| In vitro: |
| Naunyn Schmiedebergs Arch Pharmacol. 2004 Oct;370(4):290-8. | | Vasorelaxing effects of flavonoids: investigation on the possible involvement of potassium channels.[Pubmed: 15378228 ] | A flavonoid-rich diet has been associated with a lower incidence of cardiovascular diseases, probably because of the antioxidant and vasoactive properties of flavonoids. Indeed, many flavonoids show vasorelaxing properties, due to different and often not yet completely clarified mechanisms of action. Among them, the activation of vascular potassium channels has been indicated as a possible pathway, accounting, at least in part, for the vasodilatory action of some flavonoid derivatives, such as apigenin and dioclein.
METHODS AND RESULTS:
Therefore, this work aims at evaluating, on in vitro isolated rat aortic rings, the endothelium-independent vasorelaxing effects of a number of flavonoid derivatives, to identify a possible activation of calcium-activated and/or ATP-sensitive potassium channels and to indicate some possible structure-activity relationships. Among the several flavonoids submitted to the pharmacological assay, only baicalein and quercetagetin were almost completely ineffective, while quercetin, hesperidin, quercitrin and rhoifolin exhibited only a partial vasorelaxing effect. On the contrary, acacetin, apigenin, chrysin, hesperetin, luteolin, pinocembrin, 4'-hydroxyflavanone, 5-hydroxyflavone, 5-methoxyflavone, 6-hydroxyflavanone and 7-hydroxyflavone, belonging to the chemical classes of flavones and flavanones, showed full vasorelaxing effects. The vasodilatory activity of hesperetin, luteolin, 5-hydroxyflavone and 7-hydroxyflavone were antagonised by tetraethylammonium chloride, indicating the possible involvement of calcium-activated potassium channels. Moreover, iberiotoxin clearly antagonised the effects of 5-hydroxyflavone, indicating the probable importance of a structural requirement (the hydroxy group in position 5) for a possible interaction with large-conductance, calcium-activated potassium channels.
CONCLUSIONS:
Finally, glibenclamide inhibited the vasorelaxing action of luteolin and 5-hydroxyflavone, suggesting that ATP-sensitive potassium channels may also be involved in their mechanism of action. | | Molecules. 2016 Sep 28;21(10). | | New Diphenol and Isocoumarins from the Aerial Part of Lawsonia inermis and Their Inhibitory Activities against NO Production.[Pubmed: 27689981] | Lawsonia inermis Linn (Lythraceae), also known as henna, is a small shrub or tree distributed throughout Taiwan's Lanyu Island, in North Africa, and in Australia. Its leaves are used as a folk medicine for the treatment of external hemorrhage and fingernail abscesses.
METHODS AND RESULTS:
Investigation of the ethyl acetate (EtOAc)-soluble fractions from methanol extract of the aerial part of Lawsonia inermis has led to the isolation of a new diphenol, (Z)-4,4'-(prop-1-ene-1,3-diyl)diphenol (1), two new isocoumarin carbonates, inermiscarbonates A (2) and B (3), and six known compounds, 4'-hydroxyflavanone (4), apigenine (5), kampferol (6), luteolin (7), quercetin (8), and (-)-catechin (9). Their structures were determined by detailed analysis of spectroscopic data and comparison with the data of known analogues.
CONCLUSIONS:
Compounds 1 and 4-9 were evaluated for the inhibition of nitric oxide production in lipopolysaccharide (LPS)-stimulated product of nitrite in RAW 264.7 cells with IC50 values of 5.63, 15.72, 8.67, 6.67, 6.17, 7.61, and 14.52 μg/mL, respectively. |
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