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In order to establish the reactivity of positions 3 an d 4 in substituted coumarins, the values of the chemical shifts in several coumarins have been correlated with the σ Hammett constant. The statistically results computed show that there is a direct relation between the frequencies of proton 3 in the NMR spectra and the Hammett constant, whereas no direct correlation is possible for position 4 due to the conjugation of the carbonyl group.
È stata studiata la composizione di Chuquiraga Huamampinta (Compositae), una pianta usata nella medicina popolare peruviana. È stato possibile isolare ed identificare quattro triterpeni (lupeolo, β-amirina, e i rispettivi acetati) e un glucoside (p-idrossiacetofenone-β-D-glucoside), al quale è attribuibile l'attività biologica della pianta.
Da una Guttifera tipica della zona Andina del Venezuela la Vismia baccifera (L.) Tr. & Pl., usata con il nome di onotillo quale colorante, sono state isolate due nuove sostanze giallo arancio il Vismione A e il Vismione B, delle quali sono state determinate le caratteristiche chimico fisiche. Questi due composti sono accompagnati da una miscela di terpeni che sono stati identificati con il (—) copaene, il (+) -selinene, il (—) isocariofillene, il (—) -curcumene, il (—) -curcumene e l'-humulene....
Lo studio di un campione di epéna, polvere allucinogena per inalazione preparata dai Bisashi-teri a partire da corteccia di Virola sp. consente di rilevare la presenza di un solo alcaloide la 5-0-metil-bufotenina. In base al confronto delle composizioni di vari campioni di polveri allucinogene si propone di limitare la denominazione di yopo alle preparazioni ottenute da semi di Leguminosae [Piptadenia sp. (syn. Anadenanthera), Acacia sp. Mimosa sp.] e quella di epéna agli allucinogeni preparati...
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