Cell protection induced by Acacia salicina extracts: Inhibition of genotoxic damage and determination of its antioxidant capacity

Antioxidant activity of Acacia salicina extracts was determined by the ability of each extract to inhibit lipid peroxidation, to protect against DNA strand scission induced by hydroxyl radicals, and to scavenge the free radical, 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^?+). The IC₅₀ values of the inhibitory activity toward lipid peroxidation of total oligomer flavonoids (TOF), methanol, ethyl acetate, and aqueous extracts were respectively 28, 52, 472, and 480 μg/mL. All extracts have the ability to scavenge the ABTS^?+ radical by a hydrogen-donating mechanism and to protect pKS plasmid DNA against hydroxyl radicals- induced DNA damage. An assay for the ability of A. salicina extracts to prevent mutations induced by various mutagens in Salmonella typhimurium TA102 and TA104 cells was conducted. TOF, methanol, ethyl acetate, and aqueous extracts from leaf parts of A. salicina showed no mutagenicity either with or without the metabolic enzymes preparation (S9). Protection against methylmethanesulfonate-induced mutagenicity was observed for TOF, methanol, and ethyl acetate extracts. Likewise, all extracts exhibited a high inhibition level of the Ames response induced by the indirect mutagen, 2-aminoanthracene. The antigenotoxic activity could be ascribed, at least in part, to their antioxidant properties, but we cannot exclude additionally mechanisms. Thus, A. salicina may serve as an ideal candidate for a cost- effective, readily exploitable natural phytochemical compound.     

Antioxidant, α‐Glucosidase and Xanthine Oxidase Inhibitory Activity of Bioactive Compounds From Maize (Zea mays L.)

Chemical investigations into maize (Zea mays L.) kernels yielded phenolic compounds, which were structurally established using chromatographic and spectroscopic methods. The isolated phenolic compounds from maize kernel were examined in vitro for their antioxidant abilities by DPPH (2,2‐diphenyl‐1‐picryl hydrazine) radical, OH radical scavenging activity, and reducing ability, along with α‐glucosidase and xanthine oxidase (XO) inhibition. The isolated maize phenolics revealed significant xanthine oxidase and α‐glucosidase inhibitory activity to that of allopurinol and acarbose in vitro and in vivo, respectively. The kinetics study with xanthine oxidase revealed competitive type of inhibition by isolated maize vanillic acid ( M2 ), ferulic acid ( M5 ), 3′‐methoxyhirsutrin ( M7 ), and peonidin‐3‐glucoside ( M10 ) as compared to control allopurinol. Overall, with few exceptions, all the phenolic compounds from maize kernel revealed significant biological activities with all parameters examined. Also, the phenolic compounds from maize were found to be more reactive toward DPPH radical and had considerable reducing ability and OH radical scavenging activity. These findings suggest that maize kernel phenolic compounds can be considered as potential antioxidant, α‐glucosidase, and XO inhibitory agents those might be further explored for the design of lead antioxidant, antidiabetic and antigout drug candidates using in vivo trials.     

Design,synthesis, and biological evaluation of 5‐(4‐(pyridin‐4‐yl)‐1H‐1,2,3‐triazol‐1‐yl)benzonitrile derivatives as xanthine oxidase inhibitors

A series of 5‐(4‐(pyridin‐4‐yl)‐1H‐1,2,3‐triazol‐1‐yl)benzonitrile derivatives ( 1a–p ) was designed, synthesized, and identified as xanthine oxidase inhibitors with micromolar level potencies. Among them, the most promising compounds 1j and 1k were obtained with IC₅₀ values of 8.1 and 6.7 μm , respectively. The Lineweaver–Burk plot revealed that compound 1k acted as a mixed‐type xanthine oxidase inhibitor. SAR analysis revealed that a carbon atom occupying the X³ position is not as effective as a nitrogen atom, and an iso‐pentyloxy or a cyclopentyloxy at the 2‐position of benzonitrile moiety will benefit the inhibitory potency. The basis of xanthine oxidase inhibition by 1k was rationalized by molecular modeling studies.     

