Uncaria hook

Kanno H, Kawakami Z, Iizuka S, Tabuchi M, Mizoguchi K, Ikarashi Y et al (2013) Glycyrrhiza and Uncaria Hook contribute to protective effect of traditional Japanese medicine yokukansan against amyloid p oligomer-induced neuronal death. J Ethnopharmacol 149 360-370... 

Nishi A, Yamaguchi T, Sekiguchi K, Imamura S, Tabuchi M, Kanno H, et al. Geis-soschizine methyl ether, an alkaloid in Uncaria hook, is a potent serotoninl A receptor agonist and candidate for amelioration of aggressiveness and sociahty by Yokukansan. Neuroscience 2012 207 124-36. 

Ueki T, Nishi A, Imamura S, Kanno H, Mizoguchi K, Sekiguchi K, et al. Effect of geissoschizine methyl ether, an indole alkaloid in Uncaria Hook, a constituent of Yokukansan, on human recombinant serotonin(7) receptor. Cell Mol Neurobiol 2013 33(l) 129-35. 

The hooks of Uncaria sinensis, a Chinese vine tree closely resembling U, rhyn-chophylla, are used as a drug to treat infant convulsions, as an antispasmodic, and as a tranquilizer. Recently, it was found that the hypotensive principles of Uncaria hooks are indole-alkaloid glucosides, 3a-dihydrocadambine and 3)ff-isodihydro-cadambine (42). Along with these glucosides, cadambine has been also obtained from the hooks. 

Endo K, Oshima Y, Kikuchi H, Koshihara Y, Hikino H 1983 Hypotensive principles of Uncaria hooks. Planta Med 49 188-190... 

Glycosidic indole alkaloids have also been isolated cadambine from the bark of Adina cordifolia Hook. f. (94) and 3a-dihydrocadambine from leaves of Anthocephalus chinensis (Lamk.) A. Rich ex Walp. (95). The /3-carboline alkaloid harman is found in the leaves of both Mitragyna hirsuta (64) and Uncaria canescens Korth. (96). 

The dried thorn hooks of Uncaria sinensis, U rhynchophylla, and U. kawakamii (Rubiaceae) are known as Cho-Toh-Koh in the Chinese herbal medicine system in Japan, and have been used as a sedative for a long time. An ethanol extract of this crude drug provides a temporary hypotensive response in the rabbit (150mg/kg), with an increase in breathing rate and a decrease in arterial blood flow [1]. 

Uncaria gambier (Rubiaceae), a woody climber with recurved hooks, grows wild in eastern India, Malaysia, and Sumatra and is also cultivated in the Malaysian... 

Uncaria rhynchophylla is a climbing vine tree growing in China, Japan, and other temperate Asian countries. Directly above its leaves are hooks into which small stems metamorphose. 

Uncaria formosa, which also closely resembles U rhynchophylla, grows wild in Formosa. Its hooks contain isoformosanine (uncarine A) and formosanine (un-carine B), and are used also in folk medicine for rheumatism and malaria. 

Rubiaceae family plant species play a significant role in day-to-day life being source of many products including, Uncaria gambir (source of taruiin), Calycophyllum, and Neolamarckia chinensis as sources of timbers [4], Gardinea spp. as source of perfume and ornamentals [5]. The plant species of this family are accessible on almost every region of world except Antarctic continents. Uncaria Schreb. (Rubiaceae) spp. are other major sources for the discovery of novel medicinal natural compounds [6]. Species of Uncaria are commonly woody climbers, shrubs, or small trees with characteristic hooks on either side of the shoots [7]. Most of the species of Uncaria are native to Asia and some of them are also distributed in Africa and South America [7]. 

Uncaria spp. have traditionally been widely used for the treatments of wounds, ulcers, fevers, headaches, and gastrointestinal illnesses [8,9]. Dried hooks of Uncaria spp. are used as major components of traditional medicines and have therapeutic applications as analgesics and sedatives for the nervous system-related disorders [8,9]. One of the important uses of Uncaria Spp. is their use in the treatment of hypertensirMi [12], Table 1 summarizes the list of ethno-medicinally important Uncaria species that are commonly used for the treatment of various diseases. 

The phytochemical studies of Uncaria spp. have begun in early 1900s [11]. Rhynchophylline (1.1) is one of the earliest reported compounds from the hooks of U. rhynchophylla [11]. Latter studies on these plants reported over 150 compounds that belong to mainly three classes of compounds (i) alkaloids, (ii) terpenoids, and (iii) flavonoids. In addition, several unusual structures were also identified [6]. Major emphasis of this chapter is on the occurrence of these compounds among various species, their structural diversity and pharmacological activities. 

Uncaria spp. are commonly used in the treatment of vascular diseases. Kim et al. [59] isolated corynoxeine (1.2) from hooks of U. rhynchophylla, that inhibited rat aortic vascular smooth muscle cells (VSMCs) [59]. The study revealed that, corynoxeine (1.2) exerted inhibitory effect on platelet-derived growth factor-BB-induced rat aortic VSMCs proliferation. Pretreatment of VSMCs with 5-50 pM of corynoxeine for 24 h decreased the cell proliferation without cytotoxicity [59]. 

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