Maria Consuelo Andrade Marques

Antihypertensive effects of isoquercitrin and extracts from Tropaeolum majus L.: Evidence for the inhibition of angiotensin converting enzyme

AIM OF THE STUDY Previous studies have shown that the extracts obtained from Tropaeolum majus L. exhibit pronounced diuretic properties. In the present study, we assessed whether the hypotensive and/or antihypertensive mechanism of hydroethanolic extract (HETM), semi-purified fraction (TMLR) obtained from T. majus and the flavonoids isoquercitrin (ISQ) and kaempferol (KPF) can be mediated by their interaction with angiotensin converting enzyme (ACE). METHODS AND METHODS Firstly, to evaluate changes in mean arterial pressure (MAP), different groups of normotensive and spontaneously hypertensive rats (SHR) were orally and intraduodenally treated with HETM (10-300 mg/kg) and TMLR (12.5-100mg/kg) and intravenously treated with ISQ and KPF being later anesthetized with ketamine (100mg/kg) and xylazine (20mg/kg). The left femoral vein and the right carotid artery were isolated, and polyethylene catheters were inserted for ISQ and KPF (0.5-4 mg/kg) administration and blood pressure recording, respectively. The plasmatic ACE activity was evaluated to indirect fluorimetry, in serum samples after orally treatment with HETM, TMLR, ISQ and KPF. RESULTS The oral administration of the HETM and its TMLR significantly reduced, in a dose-dependent manner, the MAP in both normotensive and SHR. In addition, these preparations significantly decreased the MAP for up to 3h after the administration of the extract. Additionally, the intravenous administration of ISQ, but not KPF, decreased MAP in rats. Otherwise, neither the extracts nor ISQ affected the heart rate. The oral administration of the HETM, TMLR or ISQ reduced ACE activity in serum samples at 90 min after administration. Finally, the intravenous administration of ISQ caused a significant reduction in the hypertensive response to angiotensin I, but not angiotensin II in normotensive rats. CONCLUSION Our results show that the hypotensive effects caused by the HETM, as well as by its TMLR, may be associated with the high levels of the flavonoid ISQ found in this plant. In addition, ISQ-induced hypotension in rats is an event dependent on the inhibition of angiotensin II generation by ACE.

Gastroprotective effects of a crude extract of Baccharis illinita DC in rats

Baccharis illinita DC (Compositae) is used in folk medicine to treat gastric disorders. The crude hydroalcoholic extract of leaves and stems tested on mice at doses from 1.0 to 6.0 g/kg, PO, did not produce signs of toxicity. Only the aqueous extract of leaves (0.1 g/kg, PO) increased intestinal motility in mice. The crude hydroalcoholic extract of stems and leaves (HESL) protected rats against lesions induced by ethanol or restraint-in-cold. The crude aqueous extract of roots protected against ulcers induced by ethanol, indomethacin or restraint-in-cold, and the crude aqueous extract of flowers only protected against lesions induced by ethanol. When injected into the duodenal lumen, the aqueous root extract inhibited basal acid secretion in pylorus-ligated rats. The results obtained in the present pharmacological assays indicate that this plant has a protective action against gastric lesions of the mucosa involving the maintenance of protective factors such as mucus, bicarbonate and blood flow, besides the reduction of gastric acid secretion.

Antinociceptive properties of the ethanolic extract and of the triterpene 3β,6β,16β-trihidroxilup-20(29)-ene obtained from the flowers of Combretum leprosum in mice

