal metabolite of icariin. Their inhibition profile are different. Icaritin is a potent inhibitor of UGT1A7 and UGT1A9 but icariside II is a potent inhibitor of UGT1A4, UGT1A7, UGT1A9, and UGT2B7.
in vitro
icariin inhibited the activity of pde5 and pde4 in a dose- andconcentration-dependent manner. the ic50of icariin on pde5 was 0.43 μm and the ic50 on pde4 was 73.50 μm. icariin showed a selective inhibitory effect on cgmp-specific pde5 compared to camp-specific pde4 [2].icariincould also enhance the osteogenic differentiation of rat primary bone marrow stromal cells [3].
in vivo
in castrated rats, a 4-week oral administration of icariinat 1 mg/kg/day and 5 mg/kg/day improved the erectile function and increased nnos and inos expression [4].icariin also showed its effect on stimulating angiogenesis in human endothelial cells [5].
