Chemical Composition and In Vitro Antioxidant Activity of Sida rhombifolia L. Volatile Organic Compounds

In the current study, the phytochemical constituents of volatile organic compounds (VOCs) obtained from Sida rhombifolia L. were identified by GC-FID and GC-MS analysis. A total of 73 volatile organic compounds were identified. The major components of S. rhombifolia VOCs were identified as palmitic acid (21.56%), phytol (7.02%), 6,10,14-trimethyl-2-pentadecanone (6.30%), oleic acid (5.48%), 2-pentyl-furan (5.23%), and linoleic acid (3.21%). The VOCs are rich in fatty acids (32.50%), olefine aldehyde (9.59%), ketone (9.41%), enol (9.02%), aldehyde (8.63%), and ketene (6.41%). The antioxidant capacity of S. rhombifolia VOCs was determined by 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), 2,2-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) diammonium salt (ABTS), and ferric reducing/antioxidant power (FRAP) methods with butylated hydroxytoluene (BHT) and Trolox as standard. The VOCs showed dose-dependent antioxidant activity with IC50 (50% inhibitory concentration) values of 5.48 ± 0.024 and 1.47 ± 0.012 mg/mL for DPPH and ABTS assays, respectively. FRAP antioxidant capacity was 83.10 ± 1.66 mM/g. The results show that the VOCs distilled from S. rhombifolia have a moderate antioxidant property that can be utilized as a natural botanical supplement or an antioxidant.

Colorimetric sensor array based on CoOOH nanoflakes for rapid discrimination of antioxidants in food

The identification of synthetic antioxidants has considerable significance in food safety. Here, we described the development of a colorimetric sensor array for rapid detection of eight antioxidants in food through the redox reaction between CoOOH and antioxidants in the presence of colorimetric signal indicators. The CoOOH nanoflakes exhibited high catalytic oxidation activity and can independently catalyze oxidation signal indicators showing different colors. The color reaction was inhibited to different degrees in the presence of antioxidants, which resulted in distinct signal response patterns for their discrimination. The method showed good linearity in the range from 50 to 1000 nM for butylated hydroxytoluene (BHT), butylhydroxyanisole (BHA), propyl gallate (PG) and tert-butyl hydroquinone (TBHQ). Moreover, different proportions of antioxidants were located in the middle pattern of each single antioxidant, and showed certain linear relationships among different concentration ratios. Finally, the proposed colorimetric sensor array was used for practical applications where TBHQ and BHT were detected in biscuits and sausages, and BHA and PG were detected in fried pork kebabs, respectively. The results were further confirmed by high-performance liquid chromatography, which demonstrated the great potential of the colorimetry sensor array for practical applications.

Improved Synthesis of Asymmetric Curcuminoids and Their Assessment as Antioxidants

In this paper, the syntheses of twelve asymmetric curcumin analogs using Pabon's method are reported. Generally, the previously reported yields of asymmetric curcuminoids, such as 9a (53%), 9c (38%), and 9k (38%), have been moderate or low. Herein, we propose that the low yields were due to the presence of water and n-BuNH₂ in the reaction media. To prove this formulated hypothesis, we have demonstrated that the yields can be improved by adding molecular sieves (MS) (4 Å) to the reaction mixture, thus reducing the interference of water. Therefore, improved yields (41-76%) were obtained, except for 9b (36.7%), 9g (34%), and 9l (39.5%). Furthermore, compounds 9b, 9d, 9e, 9f, 9g, 9h, 9i, 9j, and 9l are reported herein for the first time. The structures of these synthetic compounds were determined by spectroscopic and mass spectrometry analyses. The free radical scavenging ability of these synthetic asymmetric curcuminoids was evaluated and compared to that of the positive control butylated hydroxytoluene (BHT). Among the synthesized asymmetric curcuminoids, compounds 9a (IC₅₀ = 37.57 ± 0.89 μM) and 9e (IC₅₀ = 37.17 ± 1.76 μM) possessed effective 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging abilities, and compounds 9h (IC₅₀ = 11.36 ± 0.65 μM) and 9i (IC₅₀ = 10.91 ± 0.77 μM) displayed potent 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) radical scavenging abilities comparable to that of curcumin (IC₅₀ = 10.14 ± 1.04 μM). Furthermore, all the synthetic asymmetric curcuminoids were more active than BHT.

Phenolic compounds as antioxidants to improve oxidative stability of menhaden oil-based structured lipid as butterfat analog

Phenolic compounds, including propyl gallate, 1-o-galloylglycerol, ferulic, gallic, caffeic, rosmarinic, and carnosic acids, tocopherols, and butylated hydroxytoluene (BHT), were investigated as antioxidants to improve the oxidative stability of a structured lipid (SL) produced by the enzymatic acidolysis of menhaden oil with caprylic and stearic acids. SL had similar physical properties to butterfat but was more susceptible to oxidation. The above phenolic compounds were each added to SL as antioxidants. SL with 1-o-galloylglycerol, rosmarinic acid, or BHT showed the highest oxidative stability during an accelerated oxidation test with the total oxidation (TOTOX) value around 250 after 18 days. Oxidation induction time (OIT) using differential scanning calorimetry showed a good correlation with the accelerated oxidation test. A mixture of 1-o-galloylglycerol and tocopherols at 50:50 ppm had the strongest protective effect on SL (OIT = 115.1 min) compared to the other tested compounds or combinations at the same concentration (OIT < 100 min).

Identification of In Vitro Metabolites of Synthetic Phenolic Antioxidants BHT, BHA, and TBHQ by LC-HRMS/MS

Butylated hydroxytoluene (BHT) and its analogs, butylated hydroxyanisole (BHA) and tert-butyl-hydroquinone (TBHQ), are widely used synthetic preservatives to inhibit lipid oxidation in the food, cosmetic and pharmaceutical industries. Despite their widespread use, little is known about their human exposure and related biotransformation products. The metabolism of these compounds was investigated using in vitro incubations with human and rat liver fractions. Liquid chromatography coupled to high-resolution tandem mass spectrometry was employed to detect and characterize stable and reactive species formed via oxidative metabolism, as well as phase II conjugates. Several oxidative metabolites have been detected, as well as glutathione, glucuronide, and sulfate conjugates, many of which were not previously reported. A combination of accurate mass measurements, MS/MS fragmentation behavior, and isotope-labeling studies were used to elucidate metabolite structures.

New Multifunctional Agents Based on Conjugates of 4-Amino-2,3-polymethylenequinoline and Butylated Hydroxytoluene for Alzheimer's Disease Treatment

New hybrids of 4-amino-2,3-polymethylenequinoline with different sizes of the aliphatic ring linked to butylated hydroxytoluene (BHT) by enaminoalkyl (7) or aminoalkyl (8) spacers were synthesized as potential multifunctional agents for Alzheimer's disease (AD) treatment. All compounds were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with selectivity toward BChE. Lead compound 8c, 2,6-di-tert-butyl-4-{[2-(7,8,9,10- tetrahydro-6H-cyclohepta[b]quinolin-11-ylamino)-ethylimino]-methyl}-phenol exhibited an IC₅₀(AChE) = 1.90 ± 0.16 µM, IC₅₀(BChE) = 0.084 ± 0.008 µM, and 13.6 ± 1.2% propidium displacement at 20 μM. Compounds possessed low activity against carboxylesterase, indicating likely absence of clinically unwanted drug-drug interactions. Kinetics were consistent with mixed-type reversible inhibition of both cholinesterases. Docking indicated binding to catalytic and peripheral AChE sites; peripheral site binding along with propidium displacement suggest the potential of the hybrids to block AChE-induced β-amyloid aggregation, a disease-modifying effect. Compounds demonstrated high antioxidant activity in ABTS and FRAP assays as well as inhibition of luminol chemiluminescence and lipid peroxidation in mouse brain homogenates. Conjugates 8 with amine-containing spacers were better antioxidants than those with enamine spacers 7. Computational ADMET profiles for all compounds predicted good blood-brain barrier distribution (permeability), good intestinal absorption, and medium cardiac toxicity risk. Overall, based on their favorable pharmacological and ADMET profiles, conjugates 8 appear promising as candidates for AD therapeutics.

