α-Glucosidase, butyrylcholinesterase and acetylcholinesterase inhibitory activities of phenolic compounds from Carthamus tinctorius L. flowers: In silico and in vitro studies

Chemical investigation of Carthamus tinctorius L. flowers resulted in isolation of seven metabolites that were identified as; p-Hydroxybenzoic acid (1), trans hydroxy cinnamic acid (2), kaempferol-6-C-glucoside (3), astragalin (4), cartormin (5), kaempferol-3-O-rutinoside (6), and kaempferol-3-O-sophoroside (7). Virtual screening of the isolated compounds against human intestinal α-glucosidase, acetylcholinesterase, and butyrylcholinesterase was carried out. Additionally, the antioxidant activity of the bioactive compounds was assessed. Compounds 1 and 5 exhibited moderate binding affinities to acetylcholinesterase (binding energy -5.33 and -4.18 kcal/mol, respectively), compared to donepezil (-83.33kcal/mol). Compounds 1-7 demonstrated weak affinity to butyrylcholinesterase. Compounds 2 and 4 displayed moderate binding affinity to human intestinal α-glucosidase,compared to Acarbose (reference compound), meanwhile compound 2 exhibited lower affinity. Molecular dynamic studies revealed that compound 4 formed a stable complex with the binding site throughout a 100 ns simulation period. The in-vitro results were consistent with the virtual experimental results, as compounds 1 and 5 showed mild inhibitory effects on acetylcholinesterase (IC50s 150.6 and 168.7 µM, respectively). Compound 4 exhibited moderate α-glucosidase inhibition with an IC50 of 93.71 µM. The bioactive compounds also demonstrated notable antioxidant activity in ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)], ORAC (oxygen radical-absorbance capacity), and metal chelation assays, suggesting their potential in improving dementia in Alzheimer's disease (AD) and mitigating hyperglycemia.

Insights into the Biological Activity and Cytotoxic Mechanism of Epimedium pubigerum

In this work, the phytochemical characterization, biological activity, and cytotoxic mechanism of aerial and rhizome methanol extracts (SME and RME) of Epimedium pubigerum were investigated to demonstrate its potential usage in the treatment of lung cancer. LC-HRMS analysis, total phenolic/flavonoid content assay, DPPH radical scavenging assay, DNA interaction, cytotoxicity, and western blotting were investigated using different methods. Fumaric acid was found to be the most abundant compound in both extracts. SME and RME were cytotoxic on A549 cells concentration-dependently. Also, in vitro scratch assay showed that SME and RME led to a significant anti-migratory effect at 1 mg/mL. Cytochrome c, p53, and caspase 3 expression significantly increased in the presence of RME compared to the control. All of these results claimed that RME might be suggested as a theoretically more effective phytotherapeutic agent for lung cancer compared to the effect seen with the SME.

Biological activities of different plant species belonging to the Asteraceae family

Achillea biebersteinii and Anthemis tinctoria, which are widely distributed species of the Asteraceae family, are used in folk medicine in the form of herbal tea or extract in the treatment of many diseases. The aim of this study was to investigate the chemical content, antimicrobial, antioxidant, enzyme inhibitor activities and cytotoxic effects of 80% ethanol extract of these two species and make a comparative analysis. In accordance with the data obtained, the major component of A. biebersteinii was determined as Cyclododecane (14.47%), while that of A. tinctoria was determined as Phytol (23.15%). A. biebersteinii, which showed moderate activity in terms of antimicrobial activity, produced more active inhibition than A. tinctoria did. Both plants showed high levels of antioxidant activity. The total phenol and total flavonoid contents of A. tinctoria were higher than those of A. biebersteinii. It was determined that there was no significant activity when the extracts were compared with galanthamine, which is the reference drug in terms of enzyme inhibitory activity. When the in vitro anticancer activity of human breast cancer cell line was examined, it was determined that A. tinctoria had a cytotoxic effect at high concentrations (IC50;0.82mg/mL), and A. biebersteinii showed strong cytotoxicity at all concentrations (IC50;<0.0625mg/mL). These two plants of the same family were evaluated in terms of many different biological parameters and it was revealed that A. biebersteinii was more active than A. tinctoria. However, in vivo studies are needed to determine whether these plants can be used as phytotherapeutic agents.

