Trypanocidal and immunomodulatory effects of diterpenoids from Gymnocoronis spilanthoides var. subcordata (Asteraceae)

MARIANA G. SELENER; JIMENA BORGO; MARIA BELEN SARRATEA; MARIA ALICIA DELFINO; LAURA C. LAURELLA; NATACHA CERNY; JESSICA GOMEZ; MAURO COLL; EMILIO MALCHIODI; AUGUSTO E BIVONA; PATRICIA BARRERA; FLAVIA REDKO; VALERIA SULSEN; ANDRES SANCHEZ ALBERTI

Pharmaceutics

MDPI

Lugar: Basel; Año: 2024

1999-4923

Chagas disease, caused by the protozoan Trypanosoma cruzi, affects 6-7 million people worldwide. The dichloromethane extract obtained from the aerial parts of Gymnocoronis spilanthoides var subcordata showed in vitro trypanocidal activity. Based on these results, we selected this extract for the isolation of its bioactive compounds. The dewaxed dichloromethane extract was fractionated through column chromatography. Three diterpenoids were isolated: ent-9α,11α-dihydroxy-15-oxo-kaur-16-en-19-oic acid or adenostemmoic acid B, (16R)-ent-11α-hydroxy-15-oxokauran-19-oic acid and ent-11α-hydroxy-15-oxo-kaur-16-en-19-oic acid. The in vitro anti- T. cruzi activity of the compounds was evaluated against different parasitic stages showing IC50 values of 10.6, 15.9 and 4.8 µM on epimastigotes, respectively. When tested against amastigotes the diterpenoids afforded IC50 values of 6.1, 19.5, 60.6 µM, respectively. The cytotoxicity of the compounds was tested on mammalian cells by the MTT assay resulting on CC50s of 321.8, 23.3 and 14.8 µM, respectively. Based on the high selectivity of action displayed, adenostemmoic acid B (Selectivity Indexes: 30.3 and 52.7, calculated for T. cruzi epimastigotes and amastigotes, respectively) was selected for further studies. The effect of adenostemmoic acid B on T. cruzi was examined at the ultrastructural level using transmission microscopy. Treatment with 20 μM for 48 h stimulated the formation of abnormal cytosolic membranous structures in the parasite. To investigate the potential immunomodulatory and cardioprotective properties which can improve the cardiomyopathy associated with Chagas’ disease, the effects of adenostemmoic acid B on the type I interferon pathway, the secretion of NF-KB and the production of IL-10, TNF and nitric oxide, were studied. This compound showed an anti-inflammatory effect in murine macrophages stimulated with LPS and other TLR agonists. The effect of this diterpenoid was associated with an inhibition of the activity of transcription factors of the NF-kB and IRF families. Treatment of macrophages with adenostemmoic acid B was able to reduce TNF secretion and nitric oxide production while it increased the IL-10 production. The combination of adenostemmoic acid B with benznidazole resulted in a greater inhibition of NF-kB and a decrease in the nitrite concentration in comparison with the treatment with benznidazole and the compound separately. The effect of adenostemmoic acid B was also evaluated in a murine model of Chagas’ disease. The administration of this compound to mice infected with trypomastigotes of T. cruzi at the dose of 1 mg/kg/day for five days, produced a significant decrease in the parasitemia levels and weight loss. Treatment with the association with benznidazole increased the survival time of the animals. In view of these results, adenostemmoic acid B could be considered a promising candidate for further studies in the search for new treatments for Chagas disease.