A critical examination of the DPPH method: Mistakes and inconsistencies in stoichiometry and IC50 determination by UV-Vis spectroscopy

Lignin Structural Characterization and Its Antioxidant Potential: A Comparative Evaluation by EPR, UV-Vis Spectroscopy, and DPPH Assays

The natural aromatic polymer lignin and its lignin-like oligomeric fragments have attracted attention for their antioxidant capacity and free radical scavenging activities. In this study, a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was employed to assess the antioxidant capacity of fractionated and partially depolymerized organosolv lignin by electron paramagnetic resonance (EPR) and UV-Vis spectroscopy. The results show significant antioxidant activity for both the lignin and oligomeric fragments, with the EPR measurements demonstrating their efficiency in quenching the free radicals. The EPR data were analyzed to derive the kinetic rate constants. The radical scavenging activity (RSA) of lignins was then determined by UV-Vis spectroscopy and the results were compared with the EPR method. This two-method approach improves the reliability and understanding of the antioxidant potential of lignin and its derivatives and provides valuable insights for their potential applications in various industries, including pharmaceuticals, food preservation, and cosmetics.

Abuelizz H, Lafdil FZ, Er-rahmani S, Lyoussi B, Derwich E. Coriandrum sativum L., essential oil as a promising source of bioactive compounds with GC/MS, antioxidant, antimicrobial activities: in vitro and in silico predictions

Introduction: Coriandrum sativum L. essential oil (CS-EO) is being evaluated in vitro for its antioxidant and antimicrobial properties, and its volatile compounds are to be identified as part of this exploratory study. Methods: The processes underlying the in vitro biological properties were explained using in silico simulations, including drug-likeness prediction, molecular docking, and pharmacokinetics (absorption, distribution, metabolism, excretion, and toxicity-ADMET). Chemical screening of CS-EO was conducted using gas chromatography-mass spectrometry (GC-MS). Five in vitro complementary techniques were used to assess the antioxidant activity of CS-EO: reducing power (RP), 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging activity, β-Carotene bleaching test (BCBT), and phosphomolybdenum assay (TAC). Results: According to GC-MS analysis, linalool (59.04%), γ-Terpinene (13.02%), and α-Pinene (6.83%) are the main constituents of CS-EO. Based on the in vitro antioxidant assay results, CS-EO has been found to have a superior antioxidant profile. Its estimated scavenging rates for ABTS+ are 0.51 ± 0.04 mg/mL, BCBT is 9.02 ± 0.01 mg/mL, and CS-EO is 1.52 ± 0.14 mg/mL. C. sativum demonstrated 6.13 ± 0.00 μg/mL for reducing power and 213.44 ± 0.45 mg AAE/mL for total antioxidant activity. The in vitro antimicrobial activity of CS-EO was assessed against five strains, including two gram-positive bacteria, two gram-negative bacteria, and one fungal strain (Candida albicans). Significant antibacterial and antifungal activities against all strains were found using the disc-diffusion assay, with zones of inhibition larger than 15 mm. The microdilution test highlighted the lowest MIC and MBC values with gram-positive bacteria, ranging from 0.0612 to 0.125% v/v for MIC and 0.125% v/v for MBC. The fungal strain's MFC was 1.0% v/v and its MIC was measured at 0.5%. Based on the MBC/MIC and MFC/MIC ratios, CS-EO exhibits bactericidal and fungicidal activity. The ADMET study indicates that the primary CS-EO compounds are good candidates for the development of pharmaceutical drugs due to their favorable pharmacokinetic properties. Conclusion: These results point to a potential application of this plant as a natural remedy and offer empirical backing for its traditional uses. It is a promising environmentally friendly preservative that can be used extensively in the food and agricultural industries to prevent aflatoxin contamination and fungal growth in stored goods.

