Synthesis, characterization, antimicrobial, cytotoxic and carbonic anhydrase inhibition activities of multifunctional pyrazolo-1,2-benzothiazine acetamides

• Ayesha Saeed,
• Shahana Ehsan,
• Muhammad Zia-ur-Rehman,
• Erin M. Marshall,
• Sandra Loesgen,
• Abdus Saleem,
• Simone Giovannuzzi and
• Claudiu T. Supuran

Beilstein J. Org. Chem. 2025, 21, 348–357, doi:10.3762/bjoc.21.25

• , makes them a suitable linker unit [34]. The leading example is paracetamol highlighting the utility of an amide containing scaffold in medicinal chemistry. A series of novel scaffolds adjoining benzothiazine with a pyrazole moiety has been reported with antioxidant activity and antibacterial potential

Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies

• Lucía Campos-Prieto,
• Aitor García-Rey,
• Eddy Sotelo and
• Ana Mallo-Abreu

Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261

• , cholinesterase inhibition (human BuChE, hBuChE), Aβ1-42 self-aggregation inhibition, and antioxidant activity. FATH 5a (Scheme 5) emerged as a promising candidate, showing lower hepatotoxicity at 1000 µM (59.4%, 1.72-fold less toxic than tacrine), moderate and selective hBuChE inhibition (IC50 = 68.2 nM), strong

• obtained intermediates with the appropriate commercial lactams, under microwave irradiation (Scheme 8). As a result, compound 8a has been identified as a promising derivative potentially useful in further AD drug discovery for its antioxidant activity (4.7 TE in ORAC-FL assay), moderate hAChE inhibition

• channel blockade was determined by the measure of Ca2+ influx induced by K+-depolarization in SH-SY5Y neuroblastoma cells, previously loaded with the fluorescent dye Fluo-4AM. On the other hand, the antioxidant activity of the DHPs was evaluated using the ORAC-FL method. The most potent compounds

Synthesis, electrochemical properties, and antioxidant activity of sterically hindered catechols with 1,3,4-oxadiazole, 1,2,4-triazole, thiazole or pyridine fragments

• Daria A. Burmistrova,
• Andrey Galustyan,
• Nadezhda P. Pomortseva,
• Kristina D. Pashaeva,
• Maxim V. Arsenyev,
• Oleg P. Demidov,
• Mikhail A. Kiskin,
• Andrey I. Poddel’sky,
• Nadezhda T. Berberova and
• Ivan V. Smolyaninov

Beilstein J. Org. Chem. 2024, 20, 2378–2391, doi:10.3762/bjoc.20.202

• : antioxidant activity; catechol thioethers; heterocycles; redox-transformations; thiones; Introduction Synthetic derivatives of polyphenols, in particular catechol (hydroquinone), represent a promising group of pharmacologically active substances [1][2]. Catechol-containing compounds demonstrate

• the electrochemical properties of functionalized catechols allows one to suggest the mechanism of their electrooxidation, establish electron transfer centers, and predict antioxidant activity based on electrochemical data. To determine electron-transfer centers, the oxidation potentials of the

• factors: the nature of the heterocycle and its substituents, the presence/absence of a sulfur atom in the catechol ring or thione sulfur atom in the heterocyclic core. Based on electrochemical data, it can be assumed that the most pronounced antioxidant activity can be exhibited by compounds with minimal

Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

• ] and Alternaria sp. [28][47][154] (Figure 8). It showed antioxidant activity with an IC50 value of 42.8 μM [153], inhibited about 90% of iNOS (inducible nitric oxide synthase) expression when applied at 20 μM, decreased the protein expression levels of pro-inflammatory cytokines (tumor necrosis factor

A new analog of dihydroxybenzoic acid from Saccharopolyspora sp. KR21-0001

• Rattiya Janthanom,
• Yuta Kikuchi,
• Hiroki Kanto,
• Tomoyasu Hirose,
• Arisu Tahara,
• Takahiro Ishii,
• Arinthip Thamchaipenet and
• Yuki Inahashi

Beilstein J. Org. Chem. 2024, 20, 497–503, doi:10.3762/bjoc.20.44

• but showed potent antioxidant activity. Keywords: antioxidant activity; dihydroxybenzoic acid analog; rare actinomycetes; Introduction Actinomycetes are Gram-positive bacteria with high GC content in their genome. They are well-known as the main producers of bioactive compounds such as antibiotic

