Abstract Free-living amoebae of the genus Acanthamoeba are the causative agents of granulomatous encephalitis and keratitis, severe human infections. Bioactive compounds from plants are recognized as an alternative source for the development of new drugs. The Amaryllidaceae is a botanical family able to synthesize a very specific and consistent group of biologically active isoquinoline-like alkaloids. The alkaloidal fractions from the Brazilian species Hippeastrum canastrense, H. diniz-cruziae, H. puniceum, and Crinum x amabile, along with the alkaloid lycorine, were investigated against Acanthamoeba castellanii. The in vitro assays were performed with distinct concentrations of lycorine and alkaloidal fractions, while the cell viability was evaluated by the MTT method upon MDCK cells. Chlorhexidine 0.02% was used as the positive control. The effect of alkaloid fractions was concentration dependent, and 2000 μg mL-1 of H. canastrense and H. diniz-cruziae provided a 100% inhibition. At concentrations of 250, 500, and 1000 μg mL-1, the H. diniz-cruziae alkaloidal fraction showed the lowest cytotoxic effect (5%-7%) and remarkable anti-amoebic activity, demonstrating values of IC50 285.61 μg mL-1, low cytotoxicity (5%-7%), and selectivity index (7.0). Taken together, the results are indicative of the great potential that the alkaloids from H. diniz-cruziae have as new candidates for anti-amoebicidal compounds.

Hippeastrum puniceum is a species that belongs to the Amaryllidaceae family. A particular characteristic of this family is the consistent and very specific presence of isoquinoline alkaloids, which have demonstrated a wide range of biological activities such as antioxidant, antiviral, antifungal, antiparasitic, and acetylcholinesterase inhibitory activity, among others. In the present work, fifteen alkaloids were identified from the bulbs of Hippeastrum puniceum (Lam.) Kuntz using a GC-MS approach. The alkaloids 9-O-demethyllycoramine, 9-demethyl-2α-hydroxyhomolycorine, lycorine and tazettine were isolated through chromatographic techniques. The typical Amaryllidaceae alkaloids lycorine and tazettine, along with the crude and ethyl acetate extract from bulbs of the species were evaluated for their inhibitory potential on α-amylase, α-glucosidase, tyrosinase and acetylcholinesterase activity. Although no significant inhibition activity was observed against α-amylase, α-glucosidase and tyrosinase from the tested samples, the crude and ethyl acetate extracts showed remarkable acetylcholinesterase inhibitory activity. The biological activity results that correlated to the alkaloid chemical profile by GC-MS are discussed herein. Therefore, this study contributed to the knowledge of the chemical and biological properties of Hippeastrum puniceum (Lam.) and can subsidize future studies of this species.

The phytochemical study of Hippeastrum goianum led to the identification of 13 compounds by means of gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). Compounds 7-demethoxy-9-O-methylhostasine (1) and 7-deoxi-trans-dihydronarciclasine (2) had their absolute configurations determined by vibrational circular dichroism (VCD). This is the first time that compound 1 is described in the Amaryllidaceae family. The cytotoxicity of all isolated compounds was tested against colorectal carcinoma (HCT 116), breast carcinoma (MCF-7), and non-tumor human retinal pigment epithelium (RPE) cell lines. The half-maximum inhibitory concentration (IC50) of compound 2 against each cell line was equivalent to the positive control (doxorubicin), indicating a considerable cytotoxic activity.

A combined phytochemical, crystallographic and biological study of Worsleya procera roots was performed. Fifteen alkaloids were identified by gas chromatography mass spectrometry (GC-MS) and seven of them were isolated. The structures of the alkaloids were elucidated by spectroscopic methods, and a detailed crystallographic study of tazettine was carried out. The isolated alkaloids and the obtained extracts were tested in vitro against Plasmodium falciparum (3D7 and K1 strains) and human hepatocarcinoma cells (HepG2) to assess their antiplasmodial and cytotoxic effects, respectively. One of the isolated alkaloid derivatives, lycorine, exhibited antiplasmodial activity against both sensitive (3D7) and resistant (K1) parasite strains in the low micromolar range (half-maximal sample inhibitory concentration (IC50) values of 2.5 and 3.1 µM, respectively) and displayed a low cytotoxicity profile, with a selectivity index greater than 100. Our findings indicate that lycorine is a hit for antimalarial drug discovery.

Amaryllidaceae alkaloids are well-known isoquinolines which have demonstrated a wide range of biological activities such as antiviral, anticancer, acetylcholinesterase inhibition, antimalarial, among others. Mass spectrometry (MS) studies based on capillary gas chromatography (CGC), paper spray (PS), and leaf spray (LS) ionization were carried out for alkaloid investigation of the native Brazilian species Hippeastrum aulicum, along with nuclear magnetic resonance (NMR) techniques. Thirty-one alkaloids were identified including the new compound haemanthamine N-oxide. The results from PS- and LS-MS techniques were consistent with those observed in CGC-MS analysis. To the best of our knowledge, it is the first study combining NMR, CGC-MS and the ambient ionization-mass spectrometry (PS- and LS-MS) on Amaryllidaceae plants.

AbstractA new lycosinine derivative, 9-O-demethyllycosinine B, was isolated from the native Brazilian Hippeastrum breviflorumHerb., Amaryllidaceae, along with the well-known alkaloids lycosinine B and lycorine. The structure of the new compound was established by physical and spectroscopic methods. 9-O-demethyllycosinine B is the third lycosinine variant identified in the Amaryllidaceae family.