Synthesis and Isolation of Phenol- and Thiol-Derived Epicatechin Adducts Prepared from Avocado Peel Procyanidins Using Centrifugal Partition Chromatography and the Evaluation of Their Antimicrobial and Antioxidant Activity

Polyphenols from agro-food waste represent a valuable source of bioactive molecules that can be recovered to be used for their functional properties. Another option is to use them as starting material to generate molecules with new and better properties through semi-synthesis. A proanthocyanidin-rich (PACs) extract from avocado peels was used to prepare several semi-synthetic derivatives of epicatechin by acid cleavage in the presence of phenol and thiol nucleophiles. The adducts formed by this reaction were successfully purified using one-step centrifugal partition chromatography (CPC) and identified by chromatographic and spectroscopic methods. The nine derivatives showed a concentration-dependent free radical scavenging activity in the DPPH assay. All compounds were also tested against a panel of pathogenic bacterial strains formed by Listeria monocytogenes (ATCC 7644 and 19115), Staphylococcus aureus (ATCC 9144), Escherichia coli (ATCC 11775 and 25922), and Salmonella enterica (ATCC 13076). In addition, adducts were tested against two no-pathogenic strains, Limosilactobacillus fermentum UCO-979C and Lacticaseibacillus rhamnosus UCO-25A. Overall, thiol-derived adducts displayed antimicrobial properties and, in some specific cases, inhibited biofilm formation, particularly in Listeria monocytogenes (ATCC 7644). Interestingly, phenolic adducts were inactive against all the strains and could not inhibit its biofilm formation. Moreover, depending on the structure, in specific cases, biofilm formation was strongly promoted. These findings contribute to demonstrating that CPC is a powerful tool to isolate new semi-synthetic molecules using avocado peels as starting material for PACc extraction. These compounds represent new lead molecules with antioxidant and antimicrobial activity.

Preparation and characterization of Fe-ZnO cellulose-based nanofiber mats with self-sterilizing photocatalytic activity to enhance antibacterial applications under visible light

Bacterial infections and antibiotic resistance have posed a severe threat to public health in recent years. One emerging and promising approach to this issue is the photocatalytic sterilization of nanohybrids. By utilizing ZnO photocatalytic sterilization, the drawbacks of conventional antibacterial treatments can be efficiently addressed. This study examines the enhanced photocatalytic sterilizing effectiveness of Fe-doped ZnO nanoparticles (Fe-ZnO nanohybrids) incorporated into polymer membranes that are active in visible light. Using the co-precipitation procedure, Fe-ZnO nanohybrids (Fe x Zn100-x O) have been generated using a range of dopant ratios (x = 0, 3, 5, 7, and 10) and characterized. The ability to scavenge free radicals was assessed and the IC50 value was calculated using the DPPH test at different catalytic concentrations. PXRD patterns showed a hexagonal wurtzite structure, which indicated that the particle size of the nanohybrid decreased as the dopant concentration rose. It was demonstrated by UV-vis diffuse reflectance experiments that the band gap of the nanohybrid decreased (redshifted) with Fe doping. The photocatalytic activity under sunlight increased steadily to 87% after Fe was added as a dopant. The Fe 5%-ZnO nanohybrid exhibited the lowest IC50 value of 81.44 μg mL-1 compared to ZnO, indicating the highest radical scavenging activity and the best antimicrobial activity. The Fe 5%-ZnO nanohybrid, which is proven to have the best photocatalytic sterilization activity, was then incorporated into a cellulose acetate polymer membrane by electrospinning. Disc diffusion assay confirmed the highest antimicrobial activity of the Fe 5%-ZnO nanohybrid incorporated electrospun membrane against Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), and Candida albicans (ATCC 10231) under visible light. As a result, Fe 5%-ZnO nanofiber membranes have the potential to be employed as self-sterilizing materials in healthcare settings.

Ruellia angustiflora (Nees) Lindau ex Rambo: extraction and characterization of phenolic compounds and evaluation of antiradical, photoprotective and antimicrobial activities

Ruellia angustiflora is a shrub popularly known as flower of fire, used in traditional medicine as a healing agent. This study aims to verify the presence of characteristics of pharmaceutical interest in extracts from the root, stem and leaves of this species. The ideal time for ultrasound-assisted extraction is 60 min with a solid-liquid ratio of 1% (w/v). The kinetics of the reaction of the extracts with DPPH is biphasic, and IC50 values are related to the total phenolic compounds. Five phenolic compounds were identified in the extracts, where ferulic acid, rutin and quercetin showed to be the main responsible for the antiradical activity. The extracts displayed considerable photoprotective activity, mainly Ra-LE (SPF = 23). Ra-RE showed an inhibition halo similar to erythromycin against Streptococcus pyogenes. Taken together, these data reveal that Ruellia angustiflora is a source of phenolic compounds and has relevant antiradical, photoprotective and antibacterial activities.

