Researchers have identified six previously unknown compounds in roasted coffee beans, including three that inhibited a blood sugar-regulating enzyme more effectively than the prescription drug acarbose in laboratory experiments, opening new possibilities for diabetes research.
By yourNEWS Media Newsroom
Naturally occurring chemicals in roasted coffee beans have demonstrated a stronger ability to block a key carbohydrate-digesting enzyme than an established Type 2 diabetes medication under laboratory conditions, according to research conducted by scientists affiliated with the Chinese Academy of Sciences.
The findings identify a previously unrecognized group of coffee compounds that could help researchers understand why regular coffee consumption has repeatedly been associated with a lower risk of developing Type 2 diabetes. The substances, known as caffaldehydes, were found to interfere with an enzyme responsible for converting dietary carbohydrates into sugars that can enter the bloodstream.
Three newly isolated compounds produced stronger enzyme inhibition than acarbose, a prescription medication used to control blood glucose levels after meals. The comparison was based on direct biochemical testing rather than experiments involving patients, meaning the results do not establish that drinking coffee can treat diabetes or that the compounds would outperform the medication in humans.
The research was published Feb. 18, 2025, in the peer-reviewed journal Beverage Plant Research by scientists from the Kunming Institute of Botany and the University of Chinese Academy of Sciences. The original study, titled “Bioactive oriented discovery of diterpenoids in Coffea arabica basing on 1D NMR and LC-MS/MS molecular network,” describes how researchers isolated three new diterpene esters and identified three additional related compounds present in extremely small quantities.
The research team included Guilin Hu, Chenxi Quan, Abdulbaset Al-Romaima, Haopeng Dai and Minghua Qiu. Their investigation focused on a collection of organic molecules known as diterpenes, which occur naturally in coffee and have attracted scientific interest because of their potential biological activity.
The researchers selected roasted Arabica coffee beans for analysis, using a combination of chemical separation, molecular identification and enzyme testing to locate compounds that might influence glucose metabolism.
Their investigation centered on alpha-glucosidase, an enzyme found in the small intestine that helps complete the digestion of carbohydrates. After a meal containing starches or certain sugars, digestive enzymes break those substances into smaller molecules, eventually producing glucose that can be absorbed into the bloodstream.
Alpha-glucosidase helps carry out the final stages of that process. When its activity is reduced, some carbohydrates are digested more slowly, delaying glucose absorption and moderating the rise in blood sugar that normally follows eating.
That mechanism is particularly relevant to Type 2 diabetes, a metabolic disorder characterized by elevated blood glucose levels associated with insulin resistance and, over time, impaired insulin production.
Acarbose works by inhibiting carbohydrate-digesting enzymes in the intestine. By slowing the conversion of complex carbohydrates into absorbable sugars, the medication helps reduce post-meal blood glucose increases.
The Chinese research team used acarbose as a reference compound to determine whether any of the substances isolated from coffee displayed comparable biological activity.
Their findings showed that all three newly identified caffaldehydes inhibited alpha-glucosidase at lower concentrations than the pharmaceutical comparator.
Researchers measured the activity using the half-maximal inhibitory concentration, known as IC50. This laboratory measurement identifies how much of a substance is required to reduce a particular biological activity by 50%. A lower value indicates that less of the substance is needed to produce the same level of inhibition under the specific experimental conditions.
Caffaldehyde A produced an IC50 value of 45.07 micromolar, while caffaldehyde B registered 24.40 micromolar. Caffaldehyde C demonstrated the strongest activity, with an IC50 value of 17.50 micromolar.
By comparison, acarbose produced an IC50 value of 60.71 micromolar in the researchers’ assay.
The measurements indicate that caffaldehyde C was the most potent of the newly isolated substances in this particular experiment, followed by caffaldehydes B and A. All three required lower concentrations than acarbose to achieve equivalent enzyme inhibition.
Those findings are significant for identifying potential drug candidates, but laboratory potency and clinical effectiveness are different measurements. A compound that strongly inhibits an isolated enzyme may behave differently after entering the digestive system, where absorption, metabolism, chemical stability and possible adverse effects influence its biological activity.
The research did not establish whether the caffaldehydes remain intact during digestion, reach effective concentrations in the intestine or produce measurable improvements in blood glucose control after ordinary coffee consumption.
