Vasorelaxant and Antihypertensive Effects of (3β)-ursen-12-en-3,28-diol by NO/cGMP System

Objective:

the aim of this study was to determine the vasorelaxant effect of semisynthetic derivatives of ursolic acid and to establish the mode of action, and the antihypertensive effect of the most active compound.

Methods:

Isolated aorta rat rings (ex vivo assay), with and without endothelium, were used to determine the vasorelaxant effect of seven semisynthetic derivatives of ursolic acid (UA-01 to UA-07). Then, the effect of the most active compound was studied in ex vivo assay using L-NAME, ODQ and indomethacin to determine its mode action. Finally, the in vivo cardiovascular effect and molecular docking of the most active compound were determined.

Results:

UA-07 was the most potent compound of the derivatives, since UA-07 induced significant relaxant effect in a concentration- and endothelium-dependent manners (Emax = 79.09% and EC50 = 110 µM), on aortic rat rings pre-contracted with noradrenaline (NA, 0.1 µM). Also, endothelium-derived nitric oxide seems to be involved in the mechanism of action of UA-07, because pre-incubation with L-NAME (a NOS inhibitor) and ODQ (a soluble guanylate cyclase inhibitor) significantly reduced its vasorelaxant effect. Further, UA-07 showed a similar binding affinity as ursolic acid on eNOS C1 binding pocket using in silico studies. Finally, treatment with UA-07 (50 mg/Kg) on spontaneously hypertensive rats (SHR) significantly decreased diastolic blood pressure during seven hours.

Conclusion:

These results demonstrate the significant antihypertensive effect of UA-07, possibly through NO/cGMP system.

Neuroprotective effect of Buddleja cordata methanolic extract in the 1-methyl-4-phenylpyridinium Parkinson's disease rat model

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the irreversible loss of dopaminergic neurons in the nigrostriatal pathway with subsequent dopamine deficiency. Environmental causes have been proposed through molecules, such as 1-methyl-4-phenylpyridinium (MPP(+)), to induce oxidative stress. The methanolic extract of plants of the genus Buddleja has been reported to have in vitro and in vivo antioxidant properties to protect against neuronal death. In the present study, the neuroprotective effect of Buddleja cordata methanolic extract in the MPP(+) PD rat model was investigated. Animals were administered orally with 50 or 100 mg/kg of methanolic extract every 24 h for 14 days. Twenty hours later, rats were infused with an intrastriatal stereotaxic microinjection of 10 µg MPP(+) in 8 μl sterile saline solution. Six days later, the animals were treated with 1 mg/kg apomorphine to record ipsilateral rotations for 1 h. All the rats were killed by decapitation and the lesioned striatum was dissected for dopamine and lipid peroxidation quantifications. Both methanolic extract doses led to a significantly lower (P < 0.05) number of ipsilateral rotations (75-80 %). This behavioral protection was corroborated with 60 % level of dopamine preservation (P < 0.05) and 90 % decrease in the formation of lipidic fluorescent products in the striatum (P < 0.05). This study demonstrates the antioxidant and neuroprotective effect of Buddleja cordata methanolic extract in the MPP(+) PD rat model, possibly due to the involvement of phenylpropanoids.

Additive effect of DL-penicillamine plus Prussian blue for the antidotal treatment of thallotoxicosis in rats

DL-penicillamine (DL-P) and Prussian blue (PB) given alone or in combination were tested as possible treatments against acute thallium toxicity. Rats were intoxicated by i.p. injection of thallium (I) acetate at LD(50) (32 mg/kg). A day later, pharmacological treatment was administered until day 4 as follows: (1) vehicles, (2) PB 50mg/kg, by oral route, twice a day, (3) DL-P 25mg/kg i.p. route, twice daily and (4) PB+DL-P. The Estimated Probability Survival (EPS) was recorded during the experiment for each treatment. DL-P alone did not show a significant effect on survival. However, when it was used in combination with PB, it increased the survival significantly (EPS=0.8, P<0.05) as compared to the control group (EPS=0.4). In a different experiment, using 16 mg/kg of Thallium I acetate, the metal levels were analyzed in blood, body organs and brain regions after treatments. DL-P given alone decreased slightly the thallium content in blood, organs and brain. Meanwhile, its administration in combination with PB diminished the thallium levels significantly (P<0.05) in the majority of tissues, at levels lower than those achieved in the PB group. Those results indicate that DL-P administered alone did not prevent the mortality nor accumulation of the metal in body tissues. Its combination with PB could be considered an alternative antidotal treatment in thallium toxicity, because this chelating agent given alone did not cause thallium redistribution to the brain. When given in combination with PB it has an additive effect in the treatment of acute thallotoxicosis.