Julie Henriette Antoinette Dutilh

Effect of isoquinoline alkaloids from two Hippeastrum species on in vitro acetylcholinesterase activity.

The treatment of neurological disorders and neurodegenerative diseases is related to the levels of acetylcholine (ACh) through the inhibition of acetylcholinesterase (AChE). Galanthamine, an important alkaloid isolated from the Amaryllidaceae family, is approved for the pharmacological treatment of Alzheimers disease (AD) and acts by inhibiting the acetylcholinesterase (AChE) activity. In the present study, Ellmans method was used to verify the inhibition of AChE activity of some isoquinolines alkaloids such as galanthamine, montanine, hippeastrine and pretazettine. At the concentrations 1mM, 500 microm and 100 microm, galanthamine presented an AChE inhibition higher than 90%. Montanine inhibited, in a dose-dependent manner, more than 50% of the enzyme at 1mM concentration. With the concentrations 500 microm and 100 microm, 30-45% of AChE activity inhibition was detected. The alkaloids hippeastrine and pretazettine presented no significant inhibition of the AChE activity. The results demonstrate that montanine significantly inhibits AChE activity at the tested concentrations, suggesting the necessity of further investigations on this alkaloid use in treating neurological disorders.

Alkaloids from Hippeastrum morelianum Lem. (Amaryllidaceae)

The Amaryllidaceae family has proven to be a rich source of active molecules. As part of an ongoing project, we report a phytochemical study of Hippeastrum morelianum (Amaryllidaceae), from which we have isolated two homolycorine‐type alkaloids, the new 2α,7‐dimethoxyhomolycorine (1) and the poorly described candimine (2), as well as six known alkaloids: tazettine, pretazettine, 3‐epimacronine, haemanthamine, hamayne and trisphaeridine. For reference purposes, the NMR of the isolated compounds was unequivocally described, based on 2D NMR measurements including 1H–1H COSY, 1H–1H NOESY, HSQC and HMBC. Copyright

Investigação do potencial antioxidante e anticolinesterásico de Hippeastrum (Amaryllidaceae)

Amaryllidaceae family is an important source of bioactive molecules and considering the taxonomic relationships, it is relevant to investigate the genus Hippeastrum. Thus, the aim of this work was to determine antioxidant and anticholinesterasic activities of Hippeastrum morelianum, Hippeastrum psittacinum and Hippeastrum santacatarina. Both antioxidant and acetylcholinesterasic activities of extracts were determinated by bioautography as 10 mg/mL and 0.1 mg/mL, respectively. The antioxidant activity of alkaloid lycorine, determinated spectrophotometrically with DPPH, indicated an IC50 value of 0.326 mM.

Alkaloids of Hippeastrum glaucescens

Hippeastrum glaucescens (Mart.) Herbert is a bulbous weed with linear plane leaves up to 50 cm long and about 5 cm wide; the flowers are showy, reddish or salmon, with up to 10 cm long and borne in scapes up to 1 m high. It ranges in Brazil from Bahia until Rio Grande do Sul and has also been collected in Argentina. This species, as well as other of the genus Hippeastrum, has been occasionally considered under the genus Amaryllis and present several nomenclatural synonyms under this genus (for a list see Dutilh, 1996).

The Brazilian Amaryllidaceae as a source of acetylcholinesterase inhibitory alkaloids

Nine Brazilian Amaryllidaceae species were studied for their alkaloid composition and acetylcholinesterase (AChE) inhibitory activity via GC–MS and a modified Ellman assay, respectively. A total of thirty-six alkaloids were identified in these plants, of which Hippeastrum papilio and H. glaucescens exhibited the highest galanthamine content and the best IC50 values against AChE. Furthermore, Hippeastrum vittatum and Rhodophiala bifida also showed notable AChE inhibitory effects. X-ray crystallographic data for four galanthamine-type compounds revealed significant differences in the orientation of the N-methyl group, which are shown to be related to AChE inhibition.

Intrapopulational chromosome number variation in Zephyranthes sylvatica Baker (Amaryllidaceae: Hippeastreae) from Northeast Brazil

Zephyranthes Herb. is a taxonomically complex and cytologically variable group, with about 65 species of Neotropical distribution. Chromosome number variability in 32 individuals of a Zephyranthes sylvatica population from Northeast Brazil was investigated. Three cytotypes were found: 2n = 12 (one metacentric, four submetacentric and one acrocentric pairs), in 24 individuals; 2n = 12 + 1B, in five and three individuals with 2n = 18, a triploid cytotype. All diploid individuals showed chromosomes with polymorphism in pair one and two, while in triploids this polymorphism was observed in all chromosome triplets, generally with two homomorphic chromosomes and a higher or lower heteromorphic chromosome. All individuals had reticulated interfasic nucleus and a slightly asymmetric chromosome complement, with one metacentric chromosome pair and the others more submetacentric to acrocentric. These data confirm the cytological variability previously registered for the genus. Mechanisms involved in karyotypic evolution in this population are discussed.

Avaliação da atividade antiviral e determinação do perfil cromatográfico de Hippeastrum glaucescens (Martius) Herbert (Amaryllidaceae)

Evaluation of antiviral activity and determination of the chromatographic profile of Hippeastrum glaucescens (Martius) Herbert (Amaryllidaceae). Plants of Amaryllidaceae are characterized by isoquinoline alkaloids. Since the first study with Amaryllidaceae alkaloids in 1877, a large number of these plants have been chemically investigated. These compounds have shown a wide range of biological activities such as: antiviral, cytotoxic, antitumoral and analgesic. In this work, the dichloromethane (CH 2 Cl 2 ) extracts obtained from different parts of the Hippeastrum glaucescens (Martius) Herbert (bulbs, roots, leaves and flowers) and the isolated alkaloids lycorine, tazettine and pretazettine were analyzed by a chromatographic method (TLC) and tested for antiviral activity. The

Habranthus (Amaryllidaceae) da Cadeia do Espinhaço, Minas Gerais e Bahia, Brasil

(O Genero Habranthus Herb. (Amaryllidaceae s. s. ) na Cadeia do Espinhaco). O presente trabalho apresenta as especies de Habranthus Herb. (Amaryllidaceae s. s. ) ocorrentes na Cadeia do Espinhaco (Minas Gerais e Bahia). Os generos estao representados na regiao por 7 especies: H. bahiensis Ravenna, H. botumirensis R. S. Oliveira, H. datensis Ravenna, H. irwinianus Ravenna, H. itaobinus Ravenna, H. lucidus R. S. Oliveira e H. sylvaticus (Mart ex Schult) Herb. Sao apresentadas chave para as especies, descricoes, ilustracoes, comentarios e distribuicao geografica.