Antioxidation mechanism of rosmarinic acid, identification of an unstable quinone derivative by the addition of odourless thiol

Sensitive Detections of Sodium Dichloroisocyanurate and Rosmarinic Acid by Polyvinylpyrrolidone Coated Copper Nanoclusters

In this article, the water-soluble blue-light-emitting copper nanoclusters (CuNCs) were prepared by polyvinylpyrrolidone (PVP) and ascorbic acid as templating and reducing agents, respectively. The optimization of synthesis conditions of PVP-CuNCs were studied and analyzed. And the quantum yield of the PVP-CuNCs was calculated to be 14.97%. It had good specificity and exceptionally sensitive detection for sodium dichloroisocyanurate (DCCNa)/rosmarinic acid (RA), with a linear response range of 0.030-2.400/0.030-0.900 μM and corresponding LOD value of 10.766/8.985 nM. Moreover, the fluorescent reaction mechanisms of the PVP-CuNCs-DCCNa and PVP-CuNCs-DCCNa-RA systems were discussed, and the sensing probe could be effectively used for the assays of DCCNa and RA in genuine samples, whose results were acceptable.

The Role of Polyphenolic Antioxidants from Tea and Rosemary in the Hydroxyl Radical Oxidation of N-Acetyl Alanine

In dead biological tissues such as human hair, the ability of antioxidants to minimise autoxidation is determined by their chemical reactions with reactive oxygen species. In order to improve our understanding of factors determining such antioxidant properties, the mechanistic chemistry of four phenolic antioxidants found in tea and rosemary extracts (epicatechin, epigallocatechin gallate, rosmarinic and carnosic acids) has been investigated. The degradation of N-acetyl alanine by photochemically generated hydroxyl radicals was used as a model system. A relatively high concentration of the antioxidants (0.1 equivalent with respect to the substrate) tested the ability of the antioxidants to intercept both initiating hydroxyl radicals (preventive action) and propagating peroxyl radicals (chain-breaking action). LC-MS data showed the formation of hydroxylated derivatives, quinones and hydroperoxides of the antioxidants. The structure of the assignment was aided by deuterium exchange experiments. Tea polyphenolics (epicatechin and epigallocatechin gallate) outperformed the rosemary compounds in preventing substrate degradation and were particularly effective in capturing the initiating radicals. Carnosic acid was suggested to act mostly as a chain-breaking antioxidant. All of the antioxidants except for rosmarinic acid generated hydroperoxides which was tentatively ascribed to the insufficient lability of the benzylic C-H bond of rosmarinic acid.

On-Site Evaluation of Constituent Content and Functionality of Perilla frutescens var. crispa Using Fluorescence Spectra

Perilla frutescens leaves are hypothesized to possess antioxidant and amyloid-β (Aβ) aggregation inhibitory properties primarily due to their polyphenol-type compounds. While these bioactivities fluctuate daily, the traditional methods for quantifying constituent contents and functional properties are both laborious and impractical for immediate field assessments. To address this limitation, the present study introduces an expedient approach for on-site analysis, employing fluorescence spectra obtained through excitation light irradiation of perilla leaves. Standard analytical techniques were employed to evaluate various constituent contents (chlorophyl (Chl), total polyphenol content (TPC), total flavonoid content (TFC), and rosmarinic acid (RA)) and functional attributes (DPPH radical scavenging activity, ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and Aβ aggregation inhibitory activity). Correlations between the fluorescence spectra and these parameters were examined using normalized difference spectral index (NDSI), ratio spectral index (RSI), and difference spectral index (DSI) analyses. The resulting predictive model exhibited a high coefficient of determination, with R2 values equal to or greater than 0.57 for constituent contents and 0.49 for functional properties. This approach facilitates the convenient, simultaneous, and nondestructive monitoring of both the chemical constituents and the functional capabilities of perilla leaves, thereby simplifying the determination of optimal harvest times. The model derived from this method holds promise for real-time assessments, indicating its potential for the simultaneous evaluation of both constituents and functionalities in perilla leaves.

