Alkaloids of Phaedranassa dubia (Kunth) J.F. Macbr. and Phaedranassa brevifolia Meerow (Amaryllidaceae) from Ecuador and its cholinesterase-inhibitory activity

Alzheimer's disease is considered the most common cause of dementia and, in an increasingly aging population worldwide, the quest for treatment is a priority. Amaryllidaceae alkaloids are of main interest because of their cholinesterase inhibition potential, which is the main palliative treatment available for this disease. We evaluated the alkaloidal profile and the in vitro inhibitory activity on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) of bulb alkaloid extract of Phaedranassa dubia and Phaedranassa brevifolia collected in Ecuador. Using gas chromatography coupled to mass spectrometry (GC-MS), we identified typical Amaryllidaceae alkaloids in these species, highlighting the presence of lycorine-type alkaloids in P. dubia and haemanthamine/crinine-type in P. brevifolia. The species P. dubia and P. brevifolia showed inhibitory activities against AChE (IC₅₀ values of 25.48 ± 0.39 and 3.45 ± 0.29 μg.mL^-1, respectively) and BuChE (IC₅₀ values of 114.96 ± 4.94 and 58.89 ± 0.55 μg.mL^-1, respectively). Computational experiments allowed us to understand the interactions of the alkaloids identified in these samples toward the active sites of AChE and BuChE. In silico, some alkaloids detected in these Amaryllidaceae species presented higher estimated binding free energy toward BuChE than galanthamine. This is the first study about the alkaloid profile and biological potential of P. brevifolia species.

A quantum chemical study of encapsulation and stabilization of gallic acid in β-cyclodextrin as a drug delivery system

This research paper describes the study of the inclusion complex formation of a 1:1 stoichiometry ratio of host–guest inclusion complex (X-β-CD) between gallic acid (GA), which is reported to have anti-cancer effects, and β-cyclodextrin (β-CD). The use of β-CD for the encapsulation of bioactive compounds can protect the drugs against conjugation and metabolic inactivation and improve the aqueous solubility for increasing their capacity to functionalize the products. The objective of this study is to give insight on the mechanism of complexation and the capability of β-CD to encapsulate GA compound (X) in gas and solution phases. We examine and compare the performances of different quantum mechanical methods, namely HF/6-31G* and density functional theory (DFT; B97D3/6-31G* functional including dispersion correction), to study the importance of the contribution of the dispersion forces and the hydrogen bonding in the mechanism of interaction. The stability of the optimized geometries of the complex was evaluated with the supermolecule method. Two modes of complexation are taken into consideration. Moreover, the inclusion complex can be confirmed using the frontier molecular orbital (FMO) theory, the global indices of reactivity, the electronic populations condensed natural bond orbital (NBO) analysis, and the molecular docking, which examine the quality and the nature of the hydrophobic interactions during the complexation process.

Cyclodextrin-based delivery systems for cancer treatment

Cyclodextrins, one of safe excipients, are able to form host-guest complexes with fitted molecules given the unique nature imparted by their structure in result of a number of pharmaceutical applications. On the other hand, targeted or responsive materials are appealing therapeutic platforms for the development of next-generation precision medications. Meanwhile, cyclodextrin-based polymers or assemblies can condense DNA and RNA in result to be used as genetic therapeutic agents. Armed with a better understanding of various pharmaceutical mechanisms, especially for cancer treatment, researchers have made lots of works about cyclodextrin-based drug delivery systems in materials chemistry and pharmaceutical science. This Review highlights recent advances in cyclodextrin-based delivery systems for cancer treatment capable of targeting or responding to the physiological environment. Key design principles, challenges and future directions, including clinical translation, of cyclodextrin-based delivery systems are also discussed.