Antidepressant-like effect of extract from Polygala paniculata: involvement of the monoaminergic systems.

CONTEXT: Polygala paniculata Linnaeus (Polygalaceae) has shown neuroprotective effects, but there is no report about its antidepressant potential. OBJECTIVE: The antidepressant-like effect of the hydroalcoholic extract from P. paniculata and some of the possible mechanisms involved in this effect were investigated in forced swimming test (FST). MATERIALS AND METHODS: Mice received extract by oral route and were submitted to FST and open-field test. Animals were forced to swim and the total immobility time was registered (6-min period). A reduction in the immobility time is considered an antidepressant-like effect. In order to investigate the involvement of the monoaminergic systems, mice were treated with pharmacological antagonists before administration of the extract. RESULTS: The acute administration of the hydroalcoholic extract from P. paniculata produced an antidepressant-like effect, since it significantly reduced the immobility time in FST (0.01-30 mg/kg) as compared to control group, without changing locomotor activity. Pretreatment of mice with yohimbine (1 mg/kg, i.p., α2-adrenoceptor antagonist), propranolol (1 mg/kg, i.p., ß-adrenoceptor antagonist), SCH23390 (0.05 mg/kg, s.c., dopamine D1 receptor antagonist) or sulpiride (50 mg/kg, i.p., dopamine D2 receptor antagonist) prevented the antidepressant-like effect of the extract in FST (30 mg/kg). Moreover, ketanserin (5 mg/kg, i.p., preferential 5-HT(2A) receptor antagonist) enhanced the effect of the extract in FST. DISCUSSION AND CONCLUSION: The results of the present study indicate that the extract from P. paniculata has an antidepressant-like action that is likely mediated by an interaction with the serotonergic (5-HT2A receptors), noradrenergic (α2 and ß-receptor) and dopaminergic (D1 and D2 receptors) systems.

Vasorelaxant and hypotensive effects of the extract and the isolated flavonoid rutin obtained from Polygala paniculata L.

OBJECTIVES: This study aimed to investigate the in-vitro and in-vivo cardiovascular effects of the crude hydroalcoholic extract from Polygala paniculata (HEPP) in rats. METHODS: The procedures were performed on aortic rings and on normotensive anaesthetized rats. KEY FINDINGS: When tested in endothelium-intact aorta rings, HEPP (30-1000 µg/ml) produced a significant non-concentration-dependent relaxing effect (∼40%), which was completely prevented by incubation with L-NAME (nitric oxide synthase inhibitor), ODQ (soluble guanylate cyclase inhibitor) and partially inhibited by tetraethylammonium (TEA; a non-selective potassium channel blocker) and charybdotoxin (a large- and intermediate-conductance calcium-activated potassium channel blocker). In contrast, atropine (a muscarinic receptor antagonist) or pyrilamine(a histamine H1 receptor antagonist) had no effect. Furthermore, oral administration of HEPP (30-300 mg/kg) in anaesthetized rats caused a dose-dependent and sustained hypotensive action. This effect was unchanged by atropine or TEA, but was strongly reduced in rats continuously infused with L-NAME or methylene blue. Moreover, rutin (1-3 mg/kg) administered by an intravenous route also caused a dose-dependent hypotensive effect in rats. CONCLUSIONS: Our results demonstrated that the extract obtained from P. paniculata induces potent hypotensive and vasorelaxant effects that are dependent on the nitric oxide/guanylate cyclase pathway. These effects could be related, at least in part, to the rutin contents in this extract.

Structure-activity relationship of flavonoids derived from medicinal plants in preventing methylmercury-induced mitochondrial dysfunction.

In the present study, we investigated the potential protective effects of three flavonoids (myricetin, myricitrin and rutin) derived from medicinal plants against methyl mercury (MeHg)-induced mitochondrial dysfunction in vitro. Incubation of mouse brain mitochondria with MeHg induced a significant decrease in mitochondrial function, which was correlated with decreased glutathione (GSH) levels and increased generation of reactive oxygen species (ROS) and lipid peroxidation. The co-incubation of mouse brain mitochondria with myricetin or myricitrin caused a concentration-dependent decrease of MeHg-induced mitochondrial dysfunction and oxidative stress. The flavonoid rutin was ineffective in counteracting MeHg toxicity. Among the three tested flavonoids, myricetin was the most efficient in protecting against MeHg-induced mitochondrial dysfunction. Moreover, myricetin completely blocked MeHg-induced ROS formation and lipid peroxidation and partially prevented MeHg-induced GSH depletion. The ability of myricetin to attenuate MeHg-induced mitochondrial dysfunction and oxidative stress appears to be related to its higher scavenging capability when compared to myricitrin and rutin. Overall, the results suggest that MeHg-induced mitotoxicity is associated with oxidative stress. The ability of myricetin to prevent MeHg-induced oxidative damage in brain mitochondria renders this flavonoid a promising molecule for further in vivo studies in the search for potential antidotes to counteract MeHg-induced neurotoxicity.

