Pharmacological evidence of α-adrenergic receptors in the hypotensive effect of Chamaemulum nobile L.

This study aims to evaluate the underlying mechanism of action involved in the hypotensive effect of Chamaemulum nobile L. (Cn) aqueous extract and in anesthetized Wistar rats. Lyophilized aqueous extract was administered in the jugular vein, arterial blood pressure and heart rate were measured in the carotide artery over 120 min of injection throughout an invasive direct blood pressure measuring procedure. Intravenous bolus injection of aqueous Cn extract at the doses of 50, 100 and 200 mg/kg produced a dose dependent reduction in arterial blood pressure and heart rate (p<0.001). Specific receptor antagonists (Phentolamine, Terazosin and Atropine) and pharmacological agents (N(omega)-Nitro-L-Arginine Methyl Ester and Captopril) were used for determining the underlying mechanism involved in the hypotensive effect of Cn. Only Phentolamine treatment (2 mg/kg) reduced significantly the hypotensive effect of aqueous Cn extract at a dose of 200 mg/kg. Intravenous perfusion of aqueous Cn extract caused a significant reduction of arterial blood pressure (p<0.01) and reduced the hypertensive effect of intravenous injection of norepinephrine at a dose of 1 µg/kg. We conclude that aqueous Cn extract exhibits a hypotensive effect which may be probably due to an alpha adrenergic receptor blockade mechanism.

Cardiovascular effect of Artemisia herba alba aqueous extract in spontaneously hypertensive rats.

This study aimed to evaluate the hypotensive activity of Artemisia herba alba aqueous extract (AHAE) in spontaneously hypertensive rats (SHR). AHAE was lyophilized and administered daily at a dose of 150 mg/kg for 20 days. AHAE administration produced a significant reduction in systolic blood pressure after 8 days of oral administration (P < 0.01), and a sustained reduction was observed at the end of treatment (P < 0.01). Heart rate remained unchanged during the 20 days of oral AHAE administration. In addition, AHAE administration produced a significant increase in urinary output (P < 0.01) and glomerular filtration rate (P < 0.01) on day 8 of treatment. Urinary electrolyte excretion was also modified during the 20 days of AHAE administration, and a significant increase in urinary sodium and potassium excretion was observed from day 4 (P < 0.01) to day 20 (P < 0.001). However, urinary chloride excretion was increased from day 8 (P < 0.01) to the end of treatment (P < 0.001). The hypotensive effect appeared to be independent of the renin-angiotensin system since AHAE did not affect plasma angiotensin-converting enzyme or renin activities (P > 0.05) after 20 days of oral administration. We conclude that AHAE possesses antihypertensive activity in SHR and that the underlying mechanism appears to involve, at least in part, an increase in urine and electrolyte output.

Study of hypoglycaemic and hypolipidemic effects of Inula viscosa L. aqueous extract in normal and diabetic rats.

The present study was designed to examine the hypoglycaemic and hypolipidemic activity of Inula viscsa aqueous extract on normal and diabetic rats. In normal rats, a significant reduction in blood glucose levels 2 h was observed after a single oral administration (p<0.001). Repeated daily oral administration significantly reduced blood glucose levels after 4 days of treatment (p<0.01). In diabetic rats, a significant reduction in blood glucose levels was observed 1 h after a single oral administration (p<0.001). Repeated oral administration reduced blood glucose levels at the 4th day (p<0.001). No change in total plasma cholesterol and triglyceride levels was observed after both a single and repeated oral administration in both normal and diabetic rats. In addition, plasma insulin levels and body weight remained unchanged after 15 days of repeated oral administration in normal and diabetic rats. We conclude that Inula viscosa possess a hypoglycaemic but not hypolipidemic activity in normal and diabetic rats. The observed hypoglycaemic activity seems to be independent of insulin secretion.

Acute diuretic effect of aqueous extract of Retama raetam in normal rats.

The purpose of this study was to examine the acute diuretic effect of the water extract of the aerial parts of Retama raetam (RR) at a dose of 5 mg/kg/h in normal rats. The aqueous extract was administered intravenously and the diuresis was followed within 4 h after starting the treatment. Intravenous administration of the aqueous RR extract produced a significant increment on diuresis from the second hour (p<0.01) to the fourth hour (p<0.001). Furosemide at a dose of 0.1 mg/kg/h had a similar effect when compared to RR administration. Parallel, the noticed increase of diuresis was associated with an elevation of glomerular filtration rate (p<0.05) and a significant decrease of urinary osmolarity (p<0.001). However, RR extract did not affect plasma urea levels, urine pH, plasma osmolarity and hematocrite. It is then concluded that the water extract of the aerial parts of RR exhibited a significant diuretic effect in normal rat.

