Antihypertensive effect of an aqueous extract of Zygophyllum coccineum L. in rats

The effects of an aqueous extract of Zygophyllum coccineum L. on rat blood pressure (BP) and on the mesenteric vascular bed were investigated. The extract dose-dependently reduced BP and heart rate in normotensive and spontaneously hypertensive rats (SHRs). It also reduced BP in pithed SHRs. In vitro, the extract had no effect on basal perfusion pressure of the mesenteric vascular bed. When the perfusion pressure was raised with noradrenaline or potassium chloride, the extract produced a dose-dependent reduction in perfusion pressure. However, in preparations in which the perfusion pressure was raised with KCl, the depressor response to lower doses of the extract was abolished while higher doses produced responses that were reduced in magnitude when compared with similar responses in preparations in which the perfusion pressure was raised with noradrenaline. It was concluded that extracts of Z. coccineum possess significant antihypertensive activity that may involve some membrane hyperpolarization.     

Saponins from the leaves of Musanga cecropioïdes (cecropiaceae) constitute a possible source of potent hypotensive principles

The aqueous leaf extract and saponins extracted from the aqueous leaf extract of Musanga cecropioïdes exhibited potent hypotensive effects in both normotensive and hypertensive rats. The intravenous administration (direct invasive blood pressure study technique) of 15–30 mg/kg body weight of the aqueous leaf extract produced a fall in blood pressure (BP) of 35%–57% in hypertensive rats and 27% in normotensive individuals. This BP fall was followed by a transient rise, while saponins extracted from the aqueous extract of the leaves of MC produced a fall in BP of 55% in hypertensive and 30% in normotensive rats. In the indirect (tail cuff) blood pressure study, the effect was also dose-dependent. The oral administration of 300 mg/kg body weight of the aqueous leaf extract produced a BP fall of over 30% by 12 h following extract administration while the saponins (0.02–0.8 mg/kg body weight) produced a fall of 10% to 53%.     

Tribulus terrestris: preliminary study of its diuretic and contractile effects and comparison with Zea mays

OBJECTIVES: Tribulus terrestris L. (Zygophyllaceae) which is called Al-Gutub (in Iraqi dialect) or Quti;ba (in classical Arabic medicine), and Zea mays were both used alone or in combination by Iraqi herbalists to propel urinary stones. We studied the aqueous extract of the leaves and fruits of T. terrestris and the hair of Z. mays, to determine their diuretic activity and the contractile effect of T. terrestris. METHODS: The aqueous extract was filtered and the solvent was evaporated to produce a dry crude extract. The dry extract was then dissolved in physiological saline to make the required concentrations. Wistar male rats were used for the diuresis test and strips of isolated Guinea pig ileum were used for the contractility test. RESULTS: The aqueous extract of T. terrestris, in oral dose of 5g/kg elicited a positive diuresis, which was slightly more than that of furosemide. Z. mays aqueous extract did not result in significant diuresis when given alone in oral dose of 5g/kg, while combination of Z. mays and T. terrestris extracts produced the same extent of diuresis as that produced by T. terrestris alone. Na(+), K(+) and Cl(+) concentrations in the urine had also much increased. In addition to its diuretic activity T. terrestris had evoked a contractile activity on Guinea pig ileum. CONCLUSION: T. terrestris has long been used empirically to propel urinary stones. The diuretic and contractile effects of T. terrestris indicate that it has the potential of propelling urinary stones and merits further pharmacological studies.     

The antihypertensive and vasodilator effects of aqueous extract from Berberis vulgaris fruit on hypertensive rats

