Coumarins as cholinesterase inhibitors: A review

Antioxidant and Anticholinesterase Potential of Two Nigerian Bitter Yams Using a Simulated Gastrointestinal Digestion Model and Conventional Extraction

The purpose of this study was to evaluate the antioxidant and anticholinesterase activities of yellow and white bitter yams from South Western Nigeria using methanolic extraction and simulated gastrointestinal digestion models. The phenolic compounds in the bitter yam varieties were evaluated by high performance liquid chromatography with a diode array detector (HPLC-DAD). The total phenolic content of the bitter yams was measured by the Folin-Ciocalteu method, reductive potential by assessing the ability of the bitter yam to reduce FeCl₃ solution, and the antioxidant activities were determined by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^·) scavenging activity, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS^·+) scavenging activity, nitric oxide radical (NO^·) scavenging ability, hydroxyl radical scavenging ability, and ability to inhibit Fe²⁺-induced lipid oxidation. The HPLC-DAD analysis revealed the presence of some phenolic compounds in the studied bitter yam varieties, with varying degree of quantitative changes after cooking. The antioxidant indices (total phenolic content, total flavonoid content, reducing power, DPPH^· scavenging activity, ABTS^·+ scavenging activity, and NO^· scavenging activity) were higher in the simulated gastrointestinal digestion model compared to the methanolic extract, with the in vitro digested cooked white bitter yam ranking higher. Similarly, the in vitro digested yams had a higher inhibitory action against lipid oxidation compared to the methanolic extracts, with the cooked white bitter yam ranking high. The methanolic extracts and in vitro enzyme digests showed no acetylcholinesterase inhibitory abilities, while methanolic extracts and the in vitro enzyme digest displayed some level of butyrylcholinesterase inhibitory activities. Therefore the studied bitter yams could be considered as possible health supplements.

Toxicity of coumarins synthesized by Pechmann-Duisberg condensation against Drosophila melanogaster larvae and antibacterial effects

On the background of the search of new insecticides friendly with the environment for replace those from synthesis organic origin with adverse effects on animals, soils and vegetables. It is reported in this study, the synthesis of a series of coumarins derivatives synthesized by Pechmann-Duisberg condensation assisted by microwave irradiation, their antibacterial and insecticidal activities. The most relevant results show that all compounds exhibit a mortality effect of 30-80% with doses between 10 and 100 μg/mL. This activity is related to alkyl or aryl substituent type at position C-4 coumarin skeleton. The coumarins 5, 6, 7 and 9 showed highest insecticidal activities, and these coumarins have at 4-position a bulky and low polarity substituent. The aim of this work is to find the effects of the 4-substitued coumarins with different lipophilic and bulky substituents. Even though many researchers were worked on coumarins, there are not reports about the insecticidal effects of specifically 4-substitued coumarins. The difference of our major findings versus current knowledge is in this scope of the research. On the other hand, was possible to find that a chloride at 4-position, drew to extend the antibacterial spectra.

Calabrian Goji vs. Chinese Goji: A Comparative Study on Biological Properties

Lycium barbarum (Goji) fruits are mainly cultivated in northwestern China and are well known for their beneficial and healthy effects. In this work, the biological and functional properties of Calabrian Goji extract, obtained from Goji berries cultivated in the Sibari Plain (in the Italian region of Calabria), were demonstrated. In order to evaluate the use of this extract as a food supplement for cognitive and mental disorders, the quantification of Carotenoids as Zeaxanthin equivalents was made. The antioxidant activity was investigated by evaluating the scavenging properties against 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals and by performing the ORAC (Oxygen Radical Absorbance Capacity) assay. The inhibition of lipid peroxidation was quantified by bleaching test and the ability to inhibit acetylcholinesterase enzyme and to scavenge nitric oxide radical was also evaluated. All the results were compared to those obtained from a Chinese Goji extract used as a reference. Based on the reported data, Calabrian Goji might be used as a food supplement with a possible application in cognitive disorders, mental impairments and other neurodegenerative diseases, due to its biological properties and the high levels of Carotenoids.

Pteryxin - A promising butyrylcholinesterase-inhibiting coumarin derivative from Mutellina purpurea

Pteryxin is a dihydropyranocoumarin derivative found in Apiaceae family. In this study, pteryxin, which was previously isolated from the fruits of Mutellina purpurea, was investigated for its inhibitory potential against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), which are the key enzymes in the pathology of Alzheimer's disease (AD). The compound was tested in vitro using ELISA microplate reader at 100 μg/ml and found to cause 9.30 ± 1.86% and 91.62 ± 1.53% inhibition against AChE and BChE, respectively. According to our results, pteryxin (IC₅₀ = 12.96 ± 0.70 μg/ml) was found to be a more active inhibitor of BChE than galanthamine (IC₅₀ = 22.16 ± 0.91 μg/ml; 81.93± 2.52% of inhibition at 100 μg/ml). Further study on pteryxin using molecular docking experiments revealed different possible binding modes with both polar and hydrophobic interactions inside the binding pocket of BChE. Top docking solution points out to the formation of two hydrogen bonds with the catalytic residues S198 and H438 of BChE as well as a strong π - π stacking with W231. Therefore, pteryxin as a natural coumarin seems to be a strong BChE inhibitor, which could be considered as a lead compound to develop novel BChE inhibitors for AD treatment.