Copper(II) and silver(I)-1,10-phenanthroline-5,6-dione complexes interact with double-stranded DNA: further evidence of their apparent multi-modal activity towards Pseudomonas aeruginosa

Tackling microbial resistance requires continuous efforts for the development of new molecules with novel mechanisms of action and potent antimicrobial activity. Our group has previously identified metal-based compounds, [Ag(1,10-phenanthroline-5,6-dione)2]ClO4 (Ag-phendione) and [Cu(1,10-phenanthroline-5,6-dione)3](ClO4)2.4H2O (Cu-phendione), with efficient antimicrobial action against multidrug-resistant species. Herein, we investigated the ability of Ag-phendione and Cu-phendione to bind with double-stranded DNA using a combination of in silico and in vitro approaches. Molecular docking revealed that both phendione derivatives can interact with the DNA by hydrogen bonding, hydrophobic and electrostatic interactions. Cu-phendione exhibited the highest binding affinity to either major (− 7.9 kcal/mol) or minor (− 7.2 kcal/mol) DNA grooves. In vitro competitive quenching assays involving duplex DNA with Hoechst 33258 or ethidium bromide demonstrated that Ag-phendione and Cu-phendione preferentially bind DNA in the minor grooves. The competitive ethidium bromide displacement technique revealed Cu-phendione has a higher binding affinity to DNA (Kapp = 2.55 × 106 M−1) than Ag-phendione (Kapp = 2.79 × 105 M−1) and phendione (Kapp = 1.33 × 105 M−1). Cu-phendione induced topoisomerase I-mediated DNA relaxation of supercoiled plasmid DNA. Moreover, Cu-phendione was able to induce oxidative DNA injuries with the addition of free radical scavengers inhibiting DNA damage. Ag-phendione and Cu-phendione avidly displaced propidium iodide bound to DNA in permeabilized Pseudomonas aeruginosa cells in a dose-dependent manner as judged by flow cytometry. The treatment of P. aeruginosa with bactericidal concentrations of Cu-phendione (15 µM) induced DNA fragmentation as visualized by either agarose gel or TUNEL assays. Altogether, these results highlight a possible novel DNA-targeted mechanism by which phendione-containing complexes, in part, elicit toxicity toward the multidrug-resistant pathogen P. aeruginosa. Graphical abstract

Evaluation of Total Phenolic, Total Flavonoid Content And Antioxidant Activity of Rhus Vulgaris

Background: Rhus vulgaris is rich in various classes of polyphenols and flavonoids that act as free radical scavengers and reduce oxidative stress and cure various harmful human diseases. The plant is a traditionally known medicinal plant which is used against a number of diseases including cancer. Methods: The current investigation points towards the investigating quantitative phenolic contents, flavonoid contents and the free radical scavenging activity & antioxidant activity of Rhus vulgaris extract in n-hexane, acetone, and 80% of aqueous methanol. The phenolic contents were estimated by Folin–Ciocalteu procedure and gallic acid as a reference molecule whereas the total flavonoid contents were determined by using aluminum chloride and catechin. In addition, the dilution serial method was used to evaluate the leaves extract of rhus vulgaris, and the DPPH (2,2-diphenyl-1-picrylhydrazyl) method was utilized to assess the above-mentioned extracts against oxidative stress. Results: The result revealed that the ranges of total phenolic content from 5.82 ± 4.6 to 83.15 ± 7.6 mg GAE/g of the dry weight of extract, expressed as gallic acid equivalents. The total flavonoid concentrations were varied from 2.21 ± 7.34to 23.47 ± 4.87 mg CE/g, expressed as catechin equivalents. Antioxidant activity of extracts was expressed as the concentration of DPPH radical’s inhibition ranges from 1.2 ± 0.32 to 22.86 ± 3.71 mg AAE/ g. Conclusion: The 80% aqueous methanolic extract of Rhus vulgaris showed the highest phenolic and flavonoid contents and strong antioxidant potential and it could be used as antibiotics for different curable and incurable diseases.

