Molecular Docking and GC/MS-Based Approach for Identification of Anxiolytic Alkaloids from Griffinia (Amaryllidaceae) Species in a Zebrafish Model.

Griffinia gardneriana Ravenna, Griffinia liboniana Morren and Griffinia nocturna Ravenna (Amarillydaceae) are bulbous plants found in tropical regions of Brazil. Our work aimed to determine the alkaloid profiles of Griffinia spp. and evaluate their anxiolytic potential through in vivo and in silico assays. The plants grown in greenhouses were dried and their ground bulbs were subjected to liquid-liquid partitions, resulting in alkaloid fractions that were analyzed by gas chromatography coupled to mass spectrometry (GC-MS). Anxiolytic activity was evaluated in zebrafish (Danio rerio) through intraperitoneal injection at doses of 40, 100 and 200 mg/kg in light-dark box test. GC-MS analyses revealed 23 alkaloids belonging to different skeleton types: lycorine, homolychorine, galanthamine, crinine, haemanthamine, montanine and narcisclasine. The chemical profiles were relatively similar, presenting 8 alkaloids common to the three species. The major component for G. gardneriana and G. liboniana was lycorine, while G. nocturna consisted mainly of anhydrolycorine. All three alkaloid fractions demonstrated anxiolytic effect. Furthermore, pre-treatment with diazepam and pizotifen drugs was able to reverse the anxiolytic action, indicating involving the GABAergic and serotonergic receptors. Molecular docking showed that the compounds vittatine, lycorine and 11,12-dehydro-2-methoxyassoanine had high affinity with both receptors, suggesting them to be responsible for the anxiolytic effect.

Ligand fishing approach to explore Amaryllidaceae alkaloids as potential antiviral candidates targeting SARS-CoV-2 Nsp4.

Ligand fishing, also described as affinity-based assay, represents a convenient and efficient approach to separate potential ligands from complex matrixes or chemical libraries. This approach contributes to the identification of lead compounds that can bind to a specific target. In the context of COVID-19, the search for novel therapeutic agents is crucial. Small molecule-based antiviral drugs, such as Amaryllidaceae alkaloids, have been described as potential candidates because they can inhibit RNA viruses. Among various SARS-CoV-2 proteins, Nsp3, Nsp4, and Nsp6 play a crucial role in the pathogenicity of the virus and are attractive targets for developing COVID-19 treatments. These proteins are responsible for the replication/transcription complex (RTC) within double-membrane vesicles (DMVs), and their inhibition disrupts the virus's infectious cycle. Herein, we have successfully expressed and immobilized the SARS-CoV-2 Nsp4 protein on magnetic beads (Nsp4-MBs) and employed a ligand fishing assay to screen a collection of ten Amaryllidaceae-based alkaloids and applied to Hippeastrum aulicum extract. Remarkably, four out of ten alkaloids, namely 2-α-7-dimethoxyhomolycorine (6), haemanthamine (5), albomaculine (8), and tazettine (9), exhibited selective affinities for Nsp4. Albomaculine (8) and haemanthamine (5) were also identified from extract by the affinity assay. These findings highlight the potential of these alkaloids as model compounds for future drug discovery studies aimed at developing therapeutic interventions against SARS-CoV-2 infections.

Chemical and Biological Aspects of Different Species of the Genus Clinanthus Herb. (Amaryllidaceae) from South America.

