Unveiling the tyrosinase inhibitory potential of phenolics from Centaurium spicatum: Bridging in silico and in vitro perspectives.

Phenolics, abundant in plants, constitute a significant portion of phytoconstituents consumed in the human diet. The phytochemical screening of the aerial parts of Centaurium spicatum led to the isolation of five phenolics. The anti-tyrosinase activities of the isolated compounds were assessed through a combination of in vitro experiments and multiple in silico approaches. Docking and molecular dynamics (MD) simulation techniques were utilized to figure out the binding interactions of the isolated phytochemicals with tyrosinase. The findings from molecular docking analysis revealed that the isolated phenolics were able to bind effectively to tyrosinase and potentially inhibit substrate binding, consequently diminishing the catalytic activity of tyrosinase. Among isolated compounds, cichoric acid displayed the lowest binding energy and the highest extent of polar interactions with the target enzyme. Analysis of MD simulation trajectories indicated that equilibrium was reached within 30 ns for all complexes of tyrosinase with the isolated phenolics. Among the five ligands studied, cichoric acid exhibited the lowest interaction energies, rendering its complex with tyrosinase the most stable. Considering these collective findings, cichoric acid emerges as a promising candidate for the design and development of a potential tyrosinase inhibitor. Furthermore, the in vitro anti-tyrosinase activity assay unveiled significant variations among the isolated compounds. Notably, cichoric acid exhibited the most potent inhibitory effect, as evidenced by the lowest IC50 value (7.92 ± 1.32 µg/ml), followed by isorhamnetin and gentiopicrin. In contrast, sinapic acid demonstrated the least inhibitory activity against tyrosinase, with the highest IC50 value. Moreover, cichoric acid exhibited a mixed inhibition mode against the hydrolysis of l-DOPA catalyzed by tyrosinase, with Ki value of 1.64. Remarkably, these experimental findings align well with the outcomes of docking and MD simulations, underscoring the consistency and reliability of our computational predictions with the actual inhibitory potential observed in vitro.

Solvent System-Guided Extraction of Centaurium spicatum (L.) Fritch Provides Optimized Conditions for the Biological and Chemical Characteristics of the Herbal Extracts.

Spiked centaury (Centaurium spicatum) is a well-known medicinal plant from the Mediterranean region with various bioactivities, but there are no studies addressing the use of different solvent systems to improve its pharmacological potential. Nine extraction procedures were adapted to study the effects of solvent composition on the content of bioactive compounds in C. spicatum extracts and on corresponding bioactivities. Targeted metabolomics was performed to obtain information on the chemical composition of extracts. Ethanol-water-based extraction procedures were the most efficient in isolating polyphenols, while less polar butanol extract contained the highest amount of iridoids. Antioxidant potential analysis revealed stronger activity in extracts with higher polyphenol content. Bacillus cereus and Staphylococus aureus were designated as the most sensitive bacterial strains to the activity of extracts, while among the micromycetes tested, Penicillium funiculosum was the most susceptible strain. Butanol extract showed antivirulence potential on Candida albicans morphological transition from yeast to hyphal form, and selected extracts were effective against biofilm formation in two Candida species. All the extracts tested in this study showed no cytotoxic activity to immortalize human skin keratinocyte cell line (HaCaT), whereas extracts obtained by ethanol-water extraction stand out for their potent wound healing effects. Moreover, the influence of the extraction solvent system on various bioactivities of C. spicatum is reported herein for the first time. Overall, the results presented in this study promote the use of C. spicatum as a source of natural products with potential antioxidant, wound healing, and antimicrobial applications that are potentially safe for human use.

Sweroside: An iridoid glycoside of potential neuroprotective, antidiabetic, and antioxidant activities supported by molecular docking.

Oxidative stress can be a series burden on human health and may lead to many chronic diseases such as diabetes and neurological disorders. The use of natural products to scavenge the reactive oxygen species has attracted the attention of many researchers, to safely manage these conditions with fewer side effects, in available and cost-effective ways. The current study aimed at the isolation and structure elucidation of sweroside from Schenkia spicata (Gentianaceae) and the evaluation of its antioxidant, antidiabetic, neuroprotective, and enzyme inhibitory potential via in vitro and in silico studies. The antioxidant potential was evaluated by a variety of assays as ABTS, CUPRAC and FRAP, showing values of 0.34 ± 0.08, 21.14 ± 0.43, and 12.32 ± 0.20 mg TE/g, respectively, while demonstrating 0.75 ± 0.03 mmol TE/g for phosphomolybdenum (PBD) assay. Acetylcholinestrase (AChE), butyrylcholinesterase (BChE) and tyrosinase inhibitory activities were used to evaluate the neuroprotective effect, while the antidiabetic potential was evaluated by measuring α-amylase and glucosidase inhibitory activities. Results revealed that sweroside showed antioxidant and inhibitory effects on the enzymes tested with the exception of AChE. It demonstrated good tyrosinase inhibitory ability with 55.06 ± 1.85 mg Kojic acid equivalent /g. Regarding the antidiabetic ability, the compound displayed both amylase and glucosidase (0.10 ± 0.01 and 1.54 ± 0.01 mmol Acarbose equivalent/g, respectively) inhibitory activities. Molecular docking studies of sweroside on the active sites of the aforementioned enzymes in addition to NADPH oxidase were performed using Discovery Studio 4.1 software. Results revealed good binding affinities of sweroside to these enzymes mainly through hydrogen bonds and van der Waals interactions. Sweroside can be an important antioxidant and enzyme inhibitory supplement, yet further in vivo and clinical studies are required.

Phytochemical and in silico studies for potential constituents from Centaurium spicatum as candidates against the SARS-CoV-2 main protease and RNA-dependent RNA polymerase.

In the present study, a new secoiridoid glycoside lisianthoside II 1, along with seven known compounds 2-8, were isolated from Centaurium spicatum L. In-silico molecular docking and molecular dynamic simulation against SARS-CoV-2 Main protease (Mpro) and RNA-dependent RNA polymerase (RdRp) were conducted. The affinity docking scores revealed that 8 is the best bound ligand to Mpro active site with binding energy of -14.9877 kcal/mol (RSMD = 1.16 Å), while 6 was the highest against RdRp (-16.9572 kcal/mol, RMSD = 1.01 Å). Moreover, the molecular dynamic simulation revealed that 8 with a (ΔG) of -7.9 kcal/mol (RMSD value of 2.6 Å) and 6 (RMSD value of 1.6 Å) and binding free energy (ΔG) of -7.1 kcal/mol achieved the highest stability over 50 ns of MDS inside the Mpro and RdRp enzyme's active site, respectively. Hence, the isolated compounds could be a good lead for development of new leads targeting COVID-19.