Triterpenes G-A and G-E from Galphimia glauca with anti-inflammatory and anti-arthritic activity in mice

Abstract

Ethnopharmacological relevance: Galphimia glauca is a medicinal plant that treats inflammatory and anti-rheumatic problems. Its anti-inflammatory capacity has been reported pharmacologically, attributed to the triterpenes G-A and G-E.

Aim: The objective of the present work was to measure the anti-inflammatory and immunomodulatory effect of the methanolic extract (GgMeOH) of Galphimia glauca and the isolated galphimines G-A and G-E, first in an acute test of plantar edema with carrageenan, and later in the model of experimental-induced arthritis with CFA. The effect was measured by quantifying joint inflammation, the concentration of pro- (TNF-α, IL-6, IL-17) and anti-inflammatory (IL-10, and IL-4) cytokines, and the ADA enzyme in joints, kidneys, and spleen from mice with experimental arthritis.

Method: The extract and the active triterpenes were obtained according to established methods using different chromatographic techniques. Female ICR strain mice were subjected to intraplantar administration with carrageenan and treated with different doses of GgMeOH, G-A, and G-E; edema was monitored at different times. Subsequently, the concentration of TNF-a and IL-10 in the spleen and swollen paw was quantified. Meloxicam (MEL) was used as an anti-inflammatory control drug. The most effective doses of each treatment were analyzed using a complete Freunds adjuvant (CFA)-induced experimental arthritis model. Joint inflammation was followed throughout the experiment. Ultimately, the concentration of inflammation markers, oxidant stress, and ADA activity was quantified. In this experimental stage, methotrexate (MTX) was used as an antiarthritic drug.

Results: Treatments derived from G. glauca, GgMeOH (DE50 = 158 mg/kg), G-A (DE50 = 2 mg/kg), and G-E (DE50 = 1.5 mg/kg) caused an anti-inflammatory effect in the plantar edema test with carrageenan. In the CFA model, joint inflammation decreased with all natural treatments; GgMeOH and G-A inhibited the ADA enzyme in all organs analyzed (joints, serum, spleen, left and right kidneys), while G-E inhibited the enzyme in joints, serum, and left kidney. CFA caused an increase in the weight index of the organs, an effect that was counteracted by the administration of G. glauca treatments, which also modulate the response to the cytokines analyzed in the different organs (IL-4, IL-10, IL-17, IL-6, and TNF- α).

Conclusion: It is shown, for the first time, that the GgMeOH extract and the triterpenes G-A and G-E of Galphimia glauca have an anti-arthritic effect (anti-inflammatory, immunomodulatory, antioxidant, and ADA inhibitor), using an experimental arthritis model with CFA. Therefore, knowledge of the plant as a possible therapeutic agent for this rheumatic condition is expanding.

Keywords: Cytokines; Galphimia glauca; Rheumatoid arthritis; Triterpenes.