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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., Competing Interests: The authors report no conflicts of interest in this work.

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.

The Amaryllidaceae alkaloids are a distinctive chemotaxonomic feature of the subfamily Amaryllidoideae of the family Amaryllidaceae, which consists of 59 genera and >800 species distributed primarily in tropical and subtropical areas. Since the first isolation, ca. 140 ago, >600 structurally diverse Amaryllidaceae alkaloids have been reported from ca. 350 species (44% of all species in the subfamily). A few have been found in other plant families, but the majority are unique to the Amaryllidoideae. These alkaloids have attracted considerable research interest due to their wide range of biological and pharmacological activities, which have been extensively reviewed. In this chapter we provide a review of the 636 structures of isolated or tentatively identified alkaloids from plants of the Amaryllidoideae and their classification into 42 skeleton types, as well as a discussion on their distribution, and chemotaxonomical and chemoecological aspects., (© 2020 Elsevier Inc. All rights reserved.)

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., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Abstract: 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. [ABSTRACT FROM AUTHOR]

Plants of the Amaryllidoideae subfamily are characterized by the presence of isoquinoline alkaloids called Amaryllidaceae alkaloids. These compounds have exhibited a broad spectrum of pharmacological effects, including anti-Alzheimer and anti-cancer. In this study, Caliphruria tenera Baker, Amaryllidaceae, an endangered and endemic species, was selected to evaluate the effect of growth regulators on plant micropropagation, biomass increase, and production of cytotoxic alkaloids. Different growth regulators were used individually and mixed, and the Amaryllidaceae alkaloids were identified and quantified by GC-MS. The maximum number of in vitro shoots (4.8) was recorded with 6-benzylaminopurine (BAP) (1 mg/L) + Kinetin (KIN) (1 mg/L) + Naphthaleneacetic acid (NAA) (0.2 mg/L). In addition, nineteen alkaloids were identified as crinine, galantamine, lycorine, narciclasine, and tazzetine-type alkaloids in cultivated and micropropagated plants. In general, the biomass was maximized with the growth hormone combination BAP + KIN + NAA, but the biosynthesis of alkaloids was minimized. However, the combination BAP + NAA showed the greatest productivity of trisphaeridine (632.01 μg/g). The growth regulators showed also a positive effect on the production of lycorine-type alkaloids with a content of 396.33 μg/g for KIN, 142.38 μg/g for BAP, and 41.67 μg/g for NAA. All alkaloid fractions were evaluated for their antiproliferative effects against human lung carcinoma (A549) and human keratinocytes (HaCat) cells. The alkaloids produced in the BAP + NAA treatment present a potent and selective cytotoxic against the A549 cell line at 30 μg/mL. This study shows that micropropagation is a promising approach for the production of cytotoxic Amaryllidaceae alkaloids in C. tenera without affecting natural populations. [Display omitted] • Amaryllidoideae subfamily is characterized by the presence of Amaryllidaceae alkaloids. • Caliphruria tenera was selected for their micropropagation and alkaloid production. • Nineteen alkaloids were identified in cultivated and micropropagated plants. • The growth regulators showed a positive effect on the production of lycorine type alkaloids. • The alkaloids produced in the BAP + NAA treatment contributed to the cytotoxic effects. [ABSTRACT FROM AUTHOR]

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 (IC 50 = 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. [ABSTRACT FROM AUTHOR]