Identifying the compounds required an extensive analytical process because roasted coffee contains a complex combination of organic chemicals, many of which occur in overlapping concentrations.
The team began by preparing an extract enriched in diterpenes from roasted Coffea arabica beans. Scientists then separated the extract into different chemical fractions using silica gel chromatography, a technique that divides compounds according to their interactions with a stationary material and a moving solvent.
Each fraction underwent additional examination to determine its molecular composition and potential biological activity.
Rather than relying exclusively on traditional compound-by-compound isolation, the investigators combined chemical profiling with direct testing for alpha-glucosidase inhibition. This approach allowed them to concentrate on fractions containing substances that appeared most likely to affect the targeted enzyme.
Researchers used proton nuclear magnetic resonance spectroscopy, commonly called 1D NMR, to examine the chemical characteristics of the different fractions. The technique provides information about molecular structure by measuring how atomic nuclei respond within a magnetic field.
They also evaluated the ability of the fractions to inhibit alpha-glucosidase, comparing chemical measurements with the results of biological testing.
A cluster heatmap helped organize the data and identify fractions displaying both distinctive molecular signatures and promising inhibitory activity. One fraction, designated Fr.9, emerged as a particularly useful target for further purification.
By concentrating on that fraction, scientists isolated three related compounds that had not previously been described in the scientific literature.
Additional structural analysis established that the substances were diterpene esters containing different fatty acid components. The researchers named them caffaldehydes A, B and C.
Although the three molecules shared a common structural framework, differences in their attached fatty acid chains appeared alongside differences in their inhibitory activity.
Caffaldehyde A contained a palmitic acid component, while caffaldehyde B contained a stearic acid component and caffaldehyde C contained an arachidic acid component.
The researchers established the structures using multiple analytical measurements, including nuclear magnetic resonance and high-resolution mass spectrometry.
After determining the identity and activity of the three compounds, the team continued examining the coffee extracts for other molecules that might have escaped detection during the initial screening.
That additional investigation relied on liquid chromatography coupled with tandem mass spectrometry, abbreviated LC-MS/MS, an analytical method capable of detecting compounds present at very low concentrations.
The researchers constructed a molecular network using the resulting data, grouping chemical signals according to similarities in molecular fragmentation patterns.
Because structurally related compounds often produce recognizable relationships in mass spectrometry measurements, the network helped identify additional diterpene esters with chemical characteristics resembling those of the caffaldehydes.
This process revealed three more previously unidentified compounds, bringing the total number of newly recognized diterpene esters to six.
Unlike the original three compounds, the additional substances were identified through molecular analysis rather than isolated in sufficient quantities for the same level of biological testing.
The discovery therefore established the presence of a broader family of previously unknown coffee chemicals, while direct evidence of alpha-glucosidase inhibition was strongest for the three purified caffaldehydes.
The findings build on earlier research examining coffee-derived substances and their potential effects on metabolism.
In December 2023, another study published in the Journal of Agricultural and Food Chemistry reported the identification of six previously unknown diterpenoids from Arabica coffee pulp. Several of those compounds also inhibited alpha-glucosidase in laboratory experiments, providing additional evidence that different parts of the coffee plant contain molecules capable of affecting carbohydrate-digesting enzymes.
Other investigations have examined related compounds in roasted coffee beans, including cafestol derivatives and nitrogen-containing diterpenoids.
The broader scientific interest in these substances is partly connected to epidemiological research documenting a relationship between habitual coffee consumption and Type 2 diabetes risk.
A major analysis conducted by researchers affiliated with Harvard and published in Diabetes Care examined 28 prospective studies involving more than 1.1 million participants and 45,335 cases of Type 2 diabetes.
The 2014 systematic review and meta-analysis found that people who consumed larger amounts of coffee generally had a lower observed risk of developing the disease compared with those who drank little or none.
The association followed a dose-response pattern, with greater reported coffee consumption corresponding to progressively lower diabetes incidence across the combined studies.
Researchers found that consumption of approximately six cups daily was associated with a 33% lower relative risk of Type 2 diabetes compared with no coffee consumption.
Importantly, both caffeinated and decaffeinated coffee were associated with reduced diabetes risk.
That observation suggested that caffeine alone was unlikely to explain the relationship and encouraged further investigation into other naturally occurring substances in coffee.
