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

• to inhibit p38α MAPK and 0.5 µM for TNF-α [10]. Pyrazolobenzothiazines containing a triazole moiety have also been studied as potential antibacterial drugs [7]. Other applications of N-substituted benzyl/phenyl acetamide pyrazolobenzothiazines include superoxide anion and DPPH radical scavenging

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

• in the reaction with a diphenylpicrylhydrazyl (DPPH) radical, ABTS·+ radical cation, CUPRAC test, and inhibition process of superoxide radical anion formation by xanthine oxidase (NBT assay). The presence of a catechol fragment and thioether or thione groups determines the ability to neutralize

• different radical species. A comparative evaluation of the antioxidant activity of catechols 1–9 and Trolox was performed in a reaction with DPPH in dichloromethane at 298 K (Table 2). Based on the IC50 value, compound 3 with a 4-phenylthiazole ring linked through a sulfur atom to the catechol ring exhibits

• the highest activity (13.0 ± 1.0 µM) in the reaction with the DPPH radical. The number of converted DPPH molecules per one molecule of 3 is equal to two. Comparable IC50 values were obtained for catechol thioethers 4 and 5 with methylene bridge. As in the case of compound 3, catechol 4 contains a 4

Natural resorcylic lactones derived from alternariol

• Joachim Podlech

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

• -picrylhydrazyl radical (DPPH; IC50: 9.6 μM) and hydroxyl radicals (scavenging activity of 70% and 91% at 0.05 and 0.27 μg/mL, respectively) [169][176]. Furthermore, it turned out to be cytotoxic against SW1116 cells (IC50: 9.5 μg/mL) [168]. The trimethyl ether of 4-hydroxyalternariol was named ‘graphislactone H

• Staphylococcus aureus (MIC: 64 µg/mL) and DPPH radical-scavenging activity (IC50: 12 μg/mL) [205]. It furthermore inhibited α-glucosidase with an IC50 value of 6.3 µM [206]. Graphislactones C and D (39 and 40) were isolated from the lichen Graphis scripta var. pulverulenta [45][165], graphislactone C was later

• Leishmania donovani (IC50: 7.1, 11.7 µM) [159], and against Xanthomonas oryzae pv. oryzae (MIC: 16 μg/mL) [212]. It turned out to be a scavenger of DPPH (IC50: 99 µM) [210] and showed neuroprotective effects against oxidative injuries [213]. Ulocladol (42), a further natural product bearing a seven-membered

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

• ). 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

• activity of KR21-0001A (1) was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) (Antioxidant Assay Kit, DOJINDO© laboratory, Japan) according to the manufacturer’s protocol. Antimicrobial activity KR21-0001A (1) was investigated for antibacterial and antifungal activities with two strains of Gram

• -0001A (1) in CD3OD. IC50 value of DPPH radical scavenging activity. Supporting Information Supporting Information File 14: Additional data and NMR spectra. Acknowledgements We are grateful to Distinguished Emeritus Professor Satoshi Ōmura (Kitasato University) for his helpful support and valuable

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

• 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

• give a purple solution and present a strong absorption maximum at 517 nm. In the presence of an antioxidant compound DPPH is reduced forming DPPH-H and the color of the solution changes to yellow. The overall antioxidant capacity of compounds was measured after 30 minutes of incubation. We used the

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

• hydroperoxy radical that can next evolve into an aldehyde by β-elimination of water, or after reduction, into an alcohol. The stability of the radical 10 is surprising. Stable radicals (O2, NO, nitroxyl derivatives, DPPH) are characterized by a two-center three-electron bond [56]. Conversely, the stability of

Total synthesis of decarboxyaltenusin

• Lucas Warmuth,
• Aaron Weiß,
• Marco Reinhardt,
• Anna Meschkov,
• Ute Schepers and
• Joachim Podlech

Beilstein J. Org. Chem. 2021, 17, 224–228, doi:10.3762/bjoc.17.22

• . [3][5][6], and from the endophytic fungus Botryosphaeria dothidea in Melia azedarach [7] it turned out to be a widely occurring natural product. It shows marked DPPH radical scavenging activities with determined IC50 values of 18.7 ± 0.2 μM [7] and 148 ± 3 μM [2], respectively, and displays

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

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

• (DPPH) is one of the most common and widespread [30][31][32][33]. The free radical scavenging activity of tetrazolo[1,5-a]pyrimidines 9d,f, 11, and 14 was measured spectrophotometrically as percentage of reducing the free-radical concentration in the presence of a test compound in methanol/dimethyl