The genus Clinanthus Herb. is found in the Andes Region (South America), mainly in Peru, Ecuador, and Bolivia. These plants belong to the Amaryllidaceae family, specifically the Amaryllidoideae subfamily, which presents an exclusive group of alkaloids known as Amaryllidaceae alkaloids that show important structural diversity and pharmacological properties. It is possible to find some publications in the literature regarding the botanical aspects of Clinanthus species, although there is little information available about their chemical and biological activities. The aim of this work was to obtain the alkaloid profile and the anti-cholinesterase activity of four different samples of Clinanthus collected in South America: Clinanthus sp., Clinanthus incarnatus, and Clinanthus variegatus. The alkaloid extract of each sample was analyzed by gas chromatography coupled with mass spectrometry (GC-MS), and their potential against the enzymes acetyl- and butyrylcholinesterase were evaluated. Thirteen alkaloids have been identified among these species, while six unidentified structures have also been detected in these plants. The alkaloid extract of the C. variegatus samples showed the highest structural diversity as well as the best activity against AChE, which was likely due to the presence of the alkaloid sanguinine. The results suggest this genus as a possible interesting new source of Amaryllidaceae alkaloids, which could contribute to the development of new medicines.

Amaryllidaceae alkaloids in skin cancer management: Photoprotective effect on human keratinocytes and anti-proliferative activity in melanoma cells.

Skin cancer has high rates of mortality and therapeutic failure. In this study, to develop a multi-agent strategy for skin cancer management, the selective cytotoxicity of several alkaloid fractions and pure alkaloids isolated from Amaryllidaceae species was evaluated in melanoma cells. In addition, UVB-stimulated keratinocytes (HaCaT) were exposed to seven alkaloid fractions characterized by GC-MS, and the production of intracellular reactive oxygen species (ROS) and IL-6, were measured to evaluate their photoprotection effects. The Eucharis caucana (bulb) alkaloid fraction (20 µg/ml) had a clear effect on the viability of melanoma cells, reducing it by 45.7% without affecting healthy keratinocytes. This alkaloid fraction and tazettine (both at 2.5 µg/ml) suppressed UVB-induced ROS production by 31.6% and 29.4%, respectively. The highest anti-inflammatory potential was shown by the Zephyranthes carinata (bulb) alkaloid fraction (10 µg/ml), which reduced IL-6 production by 90.8%. According to the chemometric analysis, lycoramine and tazettine had a photoprotective effect on the UVB-exposed HaCaT cells, attenuating the production of ROS and IL-6. These results suggest that Amaryllidaceae alkaloids have photoprotective and therapeutic potential in skin cancer management, especially at low concentrations.

Cytotoxic Activity of Amaryllidaceae Plants against Cancer Cells: Biotechnological, In Vitro, and In Silico Approaches.

Cancer is a major cause of death and an impediment to increasing life expectancy worldwide. With the aim of finding new molecules for chemotherapeutic treatment of epidemiological relevance, ten alkaloid fractions from Amaryllidaceae species were tested against six cancer cell lines (AGS, BT-549, HEC-1B, MCF-7, MDA-MB 231, and PC3) with HaCat as a control cell line. Some species determined as critically endangered with minimal availability were propagated using in vitro plant tissue culture techniques. Molecular docking studies were carried out to illustrate binding orientations of the 30 Amaryllidaceae alkaloids identified in the active site of some molecular targets involved with anti-cancer activity for potential anti-cancer drugs. In gastric cancer cell line AGS, the best results (lower cell viability percentages) were obtained for Crinum jagus (48.06 ± 3.35%) and Eucharis bonplandii (45.79 ± 3.05%) at 30 µg/mL. The research focused on evaluating the identified alkaloids on the Bcl-2 protein family (Mcl-1 and Bcl-xL) and HK2, where the in vitro, in silico and statistical results suggest that powelline and buphanidrine alkaloids could present cytotoxic activity. Finally, combining experimental and theoretical assays allowed us to identify and characterize potentially useful alkaloids for cancer treatment.

Lycorine Alkaloid and Crinum americanum L. (Amaryllidaceae) Extracts Display Antifungal Activity on Clinically Relevant Candida Species.

