1,721,041 research outputs found
Diterpenes and phenolic compounds from Sideritis pullulans
No full textPhytochemical investigation of Sideritis pullulans aerial part and root extracts allowed to isolate six ent-kaurane diterpenes, two phenylpropanoids, and one coumarin, identified as 1α,3α,7β,18-tetrahydroxy-ent- kaur-16-ene (sideripullol A) (1), 3α,11α,18-trihydroxy-ent-kaur-16- ene (sideripullol B) (2), 3α,7β,18-trihydroxy-17-nor-ent-kauran-16- one (sideritone A) (3), 3α,7β-dihydroxy-18-acetyloxy-17-nor-ent- kauran-16-one (sideritone B) (4), 3α,7β,16α,17-tetrahydroxy-18- acetyloxy-ent-kaurane (sideripullol C) (5), 7β,16α,17,18- tetrahydroxy-ent-kaurane (sideripullol D) (6), β-(3-methoxy-4- hydroxyphenyl)-ethyl-O-α-l-arabinopiranosyl-(1 → 2)-α-l- rhamnopyranosyl-(1 → 3)-6-O-t-feruloyl-β-d-glucopyranoside (sideritiside A) (7), β-(3,4-dihydroxyphenyl)-ethyl-O-α-l- arabinopiranosyl-(1 → 2)-α-l-rhamnopyranosyl-(1 → 3)-6-O-t-feruloyl-β-d-glucopyranoside (sideritiside B) (8), and 7-demethyl-8-methoxycoumarsabin (9), respectively. Twenty known compounds, including phenolics, flavonol glycosides, iridoids, diterpenes, sesquiterpenes, lignans, coumarins, and phenylpropanoids were also isolated and characterized. All diterpenes were evaluated for their cytotoxic activity
Lipid A structure of Pseudoalteromonas haloplanktis TAC 125: use of electrospray ionization tandem mass spectrometry for the determination of fatty acid distribution
No full textLipid A structure of Pseudoalteromonas haloplanktis TAC 125: use of electrospray ionization tandem mass spectrometry for the determination of fatty acid distribution
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Nuovi derivati pregnanici da Trichilia emetica
No full textTrichilia emetica Vahl (nota comunemente come Natal Mahogany ‘‘Musikili’’) è una pianta appartenente alla famiglia delle Meliaceae originaria delle zone tropicali del Vecchio e del Nuovo Mondo. In Africa la Trichilia emetica è comunemente utilizzata nella medicina popolare del Mali come: purgante, antiepilettico, antipiretico, agente antimalarico e nei disturbi epatici1. Gli usi tradizionali riportati per questa specie hanno indirizzato numerose ricerche alla verifica delle attività antibatterica, antiinfiammatoria, antimalarica, antiossidante, antimutagenica e citotossica2. Studi precedenti su Trichilia emetica riportano l’isolamento di tannini, derivati fenolici, derivati steroidei, ed in particolare di triterpeni e tetranortriterpeni (limonoidi)3. L’interesse verso lo studio di Trichilia emetica nasce dalle molteplici attività biologiche riportate in letteratura per i limonoidi4.
Lo studio fitochimico è stato condotto sulle radici di Trichilia emetica, le quali sono state sottoposte ad estrazione con solventi a polarità crescente (n-esano, CHCl3, CHCl3:CH3OH, CH3OH ); i rispettivi residui ottenuti, 2.5 g, 4.2 g, 3.15 g, 12.6 g sono stati frazionati con differenti tecniche cromatografiche: Silice, Sephadex LH-20, MPLC, HPLC.
In particolare lo studio dell’estratto cloroformico ha condotto all’isolamento in forma pura di 4 composti naturali: 1-acetyl-trichilin , trichilin, nymania 2 e sendanin 2 e due nuovi derivati pregnanici; mentre dall’estratto metanolico è stato isolato un neolignano glucoside noto: (+)-lyoniresinol 3a-O-β-D-glucopyranoside 5. Tutte le molecole isolate da Trichilia emetica sono state caratterizzate principalmente mediante tecniche spettroscopiche.
L’ attività antitumorale riportata in letteratura ed in particolare l’interazione con la proteina HSP90 messa in evidenza per il limonoide gedunin 4 è stato il punto di partenza per la messa a punto di una libreria di small molecules, destinata a screening biologici. L’ attività biologica dei triterpeni e tetranortriterpeni isolati è stata valutata mediante risonanza plasmonica di superficie (SPR)
Trypsin sheds light on the singular case of seminal rnase, a dimer with two quaternary conformations.
No full textNew phenolic glycosides from Securinega virosa and their antioxidant activity.
No full textOne new flavonoid glycoside, 3-O-kaempferol 4-O-(galloyl)-beta-D-glucoside, one new bergenin derivative, 11-O-caffeoylbergenin, along with other known flavonoids and phenolic derivatives, were isolated from the leaves of Securinega virosa. Their structures were established on the basis of detailed spectral analysis. In vitro biological analysis of the isolated compounds showed that they were able to quench DPPH radicals and had a direct scavenging activity on superoxide anion. Kaempferol 3-O-(4-galloyl)-beta-D-glucopyranoside (1), 11-O-caffeoylbergenin (2), and glucogallin (6) exhibited the highest antioxidant capacity, being also able to modulate hydroxyl radical fori-nation more efficiently than the other compounds, acting as direct hydroxyl radical scavengers and chelating iron
Identification and characterization of two Bifidobacterium proteins involved in the adhesion process to human intestinal epithelian cells
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