• mixture of isomers. Some of the prepared tetrazolopyrimidines showed free-radical scavenging activity towards DPPH. Experimental General. The melting points were determined with a Gallenkamp melting point apparatus. The NMR spectra were recorded at 400 MHz with a Varian MR-400 spectrometer. The EIMS

• of 0.1 mmol/L DPPH (2 mL) in methanol was added to 2 mL of a solution of the investigated substance (9, 11, 14) in dimethyl sulfoxide (DMSO) at different concentrations (10−3, 10−5, 10−7 mol/L). The control solution was prepared by mixing 2 mL of DMSO and 0.1 mmol/L DPPH solution (2 mL). The mixture

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

• 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

• radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Results and Discussion The present report is divided into two main parts, the first one being the preparation of the inclusion compound of fisetin with γ-CD and its characterization by a collection of solid-state techniques. The second part comprises the

• evaluation of the antioxidant activity of the inclusion compound by the DPPH assay, and its comparison with that of pure fisetin. Preparation and characterization of γ-CD·fisetin The preparation of the γ-CD·fisetin inclusion complex was carried out by co-dissolution, followed by either co-crystallization or

Synthesis and evaluation of anti-oxidant and cytotoxic activities of novel 10-undecenoic acid methyl ester based lipoconjugates of phenolic acids

• Naganna Narra,
• Shiva Shanker Kaki,
• Rachapudi Badari Narayana Prasad,
• Sunil Misra,
• Koude Dhevendar,
• Venkateshwarlu Kontham and
• Padmaja V. Korlipara

Beilstein J. Org. Chem. 2017, 13, 26–32, doi:10.3762/bjoc.13.4

• structures were confirmed by spectral data. The anti-oxidant activity of the synthesized lipoconjugates of phenolic acids was studied by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and also by the inhibition of linoleic acid oxidation in micellar medium by differential scanning

• acids have been derivatized with other functionalities apart from esters. The reported compounds other than esters were amides where bioconjugates of fatty acids and amino acids were prepared and evaluated for their anti-oxidant activity by a DPPH radical assay [9]. In view of developing new conjugates

• of the prepared derivatives were studied by the well-established DPPH radical scavenging assay and also by studying the oxidation of linoleic acid using DSC. The DPPH radical is a commercially available stable free radical which is widely used to preliminarily determine the radical scavenging

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

• measured, but these compounds, along with naringenin were virtually inactive in the DPPH radical scavenging test (IC50 > 200 µg/mL), compared to the positive control quercetin (IC50 = 9.4 ± 0.6 µg/mL). Conclusion An efficient one pot synthesis of dracocephins A (2a–d) and B (3a–d) was achieved starting

Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

• Nikolay O. Chalkov,
• Vladimir K. Cherkasov,
• Gleb A. Abakumov,
• Andrey G. Starikov and
• Viacheslav A. Kuropatov

Beilstein J. Org. Chem. 2016, 12, 2450–2456, doi:10.3762/bjoc.12.238

• purified by standard methods [18]. X-band EPR spectra were recorded with a Bruker EMX spectrometer. The syntheses of reduced species as well as all spectroscopic investigations were carried out in the absence of oxygen. The standard for g-factor was DPPH (g = 2.0037). The 2,2’-benzene-1,4-diylbis(6-hydroxy

Methylenelactide: vinyl polymerization and spatial reactivity effects

• Judita Britner and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 2378–2389, doi:10.3762/bjoc.12.232

• ]. Thus, the ring shaped MLA is much more reactive in respect to the self-initiated polymerization. Calculated initial rate for the self-initiated polymerization of MLA by the use of DPPH As discussed above, the formation of free radicals is a key step for spontaneous polymerization of MLA. Accordingly

• , spontaneously formed radicals can be proved by the use of the strongly colored 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) which reacts with H radicals under decolorization. The consumption of DPPH-radicals can be followed by the naked eye. Figure 6 shows the UV–vis absorption spectra of DPPH from the

• beginning of the self-initiated polymerization at 70 °C and after 15 h. The concentration of DPPH plotted against the time at 70 °C and 30 °C gives a straight line indicating that the reaction follows pseudo zero-order kinetics (Figures S10 and S11, Supporting Information File 1). The slope of this plot

New furoisocoumarins and isocoumarins from the mangrove endophytic fungus Aspergillus sp. 085242

• Ze’en Xiao,
• Senhua Chen,
• Runlin Cai,
• Shao’e Lin,
• Kui Hong and
• Zhigang She