Unravelling the phenolic compound reserves, antioxidant and enzyme inhibitory activities of an endemic plant species, Achillea pseudoaleppica

The present ethnobotanical study unravelled the phenolic reservoir (UHPLC-MS/TQ-MS) and pharmacological activity (antioxidant and enzyme inhibitory activities) of an endemic plant, Achillea pseudoaleppica Hub.-Mor. (Asteraceae). The effective antioxidant properties of ethanol and water extracts of A. pseudoaleppica leaves were determined by using six different in vitro bioanalytical methods including three reducing antioxidant methods and three radical scavenging antioxidant methods. In the other step of the study, the enzyme inhibitory effects of water and ethanol extracts of A. pseudoaleppica were determined against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase, and α-glucosidase enzymes. The ethanol extract was found to have effective inhibition potential for all four respected enzymes. The IC₅₀ values of A. pseudoaleppica extract against AChE, BChE, α-amylase, and α-glucosidase enzymes were found to be 2.67 mg/mL, 4.55 mg/mL, 16.51 mg/mL, and 12.37 mg/mL, respectively. Also, UHPLC-MS/TQ-MS analyses revealed quinic acid as the most abundant phenolic compound of the water extract (31.12 ± 1.65 µg/mg) and ethanol extract (11.75 ± 0.82 µg/mg). In addition, the molecular docking interaction of the most abundant phenolic compound of A. pseudoaleppica (quinic acid) with AChE, BChE, α-amylase, and α-glucosidase target enzymes were evaluated using Chimera and AutoDock Vina softwares. In conclusion, the rich phenolic content and the potent antioxidant and enzyme inhibitory properties of A. pseudoaleppica extracts may support the widespread ethnobotanical use of the plant application.Communicated by Ramaswamy H. Sarma.

Comparative Studies on Essential Oil and Phenolic Content with In Vitro Antioxidant, Anticholinesterase, Antimicrobial Activities of Achillea biebersteinii Afan. and A. millefolium subsp. millefolium Afan. L. Growing in Eastern Turkey

The potential applications of Achillea species in various industries have encouraged the examination of their phytochemical components along with their biological potential. In the present study, phenolic contents and essential oil compositions together with the in vitro biological activities of the aerial parts from Achillea biebersteinii Afan. and Achillea millefolium subsp. millefolium Afan. collected from Turkey were evaluated. Different solvent extracts (n-hexane, chloroform, methanol, water) were prepared and their antimicrobial, anticholinesterase, and antioxidant activities were studied. The LC-MS/MS results revealed the presence of 16 different phenolic compounds, including chlorogenic acid, rutin, quercetin, and luteolin glycosides, in methanolic extracts. According to GC-FID and GC/MS results, the primary components of the oils were identified as 1,8-cineole (32.5%), piperitone (14.4%), and camphor (13.7%) in A. biebersteinii and 1,8-cineole (12.3%) and β-eudesmol (8.9%) in A. millefolium subsp. millefolium. The infusion and methanolic extracts of both species were found to be rich in their total phenolic content as well as their antioxidant and anticholinesterase activity. In contrast, the n-hexane and chloroform extracts of both species showed strong antimicrobial activity with MIC values ranging from 15 to 2000 μg/mL. Our findings suggest that the investigated Achillea species could be evaluated as potent natural agents, and further studies into the promising extracts are needed.

Flavones as tyrosinase inhibitors: kinetic studies in vitro and in silico

INTRODUCTION

Tyrosinase is a multifunctional copper-containing oxidase enzyme that catalyses the first steps in the formation of melanin pigments. Identification of tyrosinase inhibitors is of value for applications in cosmetics, medicine and agriculture.

OBJECTIVE

To develop an analytical method that allows identification of drug-like natural products that can be further developed as tyrosinase inhibitors. Results of in vitro and in silico studies will be compared in order to gain a deeper insight into the mechanism of action of enzyme inhibition.

METHOD

Using an in vitro assay we tested tyrosinase inhibitor effects of five structurally related flavones, i.e. luteolin (1), eupafolin (2), genkwanin (3), nobiletin (4), and chrysosplenetin (5). The strongest inhibitors were further investigated in silico, using enzyme docking simulations.

RESULTS

All compounds tested showed modest tyrosinase inhibitory effect compared to the positive control, kojic acid. The polymethoxy flavones 4 and 5 exhibited the strongest tyrosinase inhibitory effect with the half maximal inhibitory concentration (IC₅₀ ) values of 131.92 ± 1.75 μM and 99.87 ± 2.38 μM respectively. According to kinetic analysis 2, 4 and 5 were competitive inhibitors, whereas 1 and 3 were non-competitive inhibitors of tyrosinase. Docking studies indicated that methoxy groups on 4 and 5 caused steric hindrance which prevented alternative binding modes in the tyrosinase; the methoxy groups on the B-ring of these flavones faced the catalytic site in the enzyme.

CONCLUSIONS

The docking simulations nicely complemented the in vitro kinetic studies, opening the way for the development of predictive models for use in drug design.