Pseudolycorine

Lycoris aura (L Her.) Herb. L. longituba Y. Han et Fan L. radiata (L Her.) Herb. Shi Suan (Amaryllis) (rhizome) Galanthamine, lycoremine, lycorine, lycoramine, lycorenine, tazettine, pseudolycorine, dihydrolycorine, homolycorine, lycoricidine, lycoricidinol.33 As a cholinesterase inhibitor, lower blood pressure, stimulate secretion from the pituitary gland, increase natidiuretic hormone secretion. 

Extracts of Amaryllidaceae alkaloids have long been used in traditional medicine for the treatment of a variety of illnesses. As early as the fourth century B.C., Hippocrates had reputedly advised the use of preparations of Amaryllidaceae plants to control uterine tumours [157]. More recently, a systematic bioassay of these alkaloids of different structural types has revealed a diversity of interesting biological properties. Thus, (+)-pretazettine (369) [158,159], and ungeremine (182) [160] show anti-leukemic activity. Cytotoxicity was observed for (-)-lycorine (245) [161], (-)-pseudolycorine (574) [162], 6-a-hydroxycrinamine (575) [163],... 

The discovery of lycorine-1-O-p-D-glucoside (4) and the related alkaloid pseudolycorine-1 -0- (i-D-glucoside (10) in Pancratium biflorum represented the first report of the natural occurrence of glucosyloxy alkaloids in the family Amaryllidaceae (73). The structures of 4 and 10 were deduced from H NMR and mass spectroscopy coupled with the observation that hydrolysis of the glycosides with emulsin afforded lycorine (1) and pseudolycorine (9), respectively, together with D-glucose. 

The phenanthridine alkaloid lycorine (narcissine, galanthidine) (MD—Phe G5N C6) has a widespread occurrence and inhibits protein synthesis. Like lycorine, the structurally similar alkaloids dihydrolycorinine, haemanthamine, narciclasine, pretazettine and pseudolycorine also inhibit protein synthesis at the level of peptide bond formation. Galanthamine (lycorimine) (Phe C6N C40 C6 ), from daffodil bulbs but also of widespread occurrence, is both a nACh-R allosteric modulator and an inhibitor of AChE. Galanthamine is clinically employed in the treatment of Alzheimer s disease (dementia linked to deficiency in acetylcholine-mediated signalling in the central nervous system). 

Aside from those mentioned in the Table, three other alkaloids were detected in Galanthus caucasicus, but were not identified.9 It is possible that galanthusine (5), isolated10 from the same species, may be correlated with the degradation product (3) of clividine and hippeastrine (see above).7 Leucojum vernum yielded the alkaloids listed in the Table and three others which were not characterized.12 Pseudolycorine (6 R1 = R3 = R4 = H, R2 = Me), from Narcissus tazetta, and the residual alkaloid extract from this species appear to show excellent activity against a specific type of leukaemia.13... 

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