Petroselinum crispum L., essential oil as promising source of bioactive compounds, antioxidant, antimicrobial activities: In vitro and in silico predictions

This exploratory study aims to identify the volatile compounds in PC-Eo (Petroselinum crispum L. essential oil) and evaluate its antioxidant and antimicrobial properties in vitro. Molecular docking, drug-likeness prediction, and pharmacokinetics (absorption, distribution, metabolism, excretion, and toxicity-ADMET) were among the in silico simulations that were used to explain the biological properties observed in vitro. For PC-Eo's chemical screening, gas chromatography-mass spectrophotometry (GC-MS) was employed. The antioxidant activity of PC-Eo was evaluated using five in vitro complementary techniques, including 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging activity, β-Carotene bleaching test (BCBT), reducing power (RP), and phosphomolybdenum assay (TAC). GC-MS analysis revealed that the primary components of PC-Eo are apiol (49.05 %), Myristicin (21.01 %), and 1-allyl-2,3,4,5-tetramethoxybenzene (13.14 %). The results of the in vitro antioxidant assays indicate that PC-Eo exhibits a superior antioxidant profile. The in vitro antimicrobial activity of PC-Eo was assessed against five strains, including 2 g-positive bacteria, 2 g-negative bacteria, and one fungal strain (Candida albicans). The disc-diffusion assay revealed significant antibacterial and antifungal activities against all strains, with zones of inhibition exceeding 15 mm. The microdilution test highlighted the lowest MIC and MBC values with gram-positive bacteria, ranging from 0.25 to 0.5 % v/v for MIC and 0.5-1.0 % v/v for MBC. For the fungal strain, MIC was recorded at 1.25 % and MFC at 2.5 % v/v. PC-Eo demonstrates bactericidal and fungicidal activity based on the MBC/MIC and MFC/MIC ratios. According to the ADMET study, the primary PC-Eo compounds have advantageous pharmacokinetic characteristics. These findings provide empirical support for the traditional uses of this plant and indicate its possible use as a natural remedy.

Comprehensive analysis of different solvent extracts of Ferula communis L. fruit reveals phenolic compounds and their biological properties via in vitro and in silico assays

Although giant fennel is recognized as a "superfood" rich in phytochemicals with antioxidant activity, research into the antibacterial properties of its fruits has been relatively limited, compared to studies involving the root and aerial parts of the plant. In this study, seven solvents-acetone, methanol, ethanol, ethyl acetate, chloroform, water, and hexane-were used to extract the chemical constituents of the fruit of giant fennel (Ferula communis), a species of flowering plant in the carrot family Apiaceae. Specific attributes of these extracts were investigated using in silico simulations and in vitro bioassays. High-performance liquid chromatography equipped with a diode-array detector (HPLC-DAD) identified 15 compounds in giant fennel extract, with p-coumaric acid, 3-hydroxybenzoic acid, sinapic acid, and syringic acid being dominant. Among the solvents tested, ethanol demonstrated superior antioxidant activity and phenolic and flavonoid contents. F. communis extracts showed advanced inhibition of gram-negative pathogens (Escherichia coli and Proteus mirabilis) and variable antifungal activity against tested strains. Molecular docking simulations assessed the antioxidative, antibacterial, and antifungal properties of F. communis, facilitating innovative therapeutic development through predicted compound-protein interactions. In conclusion, the results validate the ethnomedicinal use and potential of F. communis. This highlights its significance in natural product research and ethnopharmacology.

Vegetal Polyphenol Extracts as Antioxidants for the Stabilization of PLA: Toward Fully Biobased Polymer Formulation

