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.

Chemical Profiling and Cholinesterase Inhibitory Activity of Five Phaedranassa Herb. (Amaryllidaceae) Species from Ecuador.

It is estimated that 50 million people in the world live with dementia, 60-70% of whom suffer from Alzheimer's disease (AD). Different factors are involved in the development of AD, including a reduction in the cholinergic neurotransmission level. The Amaryllidaceae plant family contains an exclusive, large, and still understudied alkaloid group characterized by a singular skeleton arrangement and a broad spectrum of biological activities. The chemistry and biodiversity of Ecuadorian representatives of the Phaedranassa genus (Amaryllidaceae) have not been widely studied. In this work, five Ecuadorian Phaedranassa species were examined in vitro for their activity towards the enzymes acetyl- (AChE) and butyrylcholinesterase (BuChE), and the alkaloid profile of bulb extracts was analyzed by GC-MS. The species Phaedranassa cuencana and Phaedranassa dubia showed the most AChE and BuChE inhibitory activity, respectively. To obtain insight into the potential role of the identified alkaloids in these inhibitory effects, docking experiments were carried out, and cantabricine showed in silico inhibitory activity against both cholinesterase structures. Our results show that Amaryllidaceae species from Ecuador are a potential source of new drugs for the palliative treatment of AD.

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.

Alkaloids of Amaryllidaceae as Inhibitors of Cholinesterases (AChEs and BChEs): An Integrated Bioguided Study.

INTRODUCTION: Enzymatic inhibition of acetylcholinesterase (AChE) is an essential therapeutic target for the treatment of Alzheimer's disease (AD) and AChE inhibitors are the first-line drugs for it treatment. However, butyrylcholinesterase (BChE), contributes critically to cholinergic dysfunction associated with AD. Thus, the development of novel therapeutics may involve the inhibition of both cholinesterase enzymes. OBJECTIVE: To evaluate, in an integrated bioguided study, cholinesterases alkaloidal inhibitors of Amaryllidaceae species. METHODOLOGY: The proposed method combines high-performance thin-layer chromatography (HPTLC) with data analysis by densitometry, enzymatic bioautography with different AChEs and BChEs, the detection of bioactive molecules through gas chromatography mass spectrometry (GC-MS) analysis of spots of interest, and theoretical in silico studies. RESULTS: To evaluate the bioguided method, the AChE and BChE inhibitory activities of seven Amaryllidaceae plant extracts were evaluated. The alkaloid extracts of Eucharis bonplandii exhibited a high level of inhibitory activity (IC50  = 0.72 ± 0.05 µg/mL) against human recombinant AChE (hAChE). Regarding human serum BChE (hBChE), the bulb and leaf extracts of Crinum jagus had the highest activity (IC50  = 8.51 ± 0.56 µg/mL and 11.04 ± 1.21 µg/mL, respectively). In the HPTLC spots with high inhibitory activity, several alkaloids were detected using GC-MS, and some of these alkaloids were identified. Galanthamine, galanthamine N-oxide and powelline should be the most prominent inhibitors of substrate accommodation in the active site of the Torpedo californica AChE (TcAChE), hAChE and hBChE enzymes. CONCLUSIONS: These results are evidence of the chemical relevance of the Colombian's Amaryllidaceae species for the inhibition of cholinesterases and as potent sources for the palliative treatment of AD. Copyright © 2017 John Wiley & Sons, Ltd.

Hippeastrum reticulatum (Amaryllidaceae): Alkaloid Profiling, Biological Activities and Molecular Docking.

The Amaryllidaceae family has proven to be a rich source of active compounds, which are characterized by unique skeleton arrangements and a broad spectrum of biological activities. The aim of this work was to perform the first detailed study of the alkaloid constituents of Hippeastrum reticulatum (Amaryllidaceae) and to determine the anti-parasitological and cholinesterase (AChE and BuChE) inhibitory activities of the epimers (6α-hydroxymaritidine and 6ß-hydroxymaritidine). Twelve alkaloids were identified in H. reticulatum: eight known alkaloids by GC-MS and four unknown (6α-hydroxymaritidine, 6ß-hydroxymaritidine, reticulinine and isoreticulinine) by NMR. The epimer mixture (6α-hydroxymaritidine and 6ß-hydroxymaritidine) showed low activity against all protozoan parasites tested and weak AChE-inhibitory activity. Finally, a molecular docking analysis of AChE and BuChE proteins showed that isoreticulinine may be classified as a potential inhibitory molecule since it can be stabilized in the active site through hydrogen bonds, π-π stacking and hydrophobic interactions.

Alkaloid metabolite profiles by GC/MS and acetylcholinesterase inhibitory activities with binding-mode predictions of five Amaryllidaceae plants.

Acetylcholinesterase (AChE) enzymatic inhibition is an important target for the management of Alzheimer disease (AD) and AChE inhibitors are the mainstay drugs for its treatment. In order to discover new sources of potent AChE inhibitors, a combined strategy is presented based on AChE-inhibitory activity and chemical profiles by GC/MS, together with in silico studies. The combined strategy was applied on alkaloid extracts of five Amaryllidaceae species that grow in Colombia. Fifty-seven alkaloids were detected using GC/MS, and 21 of them were identified by comparing their mass-spectral fragmentation patterns with standard reference spectra in commercial and private library databases. The alkaloid extracts of Zephyranthes carinata exhibited a high level of inhibitory activity (IC50 = 5.97 ± 0.24 µg/mL). Molecular modeling, which was performed using the structures of some of the alkaloids present in this extract and the three-dimensional crystal structures of AChE derived from Torpedo californica, disclosed their binding configuration in the active site of this AChE. The results suggested that the alkaloids 3-epimacronine and lycoramine might be of interest for AChE inhibition. Although the galanthamine group is known for its potential utility in treating AD, the tazettine-type alkaloids should be evaluated to find more selective compounds of potential benefit for AD.