Chemical Characterization and Evaluation of Antioxidant, Anti-PAF and Anti-ADP Activities of Amphiphilic and Lipophilic Extracts from Caprine Milk and Commercial Kefir-Based Yogurt-Type Fermented Product

Commercially available caprine dairy matrices are rich sources of lipid-associated bioactive constituents; however, comparative evaluations of their polarity-separated fractions remain limited. This study aimed to characterize and compare the chemical composition, antioxidant capacity, and inhibitory effects on thrombo-inflammatory agonist-induced platelet aggregation of amphiphilic (total amphiphilic content, TAC) and lipophilic (total lipophilic content, TLC) fractions isolated from three independently produced commercial goat milk and three independently produced commercial kefir-based goat yogurt-type fermented products, with different LOT numbers. Total lipid (lipophilic and amphiphilic) extracts were obtained by Bligh and Dyer extraction and then fractionated to TAC and TLC by counter-current separation using a green hexane/ethanol–water solvent system. Analytical determinations included spectrophotometric quantification of total carotenoid and phenolic contents, attenuated total reflectance Fourier-transform infrared (ATR–FTIR) structural profiling, and liquid chromatography–mass spectrometry (LC–MS) relative fatty-acid profiling. Antioxidant capacity was assessed using DPPH and ABTS radical-scavenging assays, while ex vivo light-transmission aggregometry in human platelet-rich plasma, obtained from six independent healthy donors (n = 6) for each fraction, was employed to evaluate potential inhibitory effects against platelet-activating factor (PAF) and adenosine diphosphate (ADP). Across both matrices, TAC fractions exhibited markedly higher radical-scavenging responses than the corresponding TLC fractions, particularly in the ABTS assay. In platelet aggregometry, TAC fractions showed significantly stronger inhibition of both PAF- and ADP-induced aggregation than their corresponding TLC fractions. Specifically, the TAC fraction from the kefir-based yogurt product exhibited the lowest IC50 value against PAF-induced aggregation, whereas the two TAC fractions showed comparable inhibitory potency against ADP-induced aggregation. ATR–FTIR spectroscopy revealed spectral features consistent with lipid-associated, hydroxyl-containing, and phosphate-containing amphiphilic structures, while LC–MS profiling identified palmitic, stearic, oleic, and α-linolenic acids among the predominant fatty acids in the free and esterified fatty-acid pools. Overall, the TAC fractions exhibited substantial in vitro radical-scavenging activity and ex vivo inhibition of agonist-induced platelet aggregation, suggesting potential anti-inflammatory and antithrombotic relevance for these activities. Further in vivo studies are required to determine their physiological relevance.