Assessment role of total phenols and flavonoids extracted from Pleurotus columbinus mushroom on the premature ovarian failure induced by chemotherapy in rats

Background Many species of mushroom contain an assortment of free radical scavengers (Phenolics and Flavonoids compounds) that have made them nutritionally beneficial and a source of expansion of drug production. In this study, we examined the preventive and remedial role of total phenol extract from Pleurotus columbines (TP) in alleviating the consequences of cyclophosphamide (CTX) on the ovaries of female rats. Rats were randomly assigned to four groups: healthy controls, cyclophosphamide (CTX), received a TP (100 mg/kg) orally daily for 14 days and curative group: CTX-TP, we determined and identified a total phenol from a mushroom extract and examined it as an antioxidant agent. To investigate the therapeutic influence, it was administrated 2 weeks after CTX. To assess the impact of TP on ovarian damage caused by CTX, ovarian hormone tests were performed such as luteinizing hormone (LH), 17-β-estradiol (E2), and anti-mullerian hormone (AMH). Besides, follicle-stimulating hormone (FSH) in serum was evaluated, and histopathological analysis of the ovary was examined. Results This study indicates that treatment with TP decreased the severity of cyclophosphamide-induced ovary injury by reducing inflammation and apoptotic effects and increasing the activity of antioxidants. Conclusions TP could be used to alleviate cyclophosphamide-induced ovary injury.

In-vitro antifungal activity of leaf, stem bark and root extracts of Irvingia gabonensis against fungi associated with its seed deterioration

Irvingia gabonensis (Aubry-Lecomte ex O'Rorke) Baill seeds are often contaminated in storage by postharvest spoilage fungi. This study investigated the nutritional contents of the seeds, phytochemical contents and antioxidant activity of different parts of the plant as well as their antifungal effects against fungi isolated from the deteriorated seeds. Proximate, mineral and phytochemical analyses were carried out using standard laboratory techniques. The antioxidant activity was against DPPH radicals. Ethanol extracts (100 and 200 mg/ml) of the various parts were screened against the isolates using pour plate method in Potato Dextrose Agar (PDA) plates. The plates were examined for growth daily for 10 days. Data were statistically analysed. The healthy seeds contained higher protein (13.73%), fat (58.73%) and fibre (2.50%), whereas, higher content of moisture (10.17%) and carbohydrate (15.47%) were observed in the spoilt seeds. The leaf had highest contents of alkaloids (1228.3 mg/100 g), flavonoids (1345.9 mg/100 g), tannins (1345.9 mg/100 g), saponins (578.3 mg/100 g) and carotenoids (2348.3 μg/100 g). The antioxidant activity of the leaf (50.30%) was the highest. Fungi isolated from the deteriorated seeds were Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus and Curvilaria lunata. The leaf was most effective against A. niger, A. flavus and C. lunata whereas the stem bark extract was most effective against A. fumigatus. The F-values were significant for model, treatment, concentration and number of days for the leaf and root. This study confirmed the antifungal activity of extracts of various parts of the plant against isolates implicated in the deterioration of its seeds. The extracts could be used as preservative to enhance the shelf-life and nutritional quality of the seeds. Keywords: Irvingia gabonensis, Spoilage of seeds, Antifungal activity, Free radical scavengers, Preservatives

Theoretical Studies on Anti-Oxidant Activity of the Phytochemical, Coumestrol and Its Derivatives

Free radical-induced changes in cellular and organ levels have been studied as a possible underlying cause of various adverse health conditions. Important research efforts have, therefore, been made to discover more powerful and potent antioxidants/free radical scavengers for the treatment of these adverse conditions. The phytoestrogen coumestrol intensively attracted scientific interest due to their efficient pharmacological activities. In this scenario, DFT studies were carried out to test the antiradical activities of coumestrol and its derivatives. The results obtained from FEDAM plots demonstrated that the coumestrol derivatives pointed out were good radical scavengers relative to the parent molecule in the gas phase. The derivatives whose 16thposition substituted with electron-donating groups like -NH2, -OCH3 and -CH3 showed good antioxidant capacity. Three antioxidant mechanisms, including hydrogen atom transfer (HAT), electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET), were investigated by measuring thermodynamic parameters.

