The efficacy of mangosteen pericarp fruit extract for the treatment of schizophrenia.

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There is evidence of anomalies in redox biology in schizophrenia; (i) the presence of oxidative stress (where the levels of antioxidants are decreased or the levels of free radicals are increased to a point that is damaging to the function of the cell, increasing inflammation) particularly implicating the glutathione system ; (ii) changes in oxidative status with treatment; and (iii) evidence that other glutathione and redox active agents have therapeutic value. Garcinia mangostana Linn, known colloquially as mangosteen, is a tropical evergreen fruit tree originating from Indonesia. Its rind or pericarp contains an exudate containing a large number of bioactive compounds called xanthones that have robust effects on the glutathione system and many other pathways germane to schizophrenia. Motivated by the results of the first pilot randomised, double blind placebo trial of adjunctive Garcinia mangostana Linn for the treatment of schizophrenia we speculate that this research may uncover a new class of agents for the treatment of the disorder, and uncover novel pathophysiological pathways. The trial involves 150 participants aged 18 years or older with a DSM-V diagnosis of schizophrenia or schizoaffective disorder. Participants referred to the trial will have an initial face–to-face screening interview. All randomised participants will receive two 500mg mangosteen pericarp capsules once a day to a total dose of 1000mg daily or placebo, in addition to treatment as usual, for 24 weeks. Assessment will occur at regular 4 weekly intervals throughout the 24 weeks and 1 month after completion of the study. The primary outcome will be the change in schiaophrenia symptom severity using the PANSS total scale at the end of the 24-week treatment phase. The secondary outcomes will include changes in depressive symptoms, quality of life, functioning and life satisfaction which will be measured using the PANSS subscales, Q-LES-Q scale, GAF, LIFE-RIFT, PGI and Cogstate. Blood biomarkers will also be analysed. Blood samples will be obtained at baseline and week 24. Blood will be analysed for relevant markers based on preclinical evidence including markers of antioxidant defence, oxidative stress and markers of inflammation. The research will have immediate and direct translational benefits. The safety and tolerability of Garcinia mangostana Linn, its affordability and accessibility and that the general public are accepting of plant-derived compounds, raise its attraction as a potential therapeutic agent.