Fructose metabolism and its roles in metabolic diseases, inflammatory diseases, and cancer

Fructose, a prevalent hexose, has become a widely used food additive, with its usage rising significantly because of socio-economic advancements and shifts in human dietary habits. Excessive fructose intake has been implicated in obesity, cardiovascular disease, metabolic syndromes, inflammation, and cancer, among other disorders. This review discusses the absorption, distribution, and metabolism of fructose and the links between fructose metabolism and major metabolic pathways. The role of fructose in metabolic diseases, including metabolic dysfunction-associated fatty liver disease, hyperinsulinemia, and hyperuricemia, is also highlighted. Furthermore, the role of fructose in the development of chronic inflammation, including gut inflammation, liver inflammation, and neuroinflammation, is discussed. Lastly, in the context of cancer development, this review summarizes the dual role of fructose in tumors, both pro- and anti-tumor effects. Future studies on the role of fructose in cancer should focus on the complexity of physiological and pathological conditions, such as the specific tumor microenvironment and metabolic status. Fructose has been shown to induce metabolic reprogramming of multiple immune cells and increase pro-inflammatory immune responses; therefore, inhibiting or promoting its metabolism may regulate immune responses. And targeting fructose metabolism may be a promising approach to treating metabolic diseases, inflammation, and cancer.

Design and Synthesis of Novel Di-Boronic Acid-Based Chemical Glucose Sensors

Chemical-based fluorescent sensors with the capability of long-term stability and low cost are promising agents in clinical diagnosis and medical research. Measuring glucose levels inside cells and their surroundings provides insight into cellular metabolic homeostasis and may be employed as an indicator for potential pathological conditions. Anthracene-based diboronic acid (BA) derivatives offer a reversible and covalent binding mechanism for glucose recognition, which enables robust and continuous glucose monitoring. To improve its poor solubility and biological applicability, a diboronic acid chemical structure design was explored. To date, several anthracene-based ortho-amino methylphenyl boronic acid glucose-sensors have been developed. Most recently, the structure of Mc-CDBA (((((2-(methoxycarbonyl) anthracene-9,10-diyl) bis (methylene)) bis(methylazanediyl)) bis(methylene)) bis(4-cyano-2,1-phenylene)) diboronic acid was disclosed. Mc-CDBA exhibits suitable water-solubility and sensitivity toward glucose, with limited modification sites and suitability to extra-cellular applications. Here, we present a palette of Mc-CDBA derivatives: carboxylic (BA), amid (BA 5) and acryl (BA 21)-based Mc-CDBA sensors for extra- and intracellular glucose monitoring, respectively. The developed chemical glucose sensors were designed to obtain a final product with fewer synthetic steps, allowing easier scale-up capacity. Moreover, we showed that ortho-amino site modifications do not interfere with the sensor activity, allowing alternative water solubility solutions without chemically modifying the chromophore/aromatic subunits within the molecule. Among these probes, we also developed an extracellular hydrogel-embedded sensor (BA 21) to monitor extracellular glucose levels under persistent solution flow, a feature that is lacking in other glucose sensors. The synthesized derivatives could serve as diverse fluorescent sensors for glucose monitoring in medical applications.

Fructose metabolism and its role in pig production: A mini-review

Epidemiological studies have shown that excessive intake of fructose is largely responsible for the increasing incidence of non-alcoholic fatty liver, obesity, and diabetes. However, depending on the amount of fructose consumption from diet, the metabolic role of fructose is controversial. Recently, there have been increasing studies reporting that diets low in fructose expand the surface area of the gut and increase nutrient absorption in mouse model, which is widely used in fructose-related studies. However, excessive fructose consumption spills over from the small intestine into the liver for steatosis and increases the risk of colon cancer. Therefore, suitable animal models may be needed to study fructose-induced metabolic changes. Along with its use in global meat production, pig is well-known as a biomedical model with an advantage over murine and other animal models as it has similar nutrition and metabolism to human in anatomical and physiological aspects. Here, we review the characteristics and metabolism of fructose and summarize observations of fructose in pig reproduction, growth, and development as well as acting as a human biomedical model. This review highlights fructose metabolism from the intestine to the blood cycle and presents the critical role of fructose in pig, which could provide new strategies for curbing human metabolic diseases and promoting pig production.