Beilstein J. Org. Chem. 2016, 12, 2077–2085, doi:10.3762/bjoc.12.196

• , respectively. In addition, compounds 1 and 3 exhibited weak radical scavenging activity with EC50 values of 125 and 138 μM, respectively. Keywords: α-glucosidase; Aspergillus; DPPH·; furoisocoumarin; isocoumarin; Introduction Isocoumarins are an important group of natural products with diverse structural

• epidermidis, Escherichia coli, Klebsiella pneumoniae, and Bacillus subtilis. None of the compounds was active at a concentration of 50 μg/mL. In the free radical scavenging assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH), only compounds 1 and 3 exhibited weak activity with EC50 values of 125 and 130 μM

• performed with High-Performance Grid Computing Platform of Sun Yat-Sen University. Biological assays. The assays for antibacterial [23] and α-glucosidase inhibitory [23] were carried out as described previously. The assay for DPPH radical scavenging activity was measured by a reported method [24][25], with

Varioloid A, a new indolyl-6,10b-dihydro-5aH-[1]benzofuro[2,3-b]indole derivative from the marine alga-derived endophytic fungus Paecilomyces variotii EN-291

• Peng Zhang,
• Xiao-Ming Li,
• Xin-Xin Mao,
• Attila Mándi,
• Tibor Kurtán and
• Bin-Gui Wang

Beilstein J. Org. Chem. 2016, 12, 2012–2018, doi:10.3762/bjoc.12.188

• search for structurally unique and bioactive secondary metabolites from marine fungi, especially from marine alga-derived fungi [6][7][8], we discovered evident DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and diverse antimicrobial activities in the EtOAc extract from Paecilomyces

• DPPH radical scavenging activity [11], and two new prenylated indole alkaloids with cytotoxic activity [12] had been isolated and identified. In an effort to isolate additional analogues that might show similar effects, a larger fermentation was undertaken. This study led to the isolation of two

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

• structures. Dimer 7 exhibited the highest kA value, and this result nicely correlates with scavenging towards the DPPH radical reported by Kancheva et al. [19]. The kA value of dimer 8 is a bit lower than that of dimer 6, probably due to steric factors. In general, there are no significant differences among

Effect of cyclodextrin complexation on phenylpropanoids’ solubility and antioxidant activity

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

Beilstein J. Org. Chem. 2014, 10, 2322–2331, doi:10.3762/bjoc.10.241

• ) and the solubilizing potential of CD was proposed. Molecular modeling was used to investigate the complementarities between host and guest. Finally, the antioxidant activity of encapsulated PPs was evaluated by scavenging of the stable DPPH radical. Keywords: antioxidant activity; complexation

• of hydrophobic interactions and are in good agreement with literature data [21][28][29][30][41]. Determination of DPPH radical scavenging activity The DPPH• assay was used to measure the radical scavenging activity of PPs. Depending on the studied PP, two types of kinetic behavior were observed

• . Isoeugenol (3), eugenol (4), caffeic acid (6) and ferulic acid (7) reacted rapidly with DPPH• while trans-anethole (1), estragole (2) and p-coumaric acid (5) had a slow kinetic behavior. These observations were consistent with the literature data [42]. Results obtained in the absence and presence of CDs, are

3-Pyridinols and 5-pyrimidinols: Tailor-made for use in synergistic radical-trapping co-antioxidant systems

• Luca Valgimigli,
• Daniele Bartolomei,
• Riccardo Amorati,
• Evan Haidasz,
• Jason J. Hanthorn,
• Susheel J. Nara,
• Johan Brinkhorst and
• Derek A. Pratt

Beilstein J. Org. Chem. 2013, 9, 2781–2792, doi:10.3762/bjoc.9.313

• Abraham’s β2H scale (0.44 versus 0.45). A similar trend is observed in available literature kinetic data; the rate constants for formal H-atom transfer from a variety of phenols to a variety of radicals (e.g. alkyl, alkoxyl, peroxyl and DPPH) is consistently higher in acetonitrile than in ethyl acetate [23

Interplay of ortho- with spiro-cyclisation during iminyl radical closures onto arenes and heteroarenes

• Roy T. McBurney and
• John C. Walton

Beilstein J. Org. Chem. 2013, 9, 1083–1092, doi:10.3762/bjoc.9.120

• experiments, from a Luxtel CL300BUV lamp. EPR signals were digitally filtered and double integrated by using the Bruker WinEPR software, and radical concentrations were calculated by reference to the double integral of the signal from a known concentration of the stable radical DPPH run under identical