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Brandisia hancei 695
mesangial cell proliferation and extracellular matrix overproduction by either
inhibiting ICAM-1 expression or increasing activities of MMP (47).
F. Cardioactive Effects
It has been confirmed that acteoside has cardioactive effects (48). Intravenous
administration of acteoside resulted in a significant decrease in blood pressure
in Wistar rats (49). In the Langendorff rat heart preparation, acteoside
induces a significant dose-dependent increment in chronotropism, inotropism,
and coronary perfusion (50). These cardioactive effects appear to be
associated with a striking increase in the level of intracellular cyclic 3,5adenosine
monophosphate (cAMP) (51).
Acteoside also significantly increased chronotropism, inotropism, and
CPR when tested against the competitive a-adrenergic blocker phentolamine.
It was found that acteoside induced significant increases in the levels of 6keto-PGF1a,
a rapidly formed by-product of postacyclin (PGI-2) widely used
as an index of prostacyclin production. Acteoside can significantly increase
prostacyclin levels (142%) (52). An increase in the prostacyclin level in
Langendorff rat hearts may be responsible for stimulating cAMP production
and thus account for the positive cardioactive effects mediated by acteoside.
The four purified B. hancei phenylethanoids exerted antiproliferative
effect on cultured A7r5 rat aortic smooth-muscle cells. The rank order of effectiveness
for inhibition of the cell proliferation was: brandioside z poliumoside
> 2V-acetylacteoside z acteoside in the presence of 2% or 5% fetal
bovine serum. Either brandioside or poliumoside has one additional rhamnose
molecule attached to position 6V of the glucose chain, thereby enhancing
its hydrophilic property. This may partially explain why both agents were
threefold more effective in the inhibition of cell proliferation. The 2V-O-acetyl
group in those molecules is unlikely to be involved in the antipoliferative
activity since acteoside and 2V-O-acetylacteoside (with acetyl group) or
poliumoside and brandioside (with acetyl group) exhibited the same potency.
The hydroxy groups on the aromatic rings seem to play a role in the inhibitory
effects of the four glycosides on cell proliferation (53). These results indicate
that B. hancei phenylethanoids may have a potential for prevention of vascular-wall-thickening-related
pathological processes such as arteriosclerosis.
As described in another report, acteoside can relax rat aortic rings
preconstricted by 9,11-dideoxy-11a,9a-epoxymethanoprostaglandin F2a
(U46619) with IC50 value of 0.22 F 0.01 mg/mL, but it causes an increase
in K+-induced tone. Removal of endothelium enhanced the relaxing effect of
acteoside. In addition, pretreatment with acteoside inhibited endothelium/
nitric-oxide-mediated relaxation induced by acetylcholine. Acteoside relaxed
the preconstricted aortic rings probably through multiple mechanisms by