Newly Synthesized Lignin Microparticles as Bioinspired Oral Drug-Delivery Vehicles: Flavonoid-Carrier Potential and In Vitro Radical-Scavenging Activity

The aim of the present study was to synthesize lignin microparticles, to evaluate their physicochemical, spectral, morphological and structural characteristics, to examine their encapsulation and in vitro release potential and behaviour towards the flavonoid morin in simulated physiological medium and to assess the in vitro radical-scavenging potential of the morin-loaded lignin microcarrier systems. The physicochemical, structural and morphological characteristics of alkali lignin, lignin particles (LP) and morin-encapsulated lignin microparticles (LMP) were determined based on particle size distribution, SEM, UV/Vis spectrophotometric, FTIR and potentiometric titration analyses. The encapsulation efficiency of LMP was 98.1%. The FTIR analyses proved that morin was successfully encapsulated in the LP without unexpected chemical reactions between the flavonoid and the heteropolymer. The in vitro release performance of the microcarrier system was successfully mathematically described by Korsmeyer–Peppas and the sigmoidal models outlining the general role of diffusion during the initial stages of the in vitro release process in simulated gastric fluid (SGF), and the predominant contribution of biopolymer relaxation and erosion was determined in simulated intestinal medium (SIF). The higher radical-scavenging potential of LMP, as compared to that of LP, was proven via DPPH and ABTS assays. The synthesis of lignin microcarriers not only provides a facile approach for the utilization of the heteropolymer but also determines its potential for the design of drug-delivery matrices.

The Effects of Antioxidants and Packaging Methods on Inhibiting Lipid Oxidation in Deep Fried Crickets (Gryllus bimaculatus) during Storage

This study aimed to investigate the effect of processing methods on inhibiting lipid oxidation of deep fried crickets (Gryllus bimaculatus) during storage. Four antioxidants and two packaging methods were used. The effects of different antioxidants and packaging methods on composition of fatty acids, contents of free fatty acids (FFA), peroxide value (PV), and thiobarbituric acid reactive substances (TBARSs) value of deep fried Gryllus bimaculatus were analyzed during 150 days of storage. The composition of fatty acids changed and the content of FFA, PV, and TBARs value also increased with the extension of storage time, indicating that the lipid oxidation dominated by oxidation of unsaturated fatty acids could occur in deep fried Gryllus bimaculatus during storage. In the same storage period, the total content of FFA, PV, and TBARs value of samples treated with antioxidants and vacuum-filling nitrogen packaging were lower than those of controls, suggesting that antioxidants and vacuum-filling nitrogen packaging have noticeable effects on inhibiting lipid oxidation and improving the quality of deep fried crickets, and dibutyl hydroxyl toluene (BHT) was found as the most effective antioxidant in this study. The results may provide a reliable reference for processing of deep fried edible insects.

A comprehensive review on polarity, partitioning, and interactions of phenolic antioxidants at oil-water interface of food emulsions

There has been a growing interest in developing effective strategies to inhibit lipid oxidation in emulsified food products by utilization of natural phenolic antioxidants owing to their growing popularity over the past decades. However, due to the complexity of emulsified systems, the inhibition mechanism of phenolic antioxidants against lipid oxidation is rather complicated and not yet fully understood. In order to highlight the importance of polarity of phenolic antioxidants in emulsified systems according to the polar paradox, this review covers the recent progress on chemical, enzymatic, and chemoenzymatic lipophilization techniques used to modify the polarity of antioxidants. The partitioning behavior of phenolic antioxidants at the oil-water interface, which can be influenced by the presence of synthetic surfactants and/or antioxidant emulsifiers (e.g., polysaccharides, proteins, and phospholipids), is discussed. In addition, the emerging phenolic antioxidants among phenolic acids, flavonoids, tocopherols, and stilbenes applied in food emulsions are elaborated. As well, the interactions of polar-nonpolar antioxidants are stressed as a promising strategy to induce synergistic interactions at oil-water interface for improved oxidative stability of emulsions.

