Chimgin from Ferula haussknechtii as AChE inhibitor and confirmation of the absolute configuration

Alzheimer's disease (AD) is the most common cause of dementia worldwide and is classified as a neurodegenerative disorder. From a drug design perspective, natural products (NPs) are more drug-like and are highly compatible with biological systems compared to most synthetic libraries. NPs provide a more efficient and cost-effective approach to new drug discovery. However, the complexity of NPs makes their identification a challenging task. Chimgin, a bicyclic monoterpene with three chiral centers, exhibits a wide range of biological activity. Despite this, the exact structure of chimgin has remained unclear until now. In this study, we quantified the amount of chimgin in Ferula haussknechtii using analytical Reversed-phase high-pressure liquid chromatography equipped with photodiode array detector (RP-HPLC-PDA). Furthermore, we determined the absolute configuration of chimgin through electronic circular dichroism (ECD) spectroscopy and time-dependent density functional theory (TDDFT) calculations. Finally, we evaluated its inhibitory effect on AChE through in vitro and in silico studies. The extraction process yielded an output of 2.82 ± 0.10% with an exact amount of 0.62 ± 0.04 mg of chimgin per 100 g of plant. Based on the results of ECD and TDDFT calculation, the absolute configuration of chimgin was determined to be 1S, 2S, 4S. Chimgin exhibited an inhibitory effect on AChE with an IC50 of 37.43 µM and its mechanism of action was found to be competitive. HighlightsChimgin was isolated from the roots of Ferula haussknechtii.The amount of chimgin in the plant was determined by RP-HPLC-PDA.Its absolute configuration of chimgin was determined using ECD.In vitro acetylcholinesterase activity of the chimgin was evaluated.The docking and molecular dynamic simulation of chimgin was done.Communicated by Ramaswamy H. Sarma.

Interpreting vibrational circular dichroism spectra: the Cai•factor for absolute configuration with confidence

Vibrational circular dichroism (VCD) spectroscopy can generate the data required for the assignment of absolute configuration, but the spectra are hard to interpret. We have recorded VCD data for thirty pairs of small organic compounds and we use this database to validate a method for the automated analysis of VCD spectra and the assignment of absolute configuration: the Cai•factor (Configuration: absolute information). The analysis of the data demonstrates that the procedure is a reliable and time-efficient method for determination of absolute configuration, which gives both the assignment and a measure of confidence in the outcome, even when the spectra are imperfect. The majority of molecules tested have a high confidence score and all of these have the correct assignment.

The Assignment of the Absolute Configuration of Non-Cyclic Sesquiterpenes by Vibrational and Electronic Circular Dichroism: The Example of Chiliadenus lopadusanus Metabolites

9-Hydroxynerolidol, 9-oxonerolidol, and chiliadenol B are three farnesane-type sesquiterpenoids isolated from Chiliadenus lopadusanus that have shown an interesting activity against human pathogens as Gram+ and Gram- bacteria resistant to antibiotics. However, the absolute configuration (AC) of these interesting sesquiterpenes has not been assigned so far. Vibrational and electronic circular dichroism spectra have been recorded and correlations are pointed out for the three compounds. Density functional theory (DFT) calculations are used in conjunction with Mosher's method of investigation to assign AC. Statistical analysis is considered to quantitatively define the choice of AC from VCD spectra.

Taxonomy-Focused Natural Product Databases for Carbon-13 NMR-Based Dereplication

The recent revival of the study of organic natural products as renewable sources of medicinal drugs, cosmetics, dyes, and materials motivated the creation of general purpose structural databases. Dereplication, the efficient identification of already reported compounds, relies on the grouping of structural, taxonomic and spectroscopic databases that focus on a particular taxon (species, genus, family, order, etc.). A set of freely available python scripts, CNMR_Predict, is proposed for the quick supplementation of taxon oriented search results from the naturaL prOducTs occUrrences database (LOTUS, lotus.naturalproducts.net) with predicted carbon-13 nuclear magnetic resonance data from the ACD/Labs CNMR predictor and DB software (acdlabs.com) to provide easily searchable databases. The database construction process is illustrated using Brassica rapa as a taxon example.