Strategies to Improve the Thermo-Oxidative Stability of Sunflower Oil by Exploiting the Antioxidant Potential of Blueberries Processing Byproducts

This research was conducted in order to establish the effectiveness of two freeze-dried extracts obtained from blueberry processing byproducts resulting from juice manufacturing compared to butylated hydroxytoluene (BHT) in delaying the lipid oxidation of sunflower oil subjected to high-temperature convective heating at 180 °C up to 12 h under simulated frying conditions. The fruits were harvested from spontaneous flora of two regions of Romania, Arieseni (Alba County) and Paltinis (Sibiu County) and the blueberry byproducts extracts (BBE) were noted according to the origin place as ABBE and PBBE. The progress of lipid thermo-oxidation was investigated in terms of peroxide value (PV), p-anisidine value (p-AV), the response of TBA-malondialdehyde interactions assessed by thiobarbituric acid (TBA) method, the total oxidation (TOTOX) value and inhibition of oil oxidation (IO). The recorded data highlighted that BBE exhibit a high inhibitory response on lipid thermo-oxidation. The inhibitory effect was concentration-dependent, thus, the degree of lipid oxidation was in reverse related to the BBE dose. The exposure of the oil samples supplemented with 800 ppm BBE (ABBE, PBBE) to a high-temperature heating for 12 h led to a significant decrease of the assessed indices compared to additives-free sunflower oil sample as follows: PV (46%; 45%), p-AV (21%; 17%), TOTOX (27%; 24%), TBA value (25%; 11%). Regarding the impact of the origin on the potential of BBE to inhibit the lipid oxidative degradation, it was noted that ABBE derived from blueberries grown in a region with a milder climate with moderate precipitations and higher temperatures showed a stronger inhibitory effect on lipid thermo-oxidation than PBBE. A moderate level of 500 ppm BBE inhibited the lipid oxidation similar to 200 ppm BHT. The reported results reveal that BBE represent efficient natural antioxidants that could be successfully applied to improve the thermo-oxidative stability of sunflower oil used in various high-temperature food applications.

Properties and Application of Multifunctional Composite Polypropylene-Based Films Incorporating a Combination of BHT, BHA and Sorbic Acid in Extending Donut Shelf-Life

To extend the shelf-life of packaged donut without the addition of preservative, polypropylene-based active composite films loaded with a combination of sorbic acid, BHA and BHT were prepared by the extrusion moulding method: T1 (Control-pure PP-film), T2 (PP-BHT1%-SA2%), T3 (PP-BHA3%-SA2%) and T4 (PP-BHT1%-BHA1%-SA2%). The incorporation of active additives enhanced water vapour permeability (WVP) and increased oxygen permeability of films. Active films had higher antioxidant activity than pure PP in the order T4 > T2 > T3 (89.11, 83.40 and 79.16%). In vitro examinations demonstrated a significant antibacterial effect on Escherichia coli and S. aureus growth. Overall migration was not significantly different for watery food simulants, while in acidic and fatty foods increased it significantly. The effect of the active films on the fried and packaged donut samples showed significantly higher moisture contents and peroxide values, while acidity was lower. T2 film is proposed due to the preservation of the intrinsic properties of the film, increasing the storage period up to 25 to 50 days.

Alkylated Sesamol Derivatives as Potent Antioxidants

Sesamol is a phenolic derivative. Its antioxidant activity is low than that of Trolox and depends on benzodioxole moiety. Thus, a molecular modification strategy through alkylation, inspired by natural and synthetic antioxidants, was studied by molecular modeling at the DFT/B3LYP level of theory by comparing the 6-31+G(d,p) and 6-311++G(2d,2p) basis sets. All proposed derivatives were compared to classical related antioxidants such as Trolox, t-butylated hydroxytoluene (BHT) and t-butylated hydroxyanisole (BHA). According to our results, molecular orbitals, single electron or hydrogen-atom transfers, spin density distributions, and alkyl substitutions at the ortho positions related to phenol moiety were found to be more effective than any other positions. The trimethylated derivative was more potent than Trolox. t-Butylated derivatives were stronger than all other alkylated derivatives and may be new alternative forms of modified antioxidants from natural products with applications in the chemical, pharmaceutical, and food industries.

Computational Methods for the Identification of Molecular Targets of Toxic Food Additives. Butylated Hydroxytoluene as a Case Study

Butylated hydroxytoluene (BHT) is one of the most commonly used synthetic antioxidants in food, cosmetic, pharmaceutical and petrochemical products. BHT is considered safe for human health; however, its widespread use together with the potential toxicological effects have increased consumers concern about the use of this synthetic food additive. In addition, the estimated daily intake of BHT has been demonstrated to exceed the recommended acceptable threshold. In the present work, using BHT as a case study, the usefulness of computational techniques, such as reverse screening and molecular docking, in identifying protein-ligand interactions of food additives at the bases of their toxicological effects has been probed. The computational methods here employed have been useful for the identification of several potential unknown targets of BHT, suggesting a possible explanation for its toxic effects. In silico analyses can be employed to identify new macromolecular targets of synthetic food additives and to explore their functional mechanisms or side effects. Noteworthy, this could be important for the cases in which there is an evident lack of experimental studies, as is the case for BHT.

Antioxidant Activity of Pastinaca sativa L. ssp. sylvestris [Mill.] Rouy and Camus Essential Oil

In the last decade, there has been growing interest in the food industry in replacing synthetic chemicals with natural products with bioactive properties. This study's aims were to determine the chemical composition and the antioxidant properties of the essential oil of Pastianica sylvestris. The essential oil was isolated with a yield of 0.41% (w/v) by steam distillation from the dried seeds and subsequently analysed by GC-MS. Octyl acetate (78.49%) and octyl hexanoate (6.68%) were the main components. The essential oil exhibited an excellent activity for the inhibition of primary and secondary oxidation products for cold-pressed sunflower oil comparable with butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), which were evaluated using peroxide and thiobarbituric acid values. The antioxidant activity of the essential oil was additionally validated using DPPH radical scavenging (0.0016 ± 0.0885 mg/mL), and β-carotene-linoleic acid bleaching assays. Also, the amounts of total phenol components (0.0053 ± 0.0023 mg GAE/g) were determined.

Synthetic phenolic antioxidants and transformation products in dust from different indoor environments in Toronto, Canada

Synthetic phenolic antioxidants (SPAs) are a class of anthropogenic antioxidants that are widely used in a large variety of commercial products. Although several SPAs have been listed as targets for risk assessment by Environment and Climate Change Canada, little data are available on the occurrence of SPAs in the Canadian environment. In this study, eighty-three indoor dust samples were collected from offices and homes in Toronto. Eight SPAs were detected at concentrations ranging from 67.2 to 1.55e4 ng/g, with a geometric mean (GM) concentration of 1.49e3 ng/g, among which 2,6-di-tert-butyl-4-methylphenol (BHT) was the primary congener and had a GM concentration of 658 ng/g. Four BHT transformation products (TPs) were also detected in the indoor dust samples, with concentrations ranging from 40.4 to 1.27e4 ng/g and a GM concentration of 883 ng/g. No significant concentration difference was observed between the office and home dust samples for either the summed target SPA or TP concentrations (p > 0.05). The calculated estimated daily intakes of these chemical contaminants (0.004-10.0 ng/kg BW/day) suggest that they pose no immediate health risk to the Canadian population. To the best of our knowledge, this is the first report of the occurrence of these chemical contaminants and their transformation products in Canadian indoor environments, and furthermore the first detection of 4-tert-butyl-phenol in an environmental sample.

Migration studies of butylated hydroxytoluene, tributyl acetylcitrate and dibutyl phthalate into food simulants

BACKGROUND

Migration is a mass transfer process in which chemical substances with a low molecular weight are transferred from packaging into food. This phenomenon has received great attention from a food safety point of view because these chemicals could potentially represent a risk for consumers' health. The present study investigated the process of migration of two common plasticizers [tributyl acetylcitrate (ATBC) and dibutyl phthalate (DBP)] and one antioxidant [butylated hydroxytoluene (BHT)] from a common plastic material used in food packaging (low density polyethylene) into 50% ethanol (v/v), 95% ethanol (v/v) and isooctane. A mathematical model based on Fick's second law was used to determine the partition and diffusion coefficients. In addition, the effect of temperature on the diffusion was studied by applying the Arrhenius equation.

