Anti-Trypanosoma cruzi Properties of Sesquiterpene Lactones Isolated from Stevia spp.: In Vitro and In Silico Studies

Abstract

Stevia species (Asteraceae) have been a rich source of terpenoid compounds, mainly sesquiterpene lactones, several of which show antiprotozoal activity. In the search for new trypanocidal compounds, S. satureiifolia var. satureiifolia and S. alpina were studied. Two sesquiterpene lactones, santhemoidin C and 2-oxo-8-deoxyligustrin, respectively, were isolated. These compounds were assessed in vitro against Trypanosoma cruzi stages, showing IC50 values of 11.80 and 4.98 on epimastigotes, 56.08 and 26.19 on trypomastigotes and 4.88 and 20.20 µM on amastigotes, respectively. Cytotoxicity was evaluated on Vero cells by the MTT assay. The effect of the compounds on trypanothyone reductase (TcTR), Trans-sialidase (TcTS) and the prolyl oligopeptidase of 80 kDa (Tc80) as potential molecular targets of T. cruzi was investigated. Santhemoidin C inhibited oligopeptidase activity when tested against recombinant Tc80 using a fluorometric assay, reaching an IC50 of 34.9 µM. Molecular docking was performed to study the interaction between santhemoidin C and the Tc80 protein, reaching high docking energy levels. Plasma membrane shedding and cytoplasmic vacuoles, resembling autophagosomes, were detected by transmission microscopy in parasites treated with santhemoidin C. Based on these results, santhemoidin C represents a promising candidate for further studies in the search for new molecules for the development of trypanocidal drugs.

Trypanocidal and Anti-Inflammatory Effects of Three ent-Kaurane Diterpenoids from Gymnocoronis spilanthoides var. subcordata (Asteraceae)

“…The IR spectrum displayed diagnostic absorptions at 3300–2500 cm −1 (OH), 1720 cm −1 (cyclopentanone), 1690 cm −1 (carboxyl carbonyl) and 1640 cm −1 (conjugated double bond). The 1 H-NMR spectrum in DMSO-d 6 at 600 MHz ( Table 1 ) showed two exo -methylene protons conjugated to a carbonyl group at δ 5.52 (s) and 5.15 (s) assigned to H-17a and H-17b, respectively, two tertiary methyls at δ 1.12 (Me-18) and 1.01 (Me-20), a carbinol proton at δ 3.77 (dd, J ~ 3.8 and 2 Hz; H-11) and distinctive signals at δ 2.92 (m; H-13) and 2.53 (d, 12 Hz; H-14a), while the 13 C-NMR spectrum displayed twenty carbon signals ( Table 1 ) that unveiled the structure as that corresponding to adenostemmoic acid B ( ent -9α,11α-dihydroxy-15-oxo-kaur-16-en-19-oic acid) [ 21 ]. All assignments were performed using 2D experiments (H-H COSY, HSQC, HMBC) while the relative configuration was established through coupling constants values and fundamentally through NOESY correlations as shown in Table 1 .…”

“…Three diterpenoids from ent -kaurane type, namely ent -9α,11α-dihydroxy-15-oxo-kaur-16-en-19-oic acid or adenostemmoic acid B (compound 1), (16 R )- ent -11α-hydroxy-15-oxokauran-19-oic acid (compound 2) and ent -11α-hydroxy-15-oxo-kaur-16-en-19-oic acid (compound 3), were isolated. Adenostemmoic acid B was previously isolated from Adenostemma lavenia (Asteraceae) [ 21 ]. The diterpene (16 R )- ent -11α-hydroxy-15-oxokauran-19-oic acid (compound 2), a 16,17-dihydroderivative of compound 3 was previously found in Eupatorium álbum [ 30 ] and Adenostemma caffrum [ 33 ], while ent -11α-hydroxy-15-oxo-kaur-16-en-19-oic acid, (compound 3) has been reported in Eupatorium album [ 30 ], Adenostemma caffrum [ 33 ] and Adenostemma lavenia [ 34 ].…”

“…Cultures of Trypanosoma cruzi epimastigotes (RA strain) were maintained through weekly passages in LIT medium supplemented with 10% fetal bovine serum at 28 °C. Trypanosoma cruzi bloodstream trypomastigotes (RA strain) were obtained from infected CF1 mice by cardiac puncture 15 days after infection at the peak of parasitemia while transfected trypomastigotes expressing β-galactosidase (Clone C4, e Tulahuen strain) were obtained from infected Vero cells [ 21 ].…”

Plant Extracts and Phytochemicals from the Asteraceae Family with Antiviral Properties

“…and Arn. (BAF 797) was collected in Entre Ríos Province, La Paz Department, national route N1, in December 2012 [ 29 ]. Stevia maimarensis (Hieron.)…”

“…satureiifolia was prepared and dewaxed as aforementioned to be fractionated via column chromatography on Silicagel 60 eluting with a gradient of CH 2 Cl 2 :ETAC. Crystals of Santhemoidin C ( 7 ) precipitated from the fractions eluted with CH 2 Cl 2 :ETAC (3:7) [ 29 ]…”