Candida species are the main fungal agents causing infectious conditions in hospital patients. The development of new drugs with antifungal potential, increased efficacy, and reduced toxicity is essential to face the challenge of fungal resistance to standard treatments. The aim of this study is to evaluate the in vitro antifungal effects of two crude extracts of Crinum americanum L., a rich alkaloid fraction and lycorine alkaloid, on the Candida species. As such, we used a disk diffusion susceptibility test, determined the minimum inhibitory concentration (MIC), and characterized the components of the extracts using Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (ESI FT-ICR MS). The extracts were found to have antifungal activity against various Candida species. The chemical characterization of the extracts indicated the presence of alkaloids such as lycorine and crinine. The Amaryllidaceae family has a promising antifungal potential. Furthermore, it was found that the alkaloid lycorine directly contributes to the effects that were observed for the extracts and fraction of C. americanum.

Anti-Trypanosoma cruzi activity of alkaloids isolated from Habranthus brachyandrus (Amaryllidaceae) from Argentina.

BACKGROUND: Chagas disease, caused by the parasite Trypanosoma cruzi, affects over six million people worldwide, mainly in Latin American countries. Currently available drugs have variable efficacy in the chronic phase and significant side effects, so there is an urgent need for safer chemotherapeutic treatments. Natural products provide privileged structures that could serve as templates for the synthesis of new drugs. Among them, Amaryllidaceae plants have proved to be a potential natural source of therapeutical agents due to their rich diversity in alkaloids. PURPOSE: To identify alkaloids with anti-T. cruzi activity from Habranthus brachyandrus (Baker) Sealy (Amaryllidaceae, subfamily Amaryllidoideae) collected in Argentina. METHODS: An H. brachyandrus alkaloid extract was tested against T. cruzi, and its cytotoxicity profile was evaluated against two mammalian cell lines to ascertain its selectivity against the parasite and potential liver toxicity. It was also assessed by a stage-specific anti-amastigote assay and analysed by GC/MS to determine its alkaloid profile. The isolated alkaloids were also tested using the aforementioned assays. RESULTS: The extract showed high and specific activity against T. cruzi. The alkaloids lycoramine, galanthindole, 8-O-demethylmaritidine, 8-O-demethylhomolycorine, nerinine, trisphaeridine, deoxytazettine, and tazettamide were identified by means of GC-MS. In addition, hippeastidine (also named aulicine), tazzetine, ismine, and 3-epimacronine were isolated. The alkaloid ismine was specifically active against the parasite and had low toxicity against HepG2 cells, but did not show anti-amastigote activity. CONCLUSION: The extract had specific anti-T. cruzi activity and the isolated alkaloid ismine was partially responsible of it. These results encourage further exploration of H. brachyandrus alkaloids in search of novel starting points for Chagas disease drug development.

Biosíntesis y mejoramiento de la producción de alcaloides en la familia Amaryllidaceae / Review biosynthesis and enhancement of alkaloid production in the Amaryllidaceae family

INTRODUCCIÓN: la presente revisión bibliográfica referencia diversos estudios que describen la biosíntesis de alcaloides en la familia Amaryllidacea. Se toman en cuenta los procesos enzimáticos que rigen la biosíntesis de los metabolitos secundarios y los métodos de estimulación y mejoramiento de la producción de alcaloides. OBJETIVO: determinar, mediante una amplia revisión bibliográfica, los posibles métodos de mejora de la producción de alcaloides. METODOLOGÍA: se realizó una revisión bibliográfica de los documentos más relevantes sobre la biosíntesis de alcaloides de Amaryllidaceae. RESULTADOS: en esta revisión, es posible establecer una metodología de mejoramiento de la producción de alcaloides tipo crinina/haemantamina en plantas de la familia Amaryllidaceae nativas de Bolivia y evaluar la posibilidad de aplicarla con éxito para la obtención de mejores rendimientos.(AU)