Development of 2‐(Substituted Benzylamino)‐4‐Methyl‐1, 3‐Thiazole‐5‐Carboxylic Acid Derivatives as Xanthine Oxidase Inhibitors and Free Radical Scavengers

A series of 2‐(substituted benzylamino)‐4‐methylthiazole‐5‐carboxylic acid was designed and synthesized as structural analogue of febuxostat. A methylene amine spacer was incorporated between the phenyl ring and thiazole ring in contrast to febuxostat in which the phenyl ring was directly linked with the thiazole moiety. The purpose of incorporating methylene amine was to provide a heteroatom which is expected to favour hydrogen bonding within the active site residues of the enzyme xanthine oxidase. The structure of all the compounds was established by the combined use of FT‐IR, NMR and MS spectral data. All the compounds were screened in vitro for their ability to inhibit the enzyme xanthine oxidase as per the reported procedure along with DPPH free radical scavenging assay. Compounds 5j, 5k and 5l demonstrated satisfactory potent xanthine oxidase inhibitory activities with IC₅₀ values, 3.6, 8.1 and 9.9 μm , respectively, whereas compounds 5k , 5n and 5p demonstrated moderate antioxidant activities having IC₅₀ 15.3, 17.6 and 19.6 μm , respectively, along with xanthine oxidase inhibitory activity. Compound 5k showed moderate xanthine oxidase inhibitory activity as compared with febuxostat along with antioxidant activity. All the compounds were also studied for their binding affinity in active site of enzyme (PDB ID‐1N5X).     

Evaluation of antioxidant and antigenotoxic activity of two flavonoids from Rhamnus alaternus L. (Rhamnaceae): Kaempferol 3-O-β-isorhamninoside and rhamnocitrin 3-O-β-isorhamninoside

The antioxidant activity of kaempferol 3-O-β-isorhamninoside (K3O-ir) and rhamnocitrin 3-O-β-isorhamninoside (R3O-ir), isolated from the leaves of Rhamnus alaternus L., was determined by the ability of each compound to inhibit NBT photoreduction and to scavenge the free radical ABTS⁺. Genotoxic and antigenotoxic activities were assessed using the SOS chromotest.At a concentration of 150 μg/assay the two compounds showed the most potent inhibitory activity against superoxide anion by respectively 80.4% and 85.6%. K3O-ir was a very potent radical scavenger with an IC₅₀ value of 18.75 μg/ml. Moreover, these two compounds exhibit an inhibitory activity against genotoxicity induced by nitrofurantoine and aflatoxine B1 using the SOS chromotest bacterial assay system in the presence of Escherichia coli PQ37 strain.In this study, we have also evaluated correlation between antigenotoxic and antioxidant effects of K3O-ir and R3O-ir. The highest correlation was showed with R3O-ir (r = 0.999).     

A trimethoxyellagic acid glucuronide from Conocarpus erectus leaves: Isolation,characterization and assay of antioxidant capacity

The new trimethoxy-ellagic glycoside, 3,3′,4′-tri-O-methylellagic acid 4-O-β-glucupyranuronide and twelve known phenolics were isolated from the leaves of Conocarpus erectus L. (Combretaceae). Structures of all compounds were determined on the basis of spectroscopic methods and chemical degradation. The new compound, together with four of the isolated known constituents and the plant extract itself, showed potent inhibitory effect against reactive oxygen species attack on salicylic acid in a dose-dependent manner adopting xanthine/hypoxanthine oxidase assay.     

Virtual and In Vitro Bioassay Screening of Phytochemical Inhibitors from Flavonoids and Isoflavones Against Xanthine Oxidase and Cyclooxygenase‐2 for Gout Treatment

Synthetic drugs such as allopurinol and benzbromarone are commonly used to treat the complex pathogenesis of gout, a metabolic disease that results from an inflammation of the joints caused by precipitation of uric acid. We seek to discover novel phytochemicals that could treat gout, by targeting the xanthine oxidase and cyclooxygenase‐2 enzymes. In this study, we report the screening of nine compounds of flavonoids from the ZINC and PubChem databases (containing 2092 flavonoids) using the igemdock software tool against the xanthine oxidase and cyclooxygenase‐2 3D protein structures. Each compound was also evaluated by an in vitro bioassay testing the inhibition of xanthine oxidase and cyclooxygenase‐2. Myricetin and luteolin were found to be the potential dual inhibitors of xanthine oxidase and cyclooxygenase‐2 as demonstrated by IC₅₀: 62.7 and 3.29 μg/mL (xanthine oxidase)/70.8 and 16.38 μg/mL (cyclooxygenase‐2), respectively. In addition, structure–activity relationships and other important factors of the flavonoids binding to the active site of xanthine oxidase and cyclooxygenase‐2 were discussed, which is expected for further rational drug design.     