• ). Antioxidant activity of 1 was measured via the DPPH radical. 1 showed potent DPPH radical scavenging activity with an IC50 value of 5.0 μg·mL−1, which is lower than that of trolox (IC50; 7.5 μg·mL−1) (Table 2). In contrast, 1 did not show antimicrobial activity against Gram-positive and Gram-negative bacteria

• ), fungi (e.g., Aspergillus sojae and Penicillium roquefortii), and bacteria (e.g., Acinetobacter calcoaceticus, Brucella abortus, and Bacillus sp.) [15]. It is also known to be a component of some natural products, such as enterobactin, showing strong radical scavenging activity or antioxidant activity

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• screenings and they present a wide spectrum of pharmacological activities [1][2]. Thus, for example, 3,4-dihydroxybenzylidenerhodanine (A) showed a high antioxidant activity with 71.2% of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity [3]. Naphthalen-2-ylmethylidenerhodanine (B) has been

• synthesis of NaDES plays a major role in the resulting viscosity [20]. For example, ʟ-proline/glycerol (Pro/Gly; 1:2) was found to have a pH value of 7.25 and a viscosity of 5064 cP [20]. In 2018, Molnar et al. reported the antioxidant activity of a series of rhodanine derivatives synthesized by a

• recycled for several runs [20]. As some benzylidenerhodanine derivatives were already reported for their antioxidant activities [3], we investigated those compounds for their antioxidant activity expressed as percentage of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity. DPPH free radicals

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• of oils and fats is the addition of antioxidants. Among food grade antioxidants, natural polyphenols such as flavonoids and flavonoid-based extracts are widely used [35][36][37][38][39][40][41]. Generally, flavonoids have a high number of phenolic hydroxy groups that provide the antioxidant activity

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• host against oxidative radicals generated by UV irradiation [25][32]. To verify the antioxidative effect of the isoflavone dimers, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)-based antioxidant activity was performed [33]. The results showed that while 2 and 3 had an activity roughly

• equal to the monomers 4 and 6, 1 displayed a roughly twofold radical scavenging capacity (Figure S9, Supporting Information File 1). This is in agreement with the previous report that the configuration of the hydroxy group of the B-ring plays a key role in the antioxidant activity [34]. Thus, CYP158C1

• mM NADPH, 0.2 mM DTT, and 1 mM EDTA in 50 mM PBS buffer (pH 7.4). The reaction mixture was incubated at 37 °C for 1 h and quenched by adding 50 µL MeOH. After centrifugation (10 min, 13,000 rpm), the mixture was subjected to HPLC–UV or UHPLC–HRMS analysis. Antioxidant activity The antioxidant

Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides

• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90

• dioxane for 2 h. It was generated from the intramolecular aminolysis of diphenyl 3,5-di(tert-butyl)-4-hydroxyphenyl-(2,6-diaminopyridin-3-yl)methylphosphonate (251) and showed excellent antioxidant activity (Scheme 40) [18]. Conclusion 1,2-Azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides are

Chemistry of polyhalogenated nitrobutadienes, 17: Efficient synthesis of persubstituted chloroquinolinyl-1H-pyrazoles and evaluation of their antimalarial, anti-SARS-CoV-2, antibacterial, and cytotoxic activities

• Viktor A. Zapol’skii,
• Isabell Berneburg,
• Ursula Bilitewski,
• Melissa Dillenberger,
• Katja Becker,
• Stefan Jungwirth,
• Aditya Shekhar,
• Bastian Krueger and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2022, 18, 524–532, doi:10.3762/bjoc.18.54

• falciparum strain [19]. Certain 7-chloroquinolinyl-pyrazole derivatives have also shown antibacterial [20], hypoglycemic as well as antioxidant activity [21] or can be used as selective nonpeptide neurotensin receptor type 2 compounds [22]. Some azolylquinolines have been used as agrochemical fungicides

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• evaluated against their antioxidant activity and exhibited promising activity. Protein tyrosine phosphatase 1B (PTP1B) is essential in the dephosphorylation of the activated insulin receptor, and inhibition of this enzyme would be an excellent strategy for the treatment of type 2 diabetes. Ahn and co

Host–guest interaction of cucurbit[8]uril with oroxin A and its effect on the properties of oroxin A

• Zhishu Zeng,
• Jun Xie,
• Guangyan Luo,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 2332–2337, doi:10.3762/bjoc.16.194

• addition of Q[8]. When the concentration of Q[8] was 1.0 × 10−4 mol·L−1, the solubility of OA was increased 22.47-fold. The solubility curve equation was S = 0.01c + 0.0575, R2 = 0.9986. Antioxidant activity OA has strong antioxidant activity and effectively eliminates ABTS+• radicals. If the antioxidant

