Mechanism of the Hypotensive Effect of Tetramethylpyrazine, an Amide Alkaloid from the Stem of Jatropha podagrica

Abstract

The mechanism of the hypotensive effect of an amide alkaloid, tetramethylpyrazine (TMPZ), obtained from the stem of Jatropha podagrica HOOK (Euphorbiaceae) has been investigated in some isolated vascular and extra-vascular smooth muscle preparations. The results obtained show that the amide alkaloid inhibits the contractions of the rabbit isolated perfused central ear artery induced by periarterial electrical stimulation or intraluminally administered noradrenaline; reduces, like papaverine, the amplitude of the spontaneous myogenic contractions, and noradrenaline-evoked contractions of the rat isolated portal vein; inhibits the electrical stimulation-induced or noradrenaline-evoked contractions of the guinea-pig isolated vas deferens and reduces the periarterial electrical stimulation-induced or noradrenalineevoked relaxations of the rabbit isolated duodenum. The antagonism produced by the amide alkaloid on the responses of these isolated tissue preparations to electrical stimulation or exogenously-added noradrenaline was similar to that elicited by phentolamine, an alpha-adrenoceptor antagonist. It is concluded that tetramethylpyrazine (TMPZ) probably causes hypotension in experimental animals by (a) dilating blood vessels, and/or (b) acting as a non-specific spasmolytic agent (like papaverine).

Effects of Jatropha gossypiifolia L. on the blood pressure and vascular reactivity of rats

“…Other studies also shows that compounds isolated from Jatropha genus plants inhibited the contractions induced by several agonist in heart muscle or vascular and non-vascular smooth muscle from rats, guinea pigs and rabbits (Ojewole and Odebiyi, 1981;Calixto and Sant'ana, 1987;Trebien et al, 1988). Therefore, as reported by Chan et al (2000), nifedipine, a L-type voltage-operated Ca 2+ channel blocker, also inhibited the concentrationresponse curve to CaCl 2 .…”

“…This alkaloid also inhibits the contractile responses induced by electrical stimulation or by noradrenaline (NA) in vascular and non-vascular smooth muscle from rats, guinea pigs and rabbits (Ojewole and Odebiyi, 1981). Silva et al (2011) have investigated the effect of J. gossypiifolia L. aerial parts on intestinal transit velocity and on isolated.…”

Pharmacologically Active Secondary Metabolites from Wood

“…Tetramethylpyrazine (TMP), 10, has been isolated from a variety of plant species (Table 10.6.3) and has been shown experimentally to have hypotensive (767) activity, antiarrhythmic, and antibronchoconstrictor (763) activity, and antimicrobial activity (748), and to improve coronary blood flow (1137).…”

Studies on the Pharmacology of Echitamine, an Alkaloid from the Stem Bark ofAlstonia booneiL. (Apocynaceae)

“…Portal veins were isolated from albino rats (200-500 g) of either sex, and were suspended and treated as described in detail (13). Effects of graded concentrations of echitamine were investigated on the frequency and amplitude of the spontaneous myogenic contractions of the tissues, as well as on noradrenaline-evoked contractions of the isolated muscle preparations.…”