Antioxidant and antigenotoxic activities in Acacia salicina extracts and its protective role against DNA strand scission induced by hydroxyl radical

The antioxidant potency of Acacia salicina extracts was investigated. Total antioxidant capacity was determined using an ABTS⁺ assay. Superoxide radical scavenging was measured using riboflavin-light-nitro blue tetrazolium (NBT) assay. In addition, the content of phenols, total flavonoids and sterols were measured in the tested extracts. The petroleum ether exhibited a potent scavenging activity toward ABTS radical cations. Whereas, chloroform extract showed the highest activity against superoxides radicals and was also able to protect pKS plasmid DNA against hydroxyl radicals induced DNA damages. The antimutagenicity of these extracts was assayed using the Ames assay against Salmonella typhimurium TA98 and S. typhimurium TA 1535 tester strains at different concentrations. These extracts decreased significantly the mutagenecity induced by sodium azide (SA) and 4-nitro-o-phenylenediamine (NOP). The antioxidant and antimutagenecity activities exhibited by A. salicina depended on the chemical composition of the tested extracts.     

Synthesis,In Vitro Protoporphyrinogen Oxidase Inhibition,and Herbicidal Activity of N‐(Benzothiazol‐5‐yl)hexahydro‐1H‐isoindole‐1,3‐diones and N‐(Benzothiazol‐5‐yl)hexahydro‐1H‐isoindol‐1‐ones

Protoporphyrinogen oxidase ( EC 1.3.3.4 ) is one of the most significant targets for a large family of herbicides. As part of our continuous efforts to search for novel protoporphyrinogen oxidase‐inhibiting herbicides, N‐(benzothiazol‐5‐yl)tetrahydroisoindole‐1,3‐dione was selected as a lead compound for structural optimization, leading to the syntheses of a series of novel N‐(benzothiazol‐5‐yl)hexahydro‐1H‐isoindole‐1,3‐diones ( 1a – o ) and N‐(benzothiazol‐5‐yl)hexahydro‐1H‐isoindol‐1‐ones ( 2a – i ). These newly prepared compounds were characterized by elemental analyses, ¹H NMR, and ESI‐MS, and the structures of 1h and 2h were further confirmed by X‐ray diffraction analyses. The bioassays indicated that some compounds displayed comparable or higher protoporphyrinogen oxidase inhibition activities in comparison with the commercial control. Very promising, compound 2a , ethyl 2‐((6‐fluoro‐5‐(4,5,6,7‐tetrahydro‐1‐oxo‐1H‐isoindol‐2(3H)‐yl)benzo[d]thiazol‐2‐yl)‐sulfanyl)acetate, was recognized as the most potent candidate with K_i value of 0.0091 μm . Further greenhouse screening results demonstrated that some compounds exhibited good herbicidal activity against Chenopodium album at the dosage of 150 g/ha.     

Diclofenac acid: a free‐radical‐scavenger to protect DNA against radical‐induced oxidation

The present work focused on the antioxidant effects of diclofenac acid (DaH) and its sodium salt (DaNaH) on the radical‐induced oxidation of DNA. 2,2′‐Azobis(2‐amidinopropane) dihydrochloride (AAPH) was used as radical initiator to oxidize naked DNA sodium salt, followed by the determination of thiobarbituric acid reactive substance (TBARS). DaH and DaNaH also interacted with two other radicals: 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonate) radical cation (ABTS^+.) and 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH). DaH and DaNaH produce a concentration‐dependent protection of DNA. Kinetic studies established that either DaH or DaNaH trap 3–4 radicals when they protect DNA against AAPH‐induced oxidation. DaH and DaNaH scavenged ABTS^+. efficiently. Diclofenac was thus found to be an antioxidant that concentration‐dependently reduced radicals rather than donated its hydrogen atom to radicals. Drug Dev Res 70: 520–524, 2009. © 2009 Wiley‐Liss, Inc.     

