PHARMACOLOGICAL SCREENING OF NATURAL PRODUCTS FOR THEIR ANTIHYPERTENSIVE ACTION

This research work concerns with the pharmacological screening of herbal extract for their antihypertensive action as well as the bioassay-directed fractionation of some medicinal plants, this is also resulted in the isolation of active principle from indigenous medicinal plants.Hypertension (elevated blood pressure) is one of the most common disease of modern times The drugs so far available are not only beyond the reach of a common man, but also have serious side effects, lacking curative properties thus limiting their therapeutic use. It is alarming that 12 million lives lost annually due to various cardio-vascular troubles mainly hypertension. Many medicinal plants are used in traditional system of medicine for the treatment of hypertension which require further detailed pharmacological investigation. However little systematic scientific studies with particular reference to antihypertensive activity has been undertaken on these plants. Pakistan is very rich in herbal wealth and research on these indigenous medicinal plants by the modern phyto-pharmacological methods may result in the discovery of better antihypertensive drugs.During phyto-pharamacological investigation extraction, activity-guided fractionation, isolation, identification and structure characterization of active principle were carried out. The antihypertensive effect of the extracts fractions and active principles from medicinal plant have been investigatated in vive by a direct method (cannulation) on anaesthetized rats. Isolated tissue preparation such as guinea-pig atria, rabbit aorta, guinea-pig ileum were used for the expression of mechanism of antihypertensive action Preliminary pharmacological screening for antihypertensive activity was performed on 30 plant species, most of them may have proved as therapeutic agents, but only few species selected for in vitro experiments for mechanism of action and bioassay-directed fractionation and isolation of pharmacologically active compounds.Encouraging results were obtained on pharmacological screening of antihypertensive study of different medicinal plants. On the whole thirty plants were selected for preliminary screening and on the basis of ED50 value, thereafter ten plants were selected for detail study. Out of ten plants carum copticum, castanospermum australe, Lavendula stoechas and Sesamum indicum showed cholinergic activity beside other pharmacological manifestations. There after remaining five plants Capparis cartilaginea, Cuscuta reflexa, Moringa oleifera, Ocimum basilicum and Pegnum harmala demonstrated non-specific or general spasmolytic action, and one plant extract i.e. Cassia absus was found centrally acting/ganglion blocking action During this research work, some compounds were isolated with different antihypertensive mechanism of action, which include cholinergic, antinicotinic, ganglion blocking and Ca++-channel blocking activities. Out of these clinically important class of antihypertensive drugs are the Ca++-channel blockers. Now a days Ca++-channel blockers have been considered as an important cardio-vascular drug, but in this study these were concluded as antihypertensive drug Consequently, it can be concluded that the verapamil and natural products produce a similar antihypertensive like mechanism of action and that verapmil is more effective than natural products in producing antihypertensive response.Verapmil is well known for selective cardio-depressant action, whereas natural products are less effective/selective how can it be pround from you erepiament? Cardio-depressant action, in other words natural products are less cardio-toxic/or rather having cardio-protective effect as compare to verapamil. As the toxicity of natural products were not subjectively studied due to short supply of samples. Therefore, considering the edible nature of the plants, these natural products may be of worth for further detailed toxicological and clinical explorations.It is suggested that further studies should be under taken to find out whether the isolated natural products will have pharmaceutical important and useful in hypertensio