Potent hypoglycaemic activity of the aqueous extract of Chamaemelum nobile in normal and streptozotocin-induced diabetic rats

The purpose of this study was to investigate the effect of both a single dose and daily oral administration for 15 days of the aqueous extract of the aerial part of Chamaemelum nobile ( C. nobile) at a dose of 20 mg/kg body weight on blood glucose concentrations and basal insulin levels in normal and streptozotocin-induced diabetic rats (STZ). Single oral administration of C. nobile aqueous extract reduced blood glucose levels from 6.0 ± 0.3 mmol/l to 4.9 ± 0.09 mmol/l ( P < 0.05) 6 h after administration in normal rats and from 21.1 ± 1.3 mmol/l to 14.5 ± 0.9 mmol/l ( P < 0.001) in STZ diabetic rats. Furthermore, blood glucose levels were decreased from 6.1 ± 0.06 mmol/l to 4.6 ± 0.17 mmol/l ( P < 0.01) and from 21.1 ± 1.31 mmol/l to 13.7 ± 0.90 mmol/l ( P < 0.01) in normal and STZ diabetic rats, respectively, after 15 days of treatment. Basal plasma insulin concentrations remain unchanged after treatment in both normal and STZ diabetic rats so the mechanism of this pharmacological activity seems to be independent of insulin secretion. We conclude that the aqueous extract of C. nobile exhibits a significant hypoglycaemic effect in normal and STZ diabetic rats without affecting basal plasma insulin concentrations and support, therefore, its traditional use by the Moroccan population.