The aqueous extract from Berberis vulgaris fruit (B.V.) was tested to evaluate its antihypertensive effects on DOCA-induced hypertension in the rats. Hypertension was induced in male Sprague-Dawley rats (200-250 g) by DOCA-salt injection (20 mg/kg, twice weekly, for 5 weeks, s.c.) plus NaCl (1%) which was added to the animals' drinking water. Then 5 weeks later, the rats were anaesthetized with thiopental (30 mg/kg, i.p.) and the arterial blood pressure was measured. The mean arterial blood pressure and heart rate were 231 +/- 6.4 (mmHg) and 506 +/- 12 (beats/min), respectively. Administration of B.V. extracts significantly reduced the rat arterial blood pressure. In in vitro studies, rings of descending aorta were cut and mounted for isometric tension recording in an organ chamber containing Krebs solution. Mesenteric beds were also removed and perfused with Krebs solution. After 1 h of stabilization, preparations (aortic rings or mesenteric beds) were precontracted with phenylephrine (10(-5) M), then different concentrations of B.V. (0.4, 2 and 4 mg/mL) were added which caused a relaxation in these vessels. To investigate the mechanism of action of the extract, the tissues were incubated with either L-NAME (10(-5) M) or indomethacin (10(-5) M) for 20 min. In the aortic rings L-NAME pretreatment could only reduce the vasodilatory effects of a low concentration of B.V. (0.4 mg/mL), but indomethacin was without effect. In isolated perfused mesenteric beds preincubation with either L-NAME or indomethacin did not modify the vasodilator effects of the aqueous extract from B.V. fruit. The present results suggest that the antihypertensive and vasodilatory effects of B.V. fruit extract are mainly endothelial-independent and it may be used to treat hypertension, a status with endothelial dysfunction.     

Cardiovascular effects of Urtica dioica L. (Urticaceae) roots extracts: in vitro and in vivo pharmacological studies

Urtica dioica (Urticaceae) is a plant principally used in the traditional medicine of oriental Marocco as antihypertensive remedy (J. Ethnopharmacol., 58 (1997), 45). The aim of this work was to evaluate a possible direct cardiovascular action of the plant and to investigate its mechanism of action. In aortic preparations with intact and functional endothelial layer, pre-contracted with KCl 20 mM or norepinephrine 3 microM, the crude aqueous and methanolic extracts of the plant roots, as well as purified fractions elicited a vasodilator action. Nevertheless, the vasodilator activity was not present in aortic rings without endothelial layer. In aortic rings with intact endothelial layer, the vasorelaxing effect was abolished by L-NAME, a NO-biosynthesis inhibitor, and ODQ, a guanylate cyclase inhibitor. Furthermore, potassium channel blockers (TEA, 4-aminopyridine, quinine, but not glybenclamide) antagonized the vasodilator action of the purified fraction F1W of U. dioica. The same fraction produced a marked decrease of inotropic activity, in spontaneously beating atria of guinea-pig, and a marked, but transient, hypotensive activity on the blood pressure of anaesthetized rats. It is concluded that U. dioica can produce hypotensive responses, through a vasorelaxing effect mediated by the release of endothelial nitric oxide and the opening of potassium channels, and through a negative inotropic action.     

Vascular effects and antioxidant activity of two Combretum species from Democratic Republic of Congo

Ethnopharmacological relevance

Combretum racemosum P. Beauv (Combretaceae) leaves (CrLv) and root bark (CrRB) and Combretum celastroides subsp. laxiflorum Welw (Combretaceae) leaves (ClLv) are used in Congolese traditional medicine for several therapeutic purposes, notably for the treatment of conditions consistent with hypertension. The present study aims to investigate the vasorelaxant and in vitro antioxidant activities of these plants polar extracts and to examine the in vivo antihypertensive effect of the extract which displays the most potent vasorelaxant effect.

Material and methods

The vasorelaxant effect of CrLv, CrRB and ClLv methanolic extracts was studied on rat aorta rings pre-contracted with phenylephrine (PE, 1 μM) in the presence or absence of the endothelium. In some experiments, prior to the addition of the extract, rings were incubated for 30 min with either L-N^G-nitroarginine methyl ester (L-NAME; 100 μM), a nitric oxide synthase (NOS) inhibitor, indomethacin (10 μM), a cyclooxygenase inhibitor, or 1 H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 μM), a guanylate cyclase inhibitor. The antioxidant activity was determined by the measurement of the scavenging ability of extracts towards the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Blood pressure was measured on normotensive Wistar rats and spontaneously hypertensive rats (SHR) treated orally with a daily dose (40 mg/kg) of the CILv extract for 5 weeks. Tested extracts have been characterised by TLC profiles targeted at flavonoids.

