INTRODUCTION: Unroasted green coffee bean is an increasingly popular beverage and weight loss supplement that contains higher levels of chlorogenic acid derivatives and lower alkaloid levels than roasted beans. Nonetheless, how the gut microbiome metabolizes green coffee constituents has not been studied.

OBJECTIVES: To identify possible biotransformation products of green coffee extract by the human gut microbiome, and the potential implications of this process on its biological effects or fate inside the body.

METHODS: Molecular networking via the GNPS platform was employed for the visualization of green coffee metabolite profiles acquired using LC-tandem mass spectrometry post-incubation with an ex vivo culture of the human gut microbiome.

RESULTS: 36 Metabolites were annotated including four unreported alkyl cinnamate esters in green coffee along with six novel biotransformation products.

CONCLUSION: Our finding reveals new biotransformation products of cinnamate esters by the gut microbiome mediated via oxidative reactions such as dehydrogenation and hydroxylation, along with methylation, decarboxylation, and deglycosylation. These findings reveal potential interactions between the gut microbiome and green coffee constituents, and paves the way towards studying the effects of these interactions on both microbiome and the human host.