RESULTS

High-performance liquid chromatography with diode-array detection and gas chromatography-mass spectrometry methods were applied to measure the amount of ATBC, DBP and BHT that migrated into the food simulants. A mathematical model based on Fick's second law of diffusion was used to estimate key migration parameters: diffusion and partition coefficients (D_P and K_P/F ), which were determined for each migrant and food simulant at three temperatures (10, 20 and 40 °C). The results showed that the diffusion process is significantly influenced by temperature, although the type of simulant also plays an important role in the migration process.

CONCLUSION

The model investigated is shown to be appropriate for predicting the migration from food packaging into real foodstuffs at common storage temperatures. © 2018 Society of Chemical Industry.

Chemical stabilization of polymers: Implications for dermal exposure to additives

Technical benefits of additives in polymers stand in marked contrast to their associated health risks. Here, a multi-analyte method based on gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) was developed to quantify polymer additives in complex matrices such as low-density polyethylene (LDPE) and isolated human skin layers after dermal exposure ex vivo. That way both technical aspects and dermal exposure were investigated. The effects of polymer additivation on the material were studied using the example of LDPE. To this end, a tailor-made polymer was applied in aging studies that had been furnished with two different mixtures of phenol- and diarylamine-based antioxidants, plasticizers and processing aids. Upon accelerated thermo-oxidative aging of the material, the formation of LDPE degradation products was monitored with attenuated total reflectance-Fourier transformed infrared (ATR-FTIR) spectroscopy. Compared to pure LDPE, a protective effect of added antioxidants could be observed on the integrity of the polymer. Further, thermo-oxidative degradation of the additives and its kinetics were investigated using LDPE or squalane as matrix. The half-lives of additives in both matrices revealed significant differences between the tested additives as well as between LDPE and squalane. For instance, 2-tert-butyl-6-[(3-tert-butyl-2-hydroxy-5-methylphenyl)methyl]-4-methylphenol (Antioxidant 2246) showed a half-life 12 times lower when incorporated in LDPE as compared to squalane. As a model for dermal exposure of consumers, human skin was brought into contact with the tailor-made LDPE containing additives ex vivo in static Franz diffusion cells. The skin was then analyzed for additives and decomposition products. This study proved 10 polymer additives of diverse pysicochemical properties and functionalities to migrate out of the polymer and eventually overcome the intact human skin barrier during contact. Moreover, their individual distribution within distinct skin layers was demonstrated. This is exemplified by the penetration of the procarcinogenic antioxidant N-phenylnaphthalen-2-amine (Neozon D) into the viable epidermis and the permeation through the skin of the neurotoxic plasticizer N-butylbenzenesulfonamide (NBBS). In addition, the analyses of additive degradation products in the isolated skin layers revealed the presence of 2-tert-butyl-4-methylphenol in all layers after contact to a polymer with substances of origin like Antioxidant 2246. Thus, attention needs to be paid to absorption of polymer additives together with their degradation products when it comes to dermal exposure assessment.

Inventory, loading and discharge of synthetic phenolic antioxidants and their metabolites in wastewater treatment plants

Little is known about the occurrence and fate of synthetic phenolic antioxidants (SPAs) and their metabolites in wastewater treatment plants (WWTPs). In this study, inventory, source, mass loading, and discharge of five SPAs, including 2,6-di-tert-butyl-4-methylphenol (BHT) and four of its metabolites were examined, based on the concentrations determined in wastewater influent, primary effluent, final effluent, suspended particulate matter (SPM), and sludge collected from two WWTPs (denoted as WWTP_A and WWTP_B) in the Albany area of New York State. The respective median concentrations of sum of SPAs (ΣSPAs = 6 compounds including metabolites) and SPA-metabolites (Σmetabolites = 4 metabolites) were 2455-3330 and 290-465 ng/L in influents, and 1580-1604 and 511-822 ng/L in final effluents. Adsorption to sludge (ΣSPAs ranged as 2420-4680 ng/g dry wt) accounted for ∼1% of the SPA removal. The removal efficiency (RE) for BHT in WWTPs ranged between 62.3% and 76.2%, whereas negative REs were found for SPA-metabolites ([-3020%]-[-65.6%]). WWTP-based mass loading of BHT accounted for ∼4%-10% of the total production volume reported in the USA, whereas ∼1.0% of the annual production of BHT was discharged from WWTP through effluents. BHT present in personal care products was estimated to explain for >91% of the mass loading source into WWTPs.

Pre-freezing Treatment with Butylated Hydroxytoluene and Cholesterol-loaded Methyl-β-cyclodextrin Improves Quality of Cryopreserved Boar Semen

BACKGROUND

Pre-freezing treatment of boar sperm with additives improves the quality of post-thaw sperms.

OBJECTIVES

The study aimed to determine the efficacy of butylated hydroxy-toluene (BHT) and cholesterol-loaded methyl-β-cyclodextrin (CLC) for the improvement of the frozen-thawed boar sperm quality.

METHODS

Split samples of 30 ejaculates from six boars were cryopreserved in lactose-egg yolk-glycerol extender containing BHT (0.2 mM), CLC (5 mg/ 200-240 x 10⁶ sperm) or BHT (0.2 mM) plus CLC (5 mg per 200-240 x 10⁶ sperm). Semen samples were evaluated for motility, membrane integrity, acrosomal status, mitochondrial membrane potential (MMP), DNA integrity and lipid peroxidation after equilibration and after freezing.

RESULTS

The addition of BHT and CLC into the extender significantly improved (P<0.05) plasma membrane integrity and decreased (P<0.05) lipid peroxidation after freezing. Post-thaw motility and live intact acrosome were significantly (P<0.05) higher in the extenders with BHT or BHT plus CLC. The post-thaw MMP of viable spermatozoa and DNA integrity were not affected. BHT plus CLC showed a significant (P<0.05) improvement on motility as compared to BHT and CLC alone.

CONCLUSION

Treatment of boar spermatozoa with BHT and CLC improved post-thaw sperm quality.

Rational Design and Synthesis of New, High Efficiency, Multipotent Schiff Base-1,2,4-triazole Antioxidants Bearing Butylated Hydroxytoluene Moieties

A new series of multipotent antioxidants (MPAOs), namely Schiff base-1,2,4-triazoles attached to the oxygen-derived free radical scavenging moiety butylated hydroxytoluene (BHT) were designed and subsequently synthesized. The structure-activity relationship (SAR) of the designed antioxidants was established alongside the prediction of activity spectra for substances (PASS). The antioxidant activities of the synthesized compounds 4-10 were tested by the DPPH bioassay. The synthesized compounds 4-10 inhibited stable DPPH free radicals at a level that is 10(-4) M more than the well-known standard antioxidant BHT. Compounds 8-10 with para-substituents were less active than compounds 4 and 5 with trimethoxy substituents compared to those with a second BHT moiety (compounds 6 and 7). With an IC50 of 46.13 ± 0.31 µM, compound 6 exhibited the most promising in vitro inhibition at 89%. Therefore, novel MPAOs containing active triazole rings, thioethers, Schiff bases, and BHT moieties are suggested as potential antioxidants for inhibiting oxidative stress processes and scavenging free radicals, hence, this combination of functions is anticipated to play a vital role in repairing cellular damage, preventing various human diseases and in medical therapeutic applications.

Understanding the chemistry behind the antioxidant activities of butylated hydroxytoluene (BHT): a review

Hindered phenols find a wide variety of applications across many different industry sectors. Butylated hydroxytoluene (BHT) is a most commonly used antioxidant recognized as safe for use in foods containing fats, pharmaceuticals, petroleum products, rubber and oil industries. In the past two decades, there has been growing interest in finding novel antioxidants to meet the requirements of these industries. To accelerate the antioxidant discovery process, researchers have designed and synthesized a series of BHT derivatives targeting to improve its antioxidant properties to be having a wide range of antioxidant activities markedly enhanced radical scavenging ability and other physical properties. Accordingly, some structure-activity relationships and rational design strategies for antioxidants based on BHT structure have been suggested and applied in practice. We have identified 14 very sensitive parameters, which may play a major role on the antioxidant performance of BHT. In this review, we attempt to summarize the current knowledge on this topic, which is of significance in selecting and designing novel antioxidants using a well-known antioxidant BHT as a building-block molecule. Our strategy involved investigation on understanding the chemistry behind the antioxidant activities of BHT, whether through hydrogen or electron transfer mechanism to enable promising anti-oxidant candidates to be synthesized.