Results

All tested extracts showed an important DPPH scavenging activity, ranging from 0.6 to 1.1 quercetin-equivalents. They caused a concentration-dependent vasorelaxation on intact aortic rings pre-contracted with PE (1 μM). The responses to CrRB and CrLv methanolic extracts reached 74.0±5.1% and 62.2±8.6% at a cumulative concentration of 50 μg/ml, respectively. The ClLv (10 μg/ml) extract was more active and, in the same conditions, relaxed aortic rings by 90.3±5.8%. The vasorelaxant activity of all extracts disappeared or was significantly attenuated by removal of the endothelium or after pretreatment with L-NAME or ODQ. Indomethacin only inhibited the activity of CrLv and CrRB extracts. The ClLv extract was able to lower the systolic blood pressure in SHR rats by 7% after a 5-week treatment.

Conclusions

The present study shows that methanolic extracts from ClLv, CrRB and CrLv have an antioxidant activity and an endothelium-dependent vasorelaxant effect. ClLv induces the vasorelaxant effect through the NO-cGMP pathway while CrLv and CrRB extracts also act via a prostanoid pathway. ClLv extract demonstrated a modest but significant antihypertensive activity in SHR rats.     

Terpenoid content of Valeriana wallichii extracts and antidepressant‐like response profiles

Three extracts of Valeriana wallichii DC (Valerianaceae) rhizome and fluoxetine were studied for antidepressant‐like activity in two behavioral models, namely the forced swim test (FST) and the tail suspension test (TST). Fluoxetine as well as methanolic and aqueous extracts of V. wallichii induced monophasic dose‐related decrements in immobility times in both tests. However, the aqueous‐ethanolic fraction induced a biphasic dose‐response profile since it produced a graded effect up to 200 mg/kg but the highest dose (250 mg/kg) was inactive in the FST. This extract also exhibited significantly reduced activity at 200 mg/kg compared to lower doses in the TST. The highest doses of aqueous‐ethanolic extract also reduced locomotor activity which will have led to a negative functional interaction with antidepressant‐like effects. Qualitative phytochemical analysis revealed that the aqueous‐ethanolic extract of V. wallichii was the only separated rhizome fraction containing terpenoids. Furthermore, since the methanolic and aqueous extracts were active in the tests, it is suggested that the antidepressant‐like action of this herbal plant is not contingent upon its terpenoid constituents. Copyright © 2009 John Wiley & Sons, Ltd.     

Antihypertensive effect of Lepidium sativum L. in spontaneously hypertensive rats

The antihypertensive and diuretic effects of the aqueous extract of Lepidium sativum L. (LS) were studied both in normotensive (WKY) and spontaneously hypertensive rats (SHR). Daily oral administration of the aqueous LS extract (20mg/kg for 3 weeks) exhibited a significant decrease in blood pressure (p<0.01) in SHR rats while in WKY rats, no significant change was noted during the period of treatment. The systolic blood pressure was decreased significantly from the 7th day (p<0.05) to the end of treatment (p<0.01) in SHR rats. The aqueous LS extract enhanced significantly the water excretion in WKY rats (p<0.001) but no statistically significant change was observed in SHR rats. Furthermore, oral administration of aqueous LS extract at a dose of 20mg/kg produced a significant increase of urinary excretion of sodium (p<0.05), potassium (p<0.01) and chlorides (p<0.01) in WKY rats. In spontaneously hypertensive rats, the aqueous LS extract administration induced a significant increase of urinary elimination of sodium (p<0.01), potassium (p<0.001) and chlorides (p<0.001). Glomerular filtration rate showed a significant increase after oral administration of LS in normal rats (p<0.001) while in SHR rats, no significant change was noted during the period of treatment. Furthermore, no significant changes were noted on heart rate after LS treatment in SHR as well as in WKY rats. Our results suggest that daily oral administration of aqueous LS extract for 3 weeks exhibited antihypertensive and diuretic activities.     

Effects of Crocus sativus petals' extract on rat blood pressure and on responses induced by electrical field stimulation in the rat isolated vas deferens and guinea-pig ileum

We have investigated the effects of Crocus sativus petals' extract on blood pressure in anaesthetised rats and also on responses of the isolated rat vas deferens and guinea-pig ileum induced by electrical field stimulation (EFS). Aqueous and ethanol extracts of C. sativus petals reduced the blood pressure in a dose-dependent manner. For example administration of 50 mg/100 g of aqueous extract changed the blood pressure from 133.5+/-3.9 to 117+/-2.1 (mmHg). EFS of the isolated rat vas deferens and guinea-pig ileum evoked contractions were decreased by aqueous and ethanol extracts of C. sativus petals. The aqueous extract (560 mg/ml) significantly reduced the contractile responses of vas deferens to epinephrine (1 microM) without any change in contraction induced by KCl (300 mM). The present results may suggest that the relaxatory action of C. sativus petals' extract on contraction induced by EFS in the rat isolated vas deferens is a postsynaptic effect.     

