Functional foods are known not only for their nutritional value but also for delivering biologically active compounds with potential health benefits, such as antioxidant, neuroprotective or glucose-lowering properties.
Identifying these compounds from complex food matrices remains a major challenge. Traditional methods are often time-consuming and inefficient.
As a result, scientists have been turning to advanced techniques like nuclear magnetic resonance (NMR) and liquid chromatography–mass spectrometry (LC-MS/MS) to speed up the discovery of bioactive molecules, especially in chemically diverse systems like roasted coffee.
A study published in Beverage Plant Research by Minghua Qiu’s team, Kunming Institute of Botany, Chinese Academy of Sciences, shows promising antidiabetic potential and expands our understanding of coffee’s functional components.
In this study, researchers developed a three-step, activity oriented strategy to efficiently identify bioactive diterpene esters in roasted Coffea arabica beans.
The goal was to discover both abundant and trace-level compounds with α-glucosidase inhibitory activity, while minimising solvent use and analysis time.
The first step involved dividing the crude diterpene extract into 19 fractions via silica gel chromatography, followed by 1H NMR and α-glucosidase activity screening.
A cluster heatmap based on ^1H NMR spectral data grouped the fractions and pinpointed Fr.9–Fr.13 as the most bioactive, characterised by distinct proton signals. Next, 13C-DEPT NMR of representative fraction Fr.9 revealed an aldehyde group, consistent with the 1H NMR data.
Fr.9 was then purified using semi-preparative HPLC, and three new diterpene esters—named caffaldehydes A, B, and C—were isolated.
Structural elucidation through 1D and 2D NMR and high-resolution mass spectrometry (HRESIMS) confirmed their identities.
These compounds, differing in their fatty acid chains (palmitic, stearic, and arachidic acids), showed moderate α-glucosidase inhibitory activity with IC₅₀ values of 45.07, 24.40, and 17.50 μM, respectively — more potent than the control drug acarbose.
To detect trace bioactives beyond the scope of NMR or HPLC, the team performed LC-MS/MS on pooled fraction groups and constructed a molecular network using GNPS and Cytoscape.
This revealed three additional unknown diterpene esters (compounds 4–6) closely related to caffaldehydes A–C, sharing common fragment ions but featuring different fatty acids (magaric, octadecenoic and nonadecanoic acids).
Their absence in compound databases confirmed their novelty. Together, these findings demonstrate the effectiveness of this integrative dereplication approach in discovering structurally diverse, biologically relevant compounds in complex food matrices such as roasted coffee.
This research opens the door to developing new functional food ingredients or nutraceuticals derived from coffee, targeting glucose regulation and potentially aiding in diabetes management.
More broadly, the dereplication strategy introduced here — using minimal solvent and advanced spectral analysis — can be adapted for rapid screening of bioactive metabolites in other complex food matrices.
Future work will explore the biological activity of the newly identified trace diterpenes and assess their safety and efficacy in vivo.