[Antiradical properties of essential oils and extracts from clove bud and pimento]

The antiradical properties of essential oils and extracts from the clove bud (Eugenia caryophyllata Thumb.) and berries of tree (Pimenta dioica (L.) Meriff) were studied and compared with the properties of synthetic antioxidant ionol (2,6-ditret-butyl-4-hydroxytoluene, BHT) in model reactions with the stable free 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. The essential oils of clove bud and pimento had qualitatively close composition of the main components but differed by their quantitative content. In the studied samples, eugenol was the main compound with high antiradical activity. The reaction rates of essential oils and extracts with the DPPH radical were practically the same for essential oils and twice the reaction rate of BHT. The values of antiradical efficiency (AE) were also close for essential oils and were twice that for extracts and ionol. A synergetic action of components in the essential oil and extract of pimento on antiradical efficiency values was found.

Crystal growth and properties of NLO optical crystal - Butylated Hydroxy Toluene (BHT)

Crystallographic, experimental and theoretical density functional theory (DFT) of Butylated Hydroxy Toluene (BHT) are investigated. The grown crystals were identified by single crystal X-ray analysis. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of BHT is calculated using B3LYP/6-31G(d,p) method on the finite-field approach. The stability of molecule has been analyzed by using NBO/NLMO analysis. The molecular electrostatic potential (MESP) mapping is very useful in the investigation of the molecular structure with its physiochemical property relationship. The calculated HOMO and LUMO energies show that charge transfer occurs within these molecules. Mulliken population analysis on atomic charge is also calculated. Because of vibrational analysis, the thermodynamic properties of the title compound at different temperatures have been calculated. Finally, the UV-Vis spectra and electronic absorption properties are explained and illustrated from the frontier molecular orbitals. The grown crystals were characterized by measuring their thermal properties by Differential Thermal Analysis (DTA) and Thermo Gravimetric Analysis (TGA) measurements.

Anti-inflammatory activity of the artificial antioxidants 2-tert-butyl-4-methoxyphenol (BHA), 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,4,6-tri-tert-butylphenol (TBP), and their various combinations

BACKGROUND/AIM

The artificial complex phenols, 2-tert-butyl-4-methoxyphenol (BHA), 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,4,6-tri-tert-butylphenol (TBP) exert efficient antioxidant activity; however, they are considerable toxic and potentially tumor-promoting. These phenols, particularly in combinations, have enhanced antioxidant activity due to synergistic interactions and produce bioactive intermediates such as quinone methide. We investigated the anti-inflammatory activity of BHA, BHT and TBP, and combinations of BHT/BHA (in molar ratios of 1:1, 1:2, 1:3 and 2:1), BHT/TBP (1:1), and BHA/TBP (1:1), using gene-expression systems for cyclooxygenase-2 (Cox2) and tumor necrosis facto-alpha (Tnfa) in RAW264.7 cells.

MATERIALS AND METHODS

The inhibitory effects of BHA, BHT and TBP on expression of Cox2 and Tnfa genes upon stimulation with Escherichia coli lipopolysaccharide (LPS) or Porphyomonas gingivalis (Pg) fimbriae were determined using real-time polymerase chain reaction.

RESULTS

The inhibitory effect on expression of Cox2 and Tnfa genes upon stimulation with LPS and fimbriae was greatly enhanced by the combination of two antioxidants (molar ratio 1:1), BHT/BHA. In addition, that of the Cox2 gene, but not of Tnfa gene was slightly enhanced by a combination of equimolar BHT/TBP and BHA/TBP. None of the antioxidants alone exerted any anti-inflammatory activity upon stimulation with LPS, but a slight anti-inflammatory activity was observed upon stimulation with Pg fimbriae. The inhibitory effect of the BHT/BHA combination on expression of Cox2 mRNA upon stimulation with LPS was investigated at afferent molar ratios, and a molar ratio of 1:1 was found to have considerably less effect than a molar ratio of 1:2 or 2:1. The 1:3 combination had no effect.

CONCLUSION

The combination of BHT and BHA at a molar ratio of 0.5-2 exerts potent anti-inflammatory activity. This anti-inflammatory activity on the generation of inflammatory mediators in LPS-activated RAW264.7 cells may be attributable to complex synergistic antioxidant activity of the combination of BHT and BHA. Our results suggest the potential usefulness of the BHT/BHA combination at an appropriate molar ratio as an antioxidant in foods and pharmaceuticals, whereas either antioxidant alone is unlikely to be effective.

Synthesis, characterization, and evaluation of 10-undecenoic acid-based epithio derivatives as multifunctional additives

Novel epithio compounds from alkyl epoxy undecanoates (n-alkyl, C1, C4, and C6; isoalkyl, C3, C4, and C8) were synthesized using an ammonium thiocyanate in ionic liquid 1-methylimidazolium tetrafluoroborate/H2O (2:1) solvent system in 85-90% yields by gas chromatographic (GC) analysis. The synthesized products were characterized by (1)H and (13)C nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy (FTIR), gas chromatography, and GC mass spectral (GC-MS) analyses and evaluated for their antioxidant, extreme pressure (EP), and antiwear (AW) properties in three different base oils, namely, epoxy jatropha fatty acid n-butyl esters (EJB), di-2-ethylhexyl sebacate (DOS), and mineral oil (S-105). Among the synthesized products, n-butyl epithio undecanoate exhibited superior antioxidant property (229.2 °C) compared to butylated hydroxytoluene (BHT, 193.8 °C) in base oil DOS and comparable performance in EJB and S-105 base oils. All of the epithio derivatives exhibited significantly enhanced weld point for the base oils EJB and DOS at 2 wt % level and displayed moderate enhancement in S-105 base oil. Methyl epithio undecanoate at 0.6% concentration exhibited considerable improvement in the wear scar of DOS base oil. The synthesized epithio derivatives have potential as multifunctional additives in lubricant formulations.

Spectroscopic studies on the antioxidant activity of ellagic acid

Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 μg/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), α-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTS+ scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties.

Confirmation of hydroxyl radicals (•OH) generated in the presence of TiO2 supported on AC under microwave irradiation

In order to study the degradation mechanism of technology of microwave (MW) combined with TiO2 supported on activated carbon (TiO2/AC), the reactive oxygen species (ROS) was explored through oxidation of 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). Furthermore, 2,6-di-tert-butyl-4-methylphenol (BHT), Mannitol (MT) and Vitamin C (VC) were used as radical scavengers to confirm the generation of the hydroxyl radicals ((•)OH). In addition, the influence of some parameters such as TiO2 mass ratio content, irradiation time, material dose, DPCI concentration and MW power on the determination of (•)OH were examined. The results showed that the (•)OH could be generated under MW combined with loaded TiO2/AC. Also, anatase TiO2/AC can generate more (•)OH radicals than rutile TiO2/AC under MW irradiation. This work would provide new mechanistic insights on the enhanced degradation effect of organic pollutants in water using the supported TiO2/AC coupled with MW technology.