Effects of Vitex doniana Stem Bark Extract on Blood Pressure

The effects of oral and intravenous administration of the stem bark extract of Vitex doniana on blood pressure was investigated in normotensive and hypertensive rats. Oral and intravenous administration of the stem bark extract produced a dose-dependent hypotensive effect in both normotensive and hypertensive rats. The blood pressure was markedly reduced and the reduced level maintained for longer duration when the extract was administered intravenously to hypertensive rats. The present data show that the extract affects the smooth muscle of the vascular system, suggesting a possible therapeutic application as an antihypertensive agent.     

A pharmacological study on Berberis vulgaris fruit extract

Berberis vulgaris fruit (barberry) is known for its antiarrhythmic and sedative effects in Iranian traditional medicine. The effects of crude aqueous extract of barberry on rat arterial blood pressure and the contractile responses of isolated rat aortic rings and mesenteric bed to phenylephrine were investigated. We also examined effect of the extract on potassium currents recorded from cells in parabrachial nucleus and cerebellum rejoins of rat brain. Administration of the extract (0.05-1 mg/100 g body weight of rat) significantly reduced the mean arterial blood pressure and heart rate in anaesthetized normotensive and desoxycorticosteron acetate-induced hypertensive rats in a dose-dependent manner. Concentration-response curves for phenylephrine effects on isolated rat aortic rings and the isolated mesenteric beds in the presence of the extract were significantly shifted to the right. Application of the extract (1-50 microg/ml) shifted the activation threshold voltage to more negative potentials, leading to an enhancement in magnitude of the outward potassium current recorded from cells present in rat brain slices of parabrachial nucleus and cerebellum. This effect on potassium current may explain the sedative and neuroprotective effects of barberry. The present data support the hypothesis that the aqueous extract of barberry has beneficial effects on both cardiovascular and neural system suggesting a potential use for treatment of hypertension, tachycardia and some neuronal disorders, such as epilepsy and convulsion.     

Evaluation of in vivo antihypertensive and in vitro vasodepressor activities of the leaf extract of Syzygium guineense (Willd) D.C

The aim of this work was to evaluate the antihypertensive activity of the hydroalcohol extract of the leaves of Syzygium guineense (Willd) D.C. (Myrtaceae) in a 1-kidney-1-clip rat model and its vasorelaxant effect on isolated aorta. The extract reduced blood pressure in a dose and time dependent fashion. Following 3 days of treatment, single oral daily doses of 50, 100 and 150 mg/kg caused an overall reduction (p < 0.05) of systolic blood pressure by 6.9, 34.0 and 40.8 mmHg, respectively. The diastolic blood pressure was, however, significantly reduced (p < 0.05) by 100 mg/kg (10.3 mmHg) and 150 mg/kg (18.4 mmHg) doses only. The mean blood pressure was reduced by 5.0, 18.3 and 25.9 mmHg by the respective doses. The extract also caused a dose-dependent relaxation of aorta precontracted with KCl at a concentration of 5-70 mg/mL, with a maximum relaxation of 56.22% achieved at 70 mg/mL concentration. The relaxation mechanism was found to be independent of the endothelium system, muscarinic receptors, histamine receptors, ATP dependent K(+) channels, cyclooxygenase enzymes and cGMP/NO pathway. The findings suggest that the extract had an antihypertensive effect most likely caused by dilation of the blood vessels, a confirmation for the folkloric use of the plant.     

