ABSTRACT
OBJECTIVE@#To evaluate vasorelaxant and vasoconstriction effects of Zingiber officinale var. rubrum (ZOVR) on live rats and isolated aortic rings of spontaneously hypertensive rats (SHRs).@*METHODS@#Extracts of ZOVR were subjected to in-vivo antihypertensive screening using noninvasive blood pressures in SHRs. The most potent extract, ZOVR petroleum ether extract (ZOP) was then fractionated using n-hexane, chloroform and water. Isolated thoracic aortic rings were harvested and subjected to vascular relaxation studies of n-hexane fraction of ZOP (HFZOP) with incubation of different antagonists such as N-nitro-l-arginine methyl ester (L-NAME, 10 µmol/L), indomethacin (10 µmol/L), methylene blue (10 µmol/L), atropine (1 µmol/L), glibenclamide (10 µmol/L), prazosin (0.01 µmol/L), and propranolol (1 µmol/L).@*RESULTS@#During the screening of various ZOVR extracts, ZOP produced the most reduction in blood pressures of SHRs and so did HFZOP. HFZOP significantly decreased phenylephrine-induced contraction and enhanced acetylcholine-induced relaxation. L-NAME, indomethacin, methylene blue, atropine, and glibenclamide significantly potentiated the vasorelaxant effects of HFZOP. Propranolol and prazosin did not alter the vasorelaxant effects of HFZOP. HFZOP significantly suppressed the Ca-dependent contraction and influenced the ratio of the responses to phenylephrine in Ca-free medium.@*CONCLUSION@#This study demonstrates that ZOP may exert an antihypertensive effect in the SHR model. Its possible vascular relaxation mechanisms involve nitric oxide and prostacyclin release, activation of cGMP-K channels, stimulation of muscarinic receptors, and transmembrane calcium channel or Ca release from intracellular stores. Possible active compounds that contribute to the vasorelaxant effects are 6-gingerol, 8-gingerol and 6-shogaol.
ABSTRACT
Objective: To elucidate the in vivo hypoglycemic capability, antihyperglycemic and antihyperlipidemic activities of Pereskia bleo (Kunth) leaves extracts and bioactive fraction. Methods: The various solvent extracts of Pereskia bleo were investigated for the hypoglycemic and antihyperglycemic activities using a relevant in vivo normal rat model and streptozotocin-induced diabetic rat model with glibenclamide and metformin utilized as positive controls. The effects of the most potent extract and its bioactive fraction on the insulin level, lipid profile and body weight of the diabetic rats were also analyzed. Results: All the extracts showed no hypoglycemic effect while petroleum ether, chloroform and aqueous extracts demonstrated significant (P<0.05) reduction in blood sugar level in the intraperitoneal glucose tolerance test. Aqueous extract and aqueous fraction significantly (P<0.05) reduced the blood glucose level in streptozotocin-induced diabetic rats as early as day 6 compared to the diabetic control as well as significantly restored the serum insulin of diabetic rats. Moreover, the aqueous extract and aqueous fraction disclosed a significant (P<0.05) reduction in total cholesterol, triglycerides, and low-density lipoprotein levels. An elevation in high-density lipoprotein as well as improved body weight loss of the diabetic rats were also observed. Conclusions: In summary, Pereskia bleo appears effective in the management of diabetes and correlated impairments arising from high blood sugar level. Further studies will possibly bring about the discovery of effective and secure plant derived antidiabetic drugs.
ABSTRACT
The leaves of Blumea balsamifera are used as a folk medicine in kidney stone diseases in South-East Asia. Phytochemical investigation revealed leaves contained a number of flavonoids. In view of these, the present work was aimed to quantify and preliminary pharmacokinetic investigation of five flavonoids viz. dihydroquercetin-7,4'-dimethyl ether [I], dihydroquercetin-4'-methyl ether [II], 5,7,3',5'-tetrahydroxyflavanone [III], blumeatin [IV] and quercetin [V] in rat plasma following oral administration [0.5g/Kg] of B. balsamifera leaf extract in rats. Quantification was achieved by using a validated, reproducible high-performance liquid chromatographic method. The mean recoveries of I, II, III, IV and V were 90.6, 93.4, 93.5, 91.2 and 90.3% respectively. The limit of quantification was 25 ng/mL for I and IV, 10 ng/mL for II and III and 100 ng/mL for V respectively. The within day and day-to-day precision for all the compounds were < 10%. The validated HPLC method herein was applied for pharmacokinetic studies and the main pharmacokinetic parameters were: t1/2 [hr] 5.8, 4.3, 2.9, 5.7 and 7.3, C[max] [ng/mL] 594.9, 1542.9 1659.9, 208.9 and 3040.4; T[max] [hr] 4.7, 1.0, 1.0, 3.5 and 2.3; AUC0-infinity [ng hr/mL] 5040, 5893, 9260, 1064 and 27233 for I, II, III, IV and V respectively. The developed method was suitable for pharmacokinetic studies and this preliminary study also revealed significant absorption after oral dosing in rats