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

Antiparasitic Activity of Narciclasine and Evaluation of Its Effects on Plasma Membrane and Mitochondria of Trypanosoma cruzi

The EtOAc extract from bulbs of Hymenocallis littoralis (Amaryllidaceae) exhibited antiprotozoal activity against Trypanosoma cruzi and afforded the alkaloids narciclasine (1), 7-deoxynarciclasine (2), and narciclasine-4-O-β-D-xylopyranoside (3). In silico studies showed adequate predictions for drug-likeness for alkaloids 1 and 2, with adherence to Lipinski's rules of five and no alerts for PAINS. When tested against clinical forms of T. cruzi, alkaloid 1 displayed in vitro effectiveness with IC50 values of 17.1 μM (trypomastigotes) and 8.2 μM (amastigotes), with no mammalian cytotoxicity for NCTC cells (CC50 > 200 μM), similar to the standard drug benznidazole. Alkaloid 3 exhibited moderate activity against intracellular amastigotes (IC50 = 64.6 μM) and no activity to trypomastigotes, whereas 2 was inactive against both forms of the parasite. These results suggested that free hydroxyl groups at the C-7 and C-4 positions are involved in the potency of the alkaloids. Considering the most potent and selective compound, the lethal action of alkaloid 1 was investigated against extracellular forms (trypomastigotes). Using the fluorescent probe Sytox Green, it was observed that alkaloid 1 presented a dual effect in the plasma membrane at different concentrations from a noninterfering action (at the IC50) to a significant alteration in the membrane permeability (IC90). At all tested concentrations, alkaloid 1 induced a dose-dependent depolarization of the mitochondrial membrane potential, leading to the lethal effect on T. cruzi. These results suggest alkaloid 1 as a new hit compound, eliminating both clinical forms of the parasite and successful in silico drug-like parameters for an oral candidate for Chagas disease.

Phytochemical and Cytotoxic Aspects of Amaryllidaceae Alkaloids in Galanthus Species: A Review

The genus Galanthus (Amaryllidaceae) currently contains 25 plant species naturally occurring in Europe and the Middle East region. These perennial bulbous plants possess well-known medicinal and ornamental qualities. Alkaloid diversity is their most distinctive phytochemical feature. A total of 127 compounds (≈20% of all known Amaryllidaceae alkaloids) grouped in 16 structural types have been previously found in Galanthus extracts. Some structural types like galanthindole, graciline and plicamine were first discovered in Galanthus plants. Nine Galanthus species, however, remain unstudied regarding their alkaloid patterns. Intraspecific variability has only been studied in G. nivalis and G. elwesii. Amaryllidaceae alkaloids are molecules with anticholinesterase, antibacterial, antifungal, antiviral and anticancer properties. Galanthamine, isolated for the first time from Galanthus woronowii Losinsk., stands out as an acetylcholinesterase inhibitor approved for medical use by the FDA for the treatment of symptoms of Alzheimer's disease. Lycorine, narciclasine and pancratistatin are noteworthy cytotoxic and antitumor alkaloids. Structural types like galanthamine, homolycorine and haemanthamine are fairly well studied in anticancer research, but little to no information is available on galanthindole, graciline and other types. This review aims to present an update on the alkaloid diversity of Galanthus spp. and highlight the need for further research on the antitumor potential of these molecules.

Aptamers for the Delivery of Plant-Based Compounds: A Review

Natural compounds have a high potential for the treatment of various conditions, including infections, inflammatory diseases, and cancer. However, they usually present poor pharmacokinetics, low specificity, and even toxicity, which limits their use. Therefore, targeted drug delivery systems, typically composed of a carrier and a targeting ligand, can enhance natural product selectivity and effectiveness. Notably, aptamers-short RNA or single-stranded DNA molecules-have gained attention as promising ligands in targeted drug delivery since they are simple to synthesize and modify, and they present high tissue permeability, stability, and a wide array of available targets. The combination of natural products, namely plant-based compounds, with a drug delivery system utilizing aptamers as targeting agents represents an emerging strategy that has the potential to broaden its applications. This review discusses the potential of aptamers as targeting agents in the delivery of natural compounds, as well as new trends and developments in their utilization in the field of medicine.

Lycorine eliminates B-cell acute lymphoblastic leukemia cells by targeting PSAT1 through the serine/glycine metabolic pathway

B-cell acute lymphoblastic leukemia (B-ALL) has been confirmed as the most common malignant hematologic neoplasm among children. A novel antitumor mechanism of lycorine was elucidated in this study. As revealed by the result of this study, lycorine significantly inhibited the growth and proliferation of REH and NALM-6 and induced their apoptosis. The result of the RNA-seq analysis suggested that lycorine targeted PSAT1 of serine/glycine metabolism in B-ALL cells. As indicated by the result of the GSEA analysis, the genes enriched in the amino acid metabolic pathways were down-regulated by lycorine. As revealed by the results of ectopic expression, shRNA knockdown assays, and further liquid-phase tandem mass spectrometry (LC-MS) analysis, lycorine reduced serine/glycine metabolites by down-regulating PSAT1, further disrupting carbon metabolism and eliminating B-ALL cells. Furthermore, lycorine showed a synergistic effect with cytarabine in ALL treatments. Lastly, lycorine significantly down-regulated leukemia progression in the cell line-derived xenograft (CDX) model. In brief, this study has suggested for the first time that lycorine is a promising anti-ALL drug, and a novel amino acid metabolism-associated property of lycorine was identified.

Pharmacological and toxicological effects of Amaryllidaceae

The Amaryllidaceae family is widely distributed in the tropics, presenting biological activity attributed mostly to alkaloids, such as an important inhibitory activity of acetylcholinesterase (AChE), antifungal, antibacterial, and cytotoxic activities. The present study aims to review the spectrum of action of the main biological activities and toxicity of secondary metabolites found in Amaryllidaceae through a literature review, using Prisma and the descriptors "Pharmacological effects of Amaryllidaceae" and "Amaryllidaceae family" and "Pharmacological actions of Amaryllidaceae", used in English and Portuguese. The literature search was done in March and May 2023. Original works published from 2012 to 2023, available in full, and presenting experimental and clinical studies were included. After the selection considering the inclusion and exclusion criteria, 60 articles fulfilled the defined criteria. From a pharmacological point of view, the highlight is due to the alkaloid galantamine, which has the potential- and is already used - for treating Alzheimer's. The toxicological aspect must be considered and evaluated carefully, as alkaloids have been associated with adverse effects such as nausea, vomiting, diarrhea, abdominal pain, and cardiovascular, neurological, and respiratory changes. Furthermore, some studies indicate that consuming these plants in significant quantities can lead to hepatic and renal toxicity. Therefore, the therapeutical use of this family's plant drugs and derivatives requires further studies to elucidate its effects and point out metabolites with therapeutic potential.