刺蒺藜提取物抗炎、耐缺氧及抗疲劳作用的实验研究

目的探讨刺蒺藜提取物抗炎、耐缺氧及抗疲劳作用。方法将110只小鼠随机分组:对照组、刺蒺藜小剂量组、刺蒺藜大剂量组和耐缺氧实验(维拉帕米)阳性对照组、抗炎实验(阿司匹林)阳性对照组。其中对照组、刺蒺藜小剂量组、刺蒺藜大剂量组和阿司匹林组灌胃给药,维拉帕米组腹腔注射。采用二甲苯致小鼠耳壳肿胀的方法,测定耳片的重量差;采用常压耐氧法记录小鼠耐缺氧时间;采用负重游泳的方法记录小鼠抗疲劳游泳的时间。结果刺蒺藜提取物对二甲苯所致小鼠耳壳肿胀有明显抑制作用,延长缺氧情况下小鼠的存活时间及负重情况下小鼠的游泳时间与对照组比较有均显著性差异。结论刺蒺藜提取物具有一定的抗炎、耐缺氧及抗疲劳作用。     

Hypotensive and vasorelaxant effects of the procyanidin fraction from Guazuma ulmifolia bark in normotensive and hypertensive rats

THE AIM OF THE STUDY: was to investigate the in vivo and in vitro cardiovascular activity of a procyanidin fraction (PCF) obtained from acetone extract of Guazuma ulmifolia bark which has traditionally been used as an antihypertensive agent. RESULTS: 10 mg/kg PCF doses orally administered to sugar-fed hypertensive rats decreased both the systolic arterial pressure and the heart rate, whereas the same doses intravenously administered induced arterial hypotension which was attenuated by NG-nitro-L-arginine methylester (L-NAME 31 mg/kg) pretreatment. In these experiments we employed carbachol as a positive control test. The PCF reduced the contraction induced by norepinephrine (1x10(-7) M) in isolated aortic rings of normotensive (IC50=35.3+/-12.4 ng/mL) and sugar-fed hypertensive (IC50=101.3+/-57.2 ng/mL) rats. This relaxant activity was inhibited by either vascular endothelium removal or L-NAME (30 microM) pretreatment, while indomethacin (10 microM) or atropine (10 microM) had no effect. Preliminary analysis of the PCF by HPLC-DAD-MS and FAB+ mass spectrometry allowed the detection of the main components such as the complex of procyanidin oligomers consisting mainly of tetramers and trimers. CONCLUSIONS: Guazuma ulmifolia bark possesses long-lasting antihypertensive and vasorelaxing properties linked to the endothelium related factors, where nitric oxide is involved.     

The protective effect of Allium sativum L. clove aqueous and methanolic extracts against hypoxia-induced lethality in mice

The antihypoxic activity of Allium sativum clove (garlic) aqueous and methanolic extracts was studied in mice.The extracts of garlic showed that the antihypoxic effect was dose-dependent. The minimum effective doses of aqueous and methanolic extracts were 0.2 g/kg and 5.12 g/kg, respectively. Phenytoin, 50 mg/kg, and R-phenylisopropyladenosine (R-PIA), 1.6 mg/kg (R-PIA) as positive controls increased survival time up to 52.5 +/- 2.9 min and 120.5 +/- 6 min, respectively, compared to normal saline (34.73 +/- 0.71 min). The high doses of aqueous (16.9 g/kg) and methanolic (12.8 g/kg) extracts increased survival time up to 73.17 +/- 4.9 and 68.41 +/- 3.7, respectively.These results indicated that the extracts of A. sativum cloves have a protective effect against hypoxia-induced lethality in mice.     

Sedative, antiepileptic and antipsychotic effects of Spondias mombin L. (Anacardiaceae) in mice and rats

