- Cleavage of the C-C linkage between the sugar and the aglycon in C-glycosylphloroacetophenone, and the NMR spectral characteristics of the resulting di-C-glycosyl compound
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The treatment of unprotected mono-C-β-D-glucopyranosylphloroacetophenone with a cation-exchange resin in anhydrous acetonitrile afforded both a phloroacetophenone and a di-C-β-D-glucopyranosylphloroacetophenone. Treatment of an unprotected mono-C-(2-deoxy-β-D-arabino-hexopyranosyl)phloroacetophenone (mono-C-2-deoxy-β-D-glucopyranosylphloroacetophenone) also afforded both the aglycon and di-C-(2-deoxy-β-D-arabino-hexopyranosyl)phloroacetophenone. The reaction mixtures were acetylated, and the structures of the isolated products were determined by NMR spectroscopy. This is the first demonstration of the formation of a di-C-glycosyl compound during the chemical cleavage of the C-C linkage between the sugar and the aglycon in an aryl C-glycosyl derivative.
- Kumazawa,Kimura,Matsuba,Sato,Onodera
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Read Online
- Synthesis and Antifungal Activity of Chromones and Benzoxepines from the Leaves of Ptaeroxylon obliquum
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This study reports the first total synthesis of the bioactive oxepinochromones 12-O-acetyleranthin (8) (angular isomer) and 12-O-acetylptaeroxylinol (9) (linear isomer). The antifungal activity of these compounds and their derivatives was determined against Candida albicans and Cryptococcus neoformans. Most compounds had good selectivity between the two fungi and showed moderate to good activity. 12-O-Acetyleranthin (8) had the highest activity against C. albicans, with an MIC value of 9.9 μM, while 12-O-acetylptaeroxylinol (9), the compound present in Ptaeroxylon obliquum, had the highest activity against C. neoformans, with an MIC value of 4.9 μM.
- Malefo, Modibo S.,Ramadwa, Thanyani E.,Famuyide, Ibukun M.,McGaw, Lyndy J.,Eloff, Jacobus N.,Sonopo, Molahlehi S.,Selepe, Mamoalosi A.
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p. 2508 - 2517
(2020/09/15)
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- Concise synthesis of 5-methoxy-6-hydroxy-2-methylchromone-7-O- and 5-hydroxy-2-methylchromone-7-O-rutinosides. Investigation of their cytotoxic activities against several human tumor cell lines
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The synthesis of two novel 2-methylchromone-7-O-rutinosides is reported, and the in vitro biological activities of these compounds and their synthetic precursors have been investigated on the basis of their cytotoxicity against several human tumor cell lines. The synthesis features early stage assembly of the acidic labile glycosidic bond between sugar and 2-methylchromone aglycon under phase transfer catalyzed glycosidation conditions, whereas all the other standard glycosylation conditions specific to a wide array of rutinosyl donors bearing different anomeric leaving groups (e.g., SPh, OC(NH)CCl3, Br, OH groups) failed to furnish any detectable products.
- Wu, Baolin,Zhang, Wenpeng,Li, Zhonghua,Gu, Li,Wang, Xin,Wang, Peng George
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scheme or table
p. 2265 - 2268
(2011/06/11)
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- Synthesis and structure-activity relationships of cassiarin A as potential antimalarials with vasorelaxant activity
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Cassiarin A 1, a tricyclic alkaloid, isolated from the leaves of Cassia siamea (Leguminosae), shows powerful antimalarial activity against Plasmodium falciparum in vitro as well as P. berghei in vivo, which may be valuable leads for novel antimalarials. Interactions of parasitized red blood cells (pRBCs) with endothelium in aorta are especially important in the processes contribute to the pathogenesis of severe malaria. Nitric oxide (NO) reduces endothelial expression of receptors/adhesion molecules used by pRBC to adhere to vascular endothelium, and reduces cytoadherence of pRBC to vascular endothelium. Cassiarin A 1 showed vasorelaxation activity against rat aortic ring, which may be related with NO production. A series of a hydroxyl and a nitrogen-substituted derivatives and a dehydroxy derivative of 1 have been synthesized as having potent antimalarials against P. falciparum with vasodilator activity, which may reduce cytoadherence of pRBC to vascular endothelium. Cassiarin A 1 exhibited a potent antimalarial activity and a high selectivity index in vitro, suggesting that the presence of a hydroxyl and a nitrogen atom without any substituents may be important to show antimalarial activity. Relative to cassiarin A, a methoxy derivative showed more potent vasorelaxant activity, although it did not show improvement for inhibition of P. falciparum in vitro. These cassiarin derivatives may be promising candidates as antimalarials with different mode of actions.
- Morita, Hiroshi,Tomizawa, Yuichiro,Deguchi, Jun,Ishikawa, Tokio,Arai, Hiroko,Zaima, Kazumasa,Hosoya, Takahiro,Hirasawa, Yusuke,Matsumoto, Takayuki,Kamata, Katsuo,Ekasari, Wiwied,Widyawaruyanti, Aty,Wahyuni, Tutik Sri,Zaini, Noor Cholies,Honda, Toshio
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experimental part
p. 8234 - 8240
(2010/03/25)
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