The use of natural antioxidants as substitutes for traditional synthetic stabilizers has been investigated for the stabilization of biobased and biodegradable polymers, with the aim of designing fully biobased plastic formulations. This study focused on the thermo- and photostabilization of poly(lactic acid) (PLA) using vegetal polyphenol extracts as biosourced antioxidants. The polyphenols were extracted by microwave-assisted extraction from the valorization of vegetal waste, and their potential as antioxidant additives was evaluated (e.g., polyphenol content, composition, and antioxidant activity). PLA was then formulated with 2 wt % of the extracts exhibiting the highest antioxidant activities: green tea residues, pomegranate peels, grape marc, bramble leaves, and yellow onion peel extracts. The efficiency of the natural additives as thermal stabilizers was evaluated and compared with a synthetic antioxidant using rheological and thermal analyses. The results demonstrated the capacity of grape marc extract and pomegranate peel extract to significantly improve PLA thermal stability during processing and thermo-oxidation. Finally, photorheology was conducted to evaluate the influence of the bioadditives on the biopolyester photodegradation. The different polyphenol extracts seemed to significantly hinder the photo-oxidation of PLA and constitute very promising natural UV stabilizers, combining UV absorbers and antioxidant functions.

Synthesis of New Chiral β-Carbonyl Selenides with Antioxidant and Anticancer Activity Evaluation-Part I

A series of unsymmetrical phenyl β-carbonyl selenides with o-amido function substituted on the nitrogen atom with chiral alkyl groups was obtained. The compounds form a series of enantiomeric and diastereomeric pairs and present the first examples of this type of chiral Se derivatives. All obtained selenides were further evaluated as antioxidants and anticancer agents to define the influence of the particular stereochemistry of the attached functional groups on the bioactivity of the molecules. The highest H2O2 reduction potential was observed for N-(cis-2-hydroxy-1-indanyl)-2-((2-oxopropyl)selanyl)benzamide, and the best radical scavenging properties for N-(-1-hydroxy-2-butanyl)-2-((2-oxopropyl)selanyl)benzamide. Also, both enantiomers of the N-(1-hydroxy-2-butanyl) selenide expressed the highest cytotoxic potential towards human promyelocytic leukemia HL-60 cell line with similar IC50 values 14.4 ± 0.5 and 16.2 ± 1.1 µM, respectively. On the other hand, breast cancer cell line MCF-7 was most sensitive to N-((R)-(-)-1-hydroxy-2-butanyl)- 2-((2-oxopropyl)selanyl)benzamide (IC50 of 35.7 ± 0.6 µM). The structure-activity dependence of the obtained Se derivatives was discussed, and the most potent compounds were selected.

Valorization of loquat seeds by hydrothermal carbonization for the production of hydrochars and aqueous phases as added-value products

In the framework of circular bio-economy, waste loquat seeds were utilized for the production of two added-value products. The seeds were hydrothermally carbonized at a temperature range of 150-250 °C and time range 2-6 h and the resultant hydrochars and aqueous phases were characterized using various methods. The optimum higher heating value of 30.64 MJ kg-1, ash content of 1.99 wt % and alkali index of 0.05 were achieved for the hydrochar prepared at 250 °C and 6 h, establishing its suitability for energy-related applications. The aqueous phase obtained at 250 °C and 6 h achieved 90% scavenging of the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and had a IC50 value of 43.71 μg mL-1. Principal component analysis showed that the production of phenols, ketones, alkenes and organic acids was favored at >200 °C, whereas furans and aldehydes were primarily formed at 150 °C. Conclusively, both added-value products were obtained at the same optimum hydrothermal carbonization conditions of 250 °C and 6 h treatment time. In a bio-refinery context, this has the practical implication that both bio-products be obtained simultaneously, without the need to switch between different temperatures and residence times.

In Vitro Digestion of Peanut Skin Releases Bioactive Compounds and Increases Cancer Cell Toxicity

Peanut skin is a rich source of bioactive compounds which may be able to reduce the risk factors associated with metabolic syndromes. This study aimed to characterize bio-compounds from peanut skin (Arachis hypogaea) and their bioactivity (antioxidant activity, inhibition of lipase, and carbohydrase enzymes) and to evaluate their anti-proliferative properties in colorectal cancer cells (HCT116) upon in vitro digestion. Peanut skin was digested in two sequential phases, and the final content, named phase-1 (P1) and phase-2 (P2) extracts, was evaluated. Several bioactive compounds were positively identified and quantified by liquid chromatography, including quinic acid, released especially after in vitro digestion. The total phenolic content and, regardless of the method, the antioxidant activity of P1 was higher than P2. P1 also showed a lower enzyme inhibitory concentration IC₅₀ than P2, lipase, and α-glucosidase. For cell viability in HCT116 cells, lower concentrations of P1 were found for IC₅₀ compared to P2. In conclusion, bioactive compounds were released mainly during the first phase of the in vitro digestion. The digested samples presented antioxidant activity, enzyme inhibitory activity, and cancer cell cytotoxicity, especially those from the P1 extract. The potential applications of such a by-product in human health are reported.