In this study, we evaluated the effects of air-dried Spondias mombin leaves extracted with aqueous, methanol and ethanol solvents on hexobarbital-induced sleeping time and novelty-induced rearing (NIR) behaviours in mice and rats. We also studied the effect of the extracts on amphetamine- and apomorphine-induced stereotyped and picrotoxin-induced convulsive behaviour in rats. All residues from different extractions were dissolved in normal saline and administered intraperitoneally (i.p.). The methanolic and ethanolic extracts (12.5-100mg/kg i.p.) prolonged the hexobarbital-induced sleeping time and reduced the NIR in both mice and rat in a dose-dependent manner. The aqueous extract prolonged the hexobarbital-induced sleeping time and reduced (NIR) at doses of 50 and 100mg/kg. The inhibitory effect of the extracts on NIR was not reversed by atropine, yohimbine, naltrexone and flumazenil. However, the extracts blocked the facilitating effect of flumazenil. This suggests that NIR inhibitory effects of extracts of Spondia mombin are not mediated via muscarinic, alpha(2) adrenergic, and mu-opioid receptors, whereas, the extracts appear to facilitate GABAergic transmission. In addition the extracts blocked picrotoxin-induced convulsions. Phenolic compound(s) were present in the ethanolic and methanolic extracts, which exhibited anticonvulsant properties in the picrotoxin-induced convulsions model. The extracts decreased the amphetamine/apomorphine-induced stereotyped behaviour, which suggest that these extracts possess antidopaminergic activity. The effect of the extracts on hexobarbitone-induced sleeping time was blocked by flumazenil a GABA(A) antagonist, indicating that the extracts contain GABA(A) agonists. These results suggest that the leaves extracts of Spondias mombin possess sedative and antidopaminergic effects.     

Vasorelaxant and antihypertensive effects of methanolic extracts from Hymenocardia acida Tul

Ethnopharmacological relevance

In Congolese traditional medicine, decoctions of Hymenocardia acida root bark (HaRB) and trunk bark (HaTrB) are used for the treatment of conditions assumed to be hypertension. In this work, we propose to study the vasorelaxant effect of HaRB and HaTrB methanolic extracts on isolated rat thoracic aorta, to characterize the group of molecules responsible for the observed vasorelaxant activity, to evaluate the in vitro antioxidant activity of these extracts and to determine the antihypertensive activity of the HaRB extract on spontaneously hypertensive rats (SHR).

Materials and methods

The vasorelaxant effect of the HaRB and HaTrB methanolic extracts was studied on endothelium-intact aortic rings pre-contracted with phenylephrine (PE, 1 μM). The mechanism of this vasorelaxant effect was investigated on endothelium-denuded vessels and on endothelium-intact aortic rings in the presence of three inhibitors: l-N^G-nitroarginine methyl ester (100 μM), indomethacin (10 μM) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (10 μM). To determine the nature of the compounds responsible for the vasorelaxant activity, we carried out a fractionation of the extracts and a thiolysis of the most active fraction followed by a liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) analysis. The extracts antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) colorimetric assay. In vivo anti-hypertensive activity of the HaRB extract was conducted on SHR.

Results

HaRB and HaTrB methanolic extracts produced a concentration-dependent vasorelaxation on intact aortic rings pre-contracted with PE (1 μM). The vasorelaxant responses obtained were 95.3±1.5% (5 μg/ml) and 100.6±3.0% (1 μg/ml), respectively. The effect was markedly attenuated by removal of endothelium or pretreatment of aortic rings with all inhibitors except indomethacin. The LC/ESI-MS analysis of the thiolysis products indicated that the fraction which caused the most important vasorelaxation (97.9±2.5% at 3 μg/ml) was a mixture of procyanidins and prodelphinidins, with a predominance of procyanidins. Both extracts and all fractions from HaRB extract showed a DPPH scavenging activity, ranging from 0.4 to 0.8 quercetin-equivalents. The HaRB methanolic extract reduced the systolic blood pressure in SHR (from 214±3 mmHg to 194±4 mmHg) after a 5-week treatment.

Conclusions

The methanolic extracts of Hymenocardia acida root and trunk bark have vasorelaxant activity. The vasorelaxant effect observed is endothelium-dependent and seems mainly mediated through the NO-cGMP pathway. The COX pathway is not involved. The vasorelaxant activity appears to be due to polymeric procyanidins and prodelphinidins. These extracts also have an antioxidant effect. The extract of Hymenocardia acida root bark shows a significant but weak antihypertensive activity in SHR.     

