Evaluation of Cholinesterase Inhibitory Potential of Different Genotypes of Ziziphus nummularia, Their HPLC-UV, and Molecular Docking Analysis

Abstract

Ziziphus nummularia is an important source of valuable phytoconstituents, which are widely used in traditional medicine system of Indo-Pak sub-continent. In this study we investigated the distribution of phenolic compounds in the fruit pericarps of six different genotypes (ZNP01-06) of Z. nummularia growing in the unexplored hilly areas of Pakistan. The methanolic extracts of these genotypes were screened for total phenolic content (TPC), total flavonoid content (TFC), antioxidant, and cholinesterase inhibitory potentials. The observed biological potentials were explained in terms of the outcome of molecular docking and HPLC analyses. Among them, genotype ZNP02 displayed high TPC (88.50 ± 1.23 μg/mL) and showed potent scavenging activity against DPPH (67.03 ± 1.04 μg/mL) and ABTS (65.3 ± 1.74 μg/mL) in comparison to ascorbic acid (68.7 ± 0.47 μg/mL). Moreover, genotypes ZNP01, ZNP02, and ZNP04 displayed potent inhibition against acetyl and butyryl cholinesterases (AChE and BChE) with IC₅₀ values of 21.2, 20.5, and 23.7 μg/mL (AChE) and 22.7, 24.4, and 33.1 μg/mL (BChE), respectively. Furthermore, the individual compounds in the most potent species ZNP01 responsible for potent enzyme inhibition (identified through HPLC-UV analysis), were computed via docking simulation software to the enzyme structures. Among these compounds rutin exhibited significant binding affinity with value of -9.20 kcal/mol. The differences amongst the phytochemical compositions of the selected genotypes highlighted the genotypic variations in them. Based on our results it was concluded that the selected plant can be used as remedy of oxidative stress and neurodegenerative diseases. However, further studies are needed to isolate responsible compounds and test the observed potential in vivo, along with toxicological evaluations in animal models.

Keywords: HPLC; Ziziphus nummularia (Burm. f.); characterization; cholinesterase inhibition; genotypes; medicinal uses; molecular docking.

Figure 1

IC₅₀ values of six different genotypes of Z. nummularia against DPPH (A) and ABTS (B).

Figure 2

IC₅₀ values of different genotypes of Z. nummularia of AChE (A) and BChE (B) inhibitory activities.

Figure 2

IC₅₀ values of different genotypes of Z. nummularia of AChE (A) and BChE (B) inhibitory activities.

Figure 3

HPLC-UV chromatograms of different genotype of Z. nummularia: (A) ZNP01, (B) ZNP02, (C) ZNP03, (D) ZNP04, (E) ZNP05, and (F) ZNP06.

Figure 4

Chemical structures of the detected compounds.

Figure 5

The overlaid ribbon diagram of all the constituents and native ligand donepezil (yellow) into the binding site of TcAChE (1EVE) (A). Close-up view interaction plots of the docked pose showing important residues with chlorogenic acid (B) and quercetin (C).

Figure 6

Close-up view interaction plots of the docked-pose showing important residues, morin (A), pyrogallol (B), mandelic acid (C), and hydroxybenzoic acid (D). The overlaid ribbon diagram of rutin and native ligand donepezil (yellow) into the binding site of TcAChE (1EVE) (E) and close-up depiction of the lowest-energy three-dimensional (3-D) docking poses of rutin (F).