Blockade of kinin-induced responses of the guinea-pig isolated urinary bladder by the extract of Mandevilla velutina

Anti-edematogenic effects of velutinol A isolated from Mandevilla velutina: evidence for a selective inhibition of kinin B1 receptor-mediated responses

This study assesses the effects of compound velutinol A obtained from M. velutina in the rat paw edema induced by several phlogistic agents. Attempts were made to analyze how velutinol A is able to inhibit kinin B(1) receptor-mediated inflammatory responses. Velutinol A (100 nmol/paw) partially reduced (about 30%) the edema evoked by carrageenan (300 microg/paw). However, velutinol A (100 nmol/paw) failed to affect the edema induced by histamine (200 nmol/paw), substance P (30 nmol/paw), PAF (10 nmol/paw) or BK (3 nmol/paw). Interestingly, the edema caused by the selective kinin B(1) receptor agonist des-Arg(9)-BK (100 nmol/paw) in animals pre-treated with PAF or LPS was significantly inhibited by velutinol A (100 nmol/paw) (48 and 46%, respectively). A similar inhibition of des-Arg(9)-BK-induced edema after pre-treatment with PAF was obtained with the non-peptidic and selective B(1) receptor antagonist SSR 240612 (60 nmol/paw) (46%). In addition, the systemic administration of velutinol A (10 mg/kg, i.p.) or SSR 240612 (1 mg/kg, i.p.) also caused a significant reduction of des-Arg(9)-BK (100 nmol/paw)-induced edema in PAF-treated rats (51 and 43%, respectively). The results provide convincing evidence that velutinol A selectively blocks the edema responses mediated by B(1) receptor activation in vivo. This compound might represent a new non-peptidic and selective antagonist for kinin B(1) receptors.

Inhibition of enzymatic and pharmacological activities of some snake venoms and toxins by Mandevilla velutina (Apocynaceae) aqueous extract

Phospholipases A(2) (PLA(2)) are multifunctional proteins which exhibit varied biological activities correlated to the structural diversities of the sub-classes. The crude aqueous extract from subterranean system of Mandevilla velutina, a plant found in Brazilian savanna, was assayed for its ability to inhibit biological activities of several snake venoms and isolated PLA(2)s. The extract induced total inhibition of the phospholipase activity of Crotalus durissus terrificus venom and only partial inhibition of Bothrops venoms. When assayed against purified toxins, the highest efficacy was detected against CB and crotoxin, while almost ineffective against PLA(2)s from the genus Bothrops. Although M. velutina crude extract significantly inhibited the myotoxic activity of C. d. terrificus venom and CB, it produced only partial inhibition of either Bothrops jararacussu venom or its main myotoxins BthTX-I (basic Lys49), BthTX-II (basic Asp49) and BthA-I-PLA(2) (acidic Asp49). The extract exhibited also full inhibition of hemorrhage caused by Bothrops alternatus, Bothrops moojeni and Bothrops pirajai snake venoms, but partial inhibition (90%) of that induced by B. jararacussu venom. The extract was ineffective to inhibit the fibrinogenolytic activity of B. moojeni, B. alternatus and B. pirajai crude venoms, while their caseinolytic activity was only partially inhibited. No inhibition of the anticoagulant activity, although partial reduction of the edema-inducing activity of C. d. terrificus and B. alternatus crude venoms, CB, PrTX-I, BthTX-I and crotoxin was observed. Besides extending survival of mice injected with lethal doses of C. d. terrificus and B. jararacussu venoms, M. velutina extract decreased to 50% the lethality of mice. Extracts of 18 month old micropropagated plants were able to partially neutralize the effect of the crude venoms and toxins.

