Isolamento por cromatografia contracorrente de substâncias fenólicas de resíduos madeireiros amazônicos de Andira parviflora Ducke e Robrichia schomburgkii (Benth.) A.R.M.Luz & E.R.Souza bioguiado por atividade citotóxica

Abstract

The Amazon region was one of the world’s leading producers of tropical timber in 2019 and 2020, generating large amounts of waste during roundwood processing. Among the exploited species are the red sucupira (Andira parviflora – A) and the yellow sucupira (Enterolobium schomburgkii – E), both belonging to the Fabaceae family. The aim of this study was to chemically characterize the wood residues (bark – CA and heartwood – CE) of sucupira species and evaluate their cytotoxicity. The extracts of these residues were subjected to liquid–liquid partitioning, yielding fractions in hexane (ACA1, ACE1, E1), chloroform (ACA2, ACE2, E2), ethyl acetate (ACA3, ACE3, E3), butanol (ACA4, ACE4, E4), and hydroalcoholic (ACA4, ACE4, E). Phytochemical screening revealed condensed tannins and flavonoids in all extracts, as well as triterpenoids and steroids in fractions ACA1 and ACA2. Ethyl acetate, butanol, and hydroalcoholic fractions contained condensed tannins, flavones, flavonols, and xanthones in both species. Thin-layer chromatography (TLC) analyses corroborated the tube tests, confirming the presence of phenolic compounds in the fractions. Extracts and fractions were also evaluated for cytotoxic activity against different tumor cell lines, including PC3 (prostate cancer), SNB19 (astrocytoma), and HCT-116 (colon cancer). Fractions ACA2 and ACE2 exhibited activity against all tested cell lines, while fractions ACE3 (IC₅₀ = 8.74 µg/mL) and ACA3 (IC₅₀ = 74.8 µg/mL) were specifically active against HCT-116 cells. Fractions ACE3, ACA2, E3, and their subfractions were further fractionated by high-performance countercurrent chromatography (HPCCC) using biphasic systems composed of hexane, ethyl acetate, butanol, methanol, and water. Subfractions ACE3-4 and ACE3-17 were subjected to semi-preparative high-performance liquid chromatography (HPLC), leading to the isolation of five flavonoids: two epimers, coatline A and α-epi-coatline A from ACE3-4; the chalcone isoliquiritigenin; the pterocarpan medicarpin from ACE3-17; and the isoflavone biochanin A from ACE3-17 and ACA2. Three isoflavonoids—sativanone, formononetin, and arizonicanol A—and the flavone liquiritigenin were characterized by mass spectrometry (MS) and nuclear magnetic resonance (¹H, ¹³C, DEPT, and 2D NMR) in mixtures of fractions obtained from ACE3-16-18 by HPCCC. Biochanin A and the subfraction containing liquiritigenin exhibited cytotoxic activity against HL60 (promyelocytic leukemia), MDA-MB-231 (breast carcinoma), and NCI-H460 (lung carcinoma) cell lines.