Common Phenolic Compounds Research Articles

Phenolic Compounds, Fatty Acid Contents, and Antibacterial Properties of Ozonated and Non-Ozonated Tobacco Seed Oils

ABSTRACT In this study, the fatty acid content, phenolic compounds, and antimicrobial activity of seed oils from Ege Özbaş (EO), Sarıbağlar 407 (S407) and Akhisar 98 (A98) tobacco plants grown in the Aegean region were investigated. The ozonation process altered fatty acid and phenolic compound compositions and affected antimicrobial activities against Gram-positive and Gram-negative bacteria in the oils. Tobacco seed oils (TSOs) were extracted via cold pressing (CP) and Soxhlet extraction (SE). Fatty acids and phenolic compounds were analyzed using GC-FID and LC-MS/MS, respectively. Non-ozonated oils averaged 73% linoleic acid, 13% oleic acid, 9% palmitic acid, and 3% stearic acid, while ozonated oils contained 41% linoleic acid, 18% oleic acid, 22% palmitic acid, and 11% stearic acid. The presence of 33 phenolic compounds was investigated and 22 common phenolic compounds were detected in both ozonated and non-ozonated TSOs, including gallic acid, protocatechuic acid, chlorogenic acid, 3-hydroxybenzoic acid, (-)-epicatechin, 2,5-dihydroxybenzoic acid, caffeic acid, verbascoside, luteolin-7-glucoside, hesperidin, and rosmarinic acid. The increased antimicrobial activity of fatty acids and phenolic compounds following ozonation suggests the potential for developing creams to treat skin diseases and wounds caused by antibiotic-resistant pathogens, and to reduce the effects of aging skin wrinkles.

Associations of prenatal maternal urinary concentrations of triclosan and benzophenone-3 with cognition in 7.5-month-old infants

BackgroundEndocrine-disrupting chemicals (EDCs) have been linked to adverse health outcomes and prenatal exposure is known to impact infant and child development. However, few studies have assessed early developmental consequences of prenatal exposure to two common phenolic compounds, benzophenone-3 (BP-3) and triclosan (TCS). ObjectiveWe evaluated the relationship of prenatal exposure to BP-3 and TCS with infant cognition at 7.5 months via performance on a visual recognition memory (VRM) task. MethodsDrawing from the Illinois Kids Development Study (IKIDS) cohort, prenatal exposure to BP-3 and TCS was assessed in pools of five urine samples collected from each woman across pregnancy. Cognition was measured in 310 infants using a VRM task assessing information processing speed, attention, and recognition memory through infrared eye-tracking. Generalized linear regression estimated exposure-outcome associations, followed by stratification to investigate modification of associations by infant sex and stimulus set. ResultsSampled mothers were more likely to be white, college educated, and middle or high income relative to the US population. Mean chemical exposures were significantly higher than those of adult women in the NHANES cohort. In models adjusted for income, gestational age at birth, and testing age, prenatal BP-3 exposure was associated with an increase in run duration (average time spent looking at the stimuli before looking away) (β = 0.0011, CI -0.0001:0.0022), indicating slower information processing speed, while TCS was associated with significantly longer time to familiarization (time to accrue a total of 20 s of looking time to the stimuli) (β = 0.0686, CI 0.0203:0.1168, p < 0.01), indicating poorer attention. Stratum-specific analyses isolated both effects to male infants who viewed the second of two stimulus sets. ConclusionHigher prenatal exposure to triclosan was associated with poorer attention in infancy, while benzophenone-3 may be associated with slower information processing speed, particularly among males.