Abstract The present study examined the antinociceptive effects of the ethanolic extract (EE) and of the triterpene 3β,6β,16β-trihidroxilup-20(29)-ene obtained from the flowers of Combretum leprosum in chemical and thermal behavioural models of pain in mice. The EE (10–1000 mg/kg) given orally (p.o.), 1 h prior to testing, produced dose-dependent inhibition of acetic acid-induced visceral pain, with mean ID50 value of 131.9 mg/kg. In the formalin test, the EE (10–300 mg/kg, p.o.) also caused significant inhibition of both the early (neurogenic pain) and the late (inflammatory pain) phases of formalin-induced licking, however, it was more potent and efficacious in relation to the late phase of the formalin test, with mean ID50 values for the neurogenic and the inflammatory phases of ∼300 and 88.8 mg/kg, respectively. The EE (10–1000 mg/kg, p.o.) also caused significant and dose-dependent inhibition of capsaicin- and glutamate-induced pain, with mean ID50 values of 160.5 and 38.3 mg/kg, respectively. Furthermore, the triterpene 3β,6β,16β-trihidroxilup-20(29)-ene (1–30 mg/kg), given p.o., 1 h prior to testing, also produced dose-related inhibition of glutamate-induced pain, with a mean ID50 value of 5.6 mg/kg. When assessed in a thermal model of pain, the EE (10–300 mg/kg, p.o.) and fentanyl (100 μg/kg, s.c.) caused a significant and marked increase in the latency response on the hot-plate test (50 °C). The antinociception caused by EE (100 mg/kg, p.o.) in the glutamate test was significantly attenuated by intraperitoneal (i.p.) treatment of mice with naloxone (opioid receptor antagonist, 1 mg/kg), pindolol (a 5-HT1A/1B receptor/β adrenoceptor antagonist, 1 mg/kg), WAY100635 (a 5-HT1A receptor antagonist, 0.7 mg/kg) or ketanserin (a 5-HT2A receptor antagonist, 0.3 mg/kg). In contrast, EE (100 mg/kg, p.o.) antinociception was affected neither by l -arginine (precursor of nitric oxide, 600 mg/kg) nor by ondansetron (a 5-HT3 receptor antagonist, 0.5 mg/kg) i.p. treatment. It was not associated with non-specific effects such as muscle relaxation or sedation. Together, these results indicate that EE produces dose-related antinociception in several models of chemical and thermal pain through mechanisms that involve an interaction with opioid and serotonergic (i.e., through 5-HT1A/1B and 5-HT2A receptors) systems.

Antinociceptive properties of the hydroalcoholic extract and the flavonoid rutin obtained from Polygala paniculata L. in mice.

The present study examined the antinociceptive effects of a hydroalcoholic extract of Polygala paniculata in chemical and thermal behavioural models of pain in mice. The antinociceptive effects of hydroalcoholic extract was evaluated in chemical (acetic-acid, formalin, capsaicin, cinnamaldehyde and glutamate tests) and thermal (tail-flick and hot-plate test) models of pain or by biting behaviour following intratecal administration of both ionotropic and metabotropic agonists of excitatory amino acids receptors glutamate and cytokines such as interleukin-1beta (IL-1beta) and tumour necrosis factor-alpha (TNF-alpha) in mice. When given orally, hydroalcoholic extract (0.001-10 mg/kg), produced potent and dose-dependent inhibition of acetic acid-induced visceral pain. In the formalin test, the hydroalcoholic extract (0.0001-0.1 mg/kg orally) also caused significant inhibition of both the early (neurogenic pain) and the late (inflammatory pain) phases of formalin-induced licking. However, it was more potent and efficacious in relation to the late phase of the formalin test. The capsaicin-induced nociception was also reduced at a dose of only 1.0 mg/kg orally. The hydroalcoholic extract significantly reduced the cinnamaldehyde-induced nociception at doses of 0.01, 0.1 and 1.0 mg/kg orally. Moreover, the hydroalcoholic extract (0.001-1.0 mg/kg orally) caused significant and dose-dependent inhibition of glutamate-induced pain. However, only rutin, but not phebalosin or aurapten, isolated from P. paniculata, administered intraperitoneally to mice, produced dose-related inhibition of glutamate-induced pain. Furthermore, the hydroalcoholic extract (0.1-100 mg/kg orally) had no effect in the tail-flick test. On the other hand, the hydroalcoholic extract caused a significant increase in the latency to response at a dose of 10 mg/kg orally, in the hot-plate test. The hydroalcoholic extract (0.1 mg/kg orally) antinociception, in the glutamate test, was neither affected by intraperitoenal treatment of animals with l-arginine (precursor of nitric oxide, 600 mg/kg) and naloxone (opioid receptor antagonist, 1 mg/kg) nor associated with non-specific effects such as muscle relaxation or sedation. In addition, oral administration of hydroalcoholic extract produced a great inhibition of the pain-related behaviours induced by intrathecal injection of glutamate, N-methyl-D-aspartate (NMDA), IL-1beta and TNF-alpha, but not by alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA), kainate or trans-1-amino-1.3-cyclopentanediocarboxylic acid (trans-ACPD). Together, our results suggest that inhibition of glutamatergic ionotropic receptors, may account for the antinociceptive action reported for the hydroalcoholic extract from P. paniculata in models of chemical pain used in this study.

Mechanisms underlying the diuretic effects of Tropaeolum majus L. extracts and its main component isoquercitrin.