Synthesis,biological evaluation,and docking studies of some 5‐chloro‐2(3H)‐benzoxazolone Mannich bases derivatives as cholinesterase inhibitors

A series of N‐substituted‐5‐chloro‐2(3H)‐benzoxazolone derivatives were synthesized and evaluated for their acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) inhibitory, and antioxidant activities. The structures of the title compounds were confirmed by spectral and elemental analyses. The cholinesterase (ChE) inhibitory activity studies were carried out using Ellman's colorimetric method. The free radical scavenging activity was also determined by in vitro ABTS (2,2‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid)) assay. The biological activity results revealed that all of the title compounds displayed higher AChE inhibitory activity than the reference compound, rivastigmine, and were selective for AChE. Among the tested compounds, compound 7 exhibited the highest inhibition against AChE (IC₅₀ = 7.53 ± 0.17 μM), while compound 11 was found to be the most active compound against BuChE (IC₅₀ = 17.50 ± 0.29 μM). The molecular docking study of compound 7 showed that this compound can interact with the catalytic active site (CAS) of AChE and also has potential metal chelating ability and a proper log P value. On the other hand, compound 2 bearing a methyl substituent at the ortho position on the phenyl ring showed better radical scavenging activity (IC₅₀ = 1.04 ± 0.04 mM) than Trolox (IC₅₀ = 1.50 ± 0.05 mM).

     

7‐O‐Galloyl‐d‐sedoheptulose ameliorates renal damage triggered by reactive oxygen species‐sensitive pathway of inflammation and apoptosis

Objectives This study was carried out to verify the preventive effects of 7‐O‐galloyl‐d ‐sedoheptulose (GS), a phenolic compound isolated from Corni Fructus, underlying diabetic renal damage in type 2 diabetes. Methods GS was orally administered to db/db mice at doses of 20 and 100 mg/kg body weight per day for six weeks, and its effects were compared with those of the vehicle in db/db and m/m mice. Key findings In the serum and kidney, biochemical factors and expression of protein related to nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, apoptosis and inflammation were examined. GS treatment attenuated serum and renal oxidative stress through reduction of reactive oxygen species and lipid peroxidation and increase in the ratio of glutathione and its oxidised form. Importantly, GS reduced renal protein expression of Nox‐4 and p22^phox (one of the subunits of NADPH oxidase), pro‐apoptotic factors (such as Bax and cytochrome c) and nuclear factor‐kappa B‐targeting pro‐inflammatory inducible nitric oxide synthase and cyclooxygenase‐2. Conclusions These renoprotective effects of GS were achieved through attenuation of diabetes‐induced oxidative stress and its sensitive protein expression associated with inflammation and apoptosis in db/db mice.     

3‐butyl‐6‐fluoro‐1 (3H)‐isobenzofuranone,a derivative of dl‐n‐butylphthalide,attenuates hydrogen peroxide‐induced damage in PC12 cells

The anti‐cerebral ischemia agent, dl‐3‐n‐butylphthalide (NBP), is effective in models of vascular dementia in animals. The present study investigates the protective effect of 3‐butyl‐6‐fluoro‐1 (3H)‐isobenzofuranone (6‐F‐NBP), a fluoro derivative of dl‐nbutylphthalide, in hydrogen peroxide (H₂O₂)‐induced damage in PC12 cells. Exposure of PC12 cells to H₂O₂ for 24 h led to decreased cell survival, glutathione peroxidase (GSH‐PX), and mitochondrial membrane potential (MMP). In contrast, malondialdehyde (MDA) production, nitric oxide synthase (NOS) activity, nitric oxide (NO) formation, and intracellular reactive oxygen species (ROS) were increased, as was intracellular accumulation of [Ca²⁺]_i. However, pretreatment with 6‐F‐NBP markedly reversed the changes induced by H₂O₂, exhibiting a protective effect against H₂O₂‐induced cytotoxicity in PC12 cells. The compound may have therapeutic potential in the treatment of cerebral ischemia by inhibiting the oxidative damage. Drug Dev Res 72: 259–264, 2011. © 2010 Wiley‐Liss, Inc.     