Fraxinus excelsior L. evokes a hypotensive action in normal and spontaneously hypertensive rats.

The hypotensive effect of an aqueous extract of Fraxinus excelsior L. was investigated in both normotensive (WKY) and spontaneously hypertensive rats (SHR). Daily oral administration of Fraxinus excelsior (20 mg/kg) aqueous extract for 3 weeks produced a significant decrease in systolic blood pressure (SBP) with variation coefficient (Delta%) of 13.5% in SHR (p<0.01) and 9% in WKY rats (p<0.05). The aqueous extract of Fraxinus excelsior significantly enhanced the urination in both SHR (p<0.05 compared to control) and WKY (p<0.05 compared to control). Irbesartan (Avapro), an angiotensin II antagonist, was used as reference drug. Furthermore, oral administration of aqueous Fraxinus excelsior extract at a dose of 20 mg/kg produced a significant increase in urinary excretion of sodium (p<0.01 compared to control), potassium (p<0.001 compared to control) and chlorides (p<0.01) in SHR rats. In normal rats, the aqueous Fraxinus excelsior extract administration induced a significant increase of the urinary elimination of sodium (p<0.05 compared to control), chlorides (p<0.01 compared to control) and potassium (p<0.01 versus control). While there were no significant changes in heart rate (HR) after Fraxinus excelsior treatment in both SHR and WKY rats, glomerular filtration rate (GFR) showed a significant increase in SH rats (p<0.001) after Fraxinus excelsior treatment. These results suggest that oral administration of aqueous extract of Fraxinus excelsior exhibited hypotensive and diuretic actions.

Study of the hypoglycaemic activity of Lepidium sativum L. aqueous extract in normal and diabetic rats.

The hypoglycaemic effect of an aqueous extract of Lepidium sativum L. (LS) seeds was investigated in normal and streptozotocin (STZ)-induced diabetic rats. After a acute (single dose) or chronic (15 daily repeated administration) oral treatments, the aqueous LS extract (20 mg/kg) produced a significant decrease on blood glucose levels in STZ diabetic rats (p < 0.001); the blood glucose levels were normalised 2 weeks after daily repeated oral administration of aqueous LS extract (20 mg/kg) (p < 0.001). Significant reduction on blood glucose levels were noticed in normal rats after both acute (p < 0.01) and chronic treatment (p < 0.001). In addition, no changes were observed in basal plasma insulin concentrations after treatment either in normal or STZ diabetic rats indicating that the underlying mechanism of this pharmacological activity seems to be independent of insulin secretion. We conclude that the aqueous extract of LS exhibits a potent hypoglycaemic activity in rats without affecting basal plasma insulin concentrations.

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 20mg/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) 6h 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 +/- 0.9 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.

Hypoglycaemic effect of Calamintha officinalis Moench. in normal and streptozotocin-induced diabetic rats.

The purpose of this study was to investigate the effects of a water extract from the aerial parts of Calamintha officinalis Moench., after either a single dose or daily oral administration for 15 days, on plasma blood glucose concentrations and basal insulin levels in normal and streptozotocin-induced diabetic rats (STZ diabetic rats). The results clearly demonstrated the hypoglycaemic effect of this plant extract in both normal and STZ diabetic rats. In addition, no changes were observed in basal plasma insulin concentrations after treatment with this plant in normal or STZ diabetic rats, indicating that the underlying mechanism of the plant's pharmacological action seems to be independent of insulin secretion. We conclude that the aqueous C. officinalis extract exhibits a significant hypoglycaemic effect in normal and STZ diabetic rats without affecting basal plasma insulin concentrations, and supports, therefore, its traditional use by the Moroccan population.

Anti-hyperglycaemic activity of the aqueous extract of Origanum vulgare growing wild in Tafilalet region.

