Supplementary Material for: Evaluation of Antidepressant-Like Activity of Novel Water-Soluble Curcumin Formulations and St. John's Wort in Behavioral Paradigms of Despair

Background: Curcumin is the active principle of Curcuma longa, one of the widely used components in the traditional system of medicine in India. Despite its efficacy in experimental studies aiming at neuronal disorders like depression, curcu-min's poor water solubility challenges the production of therapeutic formulations. This study investigates the antidepressant-like activity of novel water-soluble curcumin formulations, dispensed in three different concentrations. Further, the study comparatively evaluates St. John's wort (SJW), another herbal preparation. Methods: These compounds were evaluated in the forced swimming test in mice, and the corresponding changes in the neurotransmitter levels were measured. Results: Three water-soluble curcumin formulations, C-5, C-20 and C-50 (50-200 mg/kg p.o.) decreased the immobility period, and increased serotonin and dopamine levels in the brain tissues. A subeffective dose (50 mg/kg) of these formulations enhanced the antidepressant-like effect of classical antidepressants with varied mechanisms of action. In addition, an SJW dose of 25 mg/kg showed a significant antidepressant-like effect in all the behavioral studies and also significantly increased brain neurotransmitter levels, especially that of serotonin. The effects produced by C-5 were comparable with those of SJW and fluoxetine, respectively. Conclusion: In all these observations, the water-soluble formulations showed a significant antidepressant-like effect, including enhancement of neurotransmitter levels as compared to the similar dose of a conventional curcumin preparation. Thus, these formulations may be used as a novel treatment option in the management of mental depression.