Synthesis and Evaluation of Benzophenone O‐Glycosides as α‐Glucosidase Inhibitors

The first total synthesis of benzophenone O‐glycosides (iriflophenone 2‐O‐α‐L ‐rhamnopyranoside: 1 and aquilarisinin: 2 ) isolated from the leaves of Aquilaria sinensis and related new derivatives ( 3 – 12 ) was accomplished through suitable protecting group manipulations and glycosylation starting from commercially available L ‐rhamnose, D ‐glucose, D ‐galactose, D ‐mannose, D ‐xylose, and 1,3,5‐trihydroxybenzene. All synthesized benzophenone O‐glycosides were evaluated for their inhibitory activities against α‐glucosidase. Of these, benzophenone O‐glycosides 4 and 10 exhibited the most potent inhibitory activity in vitro against α‐glucosidase with IC₅₀ values of 168.7 ± 13.9 and 210.1 ± 23.9 µM, respectively, when compared with that of the positive control acarbose with an IC₅₀ value of 569.3 ± 49.7 µM.     

Synthesis and Biological Evaluation of Novel FtsZ‐targeted 3‐arylalkoxy‐2,6‐difluorobenzamides as Potential Antimicrobial Agents

Novel series of 3‐O‐arylalkylbenzamide and 3‐O‐arylalkyl‐2,6‐difluorobenzamide derivatives were synthesized and evaluated for their on‐target activity and antibacterial activity. The results indicated that the 3‐O‐arylalkyl‐2,6‐difluorobenzamide derivatives possessed much better on‐target activity and antibacterial activity than the 3‐O‐arylalkylbenzamide derivatives. Among them, 3‐O‐chlorobenzyl derivative 36 was the most effective in antibacterial activity (0.5, 4, and 8 μg/mL) against Bacillus subtilis ATCC9372, methicillin‐resistant Staphylococcus aureus ATCC29213, and penicillin‐resistant Staphylococcus aureus PR, while 3‐O‐methylbenzyl derivative 41 only exhibited the most potent activity (2 μg/mL) against Staphylococcus aureus ATCC25923.     

Synthesis and in‐vitro Cytotoxicity of Poly‐functionalized 4‐(2‐Arylthiazol‐4‐yl)‐4H‐chromenes

A new series of 4‐aryl‐4H‐chromenes bearing a 2‐arylthiazol‐4‐yl moiety at the 4‐position were prepared as potential cytotoxic agents. The in‐vitro cytotoxic activity of the synthesized 4‐aryl‐4H‐chromenes was investigated in comparison with etoposide, a well‐known anticancer drug, using MTT colorimetric assay. Among them, the 2‐(2‐chlorophenyl)thiazol‐4‐yl analog 4b showed the most potent activity against nasopharyngeal epidermoid carcinoma KB, medulloblastoma DAOY, and astrocytoma 1321N1, and compound 4d bearing a 2‐(4‐chlorophenyl)thiazol‐4‐yl moiety at the 4‐position of the chromene ring exhibited the best inhibitory activity against breast cancer cells MCF‐7, lung cancer cells A549, and colon adenocarcinoma cells SW480 with IC₅₀ values less than 5 μM. The ability of compound 4b to induce apoptosis was confirmed in a nuclear morphological assay by DAPI staining in the KB and MCF‐7 cells.     

Synthesis of 3H‐, 14C‐, and stable‐isotope‐labelled galantamine

Reminyl^® is a newly approved drug, used in the treatment of mild to moderate Alzheimer disease. The active compound, galantamine, was initially isolated from the bulbs of certain Narcissus species, but is at the moment also produced synthetically. In the process leading to the final approval, the synthesis of tritium‐, carbon‐14‐ and stable‐isotope‐labelled galantamine for pharmacokinetic studies was required. Racemic (±)‐1‐bromonarwedine, a compound available as intermediate from the commercial synthesis, was transformed to racemic 1‐bromo‐galantamine. Catalytic bromo‐tritium exchange, followed by HPLC purification and resolution afforded tritium‐labelled galantamine. The [¹⁴C]‐label was introduced on the nitrogen as well as on the oxygen‐methyl position. This was achieved by N‐ and O‐demethylation of galantamine and reaction of the thoroughly purified intermediate with [¹⁴C]‐methyl iodide. Stable‐isotope‐labelled galantamine was obtained likewise by ¹³CD₃OD‐methylation of O‐demethylated galantamine under Mitsunobu conditions. Copyright © 2002 John Wiley & Sons, Ltd.     

