- Constituents of Clausena excavata. Isolation and structural elucidation of seven new carbazole alkaloids and a new coumarin
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Seven new carbazole alkaloids, named clauszoline-A (1), -B (2), -C (3), -D (4), -E (5), -F (6), and -G (7), and a new coumarin named 5-geranyloxy- 7-hydroxycoumarin (8) were isolated from stem bark of Clausena excavata (Rutaceae) collected in Singapore, and their structures were elucidated by means of spectral methods.
- Ito, Chihiro,Ohta, Hideki,Tan, Hugh T.-W.,Furukawa, Hiroshi
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- Natural oxyprenylated coumarins are modulators of melanogenesis
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Naturally occurring coumarins 7-isopentenyloxycoumarin, auraptene, and umbelliprenin are able to modulate the biosynthesis of melanin in murine Melan-a cells probably through the interaction with selected biological targets like estrogen receptor β and aryl hydrocarbon receptor. Such a modulation strictly depends on the individual structure of the coumarin: the presence of a 3,3-dimethylallyloxy side chain is a structural determinant for tanning activation whereas a farnesyl one leads to the opposite effect. The parent compound with a free OH group, umbelliferone, did not provide any interaction. Other coumarins assayed, having shorter chains and/or being substituted in other positions, and prenyloxypsoralens, were not active or not further investigated in this context being cytotoxic at low doses.
- Fiorito, Serena,Epifano, Francesco,Preziuso, Francesca,Cacciatore, Ivana,di Stefano, Antonio,Taddeo, Vito Alessandro,de Medina, Philippe,Genovese, Salvatore
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p. 274 - 282
(2018/05/14)
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