Uncaria rhynchophylla

Hou WC, Lin RD, Chen CT, Lee MH. Monoamine oxidase B (MAO-B) inhibition by active principles from Uncaria rhynchophylla. J Ethnopharmacol 2005 100 216-220. 

Hirsutine (2-795), which belongs to the corynanthe subgroup of the indole alkaloids, was isolated from the plant Uncaria rhynchophylla MIQ and used for the preparation of the old Chinese folk medicine Kampo [397]. It is of pharmacological interest as it shows a strong inhibitory effect on the influenza A virus (subtype H3N2) with an EC50 = 0.40-0.57 pg ml. which is about 11- to 20-fold higher than that of the clinically used ribavirin [398]. 

Uncaria rhynchophylla Miq. (57). The N-oxide of hirsutine (58) has been found in Uncaria tomentosa DC. (55), and 3-isopaynanthiene (59) has been isolated from Mitragyna speciosa Korth. (58). 

A limited number of alkoyl-glucoalkaloids have been reported in the literature so far. The first specimen of this class of compounds to be isolated was rubescine (43), which was found in Adina rubescens (64). More recently another esterified vincoside lactam, rhynchophine (44), was extracted from the leaves of Uncaria rhynchophylla, a member of the tribe Cinchoneae (65). Thus, chemotaxonomic correlations again tend to raise the question whether Pauridiantha should not join, along with Adina and Uncaria, the tribe Naucleae. 

The alkaloids hirsutine (1) and its 3or-epimer dihydrocorynantheine (2a) belong to the corynanthe group of indole alkaloids. They have been isolated from the plant Uncaria rhynchophylla MIQ, which was used for the preparation of the old Chinese folk medicine kampo . Nowadays, 1 and related compounds attract great attention in medicine because of their growth inhibition of the influenza A subtype H3N2 virus. With an EC50 value of 0.40-0.57 ig/mL 1 has shown itself to be 10-20 times more active than the clinically used drug ribavirine (3).1,2 Furthermore, 1 is known for its antihypertensive and antiarrhythmic activity.3... 

Tietze s synthesis of hirsutene 141, an alkaloid from Uncaria rhynchophylla used in Chinese traditional medicine and with promising activity against influenza viruses, uses many chemose-lective reactions of which we shall discuss just three - one at the start, one in the middle, and one at the end of the synthesis.25... 

Oxindole and indole alkaloids corynoxeine, hirsutine, and hirsuteine from uncaria Uncaria rhynchophylla Miq.) as the main compounds of the extract destabilize the formation of Ap aggregates [185]. They also have a neuropro-tective effect and inhibit glutamate-induced neurotoxicity in the cells of the cerebellum [186]. 

Hsieh C-L, Tang N-Y, Chiang S-Y, Hsieh C-T, Lin J-G (1999) Anticonvulsive and free radical scavenging actions of two herbs, Uncaria rhynchophylla (Miq) Jack and Gastrodia data Bl., in kainic acid-treated rats. Life Sci 65 2071-2082. doi 10.1016/S0024-3205(99) 00473-7... 

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. 

Indole alkaloids hirsutine and hirsuteine are the major constituents of the root bark of Uncaria rhynchophylla. Along with these, minor indole alkaloids cor-... 

From the leaves of Uncaria rhynchophylla, a glycoindole alkaloid, rhyn-chophine, has been isolated along with vallesiachotamine, vincoside lactam, and strictosamide (2). 

Aimi N, Shito T, Fukushima K, Itai Y, Aoyama C, Kunisawa K, Sakai S, Haginiwa J, Yamasaki K 1982 Studies on plants containing indole alkaloid glycosides and other constituents of the leaves of Uncaria rhynchophylla Miq. Chem Pharm Bull 30 4046 - 4051... 

Haginiwa J, Sakai S, Aimi N, Yamanaka E, Shinma N 1973 Studies of plants containing indole alkaloids. (2) On the alkaloids of Uncaria rhynchophylla Miq. Yakugaku Zasshi 93 448-452... 

---