• and 4.80 × 10−6 mol·L−1, respectively, which indicates that Q[8] did not affect the antioxidant activity of OA. Drug release in vitro Figure 8 shows the cumulative release of the OA and the OA@Q[8] inclusion complex in artificial gastric juice (pH 1.2) and artificial intestinal juice (pH 6.8). It can

• −1. The results of the UV absorption spectrum analysis showed that Q[8] enhanced the cumulative release of OA in artificial gastric juice by 2.3-fold, but had no effect on its antioxidant activity. The molecular structure of OA (A) and Q[8] (B). 1H NMR titration of OA with Q[8] were performed in D2O

4-Hydroxy-3-methyl-2(1H)-quinolone, originally discovered from a Brassicaceae plant, produced by a soil bacterium of the genus Burkholderia sp.: determination of a preferred tautomer and antioxidant activity

• Dandan Li,
• Naoya Oku,
• Yukiko Shinozaki,
• Yoichi Kurokawa and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1489–1494, doi:10.3762/bjoc.16.124

• -hydroxy-3-methyl-2(1H)-quinolone (1, Figure 1). This compound was recently reported from the root of woad (Isatis tinctoria, family Brassicaceae) with no details of structure characterization [17]. Herein we describe the isolation, unequivocal structure characterization, and antioxidant activity of

• Alternaria alternata [36], staphyloxanthin from a firmicute Staphylococcus aureus [37], vitamin B6 from fungi Cercospora nicotianae, [38] and Rhizoctonia solani [39], and a melanin-like pigment from Burkholderia cenocepacia [40]. The antioxidant activity of 1 was evaluated using the luminol chemiluminescence

• caused biphasic separation of the mixture. Antimicrobial assay The antimicrobial activity was evaluated by the method described previously [16]. Antioxidant assay The antioxidant activity was evaluated by the method described in [41]. Briefly, luminol (10 μM), H2O2 (1000 μM), and vehicle solvent with or

Synthesis of pyrrolidinedione-fused hexahydropyrrolo[2,1-a]isoquinolines via three-component [3 + 2] cycloaddition followed by one-pot N-allylation and intramolecular Heck reactions

• Xiaoming Ma,
• Suzhi Meng,
• Xiaofeng Zhang,
• Qiang Zhang,
• Shenghu Yan,
• Yue Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2020, 16, 1225–1233, doi:10.3762/bjoc.16.106

• crispine A isolated from Carduus crispus L has antitumor activity [3]. Erythrina alkaloids have curare-like neuromuscular blocking activities [4], and also antioxidant activity against DPPH free radicals [5]. Lamellarins isolated from marine invertebrates [6] are inhibitors for HIV-1 integrase and also

Synthesis and anticancer activity of bis(2-arylimidazo[1,2-a]pyridin-3-yl) selenides and diselenides: the copper-catalyzed tandem C–H selenation of 2-arylimidazo[1,2-a]pyridine with selenium

• Mio Matsumura,
• Tsutomu Takahashi,
• Hikari Yamauchi,
• Shunsuke Sakuma,
• Yukako Hayashi,
• Tadashi Hyodo,
• Tohru Obata,
• Kentaro Yamaguchi,
• Yasuyuki Fujiwara and
• Shuji Yasuike

Beilstein J. Org. Chem. 2020, 16, 1075–1083, doi:10.3762/bjoc.16.94

• variety of methods [14][15], and many of the targets exhibited biological activity (Figure 1). For example, bis(2-pyridyl) diselenide I has the potential to mitigate oxidative stress and inhibits the AChE activity [16], bis(quinolin-8-yl) diselenide (II) exhibited antioxidant activity in a skin cell model

The interaction between cucurbit[8]uril and baicalein and the effect on baicalein properties

• Xiaodong Zhang,
• Jun Xie,
• Zhiling Xu,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 71–77, doi:10.3762/bjoc.16.9

• solution using 1H NMR, UV–vis and IR spectroscopy, and DTA. The properties of the BALE–Q[8] inclusion complex, such as stability, solubility, in vitro antioxidant activity and release performance were studied by means of UV–vis spectroscopy. Results and Discussion Host–guest interactions Q[8] and BALE in

• Supporting Information File 1). If the BALE–Q[8] complex significantly reduces its antioxidant activity, this will affect the medicinal value of BALE. Figure 9 shows that Q[8] has no significant influence on the antioxidant activity of BALE. At 0.0005–0.004 mmol·L−1, BALE exhibited a linear increasing