Polyoxometalate-based peroxidase-mimicking sensors for colorimetric detection and discrimination of phenolic pollutants

Phenol and its derivatives represent a kind of significant hazards to both human health and the integrity of ecological systems. Exploring an efficient detection and discrimination approach for them is urgent. Herein, a kind of polyoxometalate-based peroxidase-mimicking crystalline colorimetric sensors were developed by integrating dual active sites of Keggin-type polyoxoanions and coordination unsaturated copper centers, for which the formulas are [Cu(dppeo)3]2[Cu(dppeo)2(H2O)](dppeo)0.75[PMo12O40]2·9H2O (1), [Cu(dppeo)2(H2O)]2 [SiW12O40]·6H2O (2), [Cu(dppeo)2]3[PW12O40]2·12H2O (3), (dppeo = 1,2-bis(diphenylphosphino)ethane dioxide). Structural analysis revealed that these compounds exhibit 0-D supramolecular architecture formed through the interplay of electrostatic forces and hydrogen bonding interactions between Keggin-type polyoxoanions and dppeo-chelated copper-organic cationic fragments. Sensors 1–3 exhibit favorable peroxidase-mimicking catalytic activities, which expedite the reaction involving phenol, 4-aminoantipyrine and hydrogen peroxide (H2O2), resulting in a pronounced color change for indicating the target concentration levels. These crystalline sensors responded linearly to phenol concentration within 0.01–1.0 mM, affording low detection limits of 1.19, 1.59 and 3.78 μM for 1–3. These sensors demonstrate exceptional anti-interference capabilities and exhibit excellent applicability in real water samples, ensuring high recovery rates. By incorporating a colorimetric array with principal component analysis, the sensors effectively discriminate between common phenolic compounds. This research presents an innovative methodology for the design of crystalline sensor materials, paving the way for the detection and differentiation of phenolic pollutants within environmental applications.

Highly selective and sensitive molecularly imprinted sensors for the electrochemical assay of quercetin in methanol extracts of Rubus sanctus and Fragaria vesca

Quercetin (QUE) is a powerful antioxidant and one of the common phenolic compounds found in plants, vegetables, and fruits, which has shown many pharmacological activities. The complex nature of the matrix in which QUE is found and its importance and potential uses in diverse applications force the researchers to develop selective and sensitive sensors. In the present work, a novel molecularly imprinted polymer (MIP)-based electrochemical sensor was fabricated for the selective and sensitive determination of the QUE in plant extracts and food supplements. Tryptophan methacrylate (TrpMA) was chosen as the functional monomer, whereas the photopolymerization (PP) method was applied using a glassy carbon electrode (GCE). Electrochemical and morphological characterizations of the developed sensor (TrpMA@QUE/MIP-GCE) were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The linear range of the developed sensor was determined to be in the range of 1.0–25 pM, while the limit of detection (LOD) was calculated to be 0.235 pM. In conclusion, The TrpMA@QUE/MIP-GCE sensor might be classified as a promising platform for selective and sensitive determination of QUE not only in plant extracts but also in commercial food supplements because of its reliability, reproducibility, repeatability, stability, and fast response time.

FAST MICROWAVE ASSISTED FUNCTIONALIZATION OF CARBON NANOFIBERS: A PROMISING ELECTROCHEMICAL SENSING PLATFORM FOR ELECTROACTIVE ANALYTES

This research introduces a novel approach for swiftly enhancing the electrochemical sensing capabilities of commercial screen-printed carbon electrodes through a rapid acid microwave-assisted functionalization of carbon nanofibers (f-CNFMW). A comparative analysis with the conventional refluxed system functionalization method (f-CNFRefluxed) was conducted to assess the electrochemical performance of the newly developed f-CNFMW. The voltametric study showed that f-CNF-MW significantly enhanced the electron transfer rate when testing common phenolic compounds such as hydroquinone, paracetamol, and caffeic acid. Moreover, the anodic oxidation potential for the majority of irreversible analytes was negatively shifted, indicating the high electro-catalytic activity of f-CNF-MW gained after this treatment, making it analytically useful for the electro-oxidation of some molecules that require high overpotential, mainly for purine bases and nitrite. Additionally, the developed f-CNF-MW exhibited remarkable resistance to fouling phenomena when exposed to bisphenol A and tryptophan, underscoring its potential for real-world applications. To sum up, this study highlights the potential of rapid microwave treatment in producing f-CNF-MW as a promising electrochemical nanomaterial, resulting in substantial improvements in electro-analytical capabilities compared to conventional methodologies.