Interactions between α-tocopherol and γ-oryzanol in oil-in-water emulsions

The interaction between antioxidants is affected by many factors, such as concentration, ratio and system. In this study, different concentrations of α-tocopherol and γ-oryzanol showed antagonistic effect in the oil-in-water emulsion, and the distribution of α-tocopherol increased in aqueous phase after combined with γ-oryzanol. The concentration could affect the degree of antagonism. According to fluorescence quenching, cyclic voltammetry measurements and the oxidative decomposition of antioxidants during storage, the inhibitory effect of γ-oryzanol on the regeneration of α-tocopherol was proposed to be responsible for the antagonism. This work can provide suggestions for studying the mechanism of antioxidant interaction in emulsion system.

Preparation and In Vivo Evaluation of Rosmarinic Acid-Loaded Transethosomes After Percutaneous Application on a Psoriasis Animal Model

The topical use of rosmarinic acid (RA) in skin inflammatory pathologies is restricted due to its poor water solubility, poor permeability, and chemical instability. In this study, RA-loaded transethosomes-in-Carbopol® formulations have been developed to evaluate its anti-inflammatory activity on imiquimod-induced psoriasis-like skin inflammation in mice. In vitro release profiles demonstrated sustained behavior due to the retentive action of gel and the entrapment of RA into the vesicles. However, the low viscosity of the combined formulation increased the drug release rate. Animal evaluation of anti-inflammatory activity demonstrated that transethosomes-in-gel containing dexamethasone (Dex-TE-Gel), as positive control, showed effect in all the pro-inflammatory parameters evaluated, evidencing that these drug-loaded nanocarriers have been effectively reached the site of action. In addition, transethosomes-in-gel containing RA (RA-TE-Gel) formulations produced a great reduction in the punch edema (P < 0.001) and in TNF-α and IL-6 (P < 0.05). However, non-significant differences were obtained for IL-1β, IL17, and MPO. Despite the protecting effect of Carbopol® and transethosomes on oxidation index and antioxidant activity of RA over the 7 days of treatment, however, a degradation process of this antioxidant to caffeic acid may be the cause of these in vivo results. We have also checked that the pH existing into the intercellular space of damaged cells (pH 6.8) may be affecting. Therefore, our results suggest that RA-TE-Gel could act as an effective RA formulation for skin delivery; further studies will help to understand the loss of activity at the cellular level.

The Use of Sage Oil Macerates (Salvia officinalis L.) for Oxidative Stabilization of Cod Liver Oil in Bulk Oil Systems

The aim of the study was to investigate the antioxidant properties of sage oil macerates (M) in cod liver oil (CLO) during process oxidation catalyzed by UV radiation. CLO was not only subject to oxidative stabilization but also used as a solvent for active ingredients of sage. Macerates were obtained by combining the sage with CLO, homogenization, maceration, and filtration. The effect of different maceration times (0, 3, 6, 8, 10, 13, and 15 days) and different concentrations of macerate addition (5%, 10%, 25%, and 50%) on the CLO oxidation degree, which was determined by peroxide value (PV), anisidine value (AV), and Totox index, was evaluated. Additionally, the total content of polyphenols in macerates by the Folin-Ciocalteu method, antioxidant activity DPPH, and color was determined. The macerates showed antioxidant properties in CLO. The best effect was shown by the initial macerate (maceration time 0, M0), which in 25% concentration significantly inhibited oxidative processes in CLO. It was also characterized by high content of polyphenols and antioxidant activity of DPPH. Sage macerates can effectively inhibit oxidation of fish oils and prolong their durability.

Nanoantioxidant-Based Silica Particles as Flavonoid Carrier for Drug Delivery Applications

Nanosystems used in pharmaceutical formulations have shown promising results in enhancing the administration of drugs of difficult formulations. In particular, porous silica nanoparticles have demonstrated excellent properties for application in biological systems; however, there are still several challenges related to the development of more effective and biocompatible materials. An interesting approach to enhance these nanomaterials has been the development of nanoantioxidant carriers. In this work, a hybrid nanoantioxidant carrier based on porous silica nanoplatform with rosmarinic acid antioxidant immobilized on its surface were developed and characterized. Techniques such as dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), N2 adsorption-desorption measurements, differential scanning calorimetry (DSC), Fourier transform-infrared spectroscopy (FT-IR), and 2,2-diphenyl-1-picrylhydrazyl (DPPH●) assay were used to characterize and evaluate the antioxidant activity of nanocarriers. In addition, drug release profile was evaluated using two biorelevant media. The antioxidant activity of rosmarinic acid was maintained, suggesting the correct disposition of the moiety. Kinetic studies reveal that more morin is released in the simulated intestinal fluid than in the gastric one, while an anomalous non-Fickian release mechanism was observed. These results suggest a promising antioxidant nanocarrier suitable for future application in drug delivery.