Chemistry and biological activities of Tanacetum chiliophyllum var. oligocephalum extracts

Tanacetum chiliophyllum (Fisch. & Mey.) var. oligocephalum (D.C.) Sosn. collected in Turkey was subjected to phytochemical and biological evaluations in this study. Pure compounds were obtained from ethyl acetate extracts of the stems of the plant material. Structures of isolated compounds were determined using spectral methods. Seven known flavones, i.e., 5-hydroxy-3',4',6,7-tetramethoxyflavone, eupatilin (6-hydroxyluteolin-6,3',4'-trimethylether), cirsimaritin (scuttellarin-6,7-dimethylether), cirsilineol, 5-hydroxy-3',4',7-trimethoxy flavone, desmethoxy-centaureidin, and jaceosidin and one known triterpene, taraxasterol acetate, were identified from the ethyl acetate extracts. The first seven compounds, as well as the ethyl acetate and methanol extracts, were also investigated for their insecticidal, antimicrobial, and 1,1-diphenyl-2-picrylhydrazil radical (DPPH)-scavenging activities. The insecticidal contact toxicity of the extracts were evaluated on Sitophilus granarius. The ethyl acetate (81.8%) and methanol (88.4%) extracts of T. chiliophyllum var. oligocephalum showed high toxicity against this pest. Most promising antimicrobial activity was observed for ethyl acetate extracts of the stems against Bacillus cereus. This extract showed the same inhibition concentration (125 microL/mg) with the positive control chloramphenicol. The ethyl acetate (91.9%) and methanol (93%) extracts of the stems showed significant DPPH-scavenging activity compared with the positive controls alpha-tocopherol (94.5%) and butylated hydroxytoluene (92.9%) at 10 mg/mL concentration. Among the isolated compounds, the highest DPPH-scavenging activity was observed for jaceosidin at 1 mg/mL concentration (81.5%).

Estimation of the bioaccumulation potential of a nonchlorinated bisphenol and an ionogenic xanthene dye to Eisenia andrei in field-collected soils, in conjunction with predictive in silico profiling

In silico-based model predictions, originating from structural and mechanistic (e.g., transport, bioavailability, reactivity, and binding potential) profiling, were compared against laboratory-derived data to estimate the bioaccumulation potential in earthworms of 2 organic substances (1 neutral, 1 ionogenic) known to primarily partition to soil. Two compounds representative of specific classes of chemicals were evaluated: a nonchlorinated bisphenol containing an -OH group (4,4′-methylenebis[2,6-di-tert-butylphenol] [Binox]), and an ionogenic xanthene dye (2′,4′,5′,7′-tetrabromo-4,5,6,7-tetrachloro-3′,6′-dihydroxy-, disodium salt [Phloxine B]). Soil bioaccumulation studies were conducted using Eisenia andrei and 2 field-collected soils (a clay loam and a sandy soil). In general, the in silico structural and mechanistic profiling was consistent with the observed soil bioaccumulation tests. Binox did not bioaccumulate to a significant extent in E. andrei in either soil type; however, Phloxine B not only accumulated within tissue, but was not depurated from the earthworms during the course of the elimination phase. Structural and mechanistic profiling demonstrated the binding and reactivity potential of Phloxine B; this would not be accounted for using traditional bioaccumulation metrics, which are founded on passive-based diffusion mechanisms. This illustrates the importance of profiling for reactive ionogenic substances; even limited bioavailability combined with reactivity can result in exposures to a hazardous substance not predictable by traditional in silico modeling methods.

[Determination of the antioxidant properties of activators of mitochondrial ATP-dependent potassium channels with the Amplex Red fluorescent indicator]

The effect of adaptogens-antihypoxants that participate in the activation of mitochondrial ATP-dependent potassium channels (mitoK(ATP)) at the oxidation of the Amplex Red (AR) fluorescent indicator in a peroxidase system was tested. It was shown that Extralife, Hypoxen, taurine, and synthetic antioxidant ionol can be arranged in the following row, according to the fluorescence inhibition activity: Extralife > Hypoxen > > ionol > taurine; their effect was shown to be concentration-dependent. The calculated K(i) value of fluorescence indicators demonstrate fast and slow phases of inhibition of the AR oxidation by Extralife and Hypoxen. The fast phase occurs in the presence of microdoses (0.05-3 microg/mL) of adaptogens and is related to the competition for H2O2, which is in agreement with our previous data on the mitoK(ATP) activation by doses of adaptogens related to the H2O2 consumption. The slow phase is characteristic of high adaptogen and ionol concentrations and is related to the competition for phenoxyl radicals of resorufin formed during AR oxidation. The obtained results allow one to suggest the application of a highly sensitive model peroxidase system with AR for the preliminary testing of compounds activating mitoK(ATP) channels.

Spectroscopic studies on the antioxidant activity of p-coumaric acid

p-coumaric acid (4-hydroxycinnamic acid), a phenolic acid, is a hydroxyl derivative of cinnamic acid. It decreases low density lipoprotein (LDL) peroxidation and reduces the risk of stomach cancer. In vitro radical scavenging and antioxidant capacity of p-coumaric acid were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe(2+)) chelating activity and ferric ions (Fe(3+)) reducing ability. p-Coumaric acid inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45μg/mL concentration. On the other hand, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and ascorbic acid displayed 66.8%, 69.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, p-coumaric acid had an effective DPPH scavenging, ABTS(+) scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe(3+)) reducing power and ferrous ions (Fe(2+)) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that p-coumaric acid can be used in the pharmacological and food industry because of these properties.

Drug-excipient compatibility studies in binary mixtures of avobenzone

During preformulation studies of cosmetic/pharmaceutical products, thermal analysis techniques are very useful to detect physical or chemical incompatibilities between the active and the excipients of interest that might interfere with safety and/or efficacy of the final product. Differential scanning calorimetry (DSC) was used as a screening technique for assessing the compatibility of avobenzone with some currently used cosmetic excipients. In the first phase of the study, DSC was used as a tool to detect any interaction. Based on the DSC results alone, cetearyl alcohol, isopropyl myristate, propylparaben, diethylhexyl syringylidene malonate, caprylic capric triglyceride, butylated hydroxytoluene (BHT), glycerin, cetearyl alcohol/ceteareth 20, cetearyl alcohol/sodium lauryl sulfate/sodium cetearyl sulfate, and paraffinum liquidum exhibit interaction with avobenzone. Stressed binary mixtures (stored at 50°C for 15 days) of avobenzone and excipients were evaluated by high-performance liquid chromatography. Binary mixtures were further investigated by infrared (IR) spectroscopy. Based on DSC, isothermal stress testing, and fourier transform infrared results; avobenzone is incompatible with caprylic capric triglyceride, propylparaben, and BHT.

Comparative evaluation of different co-antioxidants on the photochemical- and functional-stability of epigallocatechin-3-gallate in topical creams exposed to simulated sunlight

The catechin (−)-epigallocatechin-3-gallate (EGCG) exhibits high antioxidant activity and it has been reported to provide protection of the skin against damage induced by solar UV radiation. However, EGCG is highly unstable under sunlight. The present study aimed to compare the effectiveness of the co-antioxidant agents vitamin E, butylated hydroxytoluene, vitamin C and α-lipoic acid for their potential to protect the catechin from photochemical degradation. Model creams (oil-in-water emulsions) containing EGCG (1%, w/w) alone or combined with equimolar concentrations of co-antioxidant were exposed to a solar simulator at an irradiance corresponding to natural sunlight. Photodegradation was evaluated by HPLC-UV and HPLC-ESI-MS/MS. Addition of the co-antioxidants vitamin C and α-lipoic acid to the formulation significantly reduced the light-induced decomposition of EGCG from 76.9 ± 4.6% to 20.4 ± 2.7% and 12.6 ± 1.6%, respectively. Conversely, butylated hydroxytoluene had no effect (EGCG loss, 78.1 ± 4.6%) and vitamin E enhanced the EGCG photolysis to 84.5 ± 3.4%. The functional stability of the catechin in the creams exposed to the solar simulator was also evaluated by measuring the in vitro antioxidant activity. Following irradiation, the reduction of the EGCG formulation antioxidant power was lower (21.8%) than the extent of degradation (76.9%), suggesting the formation of photoproducts with antioxidant properties. The influence of the examined co-antioxidants on the functional stability of the catechin under simulated sunlight paralleled that measured for the EGCG photodecomposition, α-lipoic acid exerting the greatest stabilising effect (antioxidant activity decrease, 1.4%). These results demonstrated that α-lipoic acid is an effective co-antioxidant agent for the stabilization of EGCG in dermatological products for skin photoprotection.