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.

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 mg kg(-1)) significantly reduced gastric lesions induced by ethanol by 61%, 70% and 76%, respectively. Oral administration of CE (100 mg kg(-1) per day for 7 days) reduced the chronic gastric ulceration induced by acetic acid by 52%. Intraduodenal CE (100, 300 and 600 mg kg(-1)) reduced the total acidity of gastric secretion by 22%, 22% and 33%, respectively, while i.p. administration (10, 30 and 100 mg kg(-1)) inhibited total acidity by 50%, 60% and 67%, respectively. In-vitro, CE inhibited H+, K+ -ATPase activity with an EC50 of 53 microgmL(-1) and fraction A (30 and 100 microgmL(-1)) reduced this by 48% and 89%, respectively. CE had no effect on gastrointestinal motility. CE (250 microgmL(-1)) and fraction B (100 and 250 microgmL(-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.

Gastroprotective activity of the hydroalcoholic extract obtained from Polygala paniculata L. in rats.

The possible gastroprotective effects of the hydroalcoholic extract of Polygala paniculata in rats have been evaluated. We have investigated the effects of this hydroalcoholic extract on acute lesions induced by ethanol (70%, p.o.) and indomethacin (20 mg kg(-1), s.c.). Its influence on mucus secretion was investigated, measured as the amount of Alcian blue dye estimated by colorimetry, and antisecretory effects were assessed in the pylorus ligature model. The treatment of rats with a crude hydroalcoholic extract of P. paniculata (HEPP; 30, 100, 300 mg kg(-1), p.o., or 3, 10 and 30 mg kg(-1), i.p.) decreased the ulcer index, and maintained the gastric mucus production in acute gastric lesions caused by ethanol 70%. In addition, the extract partially protected the mucosa against indomethacin-induced lesions. The extract did not change the volume and acidity of gastric secretion in the pylorus-ligated rat. An additional antioxidant activity of the extract and its isolated flavonoid compound rutin, in the DPPH free radical scavenging assay, was observed. In conclusion, HEPP exhibited marked gastroprotection; these effects may have involved prostaglandins and be related to cytoprotective factors, such as antioxidant activity and maintenance of mucus production.

Protective effects of Polygala paniculata extract against methylmercury-induced neurotoxicity in mice.

We have examined the possible protective effects of Polygala paniculata extract against methylmercury (MeHg)-induced neurotoxicity in adult mice. MeHg was diluted in drinking water (40 mg L(-1), freely available) and the hydroalcoholic Polygala extract was diluted in a 150 mM NaCl solution and administered by gavage (100 mg kg(-1) b.w., twice a day). After a two-week treatment, MeHg exposure significantly inhibited glutathione peroxidase and increased glutathione reductase activity, while the levels of thiobarbituric acid reactive substances were increased in the cerebral cortex and cerebellum. These alterations were prevented by administration of Polygala extract, except for glutathione reductase activity, which remained elevated in the cerebral cortex. Behavioural interference in the MeHg-exposed animals was evident through a marked deficit in the motor performance in the rotarod task, which was completely recovered to control levels by Polygala extract co-administration. This study has shown, for the first time, the in-vivo protective effects of Polygala extract against MeHg-induced neurotoxicity. In addition, our findings encourage studies concerning the beneficial effects of P. paniculata on neurological conditions related to excitotoxicity and oxidative stress.

Cyclopeptide alkaloids from Scutia buxifolia Reiss and their antimicrobial activity.

The present study reports a cyclopeptide alkaloid, scutianine M, isolated from the methanolic root bark extract of Scutia buxifolia Reiss (Rhamnaceae) along with six known compounds, scutianines-B, -C, -D, -E, -F, and scutianene D. Its structure was established on the basis of spectroscopic analyses, including application of 2D NMR spectroscopic techniques. As part of a study of the bioactive compounds of medicinal plants from southern Brazil, we also compared the antimicrobial activity of the isolated compounds towards Gram (+), Gram (-) bacteria, and yeasts.