ETHNOPHARMACOLOGICAL RELEVANCE Previous studies have shown that the extracts obtained from Tropaeolum majus L., and its main compound isoquercitrin (ISQ), exhibit pronounced diuretic effects, supporting the ethnopharmacological use of this plant. The aim of this study was to evaluate the efficacy and mechanisms underlying the diuretic action of an ethanolic extract of Tropaeolum majus (HETM), its purified fraction (TMLR), and its main compound ISQ, in spontaneously hypertensive rats (SHR). MATERIALS AND METHODS The diuretic effects of HETM (300mg/kg; p.o.), TMLR (100mg/kg; p.o.), and ISQ (10mg/kg; p.o.), were compared with classical diuretics in 7days repeated-dose treatment. The urinary volume, sodium, potassium, chloride, bicarbonate, conductivity, pH and density were estimated in the sample collected for 15h. The plasmatic concentration of sodium, potassium, urea, creatinine, aldosterone, vasopressin, nitrite and angiotensin converting enzyme (ACE) activity were measured in samples collected at the end of the experiment (seventh day). Using pharmacological antagonists or inhibitors, we determine the involvement of bradykinin, prostaglandin and nitric oxide (NO) in ISQ-induced diuresis. In addition, reactive oxygen species (ROS) and the activity of erythrocytary carbonic anhydrase and renal Na(+)/K(+)/ATPase were evaluated in vitro. RESULTS HETM, TMLR and ISQ increased diuresis similarly to spironolactone and also presented K(+)-sparing effects. All groups presented both plasmatic aldosterone levels and ACE activity reduced. Previous treatment with HOE-140 (a B2-bradykinin receptor antagonist), or indomethacin (a cyclooxygenase inhibitor), or L-NAME (a NO synthase inhibitor), fully avoided the diuretic effect of ISQ. In addition, the 7days treatment with ISQ resulted in increased plasmatic levels of nitrite and reducing ROS production. Moreover, the renal Na(+)/K(+)/ATPase activity was significantly decreased by ISQ. CONCLUSION Our results suggest that the mechanisms through ISQ and extracts of Tropaeolum majus increase diuresis in SHR rats are mainly related to ACE inhibition, increased bioavailability of bradykinin, PGI2, and nitric oxide, besides an inhibitory effect on Na(+)/K(+)-ATPase.

Diuretic and potassium-sparing effect of isoquercitrin-an active flavonoid of Tropaeolum majus L.

AIM OF THE STUDY Previous studies have shown that the extracts obtained from Tropaeolum majus L. exhibit pronounced diuretic effects supporting the ethnopharmacological use of this plant as diuretic. In the present work, phytochemical investigation, guided by bio-assay in spontaneously hypertensive rats (SHR), was carried out in order to identify the compounds responsible for diuretic action. MATERIAL AND METHODS Chromatographic fractionation of the hydroethanolic extract yielded an active fraction (TMLR) rich in isoquercitrin. TMLR (25-100mg/kg) and isoquercitrin (5-10mg/kg), as well the reference drug hydrochlorothiazide (10mg/kg) were orally administered in a single dose or daily for 7 days to SHR. The urine excretion rate, pH, density, conductivity and content of sodium (Na(+)) and potassium (K(+)) electrolytes were measured in the urine of saline-loaded animals. RESULTS The urinary excretion rate was dose-dependently increased in both TMLR and isoquercitrin groups, as well as Na(+). Despite the changes in urinary excretion of electrolytes, the plasmatic levels of Na(+) and K(+) had not been changed. In addition, we did not find any evidence of renal toxicity or other adverse effects in these animals, even after prolonged treatment with TMLR or isoquercitrin. CONCLUSION This research supports and extends the ethnomedicinal use of T. majus as diuretic. This activity seems to be associated to the presence of the flavonol isoquercitrin.