Smartphone-assisted nanozyme sensor array constructed based on reaction kinetics for the discrimination and identification of phenolic compounds

Although the research on nanozymes has attracted widespread attention in recent years, the development of highly active and multifunctional nanozymes remains a challenge. Here, a bifunctional AMP-Cu nanozyme with laccase- and catecholase-like activities was successfully prepared at room temperature with Cu2+ as the metal ion and adenosine-5′-monophosphate (AMP) as the ligand molecule.Based on the excellent catalytic performance of AMP-Cu, a three-channel colorimetric sensor array was constructed using reaction kinetics as the sensing unit to achieve high-throughput detection and identification of six common phenolic compounds at low concentrations. This strategy simplifies the construction of sensor array and demonstrates the capacity to obtain multidimensional data from a single material. Finally, with the assistance of smartphones and homemade dark boxes, a portable on-site detection method for phenolic compounds was developed. This work would contribute to the development of portable sensors and the highly efficient identification of phenolic compounds in complex samples.

Impact of fermentation on the structure and antioxidant activity of selective phenolic compounds

The impact of fermentation on the structure and antioxidant potential of phenolic compounds in foods have received wide attention. In this study, five common phenolic compounds (ferulic acid, polydatin, cyanidin-3-O-glucoside, rutin, tannic acid) were fermented by Aspergillus oryzae, Lactobacillus plantarum and Saccharomyces cerevisiae respectively. The qualitative and quantitative analyses of the fermentation products were separately performed by HPLC-DAD-ESI-QTOF-MS/MS and HPLC-DAD, and the antioxidant properties (assessed by DPPH and ABTS assays) were also estimated. The results demonstrated that the glycosidic bonds in the phenolic compounds were hydrolyzed during fermentation, which led to the formation of additional phenolic metabolites such as gallic acid, protocatechuic acid and quercetin, as evidenced by the identification of 15 phenolic compounds in the fermented samples. The contents of these phenolics were considerably decreased (p < 0.05) to 1.72%–97.99% during fermentation, while the phenolic metabolites were detected in certain amounts (0.44–15.53 mg/L). The antioxidant activities of these phenolics also varied among different fermenting microorganisms. This study provides direct evidence of the metabolites and antioxidant properties of these common food phenolic compounds after fermentation.

In Vitro Anti-SARS-CoV-2 Activities of Curcumin and Selected Phenolic Compounds

Since the COVID-19 pandemic in 2020, many reports have highlighted several potential anti-SARS-CoV-2 drug candidates, including phenolic compounds. Therefore, this study aimed to evaluate the anti-SARS-CoV-2 activity of nine common phenolic compounds found in plants using the in vitro cellular infection model. The anti-SARS-CoV-2 activity of curcumin, quercetin, gallic acid, catechin, rutin, kaempferol, naringenin, coumaric acid and caffeic acid were evaluated on SARS-CoV-2-infected Vero E6 cells by using a cytopathic effect (CPE)-based assay. The anti-SARS-CoV-2 activity in human lung cells, A549 expressing human ACE2 and TMPRSS2, was evaluated by the RT-qPCR technique. S1-ACE2 interaction and 3CL protease activity assays were also performed for the potent compound. Of the nine phenolic compounds, only curcumin inhibited the SARS-CoV-2 induced CPE activity (EC50 of 13.63 µM) in Vero E6 cells, but with a low selective index (SI) value. Interestingly, curcumin exhibited potent anti-SARS-CoV-2 activity in A549 cells with an EC50 of 4.57 µM and an SI value of 7.96. S1-ACE2 interaction and 3CL protease inhibitory activities of curcumin were also observed. In conclusion, curcumin showed a moderate in vitro anti-SARS-CoV-2 activity. The true potential of curcumin as an anti-SARS-CoV-2 candidate could be further evaluated in a COVID-19 animal model.

The Phenolic Composition and Antioxidant Properties of Figs (Ficus carica L.) Grown in the Black Sea Region.