Optimization of Volatile Compounds Extraction from Industrial Celery (Apium graveolens) By-Products by Using Response Surface Methodology and Study of Their Potential as Antioxidant Sources

In this study, the potential of industrial celery by-products (the stalk and root) serving as sources of aromatics and antioxidants was investigated. A headspace solid phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS) procedure was optimized to isolate volatile compounds from celery by-products. A Box–Behnken experimental design was proposed to optimize the procedure through a response surface methodology. The optimal extraction conditions were found to be 1.6 g of homogenized fresh by-product at 30 °C for 60 min. Under these conditions, 26 volatile compounds in stalk and root samples were identified, monoterpenes and sesquiterpenes being the main components. The content of limonene and γ-terpinene found in the stalk was significantly higher in comparison with root samples. Total phenolic content and antioxidant activity (ABTS and FRAP) results underlined the celery wastes studied as good sources of free radical scavengers. This work suggests the potential application of these by-products in the food industry and opens new pathways to valorize celery residues, contributing to the circular economy.

Phytoantioxidant Functionalized Nanoparticles: A Green Approach to Combat Nanoparticle-Induced Oxidative Stress

Nanotechnology is gaining significant attention, with numerous biomedical applications. Silver in wound dressings, copper oxide and silver in antibacterial preparations, and zinc oxide nanoparticles as a food and cosmetic ingredient are common examples. However, adverse effects of nanoparticles in humans and the environment from extended exposure at varied concentrations have yet to be established. One of the drawbacks of employing nanoparticles is their tendency to cause oxidative stress, a significant public health concern with life-threatening consequences. Cardiovascular, renal, and respiratory problems and diabetes are among the oxidative stress-related disorders. In this context, phytoantioxidant functionalized nanoparticles could be a novel and effective alternative. In addition to performing their intended function, they can protect against oxidative damage. This review was designed by searching through various websites, books, and articles found in PubMed, Science Direct, and Google Scholar. To begin with, oxidative stress, its related diseases, and the mechanistic basis of oxidative damage caused by nanoparticles are discussed. One of the main mechanisms of action of nanoparticles was unearthed to be oxidative stress, which limits their use in humans. Secondly, the role of phytoantioxidant functionalized nanoparticles in oxidative damage prevention is critically discussed. The parameters for the characterization of nanoparticles were also discussed. The majority of silver, gold, iron, zinc oxide, and copper nanoparticles produced utilizing various plant extracts were active free radical scavengers. This potential is linked to several surface fabricated phytoconstituents, such as flavonoids and phenols. These phytoantioxidant functionalized nanoparticles could be a better alternative to nanoparticles prepared by other existing approaches.

Evaluation of the Effect of Various Antioxidants on the Shear Bond Strength of the Composite Resin to the Bleached Enamel: An In Vitro study

Objective Various intrinsic and extrinsic stains cause discolored teeth, which is of great concern to patients, which can be treated by bleaching, enamel microabrasion, veneers, and crowns. However, bleaching leads to reduced bond strength if adhesive restorations are performed immediately.Thus, the application of antioxidant agents after bleaching has been recommended, which are proved to act as free radical scavengers, improving the bond strength. Materials and Methods A total of 120 extracted human maxillary incisor teeth were taken. Using a slow-speed diamond saw and a water coolant spray, the roots of all the teeth were removed approximately 2 mm below the cementoenamel junction. With the labial surface facing upward, each sectioned sample was embedded in the acrylic resin. Then, the central portion of the embedded tooth was ground flattened with 600-grit silicon carbide paper such that the labial enamel surface becomes smooth and evenly flat.All 120 samples were divided into two control groups (n = 20), i.e., positive control group (n = 10) and negative control group (n = 10) and five experimental groups (n = 100), such that each experimental group had 20 samples.The enamel surface in both the control groups and groups treated with antioxidants was thoroughly rinsed off with distilled water for 30 seconds and subjected to bonding procedure. Result Significant differences were observed among the experimental groups (p < 0.05). The samples that were treated with 10% sodium ascorbate (group III) demonstrated significantly higher mean shear bond strength than the other experimental groups (p < 0.05).