Quantifying the efficiency of o-benzoquinones reaction with amino acids and related nucleophiles by cyclic voltammetry

The reaction efficiency of o-benzoquinones with amines (L-lysine, Nα-acetyl-L-lysine, glycine, L-methionine and L-arginine), thiols (L-cysteine and Nα-acetyl-L-cysteine) and protein (bovine serum albumin) were determined at pH 5.0, 7.0 and 8.0 and scan rate of 10, 50 and 100 mV/s by cyclic voltammetry. Nucleophiles containing multiple nucleophilic groups and nucleophilic group possessing low pKa value would enhance the reactivity of nucleophiles towards o-benzoquinones. The reactivity of different o-benzoquinones with L-lysine/L-cysteine followed the order: protocatechuic acid quinone ≈ catechol quinone > 4-methylbenzoquinone ≈ caffeic acid quinone > rosmarinic acid quinone > chlorogenic acid quinone. The reactivity of quinones would be decreased by the steric hindrance of substituents on quinone ring, and it would also be weakened by enhancing electron cloud density of quinone ring. Adducts generated by the interaction of 4-methylbenzoquinone with amines and thiols were tentatively identified as amine-quinone adduct and thiol-phenol adduct respectively by UPLC-QTOF-MS/MS and cyclic voltammetry.

Molecular Characterization of White Wines Antioxidant Metabolome by Ultra High Performance Liquid Chromatography High-Resolution Mass Spectrometry

The knowledge about the molecular fraction contributing to white wines oxidative stability is still poorly understood. However, the role of S- and N-containing compounds, like glutathione and other peptides, as a source of reductant in many oxidation reactions, and acting against heavy metals toxicity, or lipid and polyphenol oxidation as ROS-scavenger is today very well established. In that respect, the aim of the present study is to introduce an original analytical tool for the direct determination of the available nucleophilic compounds in white wine under acidic pH conditions. One step derivatization of nucleophiles has been realized directly in wines using 4-methyl-1,2-benzoquinone (4MeQ) as an electrophilic probe. Derivatization conditions considering probe concentration, pH, reaction time, MS ionisation conditions and adducts stability, were optimized using model solutions containing standard sulfur and amino compounds (GSH, Cys, HCys and Ser-Aps-Cys-Asp-Ser, Asp-Met, Met and Glu). Ultra-high-performance liquid chromatography coupled to a quadrupole-time of flight mass spectrometer (UHPLC-QqTOF-MS) analysis of up to 92 white wines from different cultivars (Chardonnay, Sauvignon and Semillon) followed by Multivariate analysis (PLS DA) and Wilcoxon test allowed to isolate up to 141 putative wine relevant nucleophiles. Only 20 of these compounds, essentially thiols, were detectable in samples before derivatization, indicating the importance of the quinone trapping on the revelation of wine unknown nucleophiles. Moreover, annotation using online database (Oligonet, Metlin and KEGG) as well as elementary formula determined by isotopic profile, provided evidence of the presence of amino acids (Val, Leu, Ile, Pro, Trp, Cys and Met) and peptides with important antioxidant properties. The complimentary set of MS/MS spectral data greatly accelerated identification of nucleophiles and enabled peptides sequencing. These results show that probing wines with 4-methyl-1,2-benzoquinone enhances thiols ionisation capacity and gives a better screening of specific S- N- containing functional compounds as part of the white wines antioxidant metabolome.

