Rheumatoid arthritis (RA) is a chronic inflammatory disease. Tumor necrosis factor-alpha (TNF-α) is the most promising treatment in RA. Previous studies have shown that α-mangostin (α-MG) has several pharmacological activities, such as antioxidant, antitumoral, anti-inflammatory, antiallergy, antibacterial, antifungal, and antiviral effects.

The aim of this work was to investigate the effect of mangosteen and its ingredients on the therapeutic effect on RA. To test the activity on the cytokines secretion, we assayed the crude extract and pure compounds isolated from the fruit shell in macrophage cells.

The natural compounds, α-MG, β-MG, γ-MG and the crude extract were incubated 30minutes with the differentiated cells before lipopolysaccharides (LPS) stimulation. The culture media were harvested 4hours after LPS stimulation, and the amounts of TNF-α were measured with enzyme-linked immunosorbent assay (ELISA). The activity of the extract and MG on TNF-α and interleukin-6 (IL-6) secretion in mice plasma was detected after LPS challenged for 1.5hours. The therapeutic effect of mangosteen was also evaluated on the carrageenan-induced paw edema in rats and on the collagen-induced arthritis (CIA) in rats. The results showed mangosteen and its ingredients inhibited TNF-α secretion from cells with IC₅₀ range from 2 to 11μg/ml, and prevented TNF-α and IL-6 secretion in LPS-stimulated mice with ED₅₀ less than 100mg/kg. The extract reduced the paw edema in the carrageenan-induced rats, and reduced the arthritis score in the CIA rats.

Mangosteen extract showed activity for immune modulation. These effects may be exerted by the active ingredients α-, β- and γ-MG.