Ethanolic extract of roots from Arctium lappa L. accelerates the healing of acetic acid-induced gastric ulcer in rats: Involvement of the antioxidant system

We evaluate the curative efficacy of the ethanolic extract (EET) of roots from Arctium lappa (bardana) in healing of chronic gastric ulcers induced by 80% acetic acid in rats and additionally studies the possible mechanisms underlying this action. Oral administration of EET (1, 3, 10 and 30mg/kg) reduced the gastric lesion area in 29.2%, 41.4%, 59.3% and 38.5%, respectively, and at 10mg/kg promoted significant regeneration of the gastric mucosa, which was confirmed by proliferating cell nuclear antigen immunohistochemistry. EET (10mg/kg) treatment did not increase the gastric mucus content but restored the superoxide dismutase activity, prevented the reduction of glutathione levels, reduced lipid hydroperoxides levels, inhibited the myeloperoxidase activity and reduced the microvascular permeability. In addition, EET reduced the free radical generation and increased scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals in vitro. Furthermore, intraduodenal EET (10 and 30mg/kg) decreased volume and acidity of gastric secretion. Total phenolic compounds were high in EET (Folin-Ciocalteau assay) and the analysis by liquid chromatography-mass spectrometry revealed that the main compounds present in EET were a serie of hydroxycinnamoylquinic acid isomers. In conclusion, these data reveal that EET promotes regeneration of damaged gastric mucosa, probably through its antisecretory and antioxidative mechanisms.

Gastroprotective constituents of Salvia officinalis L.

The gastrointestinal activity of hydroalcoholic extract (HE) of Salvia officinalis was evaluated in a model of ethanol-induced gastric lesion. HE showed excellent activity, with ID(50) 84.0 (54.8-128.9) mg/kg. The acetic acid-induced ulcer and the total acidity of the gastric secretion were also reduced by HE, and, in vitro experiments, the H(+),K(+)-ATPase activity was inhibited. Carnosol was identified as a possible active constituent for the gastroprotective effect of HE.

Gastroprotective activity of the chloroform extract of the roots from Arctium lappa L.

Arctium lappa L. is used in folk medicine as a diuretic, depurative and digestive stimulant and in dermatological conditions. The objective of this study was to evaluate the effect and the possible mechanisms involved in the gastroprotective effects of a chloroform extract (CE) of the roots from A. lappa and its fractions. Oral pretreatment with CE (10, 30 and 100 mgkg−1) significantly reduced gastric lesions induced by ethanol by 61%, 70% and 76%, respectively. Oral administration of CE (100 mgkg−1 per day for 7 days) reduced the chronic gastric ulceration induced by acetic acid by 52%. Intraduodenal CE (100, 300 and 600 mgkg−1) reduced the total acidity of gastric secretion by 22%, 22% and 33%, respectively, while i.p. administration (10, 30 and 100 mgkg−1) inhibited total acidity by 50%, 60% and 67%, respectively. In‐vitro, CE inhibited H+, K+‐ATPase activity with an EC50 of 53 μgmL−1 and fraction A (30 and 100 μgmL−1) reduced this by 48% and 89%, respectively. CE had no effect on gastrointestinal motility. CE (250 μgmL−1) and fraction B (100 and 250 μgmL−1) had free‐radical scavenging ability, inhibiting 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical activity by 50%, 20% and 55%, respectively. Collectively, the results show that the CE protects animals from gastric lesions by reducing gastric acid secretion via inhibition of gastric H+, K+‐ATPase.

Anti-inflammatory effect of crude extract and isolated compounds from Baccharis illinita DC in acute skin inflammation

UNLABELLED ETHNOPHARMACOLOGYCAL RELEVANCE: The tea from the leaves of Baccharis illinita DC (Asteraceae family) is commonly used by the population as anti-inflammatory (including topically), protective gastric and anti-infectious. However, no studies have been done with this species to confirm its topical anti-inflammatory action. AIM This study evaluated he topical effects of crude extract of leaves (CE) and its active constituents in 12-O-tetradecanoylphorbol acetate (TPA)-induced ear oedema. METHODOLOGY CE and compounds effects were tested in commonly used models of TPA-, arachidonic acid (AA)- and capsaicin-ear oedema. Polymorphonuclear (PMN) cell migration was evaluated by mieloperoxidase and analyzed histologically. RESULTS CE (0.1-1 mg/ear) caused a dose-related inhibition of TPA-induced ear oedema and PMN influx similarly to that produced by topical application of the steroidal anti-inflammatory drug dexamethasone. The active constituents of the AcOEt fraction kaurenoic acid, alpha-spinasterol, oleanolic acid and baurenol also inhibited TPA-induced ear edema. Histological analysis of the ear of CE-treated animals confirmed the reduction of edema and of PMN infiltration. Both CE and the nosteroidal anti-inflammatory drug indomethacin inhibited the AA-induced ear oedema, but did not change capsaicin-induced oedema. CONCLUSION These results indicate that the CE and the active constituents have a topical anti-inflammatory effect and the possible mechanisms for the pharmacological effects are discussed.