Facile synthesis of chiral phenylselenides as novel antioxidants and cytotoxic agents

Organoselenium compounds are well-known for their unique biological properties, including antioxidant, anticancer and anti-inflammatory. They result from the presence of a particular Se-moiety enclosed in a structure that provides physicochemical features necessary for effective drug-target interactions. Looking for a proper drug design that considers the influence of each structural element has to be conducted. In this paper, we have synthesized a series of chiral phenylselenides, possessing an additional N-substituted amide moiety, and evaluated their antioxidant and anticancer potential. The presented derivatives, as a group of enantiomeric and diastereomeric pairs, enabled a thorough investigation of the 3D structure-activity dependence in correlation with the presence of the phenylselanyl group as the potential pharmacophore. The N-indanyl derivatives possessing a cis- and trans-2-hydroxy group were selected as the most promising antioxidants and anticancer agents.

Optimization of a New Antioxidant Formulation Using a Simplex Lattice Mixture Design of Apium graveolens L., Coriandrum sativum L., and Petroselinum crispum M. Grown in Northern Morocco

A statistical Simplex Lattice Mixture design was applied to develop a new formulation based on a combination of three plants grown in northern Morocco: Apium graveolens L., Coriandrum sativum L., and Petroselinum crispum M. We examined the extraction yield, total polyphenol content (TPC), 2'2-diphenyl-l-picrylhydrazyl (DPPH) radical scavenging activity, and total antioxidant capacity (TAC). The results of this screening study showed that C. sativum L. had the highest content of DPPH (53.22%) and TAC (37.46 ± 0.29 mg Eq AA/g DW) compared to the other two plants, while P. crispum M. showed the highest TPC (18.52 ± 0.32 mg Eq GA/g DW). Furthermore, the ANOVA analysis of the mixture design showed that all three responses (DPPH, TAC, and TPC) were statistically significant, with determination coefficients of 97%, 93%, and 91%, respectively, and fit the cubic model. Moreover, the diagnostic plots showed good correlation between the experimental and predicted values. Therefore, the best combination obtained under optimal conditions (P1 = 0.611, P2 = 0.289, P3 = 0.100) was characterized by DPPH, TAC, and TPC of 56.21%, 72.74 mg Eq AA/g DW, and 21.98 mg Eq GA/g DW, respectively. The results of this study reinforce the view of stimulating the effect of plant combinations to achieve better antioxidant activities, thus providing a better formulation using designs of mixtures for the food industry and in cosmetic and pharmaceutical applications. Moreover, our findings support the traditional use of the Apiaceae plant species in managing many disorders cited in the Moroccan pharmacopeia.

ROS scavenging of SOD/CAT mimics probed by EPR and reduction of lipid peroxidation in S. cerevisiae and mouse liver, under severe hydroxyl radical stress condition

The interaction between Cu^II, Fe^III and Mn^II complexes, derived from the ligands 1-[bis(pyridine-2-ylmethyl)amino]-3-chloropropan-2-ol (hpclnol) and bis(pyridine-2-ylmethyl)amine (bpma), and the free radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) and reactive oxygen species (ROS), was investigated by colorimetric and EPR (Electron Paramagnetic Resonance) techniques. A comparison between these results and those reported to [Mn(salen)Cl] or EUK-8 was also addressed. EPR studies allowed us the identification of intermediates species such as superoxide‑copper(I) and superoxide‑copper(II), a mixed-valence Fe^IIIFe^II species and a 16-line feature attributed to Mn^III-oxo-Mn^IV species. The biomarker malondialdehyde (MDA) was determined by TBARS assay in S. cerevisiae cells, and the determination of the IC₅₀ indicate that the antioxidant activity shown dependence on the metal center (Cu^II ≈ Fe^III > Mn^II ≈ [Mn(salen)Cl]. The lipid peroxidation attenuation was also investigated in liver homogenates obtained from Swiss mice and the IC₅₀ values were in the nanomolar concentrations. We demonstrated here that all the complexes interact with the free radical DPPH and with ROS (H₂O₂, O₂^•- and hydroxyl radical), enhancing the cellular protection against oxidative stress generated by hydroxyl radical, employing two experimental model systems, S. cerevisiae (in vivo) and mouse liver (ex vivo).