INTRODUCTION: the referenced studies in this bibliographic review show the alkaloid biosynthesis in the Amaryllidaceae family. Some of the processes involved in the improvement and stimulation of alkaloid production are also taken into account and the enzymatic processes that rule secondary metabolites synthesis are described. OBJECTIVE: to determine, through a bibliographic review, possible methods of improving alkaloid production. METHODS: a wide bibliographic review of the most relevant articles about the Amaryllidaceae family alkaloid production was applied. RESULTS: it was possible to demonstrate that there is the possibility to stablish and develop a successful method to improve the production of crinine/haemanthamine type alkaloids in the Bolivian native family Amaryllidacea and to evaluate the possibility of applying it successfully to obtain better yields.(AU)

Untargeted GC/MS-based approach for identification of anti-inflammatory alkaloids from Hippeastrum elegans (Amaryllidaceae) using a human neutrophil model.

Hippeastrum elegans is an Amaryllidaceae species producing alkaloids with pharmaceutical potential including lycorine and galanthamine. Herein, we developed a non-targeted metabolomic study associated to chemometrics and biological evaluations to identify the H. elegans constituents that were able to reduce the human neutrophils proinflammatory mechanisms. The alkaloid fractions were extracted from bulbs cultivated for 15 months (m) and harvested in six harvest periods (5, 7, 9, 11, 13, and 15 m). The GC-MS analysis allowed the detection of 41 alkaloids being 31 identified. All alkaloid components varied over the cultivation and most of them were lycorine-type skeletons. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) distinguished three groups according to the chemical profile (group I: 5, 7, and 9 m; group II: 11 m and group III: 13 and 15 m). Therefore, the biological assays were only performed with one of the representative samples of each group: 7 m, 11 m and 15 m. None of them was toxic to human neutrophils by LDH activity and MTT test. The 7 m and 15 m-alkaloid fractions showed anti-inflammatory effects by reducing human neutrophil degranulation. However, the former one was more effective in inhibiting the cell activation based on the reduction of myeloperoxidase (MPO) release and reactive oxygen species (ROS) production. Afterwards, Partial Least Squares analysis (PLS) indicated lycorine and 11,12-dehydro-2-methoxy-assoanine as the compounds responsible for the anti-inflammatory activity of the bioactive fraction. Thus, the 7 m-alkaloid fraction of H. elegans seems to be a promising anti-inflammatory drug that deserves additional research.

Alkaloids Analysis of Habranthus cardenasianus (Amaryllidaceae), Anti-Cholinesterase Activity and Biomass Production by Propagation Strategies.

Plants in the Amaryllidaceae family synthesize a diversity of bioactive alkaloids. Some of these plant species are not abundant and have a low natural multiplication rate. The aims of this work were the alkaloids analysis of a Habranthus cardenasianus bulbs extract, the evaluation of its inhibitory activity against cholinesterases, and to test several propagation strategies for biomass production. Eleven compounds were characterized by GC-MS in the alkaloid extract, which showed a relatively high proportion of tazettine. The known alkaloids tazettine, haemanthamine, and the epimer mixture haemanthidine/6-epi-haemanthidine were isolated and identified by spectroscopic methods. Inhibitory cholinesterases activity was not detected. Three forms of propagation were performed: bulb propagation from seed, cut-induced bulb division, and micropropagated bulbs. Finally, different imbibition and post-collection times were evaluated in seed germination assays. The best propagation method was cut-induced bulb division with longitudinal cuts into quarters (T1) while the best conditions for seed germination were 0-day of post-collection and two days of imbibition. The alkaloids analyses of the H. cardenasianus bulbs showed that they are a source of anti-tumoral alkaloids, especially pretazettine (tazettine) and T1 is a sustainable strategy for its propagation and domestication to produce bioactive alkaloids.

Chemical evaluation and anticholinesterase activity of Hippeastrum puniceum (Lam. ) Kuntz bulbs (Amaryllidaceae)

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

Trichomonas vaginalis NTPDase inhibited by lycorine modulates the parasite-neutrophil interaction.