• 3.4 × 105 L·mol−1 (neutral water). The solubility of BALE increased 4.67-fold in the phase-solubility experiment when the concentration of Q[8] was 1 × 10−4 mol·L−1. A study of the UV–vis absorption spectra with time showed that Q[8] significantly increased the stability of BALE. The antioxidant

In water multicomponent synthesis of low-molecular-mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines

• Irina G. Tkachenko,
• Sergey A. Komykhov,
• Vladimir I. Musatov,
• Svitlana V. Shishkina,
• Viktoriya V. Dyakonenko,
• Vladimir N. Shvets,
• Mikhail V. Diachkov,
• Valentyn A. Chebanov and
• Sergey M. Desenko

Beilstein J. Org. Chem. 2019, 15, 2390–2397, doi:10.3762/bjoc.15.231

• -dihydrotetrazolo[1,5-a]pyrimidine derivatives. Under similar conditions using 4,4,4-trifluoroacetoacetic ester 5-hydroxy-4,5,6,7-tetrahydrotetrazolo[1,5-a]pyrimidines are obtained. The analogous reaction with acetylacetone requires scandium(III) triflate as catalyst. The antioxidant activity of selected compounds

• was assayed with 1,1-diphenyl-2-picrylhydrazyl. Keywords: 5-aminotetrazole; antioxidant activity; 1,3-dicarbonyl compounds; multicomponent synthesis; tetrazolo[1,5-a]pyrimidines; Introduction Tetrazolo[1,5-a]pyrimidines and their partially hydrogenated derivatives are known for their interesting

• merely weak NOE for those groups in isomer A further allowed to propose a cis-orientation of these substituents for isomer B and the opposite one for A (Scheme 4). Antioxidant properties of 9, 11, 14 Among the methods for the antioxidant activity (AOA) estimation, using 1,1-diphenyl-2-picrylhydrazyl

Solid-state studies and antioxidant properties of the γ-cyclodextrin·fisetin inclusion compound

• Joana M. Pais,
• Maria João Barroca,
• Maria Paula M. Marques,
• Filipe A. Almeida Paz and
• Susana S. Braga

Beilstein J. Org. Chem. 2017, 13, 2138–2145, doi:10.3762/bjoc.13.212

• using elemental analysis, powder X-ray diffraction (PXRD), Raman, infrared and 13C{1H} CP-MAS NMR spectroscopies, and thermal analysis (TGA) to verify fisetin inclusion and to present a hypothetical structural arrangement for the host–guest units. The antioxidant activity of the γ-CD·fisetin inclusion

• compound is evaluated by the DPPH assay. Keywords: antioxidant activity; co-lyophilization; fisetin; gamma-cyclodextrin; molecular encapsulation; solid-state analysis; Introduction Flavonoids, natural compounds with numerous beneficial actions on human health, including antioxidant [1], anti-inflammatory

• using solid-state techniques was carried out to confirm fisetin inclusion into the cavity of γ-CD, and to present the hypothetical structural arrangement of the host–guest units. Further, the retention of the antioxidant activity in the inclusion compound was evaluated by its ability to scavenge the

Use of costic acid, a natural extract from Dittrichia viscosa, for the control of Varroa destructor, a parasite of the European honey bee

• Kalliopi Sofou,
• Demosthenis Isaakidis,
• Apostolos Spyros,
• Anita Büttner,
• Athanassios Giannis and
• Haralambos E. Katerinopoulos

Beilstein J. Org. Chem. 2017, 13, 952–959, doi:10.3762/bjoc.13.96

• essential oil were found active against Staphylococcus epidermidis, Streptococcus foecalis and Proteus vulgaris [36]. The methanol extract of the aerial parts of the plant showed antioxidant activity in a study on lipid peroxidation of rat liver microsomes [30]. n-Hexane extracts from air dried D. viscosa

Biomimetic synthesis and HPLC–ECD analysis of the isomers of dracocephins A and B

• Viktor Ilkei,
• András Spaits,
• Anita Prechl,
• Áron Szigetvári,
• Zoltán Béni,
• Miklós Dékány,
• Csaba Szántay Jr,
• Judit Müller,
• Árpád Könczöl,
• Ádám Szappanos,
• Attila Mándi,
• Sándor Antus,
• Ana Martins,
• Attila Hunyadi,
• György Tibor Balogh,
• György Kalaus (†),
• Hedvig Bölcskei,
• László Hazai and
• Tibor Kurtán

