Evaluation of the Blood Pressure Lowering Activity of Acalypha Torta (Euphorbiacae)

Abstract

In Illis work the blood pressure lowerilig activity of Acalypha Torta leaves was evaluated. Differential extraction I I S ~ Hch~l orofort~i:t ~lelhanol( 2:1), e111a11oI and water as solvcnls yielded four exlracls -- rlppcr melhanol layer, 3 8% (wvlw), lower cliloroform Iaycr, 5.3% (wlw), ethanol, 2 3% (w/\v) and water, 3.8% (cv/w) exlmcts. In anacsthetized nornlolensive cats only the ethanol extracl produced n significanl (p<0.0001) and dose dependent fall in I>lood pressure. This actio~io f the etlialiol extract was antagonized by nluscarinic receptor blocker (atropine, 20 pdkdbody wveigh~) atid hislamine blocker (prornethazine, 20 pdkgl body weigll~). Results or acute tosicily sludies wi~h 200- 8000 mglkg, body weight of exlracl given i.p gave a median lellial dose (L,Uso) of 562.30 nlg/kg body weigllt. The estract had no sigrlificant (p4).50) effect oil the levels of almine Irmlsnrninase and alkaline phosphatase a1 all the sub-aclule doses (<50% I,D~o) tesled br~t dose-dcyerdmtly increased the activity of' aspartate tra~isa~ninase. I-listopalhological changes wcre noted in the liver, spleen, brain, hearl, kidney aed lung. These inclrrdcd Iiepatocyte necrosis. follicular disorganimtiot~, inflam~natiou, librosis md bronctlial dilatation 'The degree and frequency of these lesions indicaled that the extract caused mild histoyathological clrangcs on these organs. The ellim~ol exlract had vasodilatory effect by increasing the rale of flow or physiological fluid tlrrough the rat hind-quarters preparalion by approxitnatcl y 3 1 %. 11 also ,anlagonized adrenaline-induced conlraction or isolaled rabbi1 aorlic strips showing possible relaxalory effect or the eslracl on vascrrlnr smooth muscles. The resulls also revealed [hat the exlracl had no erect on heart rale but-rgdnqed !be force or contraction of Ihe isolaled rabbit heart by 7 1 %. CaC12- induced u~nlractiono f the Ilearl and plalelel aggregation were significmtly (p<0.000 1 ) antagonized a1 5. Omglml or the extracl. Findings after 2 1 -day Irealtnen t with 10 ;uid 201ngIkgb ody weight of extract also showed significa~l(l p4).0001) reductiolis in lhe le\& of serum Iriacylglycerol, lol;ll:choleslerol ald LDL-choleslerol within 1 4 (1aj.s of treatment, whereas I1DL-cholesterol level was increased. Increases in LDLcholesterol level were observed in Ihe treated groups after the 14"' day. while HDG cholesterol decreased. 'The concentrations oTser1111e1l exlrolyles ( ~ a 'K,' , CI- md IiCO-3) were 1101 affected. Atralyses for the minerds of llle ethanol extract of A. torto leaves revealed that they conlained, (mg per I00 g) -Na ( 6 1 3 0.96), K (354.0 ?s 0.86), Ca (70.2 J: 1.20), Mg (68 8 -t 0.04), Cl* (0.4 + 0 02), t-1COj (1 2.0 + 0.04). C03- (2.3 rt 0.05) and SO^" (0.2 1- 0.01). Bioactive substatlces such as flavonoids, cardiac glycosides, tannins, sterols and alkaloids were detected in whole A. torta leaves and the ethanol extracl. Proxitnale analysis of llle leaves gave noi is lure (42.0 + 0.06 ?6), crude fibre ( 1 I .O -1- 0.0 I %). crude protein (7.9 -1 0.02%), crude Tat (20.3 -t. 0.01%) and lotal carbohydrale (28.8 + 0.02 '%), whereas the ethanol eslract conlained nlois(ure (69.7 f 0.05 %), crude fibre (4.6 :k 0.02%), crude protein (2.0 rl: 0.01 X), crude fat (13.6 t- 0.01 %) and total carbohydrate (3.1 f 0.03%). Column chromatographic separation t~sings ilica gel (G60- 200) as dle stationary phase and cliloroforrn: bulanol; xylene (2:2:3) as the eluent yielded 67 rraclions (1-67). Furtlier elulion with distilled water gave rractions 68-89. Thin-layer chromatograplly, concenlrated the riurnber of frac~io~tlos 13, A to M, when fractions with si~rlilar Rf valves were pooled logelher. The effects or each fraction (A- M) on blood pressure were tested in anaesthetized normotensive cat and only fraction L (77-80) caused a reduclion ill the blootl pressure. Qt~ditativep liytochemical study of rraclion L also showed the presence of high levels of flavonoids, a ~ dca rdiac glycositles, with (races of alkaloids and tannins. The LDSo of fraction L was round lo be 1000 rngkg, body weight. 'fl~irs, ethatlol extract or A. torto leaves possesses blood pressure lowering activity that nlay be medialed by dilation of the blood vessels and, or by depression of force of contraction of the heart.