Interaction effect of tocopherol homologs with peppermint extract on the iron-catalyzed oxidation of soybean oil-in-water emulsion

Interaction between tocopherol homologs and peppermint extract added to oil-in-water emulsions was studied during iron-catalyzed oxidation. Emulsions consisted of tocopherol-stripped soybean oil and citrate buffer (4:6, w/w) with/without addition of peppermint extract (400 mg/kg) and α-, γ-, or δ-tocopherol (600 mg/kg), and were oxidized in the iron presence at 25 °C. Lipid oxidation of emulsions was evaluated based on hydroperoxide contents and p-anisidine values. Lipid oxidative stability of emulsions was improved by added peppermint extract, and co-added γ- and δ-tocopherols further reduced lipid oxidation, however, α-tocopherol increased it. Tocopherol contents did not change during oxidation. Polyphenol degradation in the emulsion with added peppermint extract was lower and slower by γ- and δ-tocopherols, however, α-tocopherol showed opposite results. The results suggest that co-addition of tocopherols to the emulsion containing peppermint extract shift a major role of polyphenols as antioxidants from scavenging lipid (peroxy) radicals to tocopherol radical scavenging.

An overview of the neuroprotective potential of rosmarinic acid and its association with nanotechnology-based delivery systems: A novel approach to treating neurodegenerative disorders

Neurodegenerative disorders (ND) are characterized by slow and progressive neuronal dysfunction induced by the degeneration of neuronal cells in the central nervous system (CNS). Recently, the neuroprotective effects of natural compounds with anti-inflammatory and antioxidant activities has been clearly demonstrated. This appears to be an attractive therapeutic approach for ND, particularly regarding the use of polyphenols. In this review, we present an overview of the neuroprotective potential of rosmarinic acid (RA) and discuss the use of nanotechnology as a novel approach to treating ND. RA presents a variety of biological important activities, i.e. the modulation of pro-inflammatory cytokine expression, prevention of neurodegeneration and damage reduction. However, its poor bioavailability represents a limitation in terms of pharmacodynamics. In this sense, nanotechnology-based carriers could allow for the administration of higher but still safe amounts of RA, aiming for CNS delivery. Nasal administration could be a pleasant route for delivery to the CNS, as this represents a direct route to the CNS. With these advantages, RA-loaded nanotechnology-based therapy through the nasal route could be promising approach for the treatment of ND.

Covalent Whey Protein-Rosmarinic Acid Interactions: A Comparison of Alkaline and Enzymatic Modifications on Physicochemical, Antioxidative, and Antibacterial Properties

The covalent interactions between whey protein isolate (WPI) and rosmarinic acid (RosA) at two different conditions, alkaline (pH 9) and enzymatic (in the presence of tyrosinase, PPO), at room temperature with free atmospheric air were studied. The conjugates formed between WPI and RosA were characterized in terms of their physicochemical and functional properties. The changes in protein structure were analyzed by intrinsic fluorescence and binding of 8-anilino-1-naphthalenesulfonic acid. The findings show that the covalent interactions caused a decrease in free amino and thiol groups and tryptophan content at both conditions. The decrease at enzymatic conditions was lower than at alkaline conditions. In addition, modified WPI at alkaline conditions exhibited higher antioxidative capacity compared to the modification at enzymatic conditions. However, WPI modified at enzymatic condition showed mild antimicrobial activity against Staphylococcus aureus LMG 10147 and MU50 compared to WPI modified at alkaline conditions and unmodified WPI (control). The modified WPI can be used as multifunctional ingredient into various food products with an additional health promoting effect of the bound phenolic compounds.

Combined effect of carnosol, rosmarinic acid and thymol on the oxidative stability of soybean oil using a simplex centroid mixture design

BACKGROUND

Oxidation taking place during the use of oil leads to the deterioration of both nutritional and sensorial qualities. Natural antioxidants from herbs and plants are rich in phenolic compounds and could therefore be more efficient than synthetic ones in preventing lipid oxidation reactions. This study was aimed at the valorization of Tunisian aromatic plants and their active compounds as new sources of natural antioxidant preventing oil oxidation.

RESULTS

Carnosol, rosmarinic acid and thymol were isolated from Rosmarinus officinalis and Thymus capitatus by column chromatography and were analyzed by nuclear magnetic resonance. Their antioxidant activities were measured by DPPH, ABTS and FRAP assays. These active compounds were added to soybean oil in different proportions using a simplex-centroid mixture design. Antioxidant activity and oxidative stability of oils were determined before and after 20 days of accelerated oxidation at 60 °C.