Thymol analogues with antioxidant and L‐type calcium current inhibitory activity

Thymol is a natural product, which has antioxidant activity. 4‐Morpholinomethyl‐2‐isopropyl‐5‐methylphenol (THMO), and 4‐Pyrrolidinomethyl‐2‐isopropyl‐ 5‐methylphenol (THPY) were synthesized by reacting thymol with formaldehyde and, respectively, morpholine or pyrrolidine. Since there is a relationship between the antioxidative status and incidence of human disease, anti‐superoxidation, free radical scavenger activity, and anti‐lipid peroxidation of the thymol analogues were determined by xanthine oxidase inhibition, cytochrome C system with superoxide anion releasing with formyl‐Met‐Leu‐Phe (fMLP)/cytochalasin (CB) or phorbol myristate acetate (PMA) activating pathway in human neutrophils. All compounds studied had antioxidant activity. Mannich bases derived from thymol were generally found to be more potent compounds than thymol. THMO demonstrated the greatest antioxidant activity with IC₅₀ values for xanthine oxidase inhibition and anti‐lipid peroxidation being 21±2.78 and 61.29±5.83 µM, respectively. Moreover, since oxidative stress by free radical regulates the activity of L‐type Ca²⁺ channel, the whole‐cell configuration of the patch‐clamp technique was used to investigate the effect of THMO upon ionic currents within NG108‐15 cells. THMO (10 µM) suppressed the peak amplitude of L‐type Ca²⁺ inward current (I_Ca,L), indicating that the antioxidative potential of the thymol analogues might be related to calcium current inhibition. The present studies suggest that THMO‐dependent antioxidant and calcium ion current inhibition activity may be useful in treating free radical‐related disorders. Drug Dev Res 64:195–202, 2005. © 2005 Wiley‐Liss, Inc.     

In vitro antioxidant and antigenotoxic potentials of myricetin-3-o-galactoside and myricetin-3-o-rhamnoside from Myrtus communis: modulation of expression of genes involved in cell defence system using cDNA microarray.

Antioxidant activity of myricetin-3-o-galactoside and myricetin-3-o-rhamnoside, isolated from the leaves of Myrtus communis, was determined by the ability of each compound to inhibit xanthine oxidase activity, lipid peroxidation and to scavenge the free radical 1,1-diphenyl-2-picrylhydrazyl. Antimutagenic activity was assessed using the SOS chromotest and the Comet assay. The IC50 values of lipid peroxidation by myricetin-3-o-galactoside and myricetin-3-o-rhamnoside are respectively 160 microg/ml and 220 microg/ml. At a concentration of 100 microg/ml, the two compounds showed the most potent inhibitory effect of xanthine oxidase activity by respectively, 57% and 59%. Myricetin-3-o-rhamnoside was a very potent radical scavenger with an IC50 value of 1.4 microg/ml. Moreover, these two compounds induced an inhibitory activity against nifuroxazide, aflatoxine B1 and H2O2 induced mutagenicity. The protective effect exhibited by these molecules was also determined by analysis of gene expression as response to an oxidative stress using a cDNA micro-array. Myricetin-3-o-galactoside and myricetin-3-o-rhamnoside modulated the expression patterns of cellular genes involved in oxidative stress, respectively (GPX1, TXN, AOE372, SEPW1, SHC1) and (TXNRD1, TXN, SOD1 AOE372, SEPW1), in DNA damaging repair, respectively (XPC, LIG4, RPA3, PCNA, DDIT3, POLD1, XRCC5, MPG) and (TDG, PCNA, LIG4, XRCC5, DDIT3, MSH2, ERCC5, RPA3, POLD1), and in apoptosis (PARP).