Zephyranthes carinata Herb., a specie of the Amaryllidoideae subfamily, has been reported to have inhibitory activity against acetylcholinesterase. However, scientific evidence related to their bioactive alkaloids has been lacking. Thus, this study describes the isolation of the alkaloids of this plant, and their inhibition of the enzymes acetylcholinesterase (eeAChE) and butyrylcholinesterase (eqBuChE), being galanthine the main component. Additionally, haemanthamine, hamayne, lycoramine, lycorine, tazettine, trisphaeridine and vittatine/crinine were also isolated. The results showed that galanthine has significant activity at low micromolar concentrations for eeAChE (IC 50 = 1.96 μg/mL). The in-silico study allowed to establish at a molecular level the high affinity and the way galanthine interacts with the active site of the TcAChE enzyme, information that corroborates the result of the experimental IC 50. However, according to molecular dynamics (MD) analysis, it is also suggested that galanthine presents a different inhibition mode that the one observed for galanthamine, by presenting interaction with peripheral anionic binding site of the enzyme, which prevents the entrance and exit of molecules from the active site. Thus, in vitro screening assays plus rapid computer development play an essential role in the search for new cholinesterase inhibitors by identifying unknown bio-interactions between bioactive compounds and biological targets. [Display omitted] • Alkaloids of Zephyranthes carinata were evaluated as inhibitors of acetylcholinesterase. • Galanthine has significant activity at low micromolar concentrations for eeAChE. • Galanthine presents a different inhibition mode that the one observed for Galanthamine. • Interaction with peripheral anionic binding site of the AChE may occur. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Alkaloid extracts from Z. carinata protect neurons against a Glu-mediated toxic stimulus in vitro. • Alkaloids from bulbs of Z. carinata reverses spatial memory impairment in old 3xTg-AD mice. • One-month treatment with alkaloids of Z. carinata decreases tauopahty in old 3xTg-AD mice. • Alkaloids of Z. carinata decreases inflammatory response in old 3xTg-AD mice. • Alkaloids of Z. carinata provide neuroprotective effects both in vitro and in 3xTg-AD mice. Abstract In Alzheimer's disease (AD), amyloid beta (Aβ) plaques initiates a cascade of pathological events where the overactivation of N -methyl- d -aspartate receptors (NMDA) by excess glutamate (Glu) triggers oxidative processes that lead to the activation of microglial cells, inflammation, and finally neuronal death. Amaryllidaceae alkaloids exert neuroprotective activities against different neurotoxin-induced injuries in vitro , and although their biological potential is well demonstrated, their neuroprotective activity has not been reported in an in vivo model of AD. The aim of our study was to determine the in vitro and in vivo neuroprotective potential of standardized alkaloidal fractions of Zephyranthes carinata. In this work, the neuroprotective effect of two alkaloidal fractions extracted from Z. carinata (bulbs and leaves) was analyzed in an in vitro excitotoxicity model in order to select the most promising one for subsequent evaluation in a triple transgenic mouse model of AD (3xTg-AD). We found that Z. carinata bulbs protect neurons against a Glu-mediated toxic stimulus in vitro , as evidenced by the decrease in apoptotic nuclei, the reduction in the lipid peroxidation product malondialdehyde and the conservation of dendritic structures. The effects of intraperitoneal administration of Z. carinata bulbs (10 mg/kg) every 12 h for 1 month on 3xTg-AD (18 months old) showed improved learning and spatial memory. Histopathologically, the alkaloidal fraction-treated 3xTg-AD mice exhibited a significant reduction in tauopathy and astrogliosis, as well as a significant decrease in the proinflammatory marker COX-2 and an increase in pAkt. The results suggest that Z. carinata bulbs provide neuroprotective effects both in vitro and in 3xTg-AD mice by intervening in the inflammatory processes, regulating the aggregation of pair helical filaments (PHFs) and activating survival pathways. [ABSTRACT FROM AUTHOR]

Aims Amaryllidaceae alkaloids exhibit a wide range of physiological effects, of which the acetylcholinesterase (AChE) inhibitory activity is the most relevant. However, scientific evidence related to their neuroprotective effectiveness against glutamate-induced toxicity has been lacking. Thus, the purpose of this study was to conduct a comparative study of the neuroprotective activity and the AChE inhibitory activity of species of Amaryllidaceae. Main methods The neuroprotective activity against glutamate-induced toxicity was measured in rat cortical neurons and the Ellman method was employed for the quantification of acetylcholinesterase inhibitory activity of alkaloidal extracts of five species of Amaryllidaceae ( Crinum jagus , Crinum bulbispermum , Hippeastrum barbatum , Hippeastrum puniceum and Zephyranthes carinata ). The alkaloid Amaryllidaceae patterns based on GC/MS analyses were also investigated. Key findings The results showed that the alkaloidal extract from C. jagus presented a high neuroprotective activity in both pre- and post-treatments against a glutamate excitotoxic stimulus. Furthermore, the alkaloid extracts from C. jagus and Z. carinata revealed an inhibitory activity of AChE from the electric eel with IC 50 values of 18.28 ± 0.29 and 17.96 ± 1.22 μg/mL, respectively. In addition, 46 alkaloids were detected by GC/MS, and 20 of them were identified based on their mass spectra and retention index. The results suggest that the neuroprotective effects might be associated with lycorine and crinine-type alkaloids, whereas the acetylcholinesterase enzyme inhibitory activity could be related to galanthamine and lycorine-type alkaloids, although not based on synergistic processes. Significance In summary, Amaryllidaceae species are sources of alkaloids with potential use for Alzheimer's disease. [ABSTRACT FROM AUTHOR]