This study compared the phenolic composition and antioxidant properties of three varieties of fig fruits (Ficus carica L) from the Eastern Black Sea region of Türkiye. Total polyphenol content (TPC), total flavonoid content (TFC), and phenolic compositions were analyzed in green, purple, and dark purple species. The mean TPC value was 42.10 ± 5.71mg GAE/100g FW, ranging from 35.98 to 47.30mg GAE/100g FW, and was highest in the dark purple species. The mean TFC value was 1.27 ± 0.93mg QUE/100 FW g, ranging between 0.35 and 2.21mg QUE/100 FW g, and was highest in the purple species. The samples' total antioxidant capacity was measured based on ferric reducing/antioxidant power (FRAP), the values ranging from 151.98 to 372.97μmol FeSO4.7H2O/100g FW, with an average value of 239.64μmol FeSO4.7H2O/100g FW, being highest in the dark purple species. The 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the fruits was expressed as SC50 (mg/mL), and the values ranged from 10.04 to 42.42mg/mL, being highest in the purple species. The phenolic composition was analyzed using HPLC-PDA according to the method in which 25 phenolic standards were used. Chlorogenic acid and t-cinnamic acid were the most common phenolic compounds, with rutin, chrysin, apigenin, and luteolin being detected at different amounts. In conclusion, the purple species contained the highest flavonoid content, was rich in apigenin, luteolin, and chrysin, and possessed the highest DPPH radical scavenging activity.

Malic acid enhances proanthocyanidin stability and their combined effects on dough rheological properties and bread quality

Proanthocyanidins, as one of the most common phenolic compounds in cereals, have various beneficial functionalities. However, baking can lead to proanthocyanidin degradation, which limits its application in baked products. This study aimed to use malic acid (MA) for the first time to stabilize grape seed proanthocyanidins (GSPs) in bread formulations and investigate the effects of the concentration ratios of two additives on dough properties and bread quality. Proanthocyanidin stability showed that MA can effectively enhance the retention of GSP in the dough up to 96.9%. Confocal laser scanning microscopy showed that the increase in MA concentration can effectively enhance the compact gluten structure of GSP dough. The dough rheological and textural properties indicated that when GSP was compounded with MA, the hardness of bread can be significantly reduced, and the color and specific volume can be improved.

Selective sensing of catechol based on a fluorescent nanozyme with catechol oxidase activity

Nanozymes, an unusual category of nanomaterials possessing enzymatic properties, and have generated considerable interest regarding their application feasibilities on several important fronts. In the present work, an innovative sensing device for catechol was established ground on a fluorescent nanozyme (Cu-BDC-NH2) that exhibited catechol oxidase activity. The fluorescent nanozyme combines both functions of catechol recognition and response signal output, and can realize the sensing of catechol without the addition of other chromogenic agents. In the existence of Cu-BDC-NH2, catechol can be oxidized efficiently to produce quinones or polymers with strong electron absorption capacity, which immediately results in efficient fluorescence quenching of Cu-BDC-NH2. However, other common phenolic compounds, such as phenol, the other two diphenols (hydroquinone and resorcinol), phloroglucinol, and chlorophenol, do not result in efficient fluorescence quenching of Cu-BDC-NH2. The method shows a nice linear relationship between catechol concentration prep the fluorescence intensity of Cu-BDC-NH2 in the scope of 0–10 μM, with a detection limit of 0.997 μM. The detection of catechol in actual water samples has also achieved the satisfactory consequences, which provides a new strategy for the convenient and selective detection of catechol.

Effect of In Vitro Digestion on the Phenolic Content of Herbs Collected from Eastern Anatolia.