Beilstein J. Org. Chem. 2016, 12, 2523–2534, doi:10.3762/bjoc.12.247

• increase P-gp inhibitory activity [18]. Based on the unaltered accumulation of rhodamine 123, a P-gp substrate fluorescent dye, in the P-gp transfected L5178MDR cells, we observed that none of the synthesized compounds inhibits this transporter. The antioxidant activity of dracocephins A and B was also

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• chestnut) showed antioxidant activity [28]. Testing urolithins A, B, C, D (23–26) in an assay using myelomonocytic HL-60 cells showed antioxidant activities for 23, 25 and 26. These three derivatives inhibited the reactive oxygen species (ROS)-dependent oxygenation of the non-fluorescent 2’,7

• ’-dichlorodihydrofluorescein (DCFH) to the fluorescent 2’,7’-dichlorofluorescein (DCF) [29]. This antioxidant activity was also linked to anti-inflammatory effects by testing the in vivo effects of 23 in a carrageenan-induced paw edema assay. Oral administration of 23 to mice prior to carrageenan injection resulted in a

A selective and mild glycosylation method of natural phenolic alcohols

• Mária Mastihubová and
• Monika Poláková

Beilstein J. Org. Chem. 2016, 12, 524–530, doi:10.3762/bjoc.12.51

• phenylpropenyl) glycosides having a free phenolic function at the para-position of the aglycone are substances widely occurring in plants. They exhibit numerous biological activities which are in many cases related to their structure–antioxidant activity relationship. 4-Hydroxy-3-methoxybenzyl β-D

Determination of formation constants and structural characterization of cyclodextrin inclusion complexes with two phenolic isomers: carvacrol and thymol

• Miriana Kfoury,
• David Landy,
• Steven Ruellan,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2016, 12, 29–42, doi:10.3762/bjoc.12.5

• 2 are described as potent free-radical scavengers [29]. Moreover, it is well accepted that a wide variety of essential oils possess important antioxidant activities due to their high content in 1 and 2 [50]. In this work, the effect of encapsulation on the antioxidant activity of 1 and 2 was

• evaluated. The ABTS•+ assay is commonly applied to determine the antioxidant activity of CD inclusion complexes [51][52][53][54]. We performed this test to determine the radical scavenging ability of 1 and 2 as well as the activity of their corresponding β-CD and HP-β-CD inclusion complexes. Trolox was used

• increased antioxidant activity could be attributed to the encapsulation of 1 and 2 in CDs [51]. Inclusion in CD cavity could protect and stabilize the formed phenoxyl radicals after reaction with ABTS•+ leading to an enhanced activity by delaying its oxidation. It has been also demonstrated that CDs could

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

• Ivan Bassanini,
• Karl Hult and
• Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

• fungal β-N-acetylhexosaminidase evaluated [28]. Similarly, dimers of sylibin (11a,b, Figure 3) and dehydrosylibin, obtained by Novozyme 435-catalyzed acylation with the divinyl esters of dodecanedioc acid, were evaluated in terms of antioxidant activity and cytotoxicity [29]. The obvious hypothesis

Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations

• Adriana K. Slavova-Kazakova,
• Silvia E. Angelova,
• Timur L. Veprintsev,
• Petko Denev,
• Davide Fabbri,
• Maria Antonietta Dettori,
• Maria Kratchanova,
• Vladimir V. Naumov,
• Aleksei V. Trofimov,
• Rostislav F. Vasil’ev,
• Giovanna Delogu and
• Vessela D. Kancheva

Beilstein J. Org. Chem. 2015, 11, 1398–1411, doi:10.3762/bjoc.11.151

• (model 4), which qualitatively supports the experimental results. Keywords: antioxidant activity; chain-breaking efficiencies; chemiluminescence kinetics; DFT calculations; scavenging activity (ORAC); Introduction Bioantioxidants have played an important role throughout the last decade in the

• the synthesis of pharmacologically and agrochemically active new compounds. The present study demonstrates experimental and theoretical models for assessing radical scavenging and antioxidant activity of curcumin-related hydroxylated biphenyls (dimers) and their corresponding monomers. Four models

• : It is evident that in this model DL-α-tocopherol (11) is also the most efficient antioxidant, and ensures the highest oxidative stability of the lipid substrate. The observed lower antioxidant activity of monomers and dimers with respect to 11 is expected as a result of the higher BDE of phenolic –OH