Comparative hypoglycemic activity of different fractions of Thymus serpyllum L. in alloxan induced diabetic rabbits.

The aim of present study was to evaluate and compare the hypoglycemic activity of different solvents extracts of Thymus serpyllum in rabbits. Diabetes was induced with single intravenous injection of alloxan monohydrate (150mg/kg). Glibenclamide and acarbose were used as standard drugs. The crude powder of Thymus serpyllum (500 mg/kg b.w) significantly reduced blood glucose level in both normal and diabetic rabbits. Various extracts of Thymus serpyllum were compared for their hypoglycemic activity in diabetic rabbits. Ether and aqueous extracts significantly reduced the blood glucose level with maximum effect (p<0.001) produced by aqueous extract, which was selected for further study. Aqueous extract significantly inhibited the rise in glucose level in oral glucose tolerance test. The extract showed synergistic effect with different doses of insulin; however serum insulin level of the diabetic rabbits was not significantly increased by the extract. HbA1c level was significantly (p<0.05) reduced whereas hemoglobin level was significantly increased in three months study. Phytochemical screening of the aqueous extract showed the presence of alkaloids, flavonoids, tannins, terpinoids, reducing sugar and cardiac glycosides. It is concluded that the aqueous extract might be used alone or in combination with insulin to manage diabetes and its associated complications.

Cardiotonic and vasoconstriction effects of aqueous methanolic extract of Paspalidium flavidum L.

The cardiovascular activity of aqueous methanolic extract of Paspalidium flavidum L. was evaluated on isolated rabbit heart and aorta. Heart rates, force of contraction and perfusion pressure were assessed in the presence of different concentrations of extract and adrenaline by using Langendorff's technique. Moreover, the vasoconstriction effects were studied in rabbit aorta using isolated organ bath. The results indicated that the extract (1ng-100 µ g/ml) exhibited a significant increase in heart rate, contractility and perfusion pressure of isolated rabbit's heart; with a maximum effect at 1ng/ml, which was comparable to adrenaline (1 µ g/ml). Similarly, adrenaline at doses from 1-10 µ g/ml produced a significant dose dependant increase in all the cardiac parameters. The cardiotonic effects of the extract were significantly blocked by propranolol (10(-5)M) while an increase in perfusion pressure was completely antagonized by verapamil (10(-6)M). Activity of cardiac marker enzymes was also significantly raised in the perfusate of isolated heart pretreated with the extract. In rabbit aorta, the extract exhibited a dose dependent vasoconstriction effect however it did not increase the tone of aorta when pre-treated with verapamil (10(-6)M). It is conceivable therefore; that the cardiotonic and vasoconstriction effects of the extract might be due to its agonistic actions on ß-receptors and Ca(+2) channels.

Possible mechanism of cardiac depressant activity of Berberis orthobotrys roots in isolated rabbit heart.

Berberis orhob, otrvs Bien. ex Aitch. (B.o.) has been reported to have antihypertensive effect in different experimental models. The aim of present study was to evaluate the possible antihypertensive mechanism. Aqueous methanolic extract of B.o. roots and its various fractions namely (ethyl acetate, n-butanol or aqueous) in different concentrations (10 ng/mL, 100 ng/mL, I pg/mL, 10 pg/mL, 100 pg/mL ) were evaluated in isolated perfused rabbit heart to assess their effect on force of contraction, HR and perfusion pressure. The crude extract of B.o. and its fractions exhibited a significant decrease in heart rate, contractility and perfusion pressure of isolated rabbit heart, however, butanolic fraction produced more prominent effect and was selected for further study. The effects of butanol fraction were not blocked by atropine (10' M) in isolated perfused heart. However, butanol fraction significantly blocked the effects of adrenaline (10' M). It is therefore conceivable that cardiac depressant activity of B.o. butanol fraction might be due to the presence of certain 3-blocking agents which might be responsible for antihypertensive effect However, further experiments are required to isolate the active compound(s) and elucidate exact mechanism of action.

Pharmacological evaluation of antihypertensive effect of aerial parts of Thymus linearis benth.

Traditionally Thymus linearis Benth. have been used for treatment of various diseases including hypertension. The present study was conducted to evaluate the hypotensive and antihypertensive effect of aqueous methanolic extract of aerial parts of Thymus linearis Benth. in normotensive and hypertensive rats. Acute and subchronic studies were also conducted. The aqueous methanolic extract produced a significant decrease in SBP, DBP, MBP and heart rate of both normotensive and hypertensive rats. LDv, of the extract was found to be 3000 mg/kg. The extract also exhibited a reduction in serum ALT, AST, ALP, cholesterol, triglycerides and LDL levels, while a significant increase in HDL level was observed. It is conceivable therefore, that Thymus linearis Benth. contains certain active compound(s) that are possibly responsible for the observed antihypertensive activity. Moreover, these findings further authenticate the traditional use of this plant in folklore medicine.