CONCLUSION

Results showed that bioactive compounds are effective in maintaining oxidative stability of soybean oil. However, the binary interaction of rosmarinic acid and thymol caused a reduction in antioxidant activity and oxidative stability of soybean oil. Optimum conditions for maximum antioxidant activity and oxidative stability were found to be an equal ternary mixture of carnosol, rosmarinic acid and thymol. © 2016 Society of Chemical Industry.

Myricetin, rosmarinic and carnosic acids as superior natural antioxidant alternatives to α-tocopherol for the preservation of omega-3 oils

22 natural polyphenols are compared to 7 synthetic antioxidants including BHT, BHA, TBHQ and PG with regard to their ability to protect omega-3 oils from autoxidation. The antioxidant efficiency of phenols is assessed using the DPPH test and the measurement of oxygen consumption during the autoxidation of oils rich in omega-3 fatty acids. Also, the bond dissociation enthalpies (BDE) of the Ar-OH bonds are calculated and excellent correlations between thermodynamic, kinetic and oxidation data are obtained. It is shown that kinetic rates of hydrogen transfer, number of radicals scavenged per antioxidant molecule, BDE and formation of antioxidant dimers from the primary radicals play an important role regarding the antioxidant activity of phenols. Based on this, it is finally shown that myricetin, rosmarinic and carnosic acids are more efficient than α-tocopherol and synthetic antioxidants for the preservation of omega-3 oils.

Effects of Environmental pH on Antioxidant Interactions between Rosmarinic Acid and α-Tocopherol in Oil-in-Water (O/W) Emulsions

Antioxidant regeneration could be influenced by various factors such as antioxidant locations and pH conditions. The effects of environmental pH on the antioxidant interaction between rosmarinic acid and α-tocopherol in oil-in-water (O/W) emulsions were investigated. Results showed that the combined antioxidants at pH 7 exhibited the strongest synergistic antioxidant activity in comparison with the combinations at other pH conditions as indicated by the interaction index. A drop in pH from 7 to 3 resulted in a reduction in the synergistic effect. However, in the case of pH 3, an additive effect was obtained. Moreover, the effect of the pH on the regeneration of α-tocopherol by rosmarinic acid in heterogeneous Tween 20 solutions was studied using EPR spectrometer. The same was true for the regeneration efficiency, where the reaction at pH 7 exhibited the highest regeneration efficiency of 0.3 mol of α-tocopheroxyl radicals reduced/mol of phenolics. However, the study on depletions of rosmarinic acid and α-tocopherol revealed that the formation of caffeic acid, an oxidative degradation product of rosmarinic acid, could be involved in enhancing the antioxidant activity observed at pH 7 rather than the antioxidant regeneration. This study has highlighted that the importance of pH-dependent antioxidant interactions does not solely rely on antioxidant regeneration. In addition, the formation of other oxidative products from an antioxidant should be taken into account.

Affinity of rosmarinic acid to human serum albumin and its effect on protein conformation stability

Rosmarinic acid (RA) is a natural polyphenol contained in many aromatic plants with promising biological activities. The interaction between RA and human serum albumin (HSA) was investigated by multi-spectroscopic, electrochemistry, molecular docking and molecular dynamics simulation methods. The fluorescence emission of HSA was quenched by RA through a combined static and dynamic quenching mechanism, but the static quenching was the major constituent. Fluorescence experiments suggested that RA was bound to HSA with moderately strong binding affinity through hydrophobic interaction. The probable binding location of RA was located near site I of HSA. Additionally, as shown by the Fourier transform infrared (FT-IR) and circular dichroism (CD) spectra, RA can result in conformational and structural alterations of HSA. Furthermore, the molecular dynamics studies were used to investigate the stability of the HSA and HSA-RA system. Altogether, the results can provide an important insight for the applications of RA in the food industry.

Natural extracts into chitosan nanocarriers for rosmarinic acid drug delivery

CONTEXT

Nanotechnology can be applied to deliver and protect antioxidants in order to control the oxidative stress phenomena in several chronic pathologies. Chitosan (CS) nanoparticles are biodegradable carriers that may protect antioxidants with potent biological activity such as rosmarinic acid (RA) in Salvia officinalis (sage) and Satureja montana (savory) extracts for safe and innovative therapies.