Phenolic compounds in herbs have high antioxidant activities, and their consumption as functional foods may impact human health positively. The main objective of this study was to investigate the total phenolic (TPC) and total flavonoid (TFC) contents as well as total antioxidant capacities (TAC) of bioactive compounds in various infusions prepared by herbs collected from the Bingöl region of Turkey during in vitro gastrointestinal digestion. According to the results, while the highest TPC (5836 ± 373 mg GAE/100 g dw), TFC (2301 ± 158 CE/100 g, dw), and TAC (1347 mg TE/100 g dw) were obtained with Anchusa azurea Mill. species, Crataegus orientalis exhibited the lowest values (863 ± 24 mg GAE/100 g dw, 242 ± 23 CE/100 g dw, 735 ± 47 mg TE/100 g dw, respectively). Gallic acid and chlorogenic acid were the most common phenolic compounds in the infusions. In detail, the highest gallic acid was found in E. spectabilis M. Bieb (27.3 ± 0.9 mg/100 g of dw) and the highest chlorogenic acid was observed in F. elaeochytris (919.2 ± 35.7 mg/100 g of dw). After in vitro gastrointestinal digestion, the highest bioaccessibility values of TPC and TFC were determined as 0.6- and 3-fold of the values observed in undigested C. orientalis, respectively. Besides, C. orientalis Pall. had the highest bioaccessibility of TAC according to the DPPH (6.7-fold increase) and CUPRAC (9.7-fold increase) assays. It can be concluded that the use of these medicinal herbs in human dietary intake due to their high bioactive compounds even after digestion can improve nutritional value and contribute to human health.

Quality of African moringa ( Moringa stenopetala ) leaf samples by liquid chromatography of phenolics, loss on drying and ash content

The aim of this study was to evaluate the quality of African moringa (Moringa stenopetala) leaf preparations using easily applicable analytical methods. For this purpose, a novel simple and fast LC-UV method was developed and validated to determine the most common phenolic compounds. The method showed good linearity with determination coefficients (r2) ≥ 0.999. Detection limits were below 0.4 μg/ml and quantification limits below 1.2 μg/ml. Relative standard deviation (RSD) values for intra- and inter-day precision were less than 2% and recoveries were close to 100%. Robustness of the method was evaluated using an experimental design. The developed method was applied to analyze some commercial moringa leaf samples obtained from Ethiopia. Unknown compounds were tentatively identified as neochlorogenic acid and kaempferol 3-O-rhamnosylglucoside (KRG) by means of mass spectrometry (MS). Rutin was found to be the most common compound. Its content in samples varied from 2 to 18 mg/g. The amounts of (neo)chlorogenic acid and KRG were less than 2 mg/g, while quercetin and caffeic acid were not detected. The method allowed to observe differences in phenolic composition between regions. Results for loss on drying and ash content revealed that 40% and 50%, respectively, of the samples were not compliant. Novelty Impact Statement Quality control of formulations of Moringa stenopetala leaves is as good as non-existent due to lack of suitable test procedures. The analytical methods proposed here are easily applicable in low-income countries and include a novel LC-UV method for the phenolic compounds, loss on drying, and ash contents. The combined tests were found to be successful in differentiating the quality of different commercial samples.

The therapeutic effects and antioxidant properties of epigallocatechin-3 gallate: A new review

The aim of this review is to investigate the possible protective and preventive effects of epigallocatechin-3 gallate (EGCG) in terms of human health including hepatoprotective, neuroprotective, cardioprotective, nephrotoxicity and anticancer effects. Green tea is one of the most consumed beverages in many countries, especially in Turkey and it plays protective roles in the treatment of various diseases via the polyphenol it contains. It is known that EGCG, which is the main bioactive polyphenol in green tea, has versatile bioactivities. It has been determined that EGCG has the highest free radical scavenging ability among common phenolic compounds. It regulates gene expression and molecular signaling pathways by inhibiting oxidative stress and inflammation. In addition, it prevents cell death by suppressing cytokine production and neutrophil migration in inflammatory diseases. With the studies conducted in the last decade, it has been determined that EGCG has anticancer, antioxidative, antiinflammatory, antidiabetic, antitumor, antihypertensive and neuroprotective activities. Especially, its anticancer effect has been found to have chemopreventive and chemotherapeutic activities in various cancer types such as colon, lung and breast cancer with in vivo and in vitro studies conducted to investigate molecular targets. This review was written to examine the possible protective and preventive effects of EGCG in terms of human health, including its hepatoprotective, neuroprotective, cardioprotective, nephrotoxicity and anticancer effects.

The mechanisms of wine phenolic compounds for preclinical anticancer therapeutics.

