Pharmacological basis for the antihypertensive activity of Grewia asiatica fruit extract.

In the management of cardiovascular disorders, medicines from herbal sources have played a vital role through centuries. The following study was commenced in order to lay possible pharmacological foundation associated with medicinal uses of edible fruit of Grewia asiatica in hypertension through in-vitro method. In this study isolated atrial preparation of Guinea pig was used where crude ethanolic extract of Grewia asiatica fruit (Ga.Cr) decreased the force and rate of spontaneous atrial contractions (0.03-10mg/kg). In isolated rat aortic ring preparations previously vasoconstricted by phenylephrine and High K+, it also resulted in dose dependent vasodilation (0.01-10 mg/kg).In the presence of L-NAME, the relaxation curve of Ga.Cr was partially inhibited showing involvement of Nitric oxide (NO) mediated pathway. The speculative analysis contemplated that Ga.Cr has blood pressure reducing potentials through inhibition of Ca++ influx via Ca++ channels, its release from intracellular stores and through other means like NO mediated pathways.

Studies on antioxidant, hepatoprotective, and vasculoprotective potential of Viola odorata and Wrightia tinctoria.

We have reported the antidyslipidemic, antihypertensive, and Ca++ channel blocking activities of Viola odorata (VO) and Wrightia tinctoria (WT). This study extends our understanding of their therapeutic potential by exploring the effects on biomarkers of hepatic and vascular dysfunction together with phytochemical standardization and antioxidant potential. Total phenolic compounds, total flavonoids content, and proanthocyanins of the methanolic extracts were identified using HPLC. Antioxidant capacity was measured using the in vitro assays. Two studies of 6-week duration were conducted on a high-fat diet rat model to test the leaves and seed extracts of VO and WT (300 and 600 mg/kg) for their effect on biomarkers for hepatic and vascular dysfunction. The HPLC analysis showed high contents of total phenolic compounds, total flavonoids content, and proanthocyanins along with distinctive phenolic composition. Both extracts exhibited significant antioxidant potential in 1,1-diphenyl-2-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), fluorescence recovery after photobleaching, and total antioxidant capacity (TAC) assays, comparable with synthetic standard antioxidants. The in vivo studies indicated a significant reduction in the high-fat-diet-induced rise in serum uric acid, phosphorus, aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase. This study indicates the potential of VO and WT to protect from vascular and hepatic damage and an antioxidant effect, thus making these herbs strong candidates for managing cardiometabolic disorders.

Pharmacological basis for the medicinal use of Wrightia tinctoria in hypertension and dyslipidemia.

This study was aimed to offer a possible pharmacological basis regarding the remedial utilization of Wrightia tinctoria in hypertension and dyslipidemia in certain South Asian traditional systems of medicine, using in vivo and in vitro assays. The aqueous methanolic extract of W. tinctoria seeds (Wt.Cr) caused a dose-dependent (1-10 mg/kg) decrease in arterial pressure in anesthetized rats. In the right atria of isolated guinea pigs, Wt.Cr equally inhibited force and rate of spontaneous atrial contractions. When tested on phenylephrine-, high K(+)-, and low K(+)-induced vasoconstrictions in isolated rat aorta, Wt.Cr produced a concentration-dependent vasorelaxation, the most potent being against low K(+)-induced contraction. It also created a rightward shift in the Ca(++) concentration-response curves and suppressed phenylephrine control peaks in a Ca(++)-free environment. In the rat model of tyloxapol-induced dyslipidemia, Wt.Cr produced a decline in the serum levels of total cholesterol and triglycerides. In high fat diet-induced dyslipidemia, it decreased serum total cholesterol and low-density lipoprotein cholesterol, improved high-density lipoprotein cholesterol, and prevented the increase in average body weights by causing a decrease in diet consumption. These data suggest that Wt.Cr(++) lowers blood pressure through a combination of K(+)-channel opening and Ca(++)-channel blocking effects along with antidyslipidemic and weight-reducing properties.