The effect of an aqueous extract of Origanum vulgare (OV) leaves on blood glucose levels was investigated in normal and streptozotocin (STZ) diabetic rats. In normal rats, the blood glucose levels were slightly decreased 6 h after a single oral administration (P<0.05) as well as 15 days after once daily repeated oral administration of aqueous OV extract (P<0.05) (20 mg/kg). After a single dose or 15 daily doses, oral administration of the aqueous extract (20 mg/kg) produced a significant decrease on blood glucose levels in STZ diabetic rats (P<0.001). In STZ rats, the blood glucose levels were normalised from the fourth day after daily repeated oral administration of aqueous OV extract (20 mg/kg) (P<0.001). However, this effect was less pronounced 2 weeks after daily repeated oral administration of OV extract. In addition, no changes were observed in basal plasma insulin concentrations after treatment in either normal or STZ diabetic rats indicating that the aqueous OV extract acted without changing insulin secretion. We conclude that an aqueous extract of OV exhibits an anti-hyperglycaemic activity in STZ rats without affecting basal plasma insulin concentrations.

Study of the hypoglycaemic activity of Fraxinus excelsior and Silybum marianum in an animal model of type 1 diabetes mellitus.

The hypoglycaemic effect of the aqueous extracts of Fraxinus excelsior (FE) seed and Silybum marianum (SM) aerial part was investigated in normal and streptozotocin (STZ) diabetic rats. After a single dose or 15 daily doses, oral administration of the aqueous extracts (20 mg/kg) produced a significant decrease of blood glucose levels in both normal and STZ diabetic rats (P < 0.001). From the first week, the body weight was increased in normal rats (P < 0.05) and decreased in STZ rats (P < 0.01) after FE administration. In addition, no changes were observed in basal plasma insulin concentrations after both FE and SM treatments in either normal and STZ diabetic rats indicating that these plants exert their pharmacological activity without affecting insulin secretion. We conclude that the aqueous extracts of FE and SM exhibit potent hypoglycaemic and anti-hyperglycaemic activities in normal and STZ rats, respectively, without affecting basal plasma insulin concentrations.

Effect of Retama raetam on lipid metabolism in normal and recent-onset diabetic rats.

The purpose of this study was to examine the effect of single and repeated oral administration of the aqueous extract of Retama raetam (Forssk) Webb (RR) (20 mg/kg) on lipid metabolism in normal and streptozotocin-induced diabetic rats. In normal rats, the aqueous extract of RR induced a significant decrease of the plasma triglycerides concentrations one week after repeated oral administration (P<0.05). This reduction was maintained two weeks after once daily repeated oral administration (P<0.05). A significant decrease of plasma cholesterol levels was also observed one week (P<0.05) and two weeks (0.05) after repeated oral administration. In diabetic rats, RR treatment caused a significant decrease of plasma triglycerides levels after a single (P<0.05) and repeated (P<0.001) oral administration. A significant decrease of cholesterol levels was observed four hours after a single oral administration of the RR aqueous extract (P<0.05). One week after repeated oral administration of RR aqueous extract, the plasma cholesterol levels were significantly decreased (P<0.05) and still dropped after two weeks (P<0.005). On the other hand, the repeated oral administration of RR aqueous extract caused a significant decrease of body weight one week after repeated oral treatment in diabetic rats (P<0.05). We conclude that the aqueous extract of RR exhibits lipid and body weight lowering activities in both normal and severe hyperglycemic rats after repeated oral administration of RR aqueous extract at a dose of 20 mg/kg.

Effects of an aqueous extract of Triticum repens on lipid metabolism in normal and recent-onset diabetic rats.

The aim of this study was to demonstrate the effects of single and repeated oral administration of the aqueous rhizomes extract of Triticum repens (TR) (20 mg/kg) on lipid metabolism in normal and streptozotocin-induced diabetic rats. In normal rats, the aqueous extract of TR induced a significant decrease in the plasma triglycerides concentrations 4 days (P<0.05) and 1 week after repeated oral administration (P<0.05). This reduction was abolished 2 weeks after once daily repeated oral administration. A significant decrease of plasma cholesterol levels was observed only 1 week (P<0.05) after repeated oral administration. In diabetic rats, TR treatment caused a significant decrease in plasma triglycerides levels after a single (P<0.01) and repeated (P<0.001) oral administration. A strong decrease in cholesterol level was observed 6 h after a single oral administration of the aqueous extract TR (P<0.001). Four days after repeated oral administration of TR aqueous extract, the plasma cholesterol level was significantly decreased (P<0.05) and still dropped after 2 weeks (P<0.001). On other hand, the repeated oral administration of aqueous TR extract caused a significant decrease in body weight 2 weeks after repeated oral treatment in diabetic rats (P<0.05). We conclude that the aqueous extract of TR exhibits lipid and body weight lowering activities in severe hyperglycaemic rats after repeated oral administration of aqueous TR extract at a dose of 20 mg/kg.