Lycorine is an Amaryllidaceae alkaloid that presents anti-Trichomonas vaginalis activity. T. vaginalis causes trichomoniasis, the most common non-viral sexually transmitted infection. The modulation of T. vaginalis purinergic signaling through the ectonucleotidases, nucleoside triphosphate diphosphohydrolase (NTPDase), and ecto-5'-nucleotidase represents new targets for combating the parasite. With this knowledge, the aim of this study was to investigate whether NTPDase and ecto-5'-nucleotidase inhibition by lycorine could lead to extracellular ATP accumulation. Moreover, the lycorine effect on the reactive oxygen species (ROS) production by neutrophils and parasites was evaluated as well as the alkaloid toxicity. The metabolism of purines was assessed by HPLC. ROS production was measured by flow cytometry. Cytotoxicity against epithelial vaginal cells and fibroblasts was tested, as well as the hemolytic effect of lycorine and its in vivo toxicity in Galleria mellonella larvae. Our findings showed that lycorine caused ATP accumulation due to NTPDase inhibition. The alkaloid did not affect the ROS production by T. vaginalis; however, it increased ROS levels in neutrophils incubated with lycorine-treated trophozoites. Lycorine was cytotoxic against vaginal epithelial cells and fibroblasts; conversely, it was not hemolytic neither exhibited toxicity against the in vivo model of G. mellonella larvae. Overall, besides having anti-T. vaginalis activity, lycorine modulates ectonucleotidases and stimulates neutrophils to secrete ROS. This mechanism of action exerted by the alkaloid could enhance the susceptibility of T. vaginalis to host immune cell, contributing to protozoan clearance.

Neuroprotective activity of isoquinoline alkaloids from of Chilean Amaryllidaceae plants against oxidative stress-induced cytotoxicity on human neuroblastoma SH-SY5Y cells and mouse hippocampal slice culture.

In this study we evaluate the chemical composition and neuroprotective effects of alkaloid fractions of the Amaryllidaceae species Rhodophiala pratensis, Rhodolirium speciosum, Phycella australis and Phaedranassa lehmannii. Gas chromatography-mass spectrometry (GC/MS) enable the identification of 41 known alkaloids. Rhodolirium speciosum and Rhodophiala pratensis were the most active extracts against acetylcholinesterase (AChE), with IC50 values of 35.22 and 38.13 µg/mL, respectively. The protective effect of these extracts on human neuroblastoma cells (SH-SY5Y) subjected to mitochondrial oxidative stress with rotenone/oligomycin A (R/O) and toxicity promoted by okadaic acid (OA) was evaluated. Only Phycella australis and Rhodophiala pratensis at 0.75 and 1.5 µg/mL, tend to reverse the cell death induced by R/O by around 12%. In OA assay, alkaloid fractions of Phycella Australis and Phaedranassa lehmannii displayed a concentration-dependent (0.375-3.0 µg/mL) effect with a maximum neuroprotective response of 78% and 84%, respectively. Afterwards, neuroprotective effects of Phycella australis (3 and 6 µg/mL) in mouse hippocampal slices stressed with oxygen glucose deprivation/reoxygenation (OGD/R), shown a protection greater than 14%. Finally, Phycella Australis (6 µg/mL) reverted the cell viability from 65% to 90% in slices treated with OA, representing a protection of 25% attributable to the alkaloids of this species.

Amaryllidaceae alkaloids: identification and partial characterization of montanine production in Rhodophiala bifida plant.