Investigation of the structure of gallate xylose polymers and their antioxidant properties for skin care products

Xylose is the second most abundant monosaccharide in nature, and gallic acid (GA) has properties of antioxidant, anti-inflammatory and anti-bacterial. Hence, the gallate xylose (GX) polymers were synthesized from d-xylose and gallic acid for skin care applications in this paper. Then, the structure, generation mechanisms and the antioxidant activity of the generated polymer were studied. It got the results that: The generated GX polymers have strong antioxidant properties, yielded in 80.1% of GA mass. The DPPH scavenging activity was over 80.0% under the polymer's solution over 0.2 mg/mL. Moreover, the reaction mechanisms of DPPH removal were explained in a new theory based on Mass spectral analysis. Therefore, it demonstrates that the GX polymers of is a potential antioxidant material for skin care products, and it does contribution to the theory of DPPH removal for application in the fields of chemistry, biology and medicine researches.

Investigation and Characterisation of New Eco-Friendly Cosmetic Ingredients Based on Probiotic Bacteria Ferment Filtrates in Combination with Alginite Mineral

In light of the fact that three of the five healthiest meals on earth are fermented, fermentation came into focus of both customers, product developers, and researchers all around the world. Even in the cosmetics industry, fermented cosmetics have been increasingly introduced, creating a market emphasising the positive image that healthy fermented substances are environment-friendly and that it also aids skin health. Moreover, discovering usages for various naturally occurring organo-mineral rocks is a growing area of research. Thus, this study’s aim was to combine the benefits of alginite and Lactobacilli (LAB) for cosmetic applications and investigate their combined effect on the skin considering the fermentation parameters as well, such as biomass and lactic acid concentration. The examined LAB strains were Lactobacillus rhamnosus, Lactobacillus acidophilus, Limosilactobacillus reuteri, and Lactococcus lactis, and a non-LAB probiotic strain Bifidobacterium adolescentis was also studied for the same purposes. The cell-free broth, also called as “filtrates”, of the fermentations—both those that included alginite and those that did not—were tested for skin moisturising with a corneometer and for antioxidant activity with DPPH scavenging, as well as for skin-whitening properties with the inhibition of mushroom tyrosinase. The findings suggest that the combination of alginite and Limosilactobacillus reuteri is a potential novel cosmeceutical component with skin tanning capabilities. This result may help create more readily available, environmentally friendly, natural, and sustainable cosmetic ingredients.

Evaluation of The Antioxidant Capacity of Food Products: Methods, Applications and Limitations

Assays of total antioxidant capacity (TAC) are popular in the analysis of food products. This review presents the most popular assays of TAC and their limitations, databases of TAC of food products, their application in clinical studies, and the effect of processing on the TAC of food. The importance of sample preparation for TAC assays and striking effects of digestion in the gastrointestinal tract on the TAC of food are discussed. Critical opinions on the validity of food TAC assays are considered. It is concluded that TAC methods can be useful as screening assays for food quality control and as low-cost, high-throughput tools used to discover potential antioxidant sources and follow changes in the content of antioxidants during food processing. However, effects revealed by TAC assays should be followed and explained using more specific methods.

Correlation between the redox activity of Polygonum multiflorum extract and its extraction technology with Chinese liquor (Baijiu): An electrochemistry-based study

Elucidating the pharmaceutical mechanisms behind traditional Chinese medicine (TCM) is the key to promote its modernization process. In China, soaking TCM in liquor has a history of thousands of years, and many TCMs have to be processed into liquor before they can be used to treat diseases. Chinese liquor (Baijiu) contains more than 2,000 trace components, the interaction mechanism between TCM and Baijiu still remains unclear, making TCM a "mystery". The TCM industry commonly employs chromatographic and spectrographic technology to investigate the redox activity of TCM substances. However, only investigating the redox differences in specific active substances cannot provide a complete understanding of the redox activity of TCM substances. Thus, we employed the electrochemical approach to study the overall redox activity of substances in TCM in situ. The key result is that the redox substances in Baijiu function as a mediator for the redox reaction of Polygonum multiflorum extract. The redox efficiency of the extract is enhanced because of the faster electron transferability of the redox mediator in Baijiu.