Mechanisms involved in the antinociception caused by compound MV8612 isolated from Mandevilla velutina in mice

The pregnane compound MV8612 isolated from the rhizome of the plant Mandevilla velutina administered by intraperitoneal (i.p.), intrathecal (i.t.) or by intracerebroventricular (i.c.v.) routes caused graded and complete inhibition of the thermal hyperalgesia caused by i.t. injection of bradykinin (BK) in mice with mean ID(50) values of 7.8 micromol/kg, 33.6 and 4.6 nmol/site, respectively. Compound MV8612 (i.p.) also inhibited both the neurogenic and inflammatory pain responses to formalin with mean ID(50) values of 5.6 and 10.6 micromol/kg, respectively. Given i.t., MV8612 produced significant inhibition of both phases of the formalin-induced licking (inhibition of 34+/-5 and 36+/-4%, respectively). Given by i.c.v. route MV8612 inhibited both phases of formalin-induced pain (32+/-6 and 63+/-5%) with mean ID(50) of 8.4 nmol/site against the late phase. MV8612, given by i.p., i.c.v. or i.t. routes, also inhibited capsaicin-induced pain (51+/-4, 25+/-8 and 39+/-6%, respectively). The i.t. injection of potassium (K(+)) channel blockers, apamin and charybdotoxin given 15 min before, markedly prevented the antinociception of MV8612 against both phases of formalin-induced nociception. In contrast, tetraethylammonium (TEA) or glibenclamide had no effect. The i.c.v. treatment with pertussis toxin resulted in a significant inhibition of both MV8612- and morphine-induced antinociception against both phases of formalin-induced pain. Taken together these results confirm and also extend our previous data by demonstrating that the greater part of the antinociception caused by MV8612 seems to be associated with its ability to interfere with BK action. Finally, both the low and high conductance calcium (Ca(2+))-activated K(+) channels and the activation of G(i/o) pertussis sensitive G-proteins take part in the mechanism by which compound MV8612 produces antinociception.

Differential effects of Mandevilla velutina compounds on paw oedema induced by phospholipase A2 and phospholipase C

This study compares the effect of Mandevilla velutina compounds with some anti-inflammatory drugs against phospholipase A2- and phospholipase C-induced rat hindpaw oedema. Injection of phospholipase A2 (Naja naja, 2.5-20 U/paw) and phospholipase C (Clostridium perfringens, 0.03-0.05 U/paw) caused a dose-and-time-related increase in paw oedema. Compounds MV 8608 (55 mumol/kg) and MV 8612 (32 mumol/kg, i.p.) inhibited phospholipase A2-induced paw oedema without interfering with phospholipase C-induced oedema. Local injection of both M. velutina compounds also partially attenuated the oedema evoked by phospholipases A2 and C. Dexamethasone (1.3 mumol/kg, p.o.) suppressed only phospholipase A2-induced paw oedema, while indomethacin (11 mumol/kg, p.o.) attenuated only the early phase of phospholipase C-induced oedema. By contrast, phenidone (616 mumol/kg, i.p.) inhibited only phospholipase C-induced oedema, while cyproheptadine (31 mumol/kg) and pyrilamine (100 mumol/kg, p.o.) inhibited only phospholipase A2 oedema. Treatment of animals with compound 48/80 markedly suppressed phospholipase A2-induced paw oedema and to a lesser degree the oedema caused by phospholipase C. Our results indicate that there are marked differences regarding the mechanisms underlying the paw oedema responses caused by phospholipase A2 and phospholipase C. In addition, our data show that M. velutina compounds cause potent and long-lasting inhibition of the pro-inflammatory action of phospholipase A2, an effect which may account for their reported anti-inflammatory activities.

Forty years of Brazilian medicinal plant research

The Brazilian Foundation of Medicinal Plants has developed a medicinal plant database. Data were obtained from communications presented in Brazilian Scientific Meetings in the 1949-1989 period and include plant species, family, local name, part used, extract analyzed, claimed therapeutic action, pharmacological activity and active compounds. The families most frequently studied and the usual popular indications are analyzed. The history of research during this period and the current state of medicinal plant research in Brazil are outlined.