Stability and antioxidant activity of semi-synthetic derivatives of 4-nerolidylcatechol

4-nerolidylcatechol (4-NC) is an unstable natural product that exhibits important antioxidant, anti-inflammatory and other properties. It is readily obtainable on a multi-gram scale through straightforward solvent extraction of the roots of cultivated Piper peltatum or P. umbellatum, followed by column chromatography on the resulting extract. Semi-synthetic derivatives of 4-NC with one or two substituent groups (methyl, acetyl, benzyl, benzoyl) on the O atoms have been introduced that have increased stability compared to 4-NC and significant in vitro inhibitory activity against the human malaria parasite Plasmodium falciparum. Antioxidant and anti-inflammatory properties may be important for the antiplasmodial mode of action of 4-NC derivatives. Thus, we decided to investigate the antioxidant properties, cytotoxicity and stability of 4-NC derivatives as a means to explore the potential utility of these compounds. 4-NC showed high antioxidant activity in the DPPH and ABTS assays and in 3T3-L1 cells (mouse embryonic fibroblast), however 4-NC was more cytotoxic (IC₅₀ = 31.4 µM) and more unstable than its derivatives and lost more than 80% of its antioxidant activity upon storage in solution at −20 °C for 30 days. DMSO solutions of mono-O-substituted derivatives of 4-NC exhibited antioxidant activity and radical scavenging activity in the DPPH and ABTS assays that was comparable to that of BHA and BHT. In the cell-based antioxidant model, most DMSO solutions of derivatives of 4-NC were less active on day 1 than 4-NC, quercetin and BHA and more active antioxidants than BHT. After storage for 30 days at −20 °C, DMSO solutions of most of the derivatives of 4-NC were more stable and exhibited more antioxidant activity than 4-NC, quercetin and BHA and exhibited comparable antioxidant activity to BHT. These findings point to the potential of derivatives of 4-NC as antioxidant compounds.

[The antiradical activity of plant extracts and healthful preventive combinations of these exrtacts with the phospholipid complex]

Using the chemiluminescence method, the effective concentration of antioxidants (AO) and its reactivity toward peroxyl radicals (ARA, the k7 constant) have been measured for 13 plant extracts. In fact all extracts demonstrated ARA higher than ionol. Larix dahurica, Hypericum perforatum, Potentilla fruticosa, Aronia melanocarpa and Rhaponticum carthamoides extracts showed the highest values of ARA. The combinations Aronia + Raponticum extracts; Larix + Hibiscus extracts; Schizandra +Aronia extracts were synergistic (the synergism effect beta of 38%, 33% and 22%). Apparently this phenomenon is the result of the synergistic interaction between compounds present in plant extracts. The Phospholipid complex--Lipoid S40, lacting any antioxidant effect alone, showed a potent synergistic effect with Aronia extract (beta3 = 60%), Silybum extract (beta3 = 41%). Clinical trials demonstrated, that combinations "Lipoid + Aronia extract", "Lipoid + Larix extract + Hibiscus extract", "Lipoid + Silybum extract", "Lipoid + Q10 + Rosa majalis extract" may be used as an additional component in the medicinal treatment, or as an individual prophylactic agent.

Acuminatol and other antioxidative resveratrol oligomers from the stem bark of Shorea acuminata

A new resveratrol dimer, acuminatol (1), was isolated along with five known compounds from the acetone extract of the stem bark of Shorea acuminata. Their structures and stereochemistry were determined by spectroscopic methods, which included the extensive use of 2D NMR techniques. All isolated compounds were evaluated for their antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (RSA) and the β-carotene-linoleic acid (BCLA) assays, and compared with those of the standards of ascorbic acid (AscA) and butylated hydroxytoluene (BHT). All compounds tested exhibited good to moderate antioxidant activity in the DPPH assay (IC₅₀s 0.84 to 10.06 mM) and displayed strong inhibition of β-carotene oxidation (IC₅₀s 0.10 to 0.22 mM). The isolated compounds were evaluated on the Vero cell line and were found to be non-cytotoxic with LC₅₀ values between 161 to 830 µM.

Free radical scavenging activity of conjugated linoleic acid as single or mixed isomers

CONTEXT

Conjugated linoleic acids (CLAs) are a mixture of positional and geometric isomers of linoleic acid (LA) and believed to have many positive biological activities.

OBJECTIVE

The present study was undertaken to assess the antioxidant activity of cis-9, trans-11 and trans-10, cis-12 as single or mixed CLA isomers at two ratios, 1:6 and 1:13 (trans-10, cis-12/cis-9, trans-11).

MATERIALS AND METHODS

A microplate reader was used to determine the free radical scavenging properties of CLAs against DPPH radical in ethanol.

RESULTS

The kinetic reactions of CLA-DPPH(•) showed that all tested CLAs have exerted radical scavenging activities in a dose-dependent manner and observed to immediately react and quench DPPH radicals at all tested levels and no lag phase was noticed in CLA-DPPH(•) reactions. The median inhibitory concentration (IC₅₀) value for cis-9, trans-11 CLA was observed to be more effective than other tested CLA. Total antioxidant capacity (TAC) of all tested CLAs were less effective radical scavengers as compared to vitamin E and butylated hydroxytoluene, although all tested CLAs were quenched a high amount (P < 0.05) of DPPH free radicals.

DISCUSSION AND CONCLUSION

All tested CLAs have the ability to directly react and quench DPPH free radicals in ethanol. Furthermore, trans-10, cis-12 CLA has greater maximal efficacy than other tested CLAs as free radical scavenger, while cis-9, trans-11 CLA is the most potent isomer to directly react and quench free radicals at low concentrations in the system, suggesting that the free radical scavenging activity of CLA isomers may contribute to their diverse biological activities.

Stability of carotenoid diets during feed processing and under different storage conditions

The stability of formulated carotenoid diets during feed processing and under different storage conditions were studied. All carotenoid diets were split into two groups with one group containing BHT (acting as an antioxidant) at 250 ppm and the other without BHT. The experiment was divided into two parts. First, all diets were evaluated in total carotenoid (TC) loss during feed processing, in dry mixed feeds after being processed and dried. In the final part, the completed dietary carotenoids were stored in an aluminum foil bag, the top of which was sealed with a bag sealer and kept under different storage conditions at 26–28 °C and 4 °C. The stability of the TC was observed during an 8-week trial period. The results showed that the diet pelleting process did not affect the carotenoid content of the diets, and the best storage temperature for the formulated carotenoid diet was at 4 °C. However, an antioxidant was added to assist in energy saving before feed processing. Thus, the addition of BHT at 250 ppm can be done at normal room temperature in order to reduce oxidation that might cause a loss of TC quantities in diets.

Cluster secondary ion mass spectrometry and the temperature dependence of molecular depth profiles

The quality of molecular depth profiles created by erosion of organic materials by cluster ion beams exhibits a strong dependence upon temperature. To elucidate the fundamental nature of this dependence, we employ the Irganox 3114/1010 organic delta-layer reference material as a model system. This delta-layer system is interrogated using a 40 keV C(60)(+) primary ion beam. Parameters associated with the depth profile such as depth resolution, uniformity of sputtering yield, and topography are evaluated between 90 and 300 K using a unique wedge-crater beveling strategy that allows these parameters to be determined as a function of erosion depth from atomic force microscope (AFM) measurements. The results show that the erosion rate calibration performed using the known Δ-layer depth in connection with the fluence needed to reach the peak of the corresponding secondary ion mass spectrometry (SIMS) signal response is misleading. Moreover, we show that the degradation of depth resolution is linked to a decrease of the average erosion rate and the buildup of surface topography in a thermally activated manner. This underlying process starts to influence the depth profile above a threshold temperature between 210 and 250 K for the system studied here. Below that threshold, the process is inhibited and steady-state conditions are reached with constant erosion rate, depth resolution, and molecular secondary ion signals from both the matrix and the Δ-layers. In particular, the results indicate that further reduction of the temperature below 90 K does not lead to further improvement of the depth profile. Above the threshold, the process becomes stronger at higher temperature, leading to an immediate decrease of the molecular secondary ion signals. This signal decay is most pronounced for the highest m/z ions but is less for the smaller m/z ions, indicating a shift toward small fragments by accumulation of chemical damage. The erosion rate decay and surface roughness buildup, on the other hand, exhibit a rather sudden delayed onset after erosion of about 150 nm, indicating that a certain damage level must be reached in order to influence the erosion dynamics. Only after that onset does the depth resolution become compromised, indicating that the temperature reduction does not significantly influence parameters like ion-beam mixing or the altered-layer thickness. In general, the wedge-crater beveling protocol is shown to provide a powerful basis for increased understanding of the fundamental factors that affect the important parameters associated with molecular depth profiling.

