Crinine type alkaloids

Galanthamine-type alkaloids derived from a dibenzofuran ring Crinine-type alkaloids derived from 5,10b-ethanophenanthridine Montanine-type alkaloids derived from 5, 11b-... 

The majority of the alkaloids that had affinity to the serotonin transporter (SERT) were crinine-type alkaloids. However, cherylline 4, tazettine 8 and 1-0-acetyllycorine 53 are the only alkaloids that showed affinity to SERT among the cheiylline-, tazettine- and lycorine-type alkaloids, respectively (80). The activity of the crinine-type alkaloids was attributed to the presence of a 1,3-dioxole moiety in common with the chnically used SSRI paroxetin (79). 

Since 1987, the isolation and characterization of several new crinine-type alkaloids have been reported. The structures of the representative alkaloids isolated are depicted in Figs. 11 and 12. 

Since the previously published review (5), some interesting methods for the synthesis of crinine-type alkaloids have appeared. 

Intramolecular 2-aza-allyl anion cycloaddition was employed for the synthesis of the crinine-type alkaloids ( )-crinine (135) 142a) and (-)-amabiline (145) 142c) and has been reported to provide potential precursors of 6a-epi-pretazettine (314) and 6a-ep/-precriwelline (methoxy epimer of 314) 142b). 

A number of new crinine-type alkaloids have been identified this year. Thus, further investigation of H. ananuca (cf. Vol. 10, p.135) resulted in the isolation of the new alkaloid (1) as well as haemanthamine the structure of compound (1) was deduced mainly... 

The alkaloid, C16H17NO4 (mp 219° [a]]j +74° in CHCI3), was isolated from the Hippeastrum hybrid Anna Powlowna . It forms pi crate (mp 249° decomp.) and hydriodide (mp 221° decomp.) salts. The compound gives a red color with concentrated sulfuric acid. It is classified as a crinine-type alkaloid because the IR-spectrum of annapawine is very similar to that of powellamine and crinine (32). 

Some Amaryllidaceae plants possess a group of alkaloids containing a Cg— C2-N-C1-C6 unit. In this unit, the C6-C2-N moiety is derived from tyrosine or tyramine, and the C -Ci part is derived from phenylalanine through cinnamic acid, p-coumaric acid, and protocatechualdehyde [1]. Tyramine (C6-C2-N unit) and protocatechualdehyde (C -Ci unit) are then combined and methylated to form O-methylnorbelladine, which is a common biosynthetic precursor of various Amaryllidaceae alkaloids. Through para,ortho -, ortho,para - and para,paw-phenol coupling of norbel-ladine, the lycorine, galanthamine, and crinine type alkaloids are formed, respectively [2]. 

From the bulbs of L. radiata, examples of the lycorine-type, galan-thamine-type, and crinine-type alkaloids were isolated, in addition to preta-zettine [17]. According to Uyeo andYajima, the amount of total alkaloids obtained from the bulbs of L. radiata was almost the same throughout the year, whereas the amount of lycorine varied, and the highest amount (December 3) was 0.0277% and the lowest (May 10) was 0.0026%, about a 10-fold difference. 

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