BackgroundWine is one of the oldest and most popular drinks worldwide, which is rich in phenolic compounds. Epidemiological studies show that moderate consumption of wine can reduce the risk of certain diseases, and this effect is attributed to its phenolic compounds.ObjectiveThe objective of this review was to elaborate the effects of wine-derived phenolic compounds for preclinical anticancer therapeutics and their major mechanisms.MethodsIn this review, we discuss the classification and content of common phenolic compounds in wine and summarize previous studies that have evaluated the anticancer properties of wine-derived phenolic compounds and their mechanisms.ResultsWine-derived phenolic compounds have been proven to participate in several mechanisms against cancers, including deoxyribonucleic acid damage, oxidative stress, cell proliferation, cell cycle arrest, cell apoptosis, autophagy, cell invasion and metastasis, immunity and metabolism, regulation of multiple signaling molecules, and gene expression. However, the exact anticancer mechanisms of the phenolic compounds in wine need to be further investigated.ConclusionWine-derived phenolic compounds are promising chemoprotective and chemotherapeutic agents for cancer.

Phytochemical Composition, Antiglycation, Antioxidant Activity and Methylglyoxal-Trapping Action of Brassica Vegetables.

Brassica vegetables are common in cuisines worldwide. The aim of this study was to investigate the antiglycation, methylglyoxal (MG)-trapping action and antioxidant activity of Brassica vegetable extract (BVE) from cabbage, cauliflower and Chinese cabbage. The results showed that cauliflower had the highest phenolic content with the strongest DPPH radical scavenging activity, ferric reducing antioxidant power and oxygen radical absorbance capacity. Seven phenolic acids and three flavonoids were identified by ESI-Q-TOF-MS analysis. The common phenolic compounds in all BVE were sinapic acid and p-hydroxybenzoic acid. The BVE (0.5mg/mL) showed significant inhibitory activity against glucose-induced fluorescent advanced glycation end products (AGEs) formation (34 - 67%) and preserved the amount of protein thiol group (30 - 35%). In addition, all extracts (0.125 - 4mg/mL) also had the ability to trap MG, a reactive glycating agent. Total phenolic content of BVE exhibited a positive correlation with DPPH radical scavenging activity (r = 0.524) and % inhibition of AGE formation (r = 0.570) and % MG-trapping capacity (r = 0.786). These findings suggest that the BVE possesses antioxidant and antiglycating activity that may help to protect against protein glycation and oxidation mediated by glycation reaction.

Ultrasonic pre-treatment modifies the pH-dependent molecular interactions between β-lactoglobulin and dietary phenolics: Conformational structures and interfacial properties

There is a need to understand the ultrasound-induced changes in the interactions between proteins and phenolic compounds at different pH. This study systematically explored the role of high-intensity ultrasound pre-treatment on the binding mechanisms of β-lactoglobulin (β-LG) to two common phenolic compounds, i.e., (−)-epigallocatechin-3-gallate (EGCG) and chlorogenic acid (CA) at neutral and acidic pH (pH 7.2 and 2.4). Tryptophan fluorescence revealed that compared to proteins sonicated at 20% and 50% amplitudes, 35%-amplitude ultrasound pre-treatment (ULG-35) strengthened the binding affinities of EGCG/CA to β-LG without altering the main interaction force. After phenolic addition, ULG-35 displayed a similar but a greater extent of protein secondary and tertiary structural changes than the native protein, ascribed to the ultrasound-driven hydrophobic stacking among interacted molecules. The dominant form of β-LG (dimer/monomer) played a crucial role in the conformational and interfacial properties of complexes, which can be explained by the distinct binding sites at different pH as unveiled by molecular docking. Combining pre-ultrasound with EGCG interaction notably increased the foaming and emulsifying properties of β-LG, providing a feasible way for the modification of bovine whey proteins. These results shed light on the understanding of protein–phenolic non-covalent binding under ultrasound and help to develop complex systems with desired functionality and delivery.

Pectin-containing antioxidant drink based on extracts of grape pomace and Chamerion

The cause of many pathological processes in the human body that entail various serious diseases is damage to cellular structures by free oxygen radicals. This has led to the urgency of developing drinks with high antioxidant and immunomodulatory properties. Various types of Chamerion, C. angustifolium L. and C. caucasicum and pomace of the Ancellotta grape variety growing in the South of Russia were selected as the objects of research. The results of determining the amino acid composition, the content of total polyphenols, flavonoids, anthocyanins and tannins confirmed the high antioxidant properties of C. angustifolium L. and C. caucasicum. It was found that the amino acid composition does not differ significantly by the type of Chamerion. The content of amino acids is not high, except for a relatively high number of four essential amino acids, such as leucine, valine, phenylalanine and isoleucine. Research results have shown that the type of Chamerion affects the content of antioxidant compounds. It was found that a small quantitative predominance of common phenolic compounds, flavonoids, anthocyanins and tannins is observed in C. angustifolium L. At the same time, the highest content of antioxidant compounds is observed in leaves and flowers. Quantitative evaluation of the anti-radical and anti-oxidative activity of the resulting beverage showed its high ability to bind free radicals, which is further confirmed by the indicators of restoring power (4.91 mmol Fe2+/1 kg of raw material).

Flavonoids as Potential anti-MRSA Agents through Modulation of PBP2a: A Computational and Experimental Study.

Recently, the interest in plant-derived antimicrobial agents has increased. However, there are no sufficient studies dealing with their modes of action. Herein, we investigate an in-house library of common plant-based phenolic compounds for their potential antibacterial effects against the methicillin-resistant Staphylococcus aureus (MRSA), a widespread life-threatening superbug. Flavonoids, which are considered major constituents in the plant kingdom, were found to be a promising class of compounds against MRSA, particularly the non-glycosylated ones. On the other hand, the glycosylated derivatives, along with the flavonolignan silibinin A, were able to restore the inhibitory activity of ampicillin against MRSA. To explore the mode of action of this class, they were subjected to an extensive inverse virtual screening (IVS), which suggested penicillin-binding protein 2a (PBP2a) as a possible target that mediates both the antibacterial and the antibiotic-synergistic effects of this class of compounds. Further molecular docking and molecular dynamic simulation experiments were conducted to support the primary IVS and the in vitro results and to study their binding modes with PBP2a. Our findings shed a light on plant-derived natural products, notably flavonoids, as a promising and readily available source for future adjuvant antimicrobial therapy against resistant strains.

Phytochemical Profiles and Antioxidant Activity of Grasses Used in South African Traditional Medicine.

Grasses are a valuable group of monocotyledonous plants, used as nourishing foods and as remedies against diseases for both humans and livestock. Phytochemical profiles of 13 medicinal grasses were quantified, using spectrophotometric methods and ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS), while the antioxidant activity was done using DPPH and ferric-reducing-power assays. The phytochemical analysis included the total soluble phenolic content, flavonoids, proanthocyanidins, iridoids and phenolic acids. Among the 13 grasses, the root methanolic extracts of Cymbopogon spp., Cymbopogon nardus and Cenchrus ciliaris contained the highest concentrations of total soluble phenolics (27–31 mg GAE/g DW) and flavonoids (4–13 mg CE/g DW). Condensed tannins and total iridoid content were highest (2.3 mg CCE/g DW and 3.2 mg HE/g DW, respectively) in Cymbopogon nardus. The most common phenolic compounds in the grass species included ρ-coumaric, ferulic, salicylic and vanillic acids. In the DPPH radical scavenging assay, the EC50 values ranged from 0.02 to 0.11 mg/mL for the different grasses. The best EC50 activity (lowest) was exhibited by Cymbopogon nardus roots (0.02 mg/mL) and inflorescences (0.04 mg/mL), Cymbopogon spp. roots (0.04 mg/mL) and Vetiveria zizanioides leaves (0.06 mg/mL). The highest ferric-reducing power was detected in the whole plant extract of Cynodon dactylon (0.085 ± 0.45; r2 = 0.898). The observed antioxidant activity in the various parts of the grasses may be due to their rich pool of phytochemicals. Thus, some of these grasses provide a source of natural antioxidants and phytochemicals that can be explored for their therapeutic purposes.