Diterpenes, ionol-derived, and flavone glycosides from Podocarpus elongatus

Eight compounds, nagilactone C 7-O-α-L-arabinopyranosyl-(1→4)-β-D-xylopyranoside, nagilactone C 7-O-β-D-glucopyranosyl-(1→4)-β-D-xylopyranoside, nagilactone C 7-O-β-D-xylopyranoside, nagilactone A 7-O-α-L-arabinopyranosyl-(1→4)-β-D-xylopyranoside, 2β,15S,16,17,19-pentahydroxy-isopimar-8(14)-ene 17-O-β-D-glucopyranoside, 2β,15R,16,17,19-pentahydroxy-isopimar-8(14)-ene 17-O-β-D-glucopyranoside, 1-(2,6,6-trimethyl-4-hydroxycyclohexenyl)-1-hydroxy-buta-1-en-3-one 4-O-β-D-glucopyranoside, and vitexin 2″-O-β-D-(6'''-acetyl)-glucopyranoside together with 13 known compounds, were isolated from the leaves of Podocarpus elongatus. Structures were elucidated by 1D and 2D NMR spectroscopy as well as by ESI mass spectrometry and chemical methods. The absolute configurations of the 15,16-diol moieties in two compounds were determined using Snatzke's method.

Molecular depth profiling by wedged crater beveling

Time-of-flight secondary ion mass spectrometry and atomic force microscopy are employed to characterize a wedge-shaped crater eroded by a 40-keV C(60)(+) cluster ion beam on an organic film of Irganox 1010 doped with Irganox 3114 delta layers. From an examination of the resulting surface, the information about depth resolution, topography, and erosion rate can be obtained as a function of crater depth for every depth in a single experiment. It is shown that when measurements are performed at liquid nitrogen temperature, a constant erosion rate and reduced bombardment induced surface roughness is observed. At room temperature, however, the erosion rate drops by ∼(1)/(3) during the removal of the 400 nm Irganox film and the roughness gradually increased to from 1 nm to ∼4 nm. From SIMS lateral images of the beveled crater and AFM topography results, depth resolution was further improved by employing glancing angles of incidence and lower primary ion beam energy. Sub-10 nm depth resolution was observed under the optimized conditions on a routine basis. In general, we show that the wedge-crater beveling is an important tool for elucidating the factors that are important for molecular depth profiling experiments.

FT-IR, FT-Raman spectra, density functional computations of the vibrational spectra and molecular geometry of butylated hydroxy toluene

The FT-IR spectrum of 2,6-di-tert-butyl-4-methylphenol [butylated hydroxy toluene] was recorded in the region 4000-400 cm(-1). The FT-Raman spectrum of butylated hydroxy toluene was also recorded in the region 3500-50 cm(-1). The molecular structure and vibrational frequencies of butylated hydroxy toluene (BHT) have been investigated with combined experimental and theoretical study. Two stable conformers of the title compound were obtained from the result of geometry optimizations of these possible conformers. The conformer 1 is (approximately 2.6 kcal/mol) more stable than conformer 2. Geometry optimizations and vibrational frequency calculations were performed by BLYP and B3LYP methods using 6-31G(d), 6-31G(d,p) and 6-31+G(d,p) as basis sets. The scaled frequencies were compared with experimental spectrum and on the basis of this comparison; assignments of fundamental vibrational modes were examined. Comparison of the experimental spectra with harmonic vibrational wavenumbers indicates that B3LYP/6-31G(d) results are more accurate. Predicted electronic absorption spectra of BHT from TD-DFT calculation have been analyzed and compared with the experimental UV-vis spectrum. The calculated HOMO and LUMO energies show that the charge transfer occurs within the molecule.

The characteristics of performance and exhaust emissions of a diesel engine using a biodiesel with antioxidants

The aim of this study is to investigate the effects of antioxidants on the oxidation stability of biodiesel fuel, the engine performance and the exhaust emissions of a diesel engine. Biodiesel fuel used in the study was derived from soybean oil. The results show that the efficiency of antioxidants is in the order TBHQ>PrG>BHA>BHT>alpha-tocopherol. The oxidative stability of biodiesel fuel attained the 6-h quality standard with 100 ppm TBHQ and with 300 ppm PrG in biodiesel fuel. Combustion characteristics and exhaust emissions in diesel engine were not influenced by the addition of antioxidants in biodiesel fuel. The BSFC of biodiesel fuel with antioxidants decreased more than that of biodiesel fuel without antioxidants, but no trends were observed according to the type or amount of antioxidant. Antioxidants had few effects on the exhaust emissions of a diesel engine running on biodiesel.

Sensitive, quantitative carbon-13 NMR spectra by mechanical sample translation

Collecting a truly quantitative carbon-13 spectrum is a time-consuming chore. Very long relaxation delays, required between transients to allow the z-magnetization, M(z), of the spin with the longest T(1) to return to the equilibrium value, M(0), must precede each transient. These long delays also reduce sensitivity, as fewer transients per unit time can be acquired. In addition, sometimes T(1) is not known to within even a factor of two: a conservative guess for the relaxation delay then leads to very low sensitivity. We demonstrate a fresh method to bypass these problems and collect quantitative carbon-13 spectra by swapping the sample volume after each acquisition with a different portion where the magnetization is already equilibrated to M(0). Loading larger sample volumes of 10-20 mL into an unusually long (1520 mm) 5 mm OD. NMR tube and vertically sliding the tube between acquisitions accomplishes the swap. The relaxation delay can then be skipped altogether. The spectra are thus both quantitative, and far more sensitive. We demonstrate the moving tube technique on two small molecules (thymol and butylhydroxytoluene) and show good carbon-13 quantification. The gain in sensitivity can be as much as 10-fold for slowly-relaxing (13)C resonances. These experiments show that quantitative, sensitive carbon-13 spectra are possible whenever sufficient sample volumes are available. The method is applicable to any slow-relaxing nuclear spin species, such as (29)Si, (15)N and other low-gamma nuclei.

Mechanisms of cytotoxicity of 2- or 2,6-di-tert-butylphenols and 2-methoxyphenols in terms of inhibition rate constant and a theoretical parameter

To clarify the mechanism of phenol toxicity, the radical-scavenging activity of 2- or 2,6-di-tert-butyl- and 2-methoxy-substituted phenols was investigated by combining two distinct approaches: first, the induction period method for methacrylate polymerization initiated by benzoyl peroxide or 2,2'-azobisisobutyronitrile; and secondly, 1,1'-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging test. The homolytic bond dissociation enthalpy (BDE) and ionization potential (IP(koopman)) were calculated by the DFT/B3LYP method. The cytotoxicity was investigated using tumor cells (human submandibular gland carcinoma cells, HSG; human promyelocytic leukemia cells, HL-60) and primary cells (human gingival fibroblasts, HGF; human periodontal ligament fibroblasts, HPLF; human pulp fibroblasts, HPF) derived from oral tissues. The cytotoxicity between tumor and primary cells was similar, except for eugenol dimer showing less toxicity for primary cells. The DPPH assay was not useful for tert-butylphenols due to their steric hindrance. For both HSG and HGF cells, a linear relationship was found between 50% cytotoxic concentration (CC(50)) and inhibition rate constant (k(inh)), but not BDE, IP, or logP. The acceptable quantitative structure-activity relationships (QSAR) obtained for cytotoxicity vs. k(inh) suggested that the cytotoxicity of phenols may be dependent on radical reactions. The cytotoxicity of vanillin and 3,5-di-tert-butyl-4-hydroxy-benzaldehyde with large k(inh) values, weak antioxidants was markedly less than that of 2,6-di-tert-butyl-4-methylphenol, 2,4,6-tri-tert-butylphenol and curcumin with small k(inh) values, potent antioxidants.

Cluster ion beam profiling of organics by secondary ion mass spectrometry--does sodium affect the molecular ion intensity at interfaces?