Caliphruria is a genus of bulbous plants in the Amaryllidaceae family. It consists of four species distributed in tropical regions of South America, three of them are endemic of Colombia. This genus is infrequent in nature, with restricted geographical distribution. C. subedentata Baker is threatened by extinction. The polar extract showed moderate cytotoxic activity. In previews phytochemical studies, by classical methods, we isolated six alkaloids: galanthamine, lycorine, haemantamine, maritidine, homolycorine and hamayna. In this work we reports 18 compounds identified by GC-MS technique: ismine, trisphaeridine, 5,6-dihydrobicolorine, galanthamine, clidantine, narwedine, kirkine, galantindol, maritidine, anhydrolycorine, deoxytazetine, 6-methoxypretazzetine, tazzetine, haemantamine, 11,12-de-hydroanhydrolycorine, lycorine, homolycorine, epimacronine and one alkaloid not identified.

Caliphruria es un género de plantas bulbosas perteneciente a la familia Amaryllidaceae. Consiste en cuatro especies distribuidas en regiones tropicales de Sur América, tres de las cuales son endémicas de Colombia. Este género es muy escaso en la naturaleza, con distribución geográfica restringida. C. subedentata Baker está considerada en vía de extinción. El extracto polar mostró una moderada actividad citotóxica. En estudios fitoquímicos previos, por el método clásico, aislamos seis alcaloides: galantamina, licorina, hemantamina, maritidina, homolicorina y hamayna. En este trabajo reportamos 18 compuestos identificados por la técnica CG-EM: ismina, trisferidina, 5,6-dihidrobicolorina, galantamina, clidantina, narwedina, kirkina, galantindol, maritidina, anhidrolicorina, deoxitazetina, 6-metoxipretazetina, tazetina, hemantamina, 11,12-deshidroanhidrolicorina, licorina, homolicorina, epimacronina y un alcaloide no identificado.

In recent years alkaloids from the genus Hippeastrum have been shown to exhibit a broad spectrum of biological activities, including antiparasitic, antiproliferative, apoptosis-induced, psychopharmacological, acetylcholinesterase-inhibitory, among others. This work presents a brief chemical and biological review of the alkaloids found in the genus Hippeastrum.

En los últimos años, los alcaloides aislados del género Hippeastrum han mostrado un amplio espectro de actividades incluyendo, entre otras, la antiparasitaria, antiproliferativas, inductoras de apoptosis, psicofarmacológicas y como inhibidores de la acetilcolinesterasa. En este trabajo se presenta una breve revisión química y biológica de los alcaloides del género Hippeastrum.

A una fracción biflavonoide (FB) caracterizada fitoquímicamente de Garcinia madruno (Clusiaceae), se le evalúa su potencial inhibitorio de la oxidación de LDL y su capacidad estabilizadora de especies radicalarias, correlacionando dichas actividades con su contenido en biflavonoides. Los biflavonoides morelloflavona, volkensiflavona y amentoflavona se identifican a partir de la FB. El extracto que contiene la FB (extracto AcOEt) se determina como el principal factor involucrado en la actividad estabilizadora de radicales libres de esta especie vegetal, obteniendo la actividad estabilizadora del radical DPPH• a una concentración de 4,50 µg/mL. La peroxidación inducida con CuSO4 de las lipoproteínas de baja densidad, se reduce significativamente en presencia de FB (CE50 = 11,85 µg/mL). El biflavonoide morelloflavona se determina como el principal responsable de la protección ejercida por la FB frente a la actividad estabilizadora de radicales libres y la peroxidación lipídica, aunque posiblemente existan procesos de sinergismo. Estas propiedades sugieren que la FB de G. madruno es un excelente candidato para ser utilizado como antioxidante.

The inhibitory LDL oxidation potential and free radical stabilization capacity of a characterized biflavonoid fraction (FB) was evaluated and correlated by its biflavonoid content. Morelloflavone, volkensiflavone and amentoflavone were identified in the FB. The extract containing the FB (AcOEt extract) was found to be the major contributor to the free radical-scavenging activity of G. madruno. The DPPH activity for the FB was 4.50 µg/mL. Lipid peroxidation, induced with CuSO4, was significantly reduced in the presence of the FB (CE50 = 11.85 µg/mL). Morelloflavone was found to be the main biflavonoid in the fraction responsible for its protection against lipid peroxidation and free radical-scavenging activity, although processes of synergy are possible. These properties suggest that the FB of G. madruno is an excellent candidate for use as an antioxidant.

A propolis sample from the western Andean slopes of the Maule Region, Chile, showed free radical scavenging activity and inhibited the enzyme xanthine oxidase "in vitro". Six flavonoids were isolated as the main active constituents of the sample. 5,7-dihydroxyflavone 4, 3,5,7-trihydroxyflavone 6 and 5,7-dihydroxyflavanone 1 displayed a strong free radical scavenging effect. At 50 mg/ml, compounds 6 and 1 inhibited the enzyme xanthine oxidase by 95 and 86%, respectively.

Una muestra de própolis producida en los Andes orientales de la Región del Maule, Chile, mostró actividad atrapadora de radicales libres e inhibió la enzima oxidasa de la xantina "in vitro". Se aislaron e identificaron seis flavonoides como los componentes activos mayoritarios de la muestra. La 5,7-dihidroxiflavona 4, 3,5,7-trihidroxiflavona 6 y 5,7-dihidroxiflavanona 1 exhibieron un fuerte efecto como atrapadores de radicales libres. A la concentración de 50 mg/ml, los compuestos 6 y 1 inhibieron la enzima oxidasa de la xantine en 95 y 86%, respectivamente.