PARAFAC modeling of dandelion phenolic compound fluorescence relation to antioxidant properties

The phenolic compounds in dandelion were extracted using different ethanol percentage solutions, identified with HPLC-MS, and their scavenging capabilities of DPPH, ABTS and OH radicals were determined. Then the excitation-emission matrix fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC) was conveyed to analyze the relationship between phenolics, components scores of PARAFAC model and antioxidant capacities, based on linear regression method. The results showed that the relative content of chicoric acid, esculetin, caffeic acid, gallic acid monohydrate, eupatilin, caffeic acid-3-glucoside, corchorifatty acid F, and luteolin was higher than 0.5%, and the extraction solutions with 100% and 75% water had a better scavenging capacity of DPPH, ABTS and OH radicals. Two components PARAFAC model was identified with the comparatively higher sum of squares, core consistency values, and lower interactions numbers, and the established equations indicated the component scores had a linear regression relationship with antioxidant capacities of DPPH, and ABTS. The paper was proposed for the first time that the component scores of PARAFAC model might be treated as a useful indication for antioxidant capacity evaluation.

Synthesis, spectral characterization, lethal dose (LD50) and acute toxicity studies of 1,4-Bis(imidazolylazo)benzene (BIAB)

The preparation and spectral identification of new heterocyclic azo ligand 1,4-Bis(imidazolylazo)benzene (BIAB) was prepared by reacting a diazonium chloride salt solution of 1,4-diaminobenzene with imidazole in alkaline ethanolic solution. Differing spectral techniques have been used to study the structure of the azo dye ligand (BIAB) such as Elemental analysis (C.H.N), 1H-NMR, Mass spectrum, UV-Vis, FT-IR, XRD, FE-SEM and thermal analysis (TGA-DTA). The pathogenic activities of the synthesized ligand (BIAB) was tested in vitro against the sensitive organisms Staphylococcus aureus (Gram-positive) and Escherichia coli (gram-negative) as antibacterial and Aspergillus Niger and Candida albicans as antifungal. The activity data show that the ligand (BIAB) higher antibacterial and slightly antifungus activity in comparison to the standard antibacterial (Amoxicillin) and antifungal (cycloheximide) drugs. The acute toxicity studies (LD50) was calculated using by Miller and Tainter methods (Estimated Probity Units) for the calculation of LD50. In this study, different doses (600, 1000, 1300, 1800, 2500 and 3600 μg/ml) of the (BIAB) was administered orally to the different groups of mice. The results exhibited high acute toxicity with LD50 of 1020.23 mg/kg upon intraperitoneal administration in mice. The antioxidant properties of the ligand was examined using the DPPH radical scavenging technique. IC50 was also determined at 224.17 μg/ml.

A DPPH· Kinetic Approach on the Antioxidant Activity of Various Parts and Ripening Levels of Papaya (Carica papaya L.) Ethanolic Extracts

Papaya fruits (Carica papaya L.) are valuable both as food, including concentrates and mixed beverages and in traditional medicine. The goal of the study was to evaluate the antioxidant activity of various parts of unripe and ripe papaya fruit from the DPPH· kinetics point of view. Peel, pulp, seed, and seed-pulp of unripe and ripe papaya fruits (¼ and >¾ level of ripening) were extracted with ethanol and monitored at 517 nm in the presence of DPPH·. The radical scavenging capacity (RSC) at various time ranges and DPPH· reaction rates for specific time intervals were determined. The highest RSC values were obtained for papaya pulp extracts, consistently higher for the ripe samples in comparison with the unripe ones (86.4% and 41.3%). The DPPH· rates significantly differ for the unripe and ripe papaya extracts, especially for the first time range. They are more than double for the ripe papaya. These values were 2.70, 4.00, 3.25, 2.75 μM/s for the peel, pulp, seed, seed-pulp extracts from the ripe papaya and only 1.00, 1.65, 1.40, 1.80 μM/s for the unripe samples. DPPH· kinetic approach can be useful for a fast and simple evaluation of the overall antioxidant properties of fruit extracts.