Phenolic compounds from spontaneously fermented coffee beans alleviate cellular stress and modulate inflammatory signaling in lipopolysaccharide-treated RAW264.7 macrophages

Spontaneous fermentation is commonly applied to coffee bean processing following harvesting, which can change the chemical composition and physiological properties of coffee beans. However, the impact of spontaneous fermentation on the anti-inflammatory properties of coffee extract have yet to be explored. This study investigated phenolic composition, in vitro anti-inflammatory potential, and potential signaling pathways of light-roasted fermented (F) and unfermented (UF) Coffea arabica coffee extracts. Totally 47 phenolic compounds were tentatively characterized through liquid chromatography-electrospray ionization-quadrupole time-of-flight tandem mass spectrometry (LC-ESI-QTOF-MS/MS). Of these, 24 phenolic compounds identified from the F extract were mainly phenolic acids and flavonoids, while only 5 phenolics were present in the UF. The anti-inflammatory potential was evaluated in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. F extract better protected against LPS-induced cell death and decreased nitric oxide (NO) production after 48 hrs. For cell morphology, although dendritic differentiation of macrophage cells was alleviated by F extracts, mRNA expression of potential transcriptional factors involved in this process ( c-Fos and Socs1 ) was downregulated early after LPS+coffee extract exposure. After 4 hrs treatment with F extract, Shp2 , Erk1/2 , p38 and Cox-2 mRNA expression were downregulated, while Il-10, Sod2, Ccl2, Il-6 , and Il-1β mRNA were significantly enhanced. Spontaneous fermentation could assist the release and microbial metabolism of phenolic compounds. The distinct phenolic profile of fermented coffee extract likely contributes to its better anti-inflammatory bioactivity and regulatory effect on cell stress, with potential involvement of the MAPK and JAK-STAT signaling pathways, supporting its potential application as a basis for developing functional coffee products. • Spontaneous fermentation aids phenolic release from coffee beans. • Coffee extract altered biological signaling in LPS-treated RAW264.7 cells. • Light-roasted fermented coffee shows greater anti-inflammatory activity. • Fermented coffee may better regulate cell stress via MAPK and JAK-STAT cascades.