The antidiarrheal and spasmolytic activities of Phyllanthus emblica are mediated through dual blockade of muscarinic receptors and Ca2+ channels.

AIM OF THE STUDY: This study was aimed at providing the possible mechanisms for the medicinal use of Phyllanthus emblica in diarrhea. MATERIALS AND METHODS: The in vivo studies were conducted in mice, while isolated rabbit jejunum and guinea-pig ileum were used for the in vitro experiments. RESULTS: The crude extract of Phyllanthus emblica (Pe.Cr), which tested positive for alkaloids, tannins, terpenes, flavonoids, sterols and coumarins, caused inhibition of castor oil-induced diarrhea and intestinal fluid accumulation in mice at 500-700 mg/kg. In isolated rabbit jejunum, Pe.Cr relaxed carbachol (CCh) and K(+) (80 mM)-induced contractions, in a pattern similar to that of dicyclomine. The preincubation of guinea pig-ileum with Pe.Cr (0.3 mg/mL), caused a rightward parallel shift in the concentration-response curves (CRCs) of acetylcholine without suppression of the maximum response. While at the next higher concentration (1 mg/mL), it produced a non-parallel rightward shift with suppression of the maximum response, similar to that of dicyclomine, suggesting anticholinergic and Ca(2+) channel blocking (CCB)-like antispasmodic effect. The CCB-like activity was further confirmed when pretreatment of the tissue with Pe.Cr, shifted the CRCs of Ca(2+) to the right with suppression of the maximum response, similar to nifedipine or dicyclomine. The activity-directed fractions of Pe.Cr showed a combination of Ca(2+) antagonist and anticholinergic like components in all fractions but with varying potency. CONCLUSION: These results indicate that the Phyllanthus emblica fruit extract possesses antidiarrheal and spasmolytic activities, mediated possibly through dual blockade of muscarinic receptors and Ca(2+) channels, thus explaining its medicinal use in diarrhea.

Antihypertensive, antidyslipidemic and endothelial modulating activities of Orchis mascula.

The objective of this study was to investigate the possible mode(s) of action for the medicinal use of Orchis mascula (OM) (family Orchidaceae) in hypertension and dyslipidemia. In spontaneously hypertensive rats (SHRs), OM significantly (P<0.05) reduced systolic blood pressure to 174.2+/-9.63 vs. 203.4+/-7.13 mm Hg (mean+/-s.e.m.; n=7-10) and improved endothelial dysfunction by increasing acetylcholine-induced relaxation. In normotensive anesthetized rats, the crude extract of OM (Om.Cr) at 10 and 30 mg kg(-1) caused a dose-dependent attenuation of mean arterial pressure. OM also decreased serum triglycerides to 29.28+/-6.99 vs. 93.84+/-5.7 mg per 100 ml (P<0.001), low-density lipoprotein-cholesterol to 5.99+/-1.27 vs. 21.9+/-3.5 mg per 100 ml (P<0.05) and atherogenic index to 0.096+/-0.017 vs. 0.36+/-0.08 mg per 100 ml (P<0.05). OM significantly reduced lipid levels in tyloxapol and high fat diet-induced hyperlipidemia. In a second model, OM also reduced gain in body weight with a reduction in daily diet consumption. In isolated rabbit aorta, Om.Cr caused concentration-dependent relaxation of both phenylephrine and high K(+) (80 mM)-induced contractions and a rightward shift of the calcium concentration-response curves similar to the effect seen with verapamil. In conclusion, OM shows antihypertensive and endothelial-modulating effects mediated through multiple pathways that include direct vasodilation by calcium channel blockade and reduction of plasma lipids by inhibition of biosynthesis, absorption and secretion. This study rationalizes the medicinal use of OM in hypertension and dyslipidemia. However, further studies are required to identify the active constituents of this plant.