Antimicrobial Agents From Higher Plants. Antimicrobial Agents From Peganum harmala Seeds

Al-Shamma, Ali; Drake, Steven D.; Flynn, Daniel L.; Mitscher, L. A.; Park, Y. H.; Rao, G. Srinivasa; Simpson, Alistair B J; Swayze, J. K.; Veysoglu, Tarik; Wu, S. T.-S.

doi:10.1021/np50018a025

Cited by 109 publications

(46 citation statements)

References 1 publication

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“…The general procedure for Bu 3 SnH and Et 3 B reactions were used except that the Bu 3 SnH was not added. 1 H NMR spectral analysis showed 2,3-dihydro-1H-pyrrolo[2,1-b]quinazolin-9-one 2 (40%), 2,3,3a,4-tetrahydro-1H-pyrrolo[2,1-b]quinazolin-9-one 32a (10%) and 3-propyl-3H-quinazolin-4-one 33a (30%).…”

Section: Bu 3 Snh and Et 3 Bmentioning

confidence: 99%

Radical reactions with 3H-quinazolin-4-ones: synthesis of deoxyvasicinone, mackinazolinone, luotonin A, rutaecarpine and tryptanthrin

et al. 2007

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Alkyl, aryl, heteroaryl and acyl radicals have been cyclised onto the 2-position of 3H-quinazolin-4-one. The side chains containing the radical precursors were attached to the nitrogen atom in the 3-position. The cyclisations take place by aromatic homolytic substitution hence retain the aromaticity of the 3H-quinazolin-4-one ring. The highest yields were obtained using hexamethylditin to facilitate cyclisation rather than reduction without cyclisation. The alkaloids deoxyvasicinone 2, mackinazolinone 3, tryptanthrin 4, luotonin A 5 and rutaecarpine 8 were synthesised by radical cyclisation onto 3H-quinazolin-4-one.The 3H-quinazolin-4-one ring system is important to the biological activity of both naturally occurring alkaloids, biosynthesised from anthranilic acid, and pharmaceuticals. The alkaloids include vasicinone 1 and deoxyvasicinone 2, 1 mackinazolinone 3, 2 tryptanthrin 4, 3 luotonins A 5, B 6 and E 7 4 and rutaecarpine 8. 5 3H-Quinazolin-4-one alkaloids have been recently reviewed. 6 All the 3H-quinazolin-4-one natural products have interesting biological activity and have therefore been extensively investigated for useful pharmaceutical activity. The 3H-quinazolin-4-one ring is regarded as a 'privileged structure' in combinatorial synthesis. 7 These are structures which represent molecules that are capable of binding at multiple sites with high affinity and facilitate more rapid discovery of useful medicinally active compounds. 7Our study involved the development of protocols involving radical cyclisation for the synthesis of polycyclic 3H-quinazolin-3-ones (Scheme 1). The protocols have also been used for the synthesis of novel polycyclic quinazolinones including the natural Department of Chemistry, Loughborough University, Loughborough, Leics, UK LE11 3TU. E-mail: g.w.weaver@lboro.ac.uk; Fax: 44(0) 1509 223925; Tel: 44(0) All of the above cyclisations are 'oxidative' i.e. the intermediate p-radicals are not reduced by triorganometal hydrides [e.g. tributyltin hydyride (Bu 3 SnH)] as normally observed for these reagents. The cyclisations proceed by aromatic homolytic substitution with abstraction of hydrogen in a rearomatisation process. Aromatic homolytic substitution has been recently reviewed 27 and the mechanism of Bu 3 SnH mediated 'oxidative' cyclisation elaborated. 28 The pyrimidin-4-one ring of the quinazolin-4-ones has some aromaticity and therefore aromatic homolytic substitution could be predicted, and was observed in our studies, as shown in Scheme 1 (9 to 11 via the p-radical 10). However, the lower aromaticity could favour reductive cyclisation in which the intermediate p-radical 10 is intercepted by reagents such as Bu 3 SnH. Our prediction that radical cyclisation onto the quinazolin-4-one ring would be 'oxidative' was supported by the 'oxidative' radical cyclisation onto related ring systems, e.g. pyrimidine-2,4-diones, 23,24This journal is

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Section: Bu 3 Snh and Et 3 Bmentioning

confidence: 99%

Radical reactions with 3H-quinazolin-4-ones: synthesis of deoxyvasicinone, mackinazolinone, luotonin A, rutaecarpine and tryptanthrin

et al. 2007

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“…[34] Its biosynthesis as well as some chemical syntheses start from anthranilic acid. [30,35] Scheme 1.…”

Section: Resultsmentioning

confidence: 99%

Tricyclic Quinazoline Alkaloids Conjugated to Ferrocene: Synthesis, Structure, and Redox Behavior of Ferrocenylmethylene‐Substituted 7H‐Deoxyvasicinones

et al. 2015

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Abstract:The first organometallic derivatives of tricyclic quinazoline derivatives are prepared by condensation of the active C-3 methylene group of 7H-deoxyvasicinones with ferrocenecarbaldehyde. By following this route the conjugated parent alkaloid and derivatives with nitro, amino, as well as some alkanoylamino groups at C-7 were attached at the ferrocene moiety, thereby significantly extending the π system. In addition, the parent compound was subjected to the reaction by treatment with ferrocene-1,1′-dicarbaldehyde, giving rise to the

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“…This technique was used to track activity through the separation process in our work. 122.076 -Carboline was initially isolated from terrestrial plants and possesses antimicrobial activities (Agurell et al 1968;Al-Shamma et al 1981). Along with the exploration of marine natural products, some carboline alkaloids have been found in marine organisms such as bryozoan, ascidian and sponges and more biological activities have been discovered (Ang et al 2000;Rashid et al 2001;Harwood et al 2003).…”

Section: Discussionmentioning

confidence: 99%

Antimicrobial screening and active compound isolation from marine bacterium NJ6-3-1 associated with the sponge Hymeniacidon perleve

Zheng

Chen

Han

et al. 2005

World J Microbiol Biotechnol

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Twenty-nine marine bacterial strains were isolated from the sponge Hymeniacidon perleve at Nanji island, and antimicrobial screening showed that eight strains inhibited the growth of terrestrial microorganisms. The strain NJ6-3-1 with wide antimicrobial spectrum was identified as Pseudoalteromonas piscicida based on its 16S rRNA sequence analysis. The major antimicrobial metabolite, isolated through bioassay-guide fractionation of TLC bioautography overlay assay, was identified as norharman (a beta-carboline alkaloid) by EI-MS and NMR.

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Antimicrobial Agents From Higher Plants. Antimicrobial Agents From Peganum harmala Seeds

Cited by 109 publications

References 1 publication

Radical reactions with 3H-quinazolin-4-ones: synthesis of deoxyvasicinone, mackinazolinone, luotonin A, rutaecarpine and tryptanthrin

Radical reactions with 3H-quinazolin-4-ones: synthesis of deoxyvasicinone, mackinazolinone, luotonin A, rutaecarpine and tryptanthrin

Tricyclic Quinazoline Alkaloids Conjugated to Ferrocene: Synthesis, Structure, and Redox Behavior of Ferrocenylmethylene‐Substituted 7H‐Deoxyvasicinones

Antimicrobial screening and active compound isolation from marine bacterium NJ6-3-1 associated with the sponge Hymeniacidon perleve

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