The use of cluster ion beam sputtering for depth profiling organic materials is of growing technological importance and is a very active area of research. At the 44th IUVSTA Workshop on "Sputtering and Ion Emission by Cluster Ion Beams", recent results were presented of a cluster ion beam depth profile of a thin organic molecular layer on a silicon wafer substrate. Those data showed that the intensity of molecular secondary ions is observed to increase at the interface and this was explained in terms of the higher stopping power in the substrate and a consequently higher sputtering yield and even higher secondary ion molecular sputtering yield. An alternative hypothesis was postulated in the workshop discussion which may be paraphrased as: "under primary ion bombardment of an organic layer, mobile ions such as sodium may migrate to the interface with the inorganic substrate and this enhancement of the sodium concentration increases the ionisation probability, so increasing the molecular ion yield observed at the interface". It is important to understand if measurement artefacts occur at interfaces for quantification as these are of great technological relevance - for example, the concentration of drug in a drug delivery system. Here, we evaluate the above hypothesis using a sample that exhibits regions of high and low sodium concentration at both the organic surface and the interface with the silicon wafer substrate. There is no evidence to support the hypothesis that the probability of molecular secondary ion ionisation is related to the sodium concentration at these levels.

Use of the Antioxidant BHT in Asymmetric Membrane Tablet Coatings to Stabilize the Core to the Acid Catalyzed Peroxide Oxidation of a Thioether Drug

The application of a controlled-release asymmetric membrane (AM) coating containing cellulose acetate and polyethylene glycol 3350 (PEG3350) to a stable osmotic tablet core resulted in the oxidative degradation of active ingredient located in the core. It was hypothesized that the production of hydroperoxides from PEG3350 in the coating was responsible for the electrophilic oxidation of drug to the sulfoxide degradation product. The type and solubility of carboxylic acid excipient used to formulate the drug release profile of the osmotic tablet significantly influenced the amount of oxidation. By adding the antioxidant butylated hydroxytoluene (BHT) to the coating, oxidation was significantly inhibited in tablets placed on accelerated stability. Of three additives that were used to prevent oxidation [BHT, ferrous sulfate, and ethylenediaminetetraacetic acid (EDTA)], BHT was shown to be the most effective at preventing sulfoxide formation. The BHT was also shown to be more effective in the coating rather than in the core due to its location closer to the source of the oxidizing species, PEG3350, in the coating.

Permeability and Retention Studies of (-)Epicatechin Gel Formulations in Human Cadaver Skin

(-)Epicatechin (EC) is a major antioxidant component of grape seed extract which has become increasingly popular in topical skin preparations. This study assessed the following: (1) the permeability through cellulose membranes of EC in three different gel formulations (Carbopol 940, Klucel, and Ultrez 10); (2) the effect of three different antioxidants (butylated hydroxytoluene (BHT), alpha-tocopherol (VE), and ascorbic acid (AA)) on the stability and penetration properties of EC; and (3) the permeability and retention of EC in Ultrez 10 gels, supplemented with BHT or VE, on human cadaver skin. Permeability studies through cellulose membranes showed that different gelling agents do not significantly affect the permeability of EC (n = 7/gel; p > 0.05). BHT and VE have antioxidant properties superior to AA (p < 0.05) and preserve 100% of the initial content of EC for 28 days. Permeation studies on cadaver human skin, following application of two anhydrous gel formulations (0.5% EC in Ultrez 10 containing BHT or VE), showed that EC was not detectable in the receiving solution. However, the EC amount in viable skin increased with time, indicating that EC penetrated and was retained in the upper part of the skin for approximately 1% and 3% of the dose for the formulations containing BHT and VE, respectively.

Chemical composition, antioxidant and antimicrobial properties of the essential oils of three Salvia species from Turkish flora

Essential oils of three different Salvia species [Salvia aucheri var. aucheri (endemic), Salvia aramiensis and Salvia pilifera (endemic)] were screened for their possible antioxidant and antimicrobial properties as well as their chemical compositions. According to the gas chromatography (GC)/EIMS (gas chromatography/electron impact mass spectrum) analysis results; 41 (97.2%), 51 (98.5%) and 83 compounds (98.2%) were identified, respectively. While 1,8-cineole (30.5%), camphor (21.3%) and borneol (8.50%) are the major compounds for S. aucheri var. aucheri oil, beta-pinene (10.3%), was the main constituent for S. aramienesis together with 1,8-cineole (46.0%) and camphor (8.7%). In the case of S. pilifera oil, alpha-thujene (36.1%) and alpha-pinene (13.8%) determined as the major compounds. Antioxidant activity was employed by two complementary test systems namely 2,2'-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and beta-carotene/linoleic acid systems. Antioxidant activity of S. aramiensis was found to be higher than those of the others for the both systems (12.26+/-1.09 and 92.46%+/-1.64 microg mg(-1), respectively). Additionally, antioxidant activities of BHT, curcumin, ascorbic acid and alpha-tocopherol were determined in parallel experiments. In the case of antimicrobial activity, similar activity pattern was obtained (both in disc diffusion and MIC tests). Antimicrobial activity of S. aramiensis was followed by S. aucheri var. aucheri and S. pilifera, respectively. In these experiments, the most sensitive microorganism Acinetobacter lwoffii was followed by Candida albicans.

A novel method to measure both the reductive and the radical scavenging activity in a linoleic acid model system

The aim of this study was to develop a combined method for measuring the total antioxidant activity, the reductive and the radical scavenging activity. Linoleic acid was used as the substrate for an iron-initiated lipid peroxidation to measure the total antioxidant activity. In addition, methyl esters of linoleic acid hydroperoxides were used as substrates to measure the reductive antioxidant activity. The radical scavenging antioxidant activity was calculated by subtracting the reductive antioxidative activity from the total antioxidative activity. As representative examples, the antioxidants alpha-tocopherol, ascorbic acid, trans-resveratrol and L-glutathione as well as commonly used food additives such as 2(3)-tert-butyl-4-hydroxyanisole (BHA) and 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT) were analyzed. The results for the novel antioxidation test showed that alpha-tocopherol, BHA and BHT are primarily acting as radical scavengers, whereas ascorbic acid and L-glutathione show a strong reductive capacity. As linoleic acid as well as its hydroperoxides both are present in foods and in the organism, the test presented here can be considered representative of radical reactions occurring in food matrixes and in vivo. Further experiments are required to document the comprehensive applicability in foods and in vivo.

Mitochondrial uncouplers with an extraordinary dynamic range

We have discovered that some weak uncouplers (typified by butylated hydroxytoluene) have a dynamic range of more than 10(6) in vitro: the concentration giving measurable uncoupling is less than one millionth of the concentration causing full uncoupling. They achieve this through a high-affinity interaction with the mitochondrial adenine nucleotide translocase that causes significant but limited uncoupling at extremely low uncoupler concentrations, together with more conventional uncoupling at much higher concentrations. Uncoupling at the translocase is not by a conventional weak acid/anion cycling mechanism since it is also caused by substituted triphenylphosphonium molecules, which are not anionic and cannot protonate. Covalent attachment of the uncoupler to a mitochondrially targeted hydrophobic cation sensitizes it to membrane potential, giving a small additional effect. The wide dynamic range of these uncouplers in isolated mitochondria and intact cells reveals a novel allosteric activation of proton transport through the adenine nucleotide translocase and provides a promising starting point for designing safer uncouplers for obesity therapy.

A rapid technique to evaluate the oxidative stability of a model drug

The objective of the current study was to investigate the oxidative induction time (OIT) as a measurement of the stability of an oxygen-sensitive model drug. The OIT was determined by differential scanning calorimetry and represents the time required for oxidative decomposition to occur at a given temperature. Samples were heated to a specific temperature under a nitrogen blanket then held isothermal while exposed to oxygen. The experiment proceeded until oxidative degradation of the sample was apparent from the real-time heat flow graphs. Variables investigated in this study included different lots and suppliers of a model drug as well as the addition of antioxidants. Results demonstrated that the stability of the drug was dependent on the supplier. All antioxidants investigated in this study improved oxygen stability of the model compound, as evidenced by a longer OIT. Butylated hydroxyanisole (BHA) was found to better stabilize the drug than butylated hydroxytoluene at equivalent concentrations. The combination of ascorbic acid and BHA provided the greatest protection against oxidation of the model compound. The results of this study demonstrate the usefulness of OIT to investigate the oxygen stability of pharmaceutical compounds.