The opposing effects of the flavonoids isoquercitrin and Sissotrin, isolated from Pterospartum tridentatum, on oral glucose tolerance in rats

Abstract

The effect of an aqueous extract of Pterospartum tridentatum on the blood glucose levels of normal Wistar rats was investigated in a situation of oral glucose challenge. The extract at 300 mg/kg showed an antihyperglycaemic effect in the first 30 min after glucose challenge but then the blood glucose levels rose above those of the control group, indicating the presence of compounds with different effects on glucose tolerance. Nine compounds of isoflavone and flavonol skeletons were identified in the extract by HPLC-ESI-MS(n), four of them being identified for the first time in this species. The isoflavone sissotrin and the flavonol derivative, isoquercitrin, were selected for the oral glucose tolerance test. Isoquercitrin (100 mg/kg) showed time-dependent antihyperglycaemic activity by delaying the post-oral glucose load glycaemic peak at 30 min, as did the sodium-dependent glucose transporter inhibitor phloridzin (100 mg/kg). In contrast, sissotrin (100 mg/kg) showed an opposite effect, impairing glucose tolerance. In conclusion, these preliminary results indicate that the effect of the extract on blood glucose may be either antihyperglycaemic or hyperglycaemic. Additionally, as far as is known, these are the first in vivo results on the acute antihyperglycaemic potential of isoquercitrin.

Antioxidant capacity and toxicological evaluation ofPterospartum tridentatumflower extracts

“…Previous studies point out that P. tridentatum flower and leaf decoctions present a high antioxidant activity and a large amount of phenols and flavonoid compounds (Luı´s et al, 2009;Vitor et al, 2004). Note that, from all the phenolic compounds determined in the P. tridentatum flower extract used in the present study, only 5,5 0 -dihydroxy-3 0 -methoxyisoflavone-7-O-ß-glucoside has been previously detected in water extracts of P. tridentatum flowers (Vitor et al, 2004;Paulo et al, 2008). Moreover, from the remaining phenolic compounds described by those authors for water extracts of P. tridentatum flowers (myricetin-6-C-glucoside, rutin, isoquercitrin, sissotrin, genistein, genistin, 7-methylorobol, and prunetin), only the latter three were detected in the present study.…”

“…Alternatively, the [M-H] 7 ion at m/z 461 was assigned to 5,5 0 -dihydroxy-3 0 -methoxy-isoflavone-7-O-ß-glucoside, as the main product ions of that ionic specie corresponded to those reported by Paulo et al (2008). Moreover, ions at m/z 477 Nota: Los resultados son la media + desviacio´n esta´ndar de experientos llevados a cabo con extracto acuoso de cuatro plantas preparados en condiciones similares.…”

“…In fact, references to this plant from Spanish and Northwest African researchers are scarce (Bremner et al, 2009;Pardo-de-Santayana et al, 2007). Even so, only in the last decade the chemical characterization and evaluation of its therapeutic efficacy have been described (Bremner et al, 2009;Grosso et al, 2007;Luı´s, Domingues, Gil, & Duarte, 2009;Paulo et al, 2008;Vitor et al, 2004). Previous studies point out that P. tridentatum flower and leaf decoctions present a high antioxidant activity and a large amount of phenols and flavonoid compounds (Luı´s et al, 2009;Vitor et al, 2004).…”

“…Phenolic composition differences between the present studied extract and those previously reported would be easily understood if P. tridentatum chemotypes had been used. Indeed, as the sample flowers of the present work were collected at a distinct place and year from those of the previous works (Vitor et al, 2004;Paulo et al, 2008), the presence of chemotypes having a distinct phenolic composition must be considered.…”

Isoquercitrin Inhibits Hydrogen Peroxide-Induced Apoptosis of EA.hy926 Cells via the PI3K/Akt/GSK3β Signaling Pathway

“…In recent studies, isoquercitrin has been reported to possess anti-Mayaro virus, anti-inflammatory, anti-oxidative, anti-allergic, anti-hypertensive, anti-hyperglycemic, and saluretic/diuretic effects [15][16][17][18][19][20][21][22][23]. Although the antioxidative and neuroprotective effects of isoquercitrin have been established, whether isoquercitrin could exert an anti-apoptotic effect on endothelial cells is not clear.…”