OBJECTIVE

Development and characterization of CS nanoparticles as a stable and protective vehicle to deliver RA for medical applications using natural extracts as sage and savory.

MATERIALS AND METHODS

Antioxidant-CS based nanoparticles were prepared by ionic gelation with sodium tripolyphosphate (TPP), at pH 5.8 with a mass ratio of 7:1 (CS:TPP), with a theoretical antioxidant-CS loading of 40-50%. The nanoparticles were then characterized by different methods such as photon correlation spectroscopy, laser Doppler anemometry, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR), high-performance liquid chromatographic (HPLC), association efficiency, and antioxidant activity.

RESULTS AND DISCUSSION

Individual and small sizing nanoparticles, around 300 nm, were obtained. SEM confirmed smooth and spherical nanoparticles after freeze-drying. No chemical interactions were found between antioxidants and CS, after encapsulation, by DSC and FTIR. The association efficiency was 51.2% for RA (with 40% loading) and 96.1 and 98.2% for sage and savory nanoparticles, respectively (both with 50% loading). Antioxidant activity values were higher than 0.0348 eq [Asc. Ac.] g/L/g extract and 0.4251 µmol/eq Trolox/g extract.

CONCLUSION

The extracts under study are promising vehicles for RA drug delivery in CS nanocarriers.

Identification and quantification of adducts between oxidized rosmarinic acid and thiol compounds by UHPLC-LTQ-Orbitrap and MALDI-TOF/TOF tandem mass spectrometry

LTQ Orbitrap MS/MS was used to identify the adducts between quinones derived from rosmarinic acid (RosA) and thiol compounds, including cysteine (Cys), glutathione (GSH), and peptides digested from myosin. Two adducts of quinone-RosA/Cys and quinone-RosA/2Cys, one quinone-RosA/GSH adduct, and three quinone-RosA/peptide adducts were identified by extracted ion and MS(2) fragment ion chromatograms. By using MALDI-TOF/TOF MS, the adduction reaction between RosA and myosin in myofibrillar protein isolates was determined, demonstrating that the accurate reaction site was at Cys949 of myosin. The effect of reaction conditions, including stirring time, temperature, and oxidative stress, on the formation of adducts was further investigated. The formation of quinone-RosA/Cys and quinone-RosA/GSH increased with stirring time. Both adducts increased with temperature, whereas the reactivity of the addition reaction of GSH was higher than that of Cys. With increasing oxidation stress, the formation of quinone-RosA/GSH adduct increased and that of quinone-RosA/Cys adduct decreased.

Quality consistency evaluation of Melissa officinalis L. commercial herbs by HPLC fingerprint and quantitation of selected phenolic acids

To evaluate the quality consistency of commercial medicinal herbs, a simple and reliable HPLC method with UV-vis detector was developed, both for fingerprint analysis and quantitation of some pharmacologically active constituents (marker compounds). Melissa officinalis L. (lemon balm) was chosen for this study because it is widely used as an aromatic, culinary and medicine remedy. About fifty peaks were found in each chromatogram of a lemon balm extract, including twelve satisfactorily resolved characteristic peaks. A reference chromatographic fingerprint for the studied medicinal herb was calculated using Matlab 9.1 software as a result of analysing all the 19 lemon balm samples obtained from 12 Polish manufacturers. The similarity values and the results of principal component analysis revealed that all the samples were highly correlated with the reference fingerprint and could be accurately classified in relation to their quality consistency. Next, a quantitation of selected phenolic acids in the studied samples was performed. The results have shown that the levels of phenolic acids, i.e. gallic, chlorogenic, syringic, caffeic, ferulic and rosmarinic were as follows (mg/g of dry weight): 0.001-0.067, 0.010-0.333, 0.007-0.553, 0.047-0.705, 0.006-1.589 and 0.158-48.608, respectively. Statistical analysis indicated that rosmarinic acid occurs in M. officinalis at the highest level, whereas gallic acid in the lowest. A detailed inspection of these data has also revealed that reference chromatographic fingerprints combined with quantitation of pharmacologically active constituents of the plant could be used as an efficient strategy for monitoring of the lemon balm quality consistency.

