Abstract:
Barakol (3a, 4-Dihydroxy-2, 5-dimethyl-1, 4-dioxaphenalene), were extracted from Cassia siamea Lamk., was tested for toxicology, sedative action, interaction with CNS stimulating drugs (picrotoxin, bicucullin, strychnine), and effect on nociceptive response, effect on serotonergic and dopaminergic system. The results showed that barakol has wide margin of safety with lo effective dose and high toxic dose. Mean convulsant dose (CD50) and mean lethal dose (LD50) have been estimated to be 296.71 (265.25-331.89) mg/kg and 324.09 (302.36-347.39) mg/kg respectively. Barakol 10, 25, 50, 75, 100 mg/kg suppressed locomotor activity by 38.28%, 65.23%, 71.78%, 78.94% respectively, while hot-plate test showed analgesic effects at higher doses 100, 125, 150, 175, 200 mg/kg increasing nociceptive threshold by 26.03%, 47.07%, 76.07%, 86.97% and 91.71% respectively. Study with CNS stimulants failed to show any antagonistic actions. Moreover, behavioral study suggested that barakol at 25, 50, 75, 100 mg/kg suppressed serotonergic activity by decresing head shake behavior produced by injection of 5-hydroxytryptophan (200 mg/kg) by 6%, 59.6%, 76.36%, 92.91% respectively. At dose 75, 100, 125, 250 mg/kg dopaminergic activity was augmented as suggested by increased turning behavior in apomorphine treated rat following unilateral 6-OH-DA lesing in substamtia nigra, the increase being 5.25%, 49.80%, 68.47% and 83.69% respectively. Several literaturs related with these results suggested that these effects may be mediated through dopaminergic system, since evidence suggested that dopaminergic system increased nociceptive threshold, decreased locomotor activity and inhibition of serotonergic transmission.