Alkaloids from Habranthus tubispathus and Habranthus jamesonii, two Amaryllidaceae with acetyl- and butyrilcholinesterase inhibition

VALERIA CAVALLARO; NATALIA PAOLA ALZA; MARÍA GABRIELA MURRAY; ANA PAULA MURRAY

NATURAL PRODUCT COMMUNICATIONS

NATURAL PRODUCTS INC

Lugar: Westerville, Ohio; Año: 2014 vol. 9 p. 159 - 162

1934-578X

Alzheimer´s disease (AD) is a neurodegenerative disorder associated with memory impairment and cognitive deficit. Despite intensive research in this field over more than three decades, an effective treatment to delay the onset and progression of AD is not available. Currently approved AD medications mainly comprise acetylcholinesterase (AChE) inhibitors that offer symptomatic treatment. Plants of the Amaryllidaceae family are known to synthesize alkaloids, which have shown AChE inhibitory activity. Habranthus tubispathus and Habranthus jamesonii are two Amaryllidaceae that can be found growing wildly in the southwest of Buenos Aires province, Argentina. Acetyl- and butyrylcholinesterase inhibition was observed for extracts obtained from bulbs of H. tubispathus and bulbs and aerial parts of H. jamesonii. The strongest cholinesterase inhibition was observed for the alkaloid extract obtained from the aerial parts for H. jamesonii (AChE IC50= 0.7 µg/mL; BChE IC50= 6.7 µg/mL). The AChE inhibition observed for H. jamesonii could be explained by the presence of galanthamine and sanguinine, two potent AChE inhibitors. The levels of lycorine and hippeastidine, moderate AChE inhibitors, observed in the bulbs of H. tubispathus could be responsible for the significant AChE inhibition observed. The alkaloids present in these Amaryllidaceae were identified by means of GC-MS analysis and in the case of H. tubispathus the major ones, hippeastidine and 3-O-demethylhippeastidine, were isolated and completely characterized by 1H and 13C NMR spectroscopy.