Rosmarinic acid from eelgrass shows nematicidal and antibacterial activities against pine wood nematode and its carrying bacteria

Pine wilt disease (PWD), a destructive disease for pine trees, is caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus and additional bacteria. In this study, extracts of Zostera marina showed a high nematicidal activity against PWN and some of the bacteria that it carries. Light yellow crystals were obtained from extracts of Z. marina through solvent extraction, followed by chromatography on AB-8 resin and crystallization. The NMR and HPLC analysis showed that the isolated compound was rosmarinic acid (RosA). RosA showed effective nematicidal activity, of which the LC₅₀ (50% lethal concentration) to PWN at 24 h, 48 h and 72 h was 1.18 mg/g, 1.05 mg/g and 0.95 mg/g, respectively. To get a high yield rate of RosA from Z. marina, single factor experiments and an L₉ (3⁴) orthogonal experiment were performed. This extraction process involved 70% ethanol for 3 h at 40 °C. The extraction dosage was 1:50 (w/v). The highest yield of RosA from Zostera was 3.13 mg/g DW (dried weight). The crude extracts of Zostera marina (10 mg/mL) and RosA (1 mg/mL) also showed inhibitory effects to some bacterial strains carried by PWN: Klebsiella sp., Stenotrophomonas maltophilia, Streptomyces sp. and Pantoea agglomerans. The results of these studies provide clues for preparing pesticide to control PWD from Z. marina.

Interactions between α-tocopherol and rosmarinic acid and its alkyl esters in emulsions: synergistic, additive, or antagonistic effect?

Many antioxidants can interact to produce synergistic interactions that can more effectively inhibit lipid oxidation in foods. Esterification of rosmarinic acid produces a variety of compounds with different antioxidant activity due to differences in polarity and thus differences in partitioning in oil, water, and interfacial regions of oil-in-water emulsions (O/W). Therefore, rosmarinic acid and rosmarinate esters provide an interesting tool to study the ability of antioxidant to interact in O/W emulsions. In O/W emulsions, rosmarinic acid (R0) exhibited the strongest synergistic interaction with α-tocopherol while butyl (R4) and dodecyl (R12) rosmarinate esters exhibited small synergistic interaction and eicosyl rosmarinate esters (R20) exhibited slightly antagonistic interaction. Fluorescence quenching and electron paramagnetic resonance (EPR) studies showed that water-soluble rosmarinic acid (R0) exhibited more interactions with α-tocopherol than any of the tested esters (R4, R12, R20). This was also confirmed in O/W emulsions where R0 altered the formation of α-tocopherol quinone and α-tocopherol increased the formation of caffeic acid from R0. This formation of caffeic acid was proposed to be responsible for the synergistic activity of R0 and α-tocopherol since the formation of an additional antioxidant could further increase the oxidative stability of the emulsion.

Chemical interaction between polyphenols and a cysteinyl thiol under radical oxidation conditions

Chemical interaction between polyphenols and thiols was investigated under radical oxidation conditions using a model cysteinyl thiol derivative, N-benzoylcysteine methyl ester. The radical oxidation was carried out with a stoichiometric amount of 2,2-diphenyl-1-picrylhydrazyl (DPPH), and the decreases in the amounts of polyphenols and the thiol were measured by HPLC analysis. Cross-coupling products between various polyphenols and the thiol were examined by LC-MS in reactions that showed decreases in both the polyphenols and the thiol. The LC-MS results indicated that three phenolic acid esters (methyl caffeate, methyl dihydrocaffeate, and methyl protocatechuate) and six flavonoids (kaempferol, myricetin, luteolin, morin, taxifolin, and catechin) gave corresponding thiol adducts, whereas three polyphenols (methyl ferulate, methyl sinapate, and quercetin) gave only dimers or simple oxidation products without thiol substituents. Thiol adducts of the structurally related compounds methyl caffeate and methyl dihydrocaffeate were isolated, and their chemical structures were determined by NMR analysis. The mechanism for the thiol addition was discussed on the basis of the structures of the products.