Rhodophiala bifida (R. bifida) is a representative of the Amaryllidaceae plant family and is rich in montanine, an alkaloid with high pharmaceutical potential. Despite the interest in these compounds, many steps of the biosynthetic pathway have not been elucidated. In this study, we identified the alkaloids produced in different organs of R. bifida under different growth conditions, set up the conditions for in vitro R. bifida regeneration and initiated the molecular characterization of two R. bifida genes involved in alkaloids biosynthesis: the Norbelladine 4'-O-Methyltransferase (RbN4OMT) and the Cytochrome P450 (RbCYP96T). We show that montanine is the main alkaloid produced in the different R. bifida organs and developed a direct organogenesis regeneration protocol, using twin-scale explants cultivated on media enriched with naphthalene acetic acid and benzyladenine. Finally, we analyzed the RbN4OMT and RbCYP96T gene expressions in different organs and culture conditions and compared them to alkaloid production. In different organs of R. bifida young, adult and regenerated plants, as well as under various growing conditions, the transcripts accumulation was correlated with the production of alkaloids. This work provides new tools to improve the production of this important pharmaceutical compound and for future biotechnological studies.

Clinanthus microstephium, an Amaryllidaceae Species with Cholinesterase Inhibitor Alkaloids: Structure-Activity Analysis of Haemanthamine Skeleton Derivatives.

Plants of the Amaryllidaceae family are well-known (not only) for their ornamental value but also for the alkaloids that they produce. In this report, the first phytochemical study of Clinanthus genus was carried out. The chemical composition of alkaloid fractions from Clinanthus microstephium was analyzed by GC/MS and NMR. Seven known compounds belonging to three structural types of Amaryllidaceae alkaloids were identified. An epimeric mixture of a haemanthamine-type compound (6-hydroxymaritidine) was tested as an inhibitor against acetyl- and butyrylcholinesterase enzymes (AChE and BChE, respectively), two enzymes relevant in the treatment of Alzheimer's disease, with good results. Structure-activity relationships through molecular docking studies with this alkaloid and other structurally related compounds were discussed.

Amaryllidaceae alkaloids as agents with protective effects against oxidative neural cell injury.

AIMS: Determine a relationship between the neuroprotective activity and the antioxidant capacity of the Amaryllidaceae alkaloids in a model of Glu excitotoxicity in rat cortical neurons. MATERIALS AND METHODS: Was evaluated several alkaloidal fractions isolated from Amaryllidaceae species, a family known to contain neuroprotective alkaloids, in a model of Glu excitotoxicity in rat cortical neurons. In addition, several mechanisms of antioxidant activity were used, and a theoretical study of the antioxidants was performed. KEY FINDINGS: The results of this study suggest that a possible neuroprotective mode of action of the alkaloidal fractions of Eucharis bonplandii (Kunth) Traub bulbs, Eucharis caucana Meerow bulbs, and Clivia miniata Regel leaves, is through their antioxidant activity and ability to stabilize free radicals generated from an excitotoxic process mediated by Glu. The chemical structure characterization and antioxidant activity of the fractions suggest that the phenol and enol groups in the structures of the alkaloids are critical for the stabilization of ROS and RNS. Additionally, the pair of free electrons on the N is spatially close to a hydroxyl group, which benefits the cleavage of this group and, consequently, the stabilization of the generated O. SIGNIFICANCE: The versatility of the structures of the studied Amaryllidaceae alkaloids suggests that they have potential as neuroprotective agents against an oxidative stimulus.

Cholinesterase-inhibitory effect and in silico analysis of alkaloids from bulbs of Hieronymiella species.

