Antileishmanial Activity of Clinanthus milagroanthus S. Leiva & Meerow (Amaryllidaceae) Collected in Peru

Alkaloid Profiling and Anti-Cholinesterase Potential of Three Different Genera of Amaryllidaceae Collected in Ecuador: Urceolina Rchb., Clinanthus Herb. and Stenomesson Herb

Ecuador is an important center of biodiversity for the plant subfamily Amaryllidoideae, known for its important bioactive molecules. This study aimed to assess the chemical and biological potential of four different Amaryllidoideae species collected in Ecuador: Urceolina formosa, Urceolina ruthiana, Clinanthus incarnatus, and Stenomesson aurantiacum. Twenty-six alkaloids were identified in the bulb extracts of these species using GC-MS. The extract of S. aurantiacum exhibited the greatest structural diversity and contained the highest amounts of alkaloids, particularly lycorine and galanthamine. Only for this species, identification of all the alkaloids belonging to this chemical profile was not possible. Six of them remain unidentified. The potential of these three Amaryllidoideae genera against Alzheimer's disease was then evaluated by measuring their AChE and BuChE inhibitory activity, revealing that C. incarnatus and U. formosa (from Sucumbíos province) showed the best results with IC50 values of 1.73 ± 0.25 and 30.56 ± 1.56 µg·mL-1, respectively. Molecular dynamic assays were conducted to characterize the possible interactions that occurs among 2-hydroxyanhydrolycorine and the AChE enzyme, concluded that it is stabilized in the pocket in a similar way to galanthamine. This study expands our understanding of the biodiversity of Amaryllidoideae species from Ecuador, highlighting their potential as source of chemical compounds with pharmaceutical applications.

Multitarget anti-parasitic activities of isoquinoline alkaloids isolated from Hippeastrum aulicum (Amaryllidaceae)

BACKGROUND

Chagas disease and leishmaniasis affect a significant portion of the Latin American population and still lack efficient treatments. In this context, natural products emerge as promising compounds for developing more effective therapies, aiming to mitigate side effects and drug resistance. Notably, species from the Amaryllidaceae family emerge as potential reservoirs of antiparasitic agents due to the presence of diverse biologically active alkaloids.

PURPOSE

To assess the anti-Trypanosoma cruzi and anti-Leishmania infantum activity of five isolated alkaloids from Hippeastrum aulicum Herb. (Amaryllidaceae) against different life stages of the parasites using in silico and in vitro assays. Furthermore, molecular docking was employed to evaluate the interaction of the most active alkaloids.

METHODS

Five natural isoquinoline alkaloids isolated in suitable quantities for in vitro testing underwent preliminary in silico analysis to predict their potential efficacy against Trypanosoma cruzi (amastigote and trypomastigote forms) and Leishmania infantum (amastigote and promastigote forms). The in vitro antiparasitic activity and mammalian cytotoxicity were investigated with a subsequent comparison of both analysis (in silico and in vitro) findings. Additionally, this study employed the molecular docking technique, utilizing cruzain (T. cruzi) and sterol 14α-demethylase (CYP51, L. infantum) as crucial biological targets for parasite survival, specifically focusing on compounds that exhibited promising activities against both parasites.

RESULTS

Through computational techniques, it was identified that the alkaloids haemanthamine (1) and lycorine (8) were the most active against T. cruzi (amastigote and trypomastigote) and L. infantum (amastigote and promastigote), while also revealing unprecedented activity of alkaloid 7‑methoxy-O-methyllycorenine (6). The in vitro analysis confirmed the in silico tests, in which compound 1 presented the best activities against the promastigote and amastigote forms of L. infantum with half-maximal inhibitory concentration (IC50) 0.6 µM and 1.78 µM, respectively. Compound 8 exhibited significant activity against the amastigote form of T. cruzi (IC50 7.70 µM), and compound 6 demonstrated activity against the trypomastigote forms of T. cruzi and amastigote of L. infantum, with IC50 values of 89.55 and 86.12 µM, respectively. Molecular docking analyses indicated that alkaloids 1 and 8 exhibited superior interaction energies compared to the inhibitors.

CONCLUSION

The hitherto unreported potential of compound 6 against T. cruzi trypomastigotes and L. infantum amastigotes is now brought to the forefront. Furthermore, the acquired dataset signifies that the isolated alkaloids 1 and 8 from H. aulicum might serve as prototypes for subsequent structural refinements aimed at the exploration of novel leads against both T. cruzi and L. infantum parasites.

Identification of Novel Flavonoids and Ansa-Macrolides with Activities against Leishmania donovani through Natural Product Library Screening

The protozoan parasite Leishmania donovani is the causative agent of visceral leishmaniasis (VL), a potentially fatal disease if left untreated. Given the limitations of current therapies, there is an urgent need for new, safe, and effective drugs. To discover novel antileishmanial compounds from previously unexplored chemical spaces, we conducted a high-throughput screening (HTS) of 2562 natural compounds, assessing their activity against L. donovani promastigotes and intracellular amastigotes. Utilizing the criteria of ≥70% parasite growth inhibition and ≥70% host cell (THP-1) viability, we selected 100 inhibitors for half-maximal inhibitory concentration (IC50) value determination. Twenty-six compounds showed activities in both forms of Leishmania with a selectivity index of over 3. Clustering analysis resulted in four chemical clusters with scaffolds of lycorine (cluster 1), 5-hydroxy-9,10-dihydro-4H,8H-pyrano[2,3-f]chromene-4,8-dione (cluster 2), and semi-synthetic derivatives of ansamycin macrolide (cluster 4). The enantiomer of lycorine, BMD-NP-00820, showed the highest anti-amastigote activity with an IC50 value of 1.74 ± 0.27 μM and a selectivity index (SI) > 29. In cluster 3, the most potent compound had an IC50 value of 2.20 ± 0.29 μM with an SI > 23, whereas in cluster 4, with compounds structurally similar to the tuberculosis drug rifapentine, BMD-NP-02085 had an IC50 value of 1.76 ± 0.28 μM, but the SI value was 7.5. Taken together, the natural products identified from this study are a potential source for the discovery of antileishmanial chemotypes for further development.