Inhibition of rat paw oedema and pleurisy by the extract from Mandevilla velutina

This study reports the oral anti-inflammatory profile of the crude extract (CE) of Mandevilla velutina, a plant which has been previously demonstrated to selectively antagonize bradykinin response of the isolated tissues on rat paw oedema and pleurisy caused by different phlogistic agents. The CE (50 to 200 mg/kg), given 60 min before, inhibited in a dose-dependent manner bradykinin (BK) and cellulose sulphate-induced paw oedema, maximal inhibition of 59% and 65%, respectively. In the same range dose the CE also significantly antagonized pleural exudate and cell infiltration caused by these substances, maximal inhibition of 34% and 46%, respectively. In addition, the CE (100 and 200 mg/kg) also inhibited paw oedema induced by serotonin, PAF-acether and zymosan, maximal inhibition of 55%, 38% and 46%, respectively, but enhanced histamine oedema. However, the CE revealed only partial or no inhibition in pleural exudate caused by these agents. The CE (100 and 200 mg/kg) also inhibited in a dose and time-dependent manner carrageenan-induced paw oedema with a maximal inhibition of 44%, but only partially affected carrageenan-induced pleural exudate. The CE also partially inhibited dextran oedema, but even at a higher dose (400 mg/kg) it failed to interfere with Bothrops Jaracaca-induced paw oedema. The CE inhibited BK and to a lesser extent cellulose sulphate-induced cell migration, but failed to interfere with the differential leukocyte migration in the pleural cavity. These findings provide evidence that the CE from M. velutina, besides antagonizing kinin action, exhibit an oral anti-oedematogenic activity against a variety of phologistic agents, but it was more effective in inhibiting those models where kinins are more involved.

Action of pregnane compounds from Mandevilla illustris against contractions induced by kinins and other oxytocics in the rat isolated uterus

1. The effects of 5 pregnane compounds isolated from the rhizomes of Mandevilla illustris were examined against bradykinin (BK), Lysyl-bradykinin (L-BK), acetylcholine (ACh) and oxytocin (Ot)-induced contractions in the isolated uteri of the rat. 2. Compounds MI 15 and MI 18 (5-40 micrograms/ml) caused a parallel and concentration-dependent rightward displacement of BK and L-BK concentration-response curves. Compound MI 21 (2.5-10 micrograms/ml) also produced a concentration-dependent displacement to the right of the BK concentration-response curve, but reduced its maximal response. Schild analysis of these data were linear (r close to 1) and furnished the following PA2 values (as G/ml): 6.0, 5.1 and 5.9, respectively. However, the slopes were significantly higher than unity. Compounds MI 25 and MI 27 (10-40 micrograms/ml) caused little or even no effect against BK and ACh responses. 3. In addition, compounds MI 18 and MI 21 (10-40 micrograms/ml) also antagonized in a concentration-dependent manner L-BK concentration-response curves. Schild plot were linear (r close to 1) and yielded the nominal pA2 values (as G/ml) of 5.0 and 5.8, respectively, but the slopes were significantly different from one. 4. Like the results obtained previously with the crude extract from M. illustris, the purified compounds from the rhizome of this plant were not selective towards kinin action since at the same range concentrations they markedly interfered with both the sensitivities and the maximal responses caused by ACh and Ot in this preparation.

Antagonism of kinin-induced contraction of isolated rat uterus by the crude hydroalcoholic extract from Mandevilla illustris

1. The crude aqueous/alcoholic extract (CE) of Mandevilla illustris (Apocynaceae) rhizomes was analysed against contractile response elicited by bradykinin (BK), lysyl-bradykinin (L-BK), oxytocin(Ot), acetylcholine (Ach), angiotensin II (AII) and barium chloride (BaCl2) in the isolated uterus of the rat. 2. The CE of this plant (0.5-2.0 mg/ml) caused a parallel and concentration-related rightward displacement of BK and L-BK contractile responses. Schild plot revealed a linear relationship (r close to one) and yielded nominal PA2 values of 3.6 and 3.2 respectively, but the slopes were significantly different from unity. 3. However, the anti-BK action of the CE of M. illustris was not selective to kinin action, since in the same range concentration the CE also affected uterine contractile responses induced by Ot, Ach, AII and BaCl2.