BACKGROUND: In Argentina, the Amaryllidaceae family (59 species) comprises a wide variety of genera, only a few species have been investigated as a potential source of cholinesterases inhibitors to treat Alzheimer disease (AD). PURPOSE: To study the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of the basic dichloromethane extracts (E) from Hieronymiella aurea, H. caletensis, H. clidanthoides, H. marginata, and H. speciosa species, as well as the isolated compounds from these plant extracts. STUDY DESIGN AND METHODS: AChE and BChE inhibitory activities were evaluated with the Ellman's spectrophotometric method. The alkaloids composition from the E was obtained by gas chromatography-mass spectrometry (GC-MS). The E were successively chromatographed on a silica gel column and permeated on Sephadex LH-20 column to afford the main alkaloids identified by means of spectroscopic data. Additionally, an in silico study was carried out. RESULTS: Nine known alkaloids were isolated from the E of five Hieronymiella species. Galanthamine was identified in all the species by GC-MS standing out H. caletensis with a relative abundance of 9.79% of the total ion current. Strong AChE (IC50 = 1.84 - 15.40 µg/ml) and moderate BChE (IC50 = 23.74 - 136.40 µg/ml) inhibitory activities were displayed by the extracts. Among the isolated alkaloids, only sanguinine and chlidanthine (galanthamine-type alkaloids) demonstrated inhibitory activity toward both enzymes. The QTAIM study suggests that sanguinine has the strongest affinity towards AChE, attributed to an additional interaction with Ser200 as well as stronger molecular interactions Glu199 and His440.These results allowed us to differentiate the molecular behavior in the active site among alkaloids possessing different in vitro inhibitory activities. CONCLUSION: Hieronymiella species growing in Argentina represent a rich and widespread source of galanthamine and others AChE and BChE inhibitors alkaloids. Additionally, the new trend towards the use of natural extracts as pharmaceuticals rather than pure drugs opens a pathway for the development of a phytomedicine derived from extracts of Hieronymiella spp.

Alkaloids from Hippeastrum argentinum and Their Cholinesterase-Inhibitory Activities: An in Vitro and in Silico Study.

Two new alkaloids, 4-O-methylnangustine (1) and 7-hydroxyclivonine (2) (montanine and homolycorine types, respectively), and four known alkaloids were isolated from the bulbs of Hippeastrum argentinum, and their cholinesterase-inhibitory activities were evaluated. These compounds were identified using GC-MS, and their structures were defined by physical data analysis. Compound 2 showed weak butyrylcholinesterase (BuChE)-inhibitory activity, with a half-maximal inhibitory concentration (IC50) value of 67.3 ± 0.09 µM. To better understand the experimental results, a molecular modeling study was also performed. The combination of a docking study, molecular dynamics simulations, and quantum theory of atoms in molecules calculations provides new insight into the molecular interactions of compound 2 with BuChE, which were compared to those of galantamine.

Crinine-type alkaloids from Hippeastrum aulicum and H. calyptratum.

An ongoing search for alkaloids in the Amaryllidaceae species using GC-MS resulted in the identification of two crinine-type alkaloids, aulicine (1) and 3-O-methyl-epimacowine, (2) from the indigenous Brazilian species Hippeastrum aulicum and Hippeastrum calyptratum, respectively. In addition, two alkaloids, 11-oxohaemanthamine (3) and 7-methoxy-O-methyllycorenine (4) were both isolated from H. aulicum. Furthermore, we provide here complete NMR spectroscopic data for the homolycorine analogues nerinine (5) and albomaculine (6). The absolute stereochemistry of the 5,10b-ethano bridge in the crinine variants was determined by circular dichroism and X-ray crystallographic analysis, thus presenting the first direct evidence for the presence of crinine-type alkaloids in the genus Hippeastrum.

Lycorine derivatives against Trichomonas vaginalis.

Six lycorine derivatives were prepared, characterized, and evaluated for their in vitro anti-Trichomonas vaginalis activity. Compounds bearing an acetyl (2), lauroyl (3), benzoyl (4 and 5), and p-nitrobenzoyl (6 and 7) groups were synthesized. The best activity was achieved with lycorine esterified at C-2 position with lauroyl group. Preliminary structure-activity relationship points that unprotected OH group at C-1 and C-2 is not necessary to the antiparasitic activity, and none of the derivative was less active than lycorine. The lycorine structural requisites required to kill this amitochondriate cell seem to be different in comparison with the derivatives most active against other parasites and tumor cell lines, both mitochondriated cells. This result is an important contribution with our ongoing studies regarding the mechanism of action of the Amaryllidaceae alkaloids on T. vaginalis cell death opening a new perspective to optimize this innovative pharmacological potential.