Oenothein B in Eucalyptus Leaf Extract Suppresses Fructose Absorption in Caco-2 Cells

Inhibition of fructose absorption may suppress adiposity and adiposity-related diseases caused by fructose ingestion. Eucalyptus leaf extract (ELE) inhibits intestinal fructose absorption (but not glucose absorption); however, its active compound has not yet been identified. Therefore, we evaluated the inhibitory activity of ELE obtained from Eucalyptus globulus using an intestinal fructose permeation assay with the human intestinal epithelial cell line Caco-2. The luminal sides of a cell monolayer model cultured on membrane filters were exposed to fructose with or without the ELE. Cellular fructose permeation was evaluated by measuring the fructose concentration in the medium on the basolateral side. ELE inhibited 65% of fructose absorption at a final concentration of 1 mg/mL. Oenothein B isolated from the ELE strongly inhibited fructose absorption; the inhibition rate was 63% at a final concentration of 5 μg/mL. Oenothein B did not affect glucose absorption. In contrast, the other major constituents (i.e., gallic acid and ellagic acid) showed little fructose-inhibitory activity. To our knowledge, this is the first report that oenothein B in ELE strongly inhibits fructose absorption in vitro. ELE containing oenothein B can prevent and ameliorate obesity and other diseases caused by dietary fructose consumption.

Fructose metabolism and metabolic disease

Increased sugar consumption is increasingly considered to be a contributor to the worldwide epidemics of obesity and diabetes and their associated cardiometabolic risks. As a result of its unique metabolic properties, the fructose component of sugar may be particularly harmful. Diets high in fructose can rapidly produce all of the key features of the metabolic syndrome. Here we review the biology of fructose metabolism as well as potential mechanisms by which excessive fructose consumption may contribute to cardiometabolic disease.

Inhibitory effects of eucalyptus and banaba leaf extracts on nonalcoholic steatohepatitis induced by a high-fructose/high-glucose diet in rats

Nonalcoholic steatohepatitis (NASH) is a liver disease associated with metabolic syndrome. The aim of this work was to examine whether eucalyptus (Eucalyptus globulus) leaf extract (ELE) and banaba (Lagerstroemia speciosa L.) leaf extract (BLE) inhibited NASH induced by excessive ingestion of fructose in rats. Wistar rats were divided into four groups according to four distinct diets: starch diet (ST), high-fructose/high-glucose diet (FG), FG diet supplemented with ELE, or FG diet supplemented with BLE. All rats were killed after 5 weeks of treatment. Serum alanine aminotransferase and total cholesterol levels were significantly lower in the BLE group than in the FG group. Liver histopathology, including steatosis, lipogranulomas, and perisinusoidal fibrosis, was significantly attenuated in the ELE and BLE groups compared with the FG group. Levels of 2-thiobarbituric acid reactive substances (TBARS), which reflect oxidative injury to the liver, were significantly suppressed by ELE and BLE. Western blotting analysis indicated that interleukin-6 expression levels were significantly lower in the ELE and BLE groups than in the FG group. These results suggest that ELE and BLE reduced lipogenesis, oxidative stress, and inflammatory cytokine expression and thus inhibited NASH induced by excessive ingestion of fructose in rats.

The role of fructose transporters in diseases linked to excessive fructose intake

Fructose intake has increased dramatically since humans were hunter-gatherers, probably outpacing the capacity of human evolution to make physiologically healthy adaptations. Epidemiological data indicate that this increasing trend continued until recently. Excessive intakes that chronically increase portal