Researchers have studied chlorogenic acids, trigonelline, magnesium, lignans and other compounds that might influence glucose metabolism, insulin sensitivity or inflammatory processes.
Chlorogenic acids, among the better-known components of coffee, have received particular attention because experimental studies suggest they may influence carbohydrate digestion and glucose handling.
BrightU.AI’s Enoch offered a similar explanation of the potential role of chlorogenic acid in coffee’s relationship with blood sugar regulation.
“Coffee is important in fighting diabetes because it contains chlorogenic acid, which slows down sugar absorption by cells,” Enoch said. “Studies on rats have shown this molecule effectively lowers blood-sugar levels. This offers a promising avenue for managing and protecting against Type 2 diabetes.”
The statement describes a proposed mechanism supported by some experimental research, although animal findings cannot establish equivalent benefits in humans.
The newly identified caffaldehydes introduce another possible mechanism involving the direct inhibition of alpha-glucosidase.
Nevertheless, their discovery does not establish that they are responsible for the lower diabetes risk observed in population studies. Coffee contains numerous biologically active substances, and dietary patterns, individual metabolic characteristics and other factors may contribute to associations observed over long periods.
The Harvard analysis also emphasized that observational findings cannot establish causation. Although the relationship between coffee consumption and diabetes risk has appeared repeatedly across different populations, those studies do not prove that drinking coffee prevents the disease.
The Chinese laboratory findings provide a possible biochemical explanation worth investigating, but substantial additional research is necessary to determine whether these particular compounds contribute meaningfully to the observed association.
One potential application involves developing functional food ingredients derived from coffee.
Functional foods generally contain components intended to provide physiological benefits beyond basic nutrition. If the safety and activity of caffaldehydes can be established in living organisms, researchers could investigate whether the compounds might be useful in specialized food formulations or other products intended to support glucose regulation.
Another possibility involves pharmaceutical research, in which scientists could examine whether the newly discovered molecular structures provide starting points for developing enzyme inhibitors.
Such development would require determining how the compounds interact with alpha-glucosidase, whether their chemical structures can be modified to improve desired properties and whether they produce unwanted effects elsewhere in the body.
Animal studies would ordinarily help evaluate absorption, metabolism, toxicity and the ability to influence glucose levels under physiological conditions.
Clinical trials would then be needed to determine whether any potential benefits extend to human participants, whether the compounds can be administered safely and how their effectiveness compares with established treatments.
Acarbose and other alpha-glucosidase inhibitors can cause gastrointestinal adverse effects, including gas, bloating and diarrhea, because undigested carbohydrates may reach the large intestine and undergo bacterial fermentation.
Finding alternative compounds with useful inhibitory activity could potentially expand the available approaches to glucose management. However, there is currently no evidence that the newly identified coffee substances would avoid those side effects or offer superior safety.
Other practical questions also remain unanswered, including how much caffaldehyde is present in ordinary roasted coffee, whether roasting conditions influence its concentration and whether different brewing methods extract meaningful quantities.
Because three of the six newly discovered substances were detected only at trace levels, their presence in roasted beans does not necessarily mean that a typical cup of coffee delivers enough of them to affect carbohydrate digestion.
The results should therefore not be interpreted as evidence that coffee can replace prescription diabetes medication or reliably lower blood glucose after meals.
The research instead demonstrates how advanced chemical analysis can uncover biologically active molecules in foods that have been consumed for centuries.
By combining enzyme-based screening with nuclear magnetic resonance, chromatography and molecular networking, the Chinese Academy of Sciences team identified substances that conventional analytical approaches might have overlooked.
The researchers’ methods may also prove useful for studying other chemically complex foods and plants containing compounds whose biological functions are not yet fully understood.
Their findings expand the known chemical composition of roasted Arabica coffee and establish that several previously unidentified constituents can inhibit an enzyme directly involved in carbohydrate digestion.
Whether those effects can eventually be translated into dietary products, pharmaceutical treatments or a clearer explanation of coffee’s relationship with diabetes will depend on future research involving living organisms and human clinical trials.
For now, the discovery adds a new group of candidate compounds to diabetes research while leaving the central clinical question unresolved: whether the strong enzyme inhibition observed in the laboratory can produce meaningful and safe blood sugar benefits in people.
Source: Natural News
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