Solvent-Guided Fractionation of Green Coffea arabica Seeds Uncovers Divergent Antioxidant and Mitochondria-Targeted Activities

Green seeds of Coffea arabica represent a rich source of bioactive compounds. This study aimed to compare the butanol-soluble (CA-BU) and the ethyl acetate-soluble (CA-EtAc) fractions in terms of their phytochemical composition and biological activity. As a first step, the fractions were analyzed by Fourier-transform infrared spectroscopy (FT-IR) and high-performance liquid chromatography coupled with mass spectrometry (HPLC–MS) in order to investigate the major constituents. Subsequently, CA-BU and CA-EtAc were evaluated for antioxidant effect, antimicrobial activity, antiproliferative properties, effects on the mitochondrial function, and on the chorioallantoic membrane. The CA-EtAc fraction was enriched in chlorogenic acids and catechins and showed superior antioxidant activity, whereas CA-BU displayed a broader profile of semi-polar polyphenols, conferring moderate antimicrobial effects and stronger antiproliferative activity in MCF-7 human breast adenocarcinoma cells, although with limited selectivity compared with HaCaT non-tumorigenic cells. Respirometric analysis demonstrated that CA-BU selectively inhibited mitochondrial oxidative phosphorylation Complex I (OXPHOS CI), without affecting Complex II (CII) or basal respiration, indicating a specific mitochondria-targeted mechanism. Both fractions were non-irritant and well tolerated in the chorioallantoic membrane (CAM) assay; CA-BU reduced vascular density. These findings demonstrate a clear mechanistic differentiation between the fractions, highlighting the decisive role of solvent polarity in obtaining extracts with distinct and targeted biological effects.