Cardiovascular effects of the South American medicinal plant Cecropia pachystachya (ambay) on rats

Cecropia pachystachya is used in South America for relieving cough and asthma. In Argentina it is known as "ambay" and grows in the neotropical forests (Ntr C.p.) and in temperate hilly regions (Tp C.p.). To evaluate their cardiovascular profile, the effect of extracts obtained from plants growing in the neotropical region as well as in temperate areas were compared by i.v. administration in normotensive rats. The following parameters were measured: blood pressure (BP) and heart rate (HR). The hypotensive effect was stronger for Ntr C.p., which aqueous extract decreased BP at doses between 90 and 300 mg lyophilised/kg until 46.2 +/- 12% of basal. The extract of Tp C.p. reduced BP to 86.1 +/- 11% of basal (p < 0.05 respect to Ntr C.p.) at 180 mg/kg, but increased HR at 90 and 180 mg/kg (until 133.6 +/- 10.8% of basal, p < 0.05) and produced death by respiratory paralysis at 320 mg/kg (about 3g dry leaves/kg). The hypotensive effects, but not the chronotropic ones, were attenuated by pretreatment with reserpine (5 mg/kg). The plant extracts had not diuretic activity by oral administration in conscious rats, nor produced vasodilation of perfused hindquarters arterial bed precontracted with high-[K] or 100 microM phenylephrine. The results suggest that neotropical ambay is more hypotensive than the one from the temperate hilly region. When it reaches plasma, it could produce hypotension (by central blockade of sympathic innervation of vessels) and tachycardia (by central cholinergic inhibition of heart), although it happens at doses higher than the oral ethnotherapeutic (about 340 mg dried leaves/kg).     

Evaluation of the anti-inflammatory properties of Sclerocarya birrea (A. Rich.) Hochst. (family: Anacardiaceae) stem-bark extracts in rats

This study was designed to evaluate the anti-inflammatory effect of Sclerocarya birrea (family: Anacardiaceae) stem-bark aqueous and methanolic extracts in rats. Young adult, male Wistar rats (Rattus norvegicus) weighing 250-300g were used. The anti-inflammatory effects of aqueous and methanolic stem-bark extracts of the plant (SB, 500mg/kg p.o.) were examined on rat paw oedema induced by subplantar injections of fresh egg albumin (0.5ml/kg). Acetylsalicylic acid (ASA, 100mg/kg p.o.) was used as the reference anti-inflammatory agent for comparison. Both the aqueous and methanolic stem-bark extracts of S. birrea (SB, 500mg/kg p.o.) progressively and time-dependently reduced rat paw oedema induced by subplantar injections of fresh egg albumin. However, the methanolic extract of the plant produced relatively greater and more pronounced anti-inflammatory effect than its aqueous extract counterpart in the experimental animal model used. The two extracts of S. birrea stem-bark were found to be markedly less potent than ASA as anti-inflammatory agent. Although both the aqueous and methanolic extracts of S. birrea stem-bark are less potent than ASA as anti-inflammatory agent, the results of this experimental animal study indicate that the extracts possess anti-inflammatory activity, and thus lend credence to the suggested folkloric use of the plant in the management and/or control of arthritis and other inflammatory conditions in certain communities of South Africa.     

丹皮酚对自发性高血压大鼠动脉血压和血流量的影响及其与血管舒缩相关的作用机制

前期研究发现丹皮酚能显著对抗大鼠急性心肌缺血和梗死,该实验进一步研究其对自发性高血压大鼠动脉血压和血流量的影响,并探索其与血管舒缩相关的作用机制。首先,采用自发性高血压大鼠30只,随机分为自发高血压对照组和丹皮酚高、低剂量组,另以10只Wistar大鼠作为健康对照组。分别于给药前和十二指肠一次性给药后用颈动脉插管法测定动脉血压,并通过在体动物血流仪测定肾动脉和颈动脉的血流量,自发高血压对照组和健康对照组同法给予相同体积的溶剂,其余操作相同。为进一步研究丹皮酚对血管舒缩功能的影响,采用离体微血管动力描记技术,以一定浓度的预收缩剂收缩血管后,累加浓度法加入丹皮酚,分别记录丹皮酚对自发性高血压大鼠肠系膜上动脉、肾动脉和冠状动脉的舒张效应。丹皮酚可显著降低自发性高血压大鼠的动脉收缩压和舒张压,其中降低收缩压的作用更为明显,可显著增加自发性高血压大鼠的颈动脉和肾动脉血流量;可浓度依赖性地舒张自发性高血压大鼠的肠系膜上动脉、肾动脉和冠状动脉。结果表明,丹皮酚对自发性高血压大鼠具有显著降低动脉血压、增加动脉血流量的作用,该作用与其显著的扩血管效应有关。