Rearrangements of azidoquinones. V. Stereoselective acid-catalyzed rearrangements of azidoquinones to .gamma.-cyanoalkylidine- (cyanoarylidine-) .DELTA..alpha.,.beta.-butenolides

Moore, Harold W.; Shelden, H. Raymond; Deters, Donald W.; Wikholm, Ronald J.

doi:10.1021/ja00709a043

Cited by 32 publications

(5 citation statements)

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“…Further, 2-azido-l,4-napthoquinone treated with azide ion and 2-chloroquinone yields azidoquinone 66 . In the given reaction, azide ions replace halogen ions in a nucleophilic displacement reaction, thereby yielding ≥ 85% azidoquinones 64 . Concomitantly, administration of sodium azide graded doses to NS callus produces an additional peak with retention time of 5.3 min whose area increases proportionately to sodium azide doses (Fig.…”

Section: Resultsmentioning

confidence: 99%

Nigella sativa callus treated with sodium azide exhibit augmented antioxidant activity and DNA damage inhibition

Iqbal

Hashem

et al. 2021

Sci Rep

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Nigella sativa L. (NS) is an herbaceous plant, possessing phytochemicals of therapeutic importance. Thymoquinone is one of the active phytochemicals of NS that confers noteworthy antioxidant properties. Sodium azide, an agent of abiotic stress, can modulates antioxidant system in plants. In the present investigation, sodium azide (0, 5 µM, 10 µM, 20 µM, 50 µM, 100 µM and 200 µM) doses administered to the in vitro NS callus cultures for production/modification of secondary metabolites with augmented activity. 200 µM sodium azide treated NS callus exhibited maximum peroxidase activity (1.286 ± 0.101 nanokatal mg−1 protein) and polyphenol oxidase activity (1.590 ± 0.110 nanokatal mg−1 protein), while 100 µM sodium azide treated NS callus for optimum catalase activity (1.250 ± 0.105 nanokatal mg−1 protein). Further, 200 µM sodium azide treated NS callus obtained significantly the highest phenolics (3.666 ± 0.475 mg g−1 callus fresh weight), 20 µM sodium azide treated NS callus, the highest flavonoids (1.308 ± 0.082 mg g−1 callus fresh weight) and 100 µM sodium azide treated NS callus, the highest carotenes (1.273 ± 0.066 mg g−1 callus fresh weight). However, NS callus exhibited a decrease in thymoquinone yield/content vis-à-vis possible emergence of its analog with 5.3 min retention time and an increase in antioxidant property. Treatment with 200 µM sodium azide registered significantly the lowest percent yield of callus extract (4.6 ± 0.36 mg g−1 callus fresh weight) and thymoquinone yield (16.65 ± 2.52 µg g−1 callus fresh weight) and content (0.36 ± 0.07 mg g−1 callus dry weight) and the highest antioxidant activity (3.873 ± 0.402%), signifying a negative correlation of the former with the latter. DNA damage inhibition (24.3 ± 1.7%) was recorded significantly maximum at 200 µM sodium azide treatment. Sodium azide treated callus also recorded emergence of a new peak at 5.3 min retention time (possibly an analog of thymoquinone with augmented antioxidant activity) whose area exhibits significantly negative correlation with callus extract yield and thymoquinone yield/content and positive correlation with antioxidant activity and in vitro DNA damage inhibition. Thus, sodium azide treatment to NS callus confers possible production of secondary metabolites or thymoquinone analog (s) responsible for elevated antioxidant property and inhibition to DNA damage. The formation of potent antioxidants through sodium azide treatment to NS could be worthy for nutraceutical and pharmaceutical industries.

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Section: Resultsmentioning

confidence: 99%

Nigella sativa callus treated with sodium azide exhibit augmented antioxidant activity and DNA damage inhibition

Iqbal

Hashem

et al. 2021

Sci Rep

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“…During attempts towards quinone reorganisation of 1 induced by sodium azide in sulfuric acid, a ring‐fusion phenomenon was observed (Scheme ). Cyclosmenospongine ( 11 ), 31 and 32 were formed stepwise by means of a Wagner–Meerwein shift/olefin addition with a 30 % global yield.…”

Section: Resultsmentioning

confidence: 99%

A Ring‐Distortion Strategy from Marine Natural Product Ilimaquinone Leads to Quorum Sensing Modulators

et al. 2018

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We report herein a ring‐distortion strategy applied to marine natural substances ilimaquinone and 5‐epi‐ilimaquinone. A chemically diverse library of molecules was synthesised that included rearrangements of the sesquiterpene moiety and original reorganisations of the quinone ring. Chemoinformatic analyses evaluated the rise of structural diversity and the exploration of chemical space. Some focussed biological activities of this library were also investigated; quorum sensing activity of Vibrio harveyi was envisaged and some of the new compounds were shown to be good quorum sensing inhibitor candidates, whereas others were activators. Toxicities were also evaluated and some products showed micromolar activities against human umbilical vein endothelium, human hepatocellular carcinoma and human lung carcinoma (A549) cells.

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“…63) and a Horner-Wadsworth-Emmons reaction followed, either with aryl aldehydes or with the more-demanding aryl pyruvates (Scheme 7). 24a The utility of this strategy was demonstrated by the total syntheses of pulvinic acid (5) and gomphidic acid (12). In + , 1 1 0 ° C L A H L I C A , -7 8 ° C 2 3 0 ° C 1 .…”

Section: Methodsmentioning

confidence: 99%

“…With the exception of Moore's beautiful synthesis of vulpinic acid based on the thermal rearrangement of azidoquinone 30 to pulvinonitrile 31 and subsequent transformation into 6 (Scheme 2), 12 the use of dilactones has dominated in the preparation of pulvinic acids since Pattenden's contribution to the field in the early 1970s. In 1975, Pattenden and co-workers exploited the properties of a-methoxy maleic anhydrides to design an unambiguous synthetic scheme towards unsymmetrical pulvinic derivatives.…”

Section: Equationmentioning

confidence: 99%

Synthetic Strategies towards Naturally Occurring Tetronic Acids

Zografos¹,

Georgiadis²

2006

Synthesis

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Many natural products are characterized by the existence of a five-membered vinylogous acid ring, named tetronic acid, in their structure. The intense synthetic interest on such compounds has led to the development of several innovative methodologies for the construction of tetronic subunits, as well as to inspired strategies towards the total synthesis of the compounds themselves. The synthetic progress on the field of naturally occurring tetronic acids is reviewed herein.

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Rearrangements of azidoquinones. V. Stereoselective acid-catalyzed rearrangements of azidoquinones to .gamma.-cyanoalkylidine- (cyanoarylidine-) .DELTA..alpha.,.beta.-butenolides

Cited by 32 publications

References 1 publication

Nigella sativa callus treated with sodium azide exhibit augmented antioxidant activity and DNA damage inhibition

Nigella sativa callus treated with sodium azide exhibit augmented antioxidant activity and DNA damage inhibition

A Ring‐Distortion Strategy from Marine Natural Product Ilimaquinone Leads to Quorum Sensing Modulators

Synthetic Strategies towards Naturally Occurring Tetronic Acids

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