Endemic in 21 countries, Chagas disease, also known as American Trypanosomiasis, is a neglected tropical disease (NTD) caused by the protozoan parasite Trypanosoma cruzi. The available drugs for the treatment of this disease, benznidazole and nifurtimox, are outdated and display severe side effects. Thus, the discovery of new drugs is crucial. Based on our continuous studies aiming towards the discovery of natural products with anti-T. cruzi potential, the MeOH extract from aerial parts of Baccharis sphenophylla Dusén ex. Malme (Asteraceae) displayed activity against this parasite and was subjected to high-performance countercurrent chromatography (HPCCC), to obtain one unreported syn-labdane diterpene — sphenophyllol (1) — as well as the known compounds gaudichaudol C (2), ent-kaurenoic acid (3), hispidulin (4), eupafolin (5), and one mixture of di-O-caffeoylquinic acids (6–8). Compounds 1–8 were characterized by analysis of nuclear magnetic resonance (NMR) and mass spectrometry (MS) data. When tested against trypomastigote forms, isolated labdane diterpenes 1 and 2 displayed potent activity, with EC₅₀ values of 20.1 μM and 2.9 μM, respectively. The mixture of chlorogenic acids 6–8, as well as the isolated flavones 4 and 5, showed significant activity against the clinically relevant amastigotes, with EC₅₀ values of 24.9, 12.8, and 2.7 μM, respectively. Nonetheless, tested compounds 1–8 displayed no cytotoxicity against mammalian cells (CC₅₀ > 200 μM). These results demonstrate the application of HPCCC as an important tool to isolate bioactive compounds from natural sources, including the antitrypanosomal extract from B. sphenophylla, allowing for the development of novel strategic molecular prototypes against tropical neglected diseases.

Natural polyphenolics, more specifically flavonoids and derivatives, constitute chemically versatile scaffolds with a broad biological potential. In this study, different flavonoid derivatives (1–37) were assessed for cytotoxicity in Ishikawa and 12Z epithelial cell lines, serving as models of eutopic endometrium and endometriosis, respectively, to elucidate structure–activity relationships. Flavonoids bearing multiple hydroxyl and methoxy substituents exhibited high polarity, an elevated topological polar surface area (TPSA), and numerous hydrogen-bond donors and acceptors, consistently demonstrating low cytotoxicity and, in several cases, cytoprotective effects. In contrast, chalcones containing electron-withdrawing substituents (−NO₂ and −Cl) and higher lipophilicity (log P > 3.5) displayed marked and selective toxicity toward 12Z cells. Among these, compounds 24 [(E)-3-(4-(dimethylamino)­phenyl)­1-(3-hydroxyphenyl)­prop-2-en-1-one] and 28 [(E)-3-(benzo­[d]­[1,3]­dioxol-5-yl)-1-(4-chlorophenyl)­prop-2-en-1-one)] emerged as the most promising selective candidates, reducing 12Z cell viability to approximately 50% while maintaining or enhancing Ishikawa cell viability (>100%). Additional derivatives, including 14 [(E)-3-(benzo­[d]­[1,3]­dioxol-5-yl)-1-phenylprop-2-en-1-one], 17 [(E)-3-(benzo­[d]­[1,3]­dioxol-5-yl)-1-(4-nitrophenyl)­prop-2-en-1-one], 23 [(E)-3-(4-(dimethylamino)­phenyl)-1-(2-hydroxyphenyl)­prop-2-en-1-one], and 30 [(E)-1-phenyl-3-(3,4,5-trimethoxyphenyl)­prop-2-en-1-one], also exhibited statistically significant selectivity. Correlation analysis further revealed a strong association between lipophilicity and 12Z cytotoxicity (r = −0.73), whereas elevated TPSA and extensive hydrogen bonding correlated with cytoprotective behavior. Collectively, these results highlight chalcones as promising molecular frameworks in which substituent-dependent physicochemical properties are associated with distinct biological outcomes, ranging from selective endometriotic cytotoxicity to endometrial cytoprotective effects.