- ALKALOIDS OF ZEPHYRANTHES FLAVA
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From fresh, mature seeds of Zephyranthes flava, two new 2-oxyphenanthridinium alkaloids, zefbetaine and zeflabetaine along with 15 known free and glucosyloxy alkaloids have been isolated by gradient solvent extraction, chromatography and derivatization.The new compounds have been characterized by comprehensive spectroscopic analyses, chemical transformations and synthesis.Additionally, changes in the major alkaloids during development of the fruits have been analysed and their biological significance appraised.
- Ghosal, Sibnath,Singh, Sushil K.,Srivastava, Radhey S.
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- Ungeremine and its hemisynthesized analogues as bactericides against flavobacterium columnare
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The Gram-negative bacterium Flavobacterium columnare is the cause of columnaris disease, which can occur in channel catfish (Ictalurus punctatus). In a previous study, the betaine-type alkaloid ungeremine, 1, obtained from Pancratium maritimum L. was found to have strong antibacterial activity against F. columnare. In this study, analogues of 1 were evaluated using a rapid bioassay for activity against F. columnare to determine if the analogues might provide greater antibacterial activity and to determine structure-activity relationships of the test compounds. Several ungeremine analogues were prepared by hydrochlorination of the alkaloid and by selenium dioxide oxidation of both lycorine, 7, and pseudolycorine, 8, which yielded the isomer of ungeremine, 3, and zefbetaine, 4, respectively. The treatment of lycorine with phosphorus oxychloride allowed the synthesis of an anhydrolycorine lactam, 5, showing, with respect to 1, the deoxygenation and oxygenation of C-2 and C-7 of the C and B rings, respectively. The results of the structure-activity relationship studies showed that the aromatization of the C ring and the oxidation to an azomethine group of C-7 of the B ring are structural features important for antibacterial activity. In addition, the position of the oxygenation of the C ring as well as the presence of the 1,3-dioxole ring joined to the A ring of the pyrrolo[de]phenanthridine skeleton also plays a significant role in imparting antibacterial activity. On the basis of 24-h 50% inhibition concentration (IC50) results, ungeremine hydrochloride, 2, was similar in toxicity to 1, whereas 5 had the lowest activity. Analogue 2 is soluble in water, which may provide the benefit for use as an effective feed additive or therapeutant compared to ungeremine.
- Schrader, Kevin K.,Avolio, Fabiana,Andolfi, Anna,Cimmino, Alessio,Evidente, Antonio
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- Total synthesis of the amaryllidaceae alkaloid ungeremine
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The synthesis of the aromatic Amaryllidaceae alkaloid ungeremine 1 with a new type of radical cyclisation as the key step is reported.
- Lauk, Urs,Duerst, Doris,Fischer, Walter
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- Concise syntheses of the amaryllidaceae alkaloids ungerimine and hippadine via the suzuki aryl-aryl cross coupling reaction
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Short syntheses of the betaine alkaloid ungerimine (1) and the lactam alkaloid hippadine (4) based on aryl boronic acid - aryl halide cross coupling methodology are described.
- Siddiqui,Snieckus
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p. 1523 - 1526
(2007/10/02)
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- OCCURRENCE OF TWO EPIMERIC ALKALOIDS AND METABOLISM COMPARED WITH LYCORINE IN CRINUM LATIFOLIUM
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Two new epimeric pyrrolophenanthridine alkaloids, 2-epilyocorine and 2-epipancrassidine, were isolated from the flower-stem fluid of Crinum latifolium.The structures of the two alkaloids were established by spectroscopic analyses, crucial chemical transformation, and synthesis in case of the former.The differences in the metabolic pathways of lycorine and 2-epilycorine were studied under simulated physiological conditions and their biochemical significance was appraised.Key Word Index - Crinum latifolium; Amaryllidaceae; epimeric alkaloids; 2-epilycorine; 2-epipancrassidine, metabolic pathways; biochemical significance.
- Ghosal, Shibnath,Unnikrishnan, Sankara,Singh, Sushil K.
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p. 2535 - 2537
(2007/10/02)
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