No abstract

Hypertension is a disease, which if left untreated affects all important organs of human body. It is known as silent killer as without showing significant symptoms, it may quietly lead to stroke, brain hemorrhage, cardiac disorders, renal failure and vision loss. Hypertension has affected 10-15% of global population and killed a large number of human race in every region of world. Drugs used for its treatment on one hand are very expensive and beyond the reach of a common man while on the other hand, side effects associated with these drugs restricted the people to use them. Hence development of a cost effective antihypertensive drug with minimum or no side effects from commonly available indigenous medicinal plants is highly required. Keeping this in view as well as blood pressure reducing property of Bombax ceiba present work describes the hypotensive evolution of its stem bark alongwith toxicology and histopathology of active fraction.Bombax ceiba (syn. Bombax malabaricum DC) commonly known as silk cotton tree is an important medicinal plant. 1,2)Earlier investigations led to the identification of a sesquiterpene lactone, a potent growth inhibitor in fungi 3) and a flavonol glycoside possessing significant hypotensive and hypoglycaemic activities.4) Both of these compounds were isolated from roots and leaves of B. ceiba respectively. This is the first report of hypotensive evaluation of it's stem bark which has resulted in the isolation of a novel benzopyran dimer, shamimicin, lupeol 5) and fractions possessing hypotensive activity. In addition to this, methanolic extracts of different parts of plant, including flowers, pulp, stem and stem bark have also been studied for their effect on mean arterial blood pressure (MABP) of rats. MATERIALS AND METHODSInstrumentation Ultraviolet spectra were recorded in MeOH on Hitachi-U-3200 and infrared spectra were measured in CHCl 3 on JASCO-A-302 spectrophotometers. The electron impact (EI) mass spectra were recorded on a Finnigan MAT-112 instrument. Field desorption (FD-MS), fast atom bombardment (FAB-MS positive and negative) and exact mass measurements were carried out on a Finnigan MAT-312 instrument. High-resolution mass spectra were recorded on a JMS HX-110 spectrometer. The 1 H-and 13 C-NMR spectra were run in CDCl 3 on a Bruker Aspect AM-500 spectrometer operating at 500 MHz for A novel constituent, shamimicin, 1ٟ,1ٟ؆؆-bis-2-(3,4-dihydroxyphenyl)-3,4-dihydro-3,7-dihydroxy-5-O-xylopyranosyloxy-2H-1-benzopyran alongwith lupeol, which possesses potent hypotensive activity has been isolated from Bombax ceiba stem bark. BCBMM-one of the most active hypotensive fractions has revealed its adverse effects on heart, liver and kidneys of mice at the dose of 1000 mg/kg/d.

Shamimin, a C-flavonol glucoside from Bombax ceiba leaves showed significant potency as a hypotensive agent at the doses of 15 mg/kg, 3 mg/kg, 1 mg/kg and significant hypoglycaemic activity at 500 mg/kg in Sprague-Dawley rats. Further studies revealed that it did not cause any mortality in mice at the dose of 1 g/kg but in rats 500 mg/kg is a lethal dose. Aqueous and methanolic extracts of Bombax ceiba leaves and one of its fractions were also subjected to pharmacological and toxicological screening.

Study of the effects of the methanolic extract of Tagetes patula roots on blood pressure led to the isolation of well known citric (1) and malic acid (7) as hypotensive, and pyridine hydrochloride (4) as hypertensive constituents of the plant along with a new constituent, 2-hydroxy, 5-hydroxymethyl furan (9). Citric acid and malic acid caused 71% and 43% fall in Mean Arterial Blood Pressure (MABP) of rats at the doses of 15 mg/kg and 30 mg/kg respectively while pyridine hydrochloride produced 34% rise in the MABP of rats at the dose of 30 mg/kg. LD50 and LD100 of citric acid in mice have been determined as 545 mg/kg and 1000 mg/kg, respectively.

Methanolic extract of Opuntia dillenii cladodes and its pure compound a a-pyrone glycoside, opuntioside-I showed potent hypotensive activity in normotensive rats. Both the extract and opuntioside-I showed comparable effect of 44-54% fall in Mean Arterial Blood Pressure (MABP) at the dose of 10 mg/kg. No mortality was observed in rats even at the doses of 1000 mg/kg/d and 900 mg/kg/d per oral of extract and opuntioside-I respectively. However, histopathology revealed adverse effects of high doses on liver and spleen of the experimental animals.