Wood Extractives of Silver Fir and Their Antioxidant and Antifungal Properties

The chemical composition of extractives in the sapwood (SW), heartwood (HW), knotwood (KW), and branchwood (BW of silver fir (Abies alba Mill.) was analyzed, and their antifungal and antioxidant properties were studied. In addition, the variability of extractives content in a centripetal direction, i.e., from the periphery of the stem towards the pith, was investigated. The extracts were analyzed chemically with gravimetry, spectrophotometry, and chromatography. The antifungal and antioxidative properties of the extracts were evaluated by the agar well diffusion method and the diphenyl picrylhydrazyl radical scavenging method. Average amounts of hydrophilic extractives were higher in KW (up to 210.4 mg/g) and BW (148.6 mg/g) than in HW (34.1 mg/g) and SW (14.8 mg/g). Extractives identified included lignans (isolariciresinol, lariciresinol, secoisolariciresinol, pinoresinol, matairesinol) phenolic acids (homovanillic acid, coumaric acid, ferulic acid), and flavonoids epicatechin, taxifolin, quercetin). Secoisolariciresinol was confirmed to be the predominant compound in the KW (29.8 mg/g) and BW (37.6 mg/g) extracts. The largest amount of phenolic compounds was extracted from parts of knots (281.7 mg/g) embedded in the sapwood and from parts of branches (258.9 mg/g) adjacent to the stem. HW contained more lignans in its older sections. Hydrophilic extracts from knots and branches inhibited the growth of wood-decaying fungi and molds. KW and BW extracts were better free radical scavengers than HW extracts. The results of the biological activity tests suggest that the protective function of phenolic extracts in silver fir wood can also be explained by their antioxidative properties. The results of this study describe BW as a potential source of phenolic extractives in silver fir.

Thiophene and its Analogs as Prospective Antioxidant Agents: A Retrospect

: The field of Free Radical Chemistry has gained considerable interest in the current scenario. The formation of free radicals is attributable to different physiochemical factors, radiation exposure, pathological conditions, environmental contaminants, and as by-products of metabolized drugs. The concentration of free radicals is regulated strongly under normal conditions by physiological antioxidants. Free radicals may cause oxidative damage to proteins, lipids, sugars, and DNA when abundantly produced or when antioxidants are depleted. This imbalance of reduction-oxidation, referred to as oxidative stress, can change the body's physiological conditions and ultimately lead to tissue injury, further contributing to various disease pathologies. A proper balance between free radicals and antioxidants is required for an effective physiological process. The oxidation mechanism is chemically hindered by antioxidants; these are often called free radical scavengers. The application of an external antioxidant source is crucial in addressing the issue of oxidative stress. Plenty of naturally occurring, semi-synthetic, and synthetic antioxidants are used, and the search for an efficient, non-toxic, and safe antioxidant is stepped up over time. As an influential scaffold, thiophene and its derivatives have become a significant source of interest for researchers due to its substantial variety of biological activities. The versatility of thiophene moiety has been identified by an affluent unveiling of its derivatives with anti-inflammatory, antioxidant, anti-cancer, and antimicrobial behaviors. Thiophene activity has been influenced greatly by the nature and orientation of the substitutions. The current study aims at addressing various synthetic compounds with thiophene or condensed thiophene as a fundamental moiety or substituent as radical scavengers.