Bacopa monniera supports the functions of the central nervous system
Mode of action of the bacosides
Anxiolytic effects of Bacopa monniera
Anti-convulsive action
Beneficial effects in the management of animal models of Alzheimer's disease
   
 
       
     
 
 
 
 
 

Another important property of Bacopa, dependent on its effects on the central nervous system, is its anti-convulsive action.

One study evaluated the anti-convulsive effects of Bacopa monniera in the prevention of epileptic attacks in animals. Aqueous and alcoholic extracts of Bacopa administered to rats for 15 days significantly reduced mortality due to seizures as well as the intensity of the seizures (Fig. 4.6). (Seizure intensity was measured by increased time of seizure onset. The longer the time of onset, the greater the protective effect of the therapeutic compound.) However, the dose used in these experiments was up to 50% of the LD50 values. The dose was administered intraperitoneally at levels of 600mg/kg of the aqueous extract and 7000mg/kg of the alcoholic extract. At the doses used, Bacopa extracts decreased spontaneous activity of tested animals, but they did not produce a sedative effect or cause uncoordinated movement in the animals.

 

Figure 4.6 Effect of 15-day administration of Bacopa extracts on mortality in rats with chemically induced epileptic convulsions
 

Another experiment studied the beneficial effects of Brahmi Rasayan on convulsions in mice. When the formula was fed to mice at doses of 1 to 30 gm/kg, it showed a significant protective effect against seizures in animals (Fig. 4.7) and significant pain relieving action (Fig. 4.8), preventing painful stimuli from reaching the brain. The protective effect of the formula was evaluated 30 minutes after its administration. At doses of 10 and 30 gm/kg, Brahmi Rasayan induced sedation in treated animals. Another interesting finding in the second part of this study (using rats) was that the compound formula at doses 10 and 30 gm/kg was effective in preventing drug (haloperidol)-induced catalepsy (Fig. 4.9). Catalepsy is a serious condition in animals and humans that is characterized by sudden loss of consciousness, muscle tone and coordination.

 


Figure 4.7 Effect of oral administration of Brahmi Rasayan on convulsive seizures in mice (Increase in response time to seizure stimulus indicates greater protective effect.)

 


Figure 4.8 Pain relieving effect of oral administration of Brahmi Rasayan in mice (The greater the reaction time, the better the pain relieving effect.)

 


Figure 4.9 Effect of oral administration of Brahmi Rasayan (30 g/kg) on haloperidol induced catalepsy in rats (The lower the cataleptic score, the greater the protective effect of the compound.)

 
Protection from phenytoin-induced cognitive deficit
 

The side effects of phenytoin, the commonly used anti-epileptic drug, include impairment of cognitive functions. Bacopa monniera extract was evaluated for efficacy in reversing this side effect in animal models. Evaluations with regard to passive avoidance response task (PA), maximal electroshock seizures and locomotor activity were performed in mice. The mice received phenytoin (25 mg/kg orally for 14 days). Bacopa monniera (40 mg/kg for 7 days) given along with phenytoin in the second week of the two-week regimen significantly reversed PHT-induced impairment of cognitive function as determined from the PA results. Both acquisition and retention of memory were improved without affecting the anti-convulsant activity of PHT. These effects were independent of motor stimulation. The authors concluded that Bacopa monniera has potential use in correcting the cognitive deficit induced by PHT.

   
Postulated mode of action:
 

It is postulated that the anti-convulsive effects could be mediated through GABA (gamma amino butyric acid) which is involved in neural impulse transmission, because substances which stimulate GABA are known to possess anticonvulsant, pain relieving and sedative activity.

A more recent study demonstrated the calcium antagonistic activity of an alcoholic extract of Bacopa monniera on vascular and intestinal smooth muscles of rats and guinea pigs. The plant extract inhibited the spontaneous movements of both guinea pig ileum (IC50 : 24± 4 mcg/ml) and rabbit jejunum (IC50 : 136± 9 mcg/ml) Contractions in the guinea pig ileum induced by acetylcholine were inhibited by the extract at levels of 100-700 mcg/ml in a concentration dependent manner.

These results indicate the direct action of the extract on smooth muscles. The authors also observed that calcium chloride-induced responses in the rabbits' blood vessels and jejunum were reduced in the presence of the plant extract (10-700 mcg/ml), suggesting direct interference with the influx of calcium ions. However, since the extract did not affect contractions induced by noradrenaline or caffeine, the authors concluded that the extract had no appreciable effect on the mobilization of intracellular calcium. Based on the results of the experiment, the authors postulated that the spasmolytic effect of Bacopa monniera extract in smooth muscles is predominantly due to the inhibition of calcium influx, applicable to both electrical impulse-mediated and receptor-mediated calcium channels in the cell membrane.

One research paper provided an exhaustive summary of the preclinical pharmacological studies on Bacopa monniera and the isolated bacosides. The cognition facilitating activity of the extract is attributed to the saponins, Bacoside A and Bacoside B, which are effective in much lower doses in various model studies, including tests for conditioned taste aversion and conditioned shock avoidance response.

 
     
     
 

© 2017 Sabinsa