Follow-up studies on glycosylated flavonoids and their complexes with vanadium: their anti-hyperglycemic potential role in diabetes.
The present study sought to evaluate the hypoglycemic activities of free glycosylated flavonoids and flavonoid complexes with vanadium(IV), (VO(IV)), on glycemia in experimental diabetic rats. Besides free kaempferol-3,7-O-(alpha)-dirhamnoside and kaempferol-3-neohesperidoside, complexes of these flavonoids with VO(IV) were administered by different routes in order to compare the potency of the compounds as well as the efficacy of insulin or VO(IV) in lowering serum glucose. Wistar rats were made diabetic by alloxan. The glycemia was assessed at different times after the administering of compounds. The equilibrium constants were determined by potentiometric study and two species with VO(IV) are proposed at physiological pH, VOH(2)L(2) for kaempferitrin and VOHL for kaempferol-3-neohesperidoside. The latter exhibited hypoglycemic activity at all times examined with 50 and 100 mg/kg and the former reduced the glycemia from 0 to 6h by i.p. route. The administering of the complexes or 0.0146 mmol/kg VO(IV) resulted in a serum glucose-lowering effect over time in the case of i.p. treatment. A marked hypoglycemic effect was observed for 0.5IU of insulin (67.5%); 0.0146 mmol VO(IV) (16.8%); 0.0294 mmol kaempferitrin-VO(IV) (17.8%) and 0.0286 mmol kaempferol-3-neohesperidoside-VO(IV) (56.0%) at 3h after i.p. treatment when compared with respective zero time in diabetic groups. Kaempferol-3-neohesperidoside-VO(IV) was 2.5 times more effective than VO(IV), twice as effective as the free compound and three times more effective than kaempferitrin-VO(IV). This is of particular interest since kaempferol-3-neohesperidoside appears to represent a suitable ligand for VO(IV) to mimic the efficacy of insulin in lowering serum glucose levels.
Cazarolli
Luisa Helena
LH
Departamento de Bioquímica, Centro de Ciências Biológicas, UFSC, Campus Universitário, Bairro Trindade, Cx Postal 5069, CEP 88040-970 Florianópolis, SC, Brazil.
Zanatta
Leila
L
Jorge
Ana Paula
AP
de Sousa
Eliandra
E
Horst
Heros
H
Woehl
Viviane Mara
VM
Pizzolatti
Moacir Geraldo
MG
Szpoganicz
Bruno
B
Silva
Fátima Regina Mena Barreto
FR
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D044949:Kaempferols / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism; D008297:Male; D009942:Organometallic Compounds / Q000494:pharmacology; D011199:Potentiometry; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D014639:Vanadium / Q000494:pharmacology*
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D044949:Kaempferols; D009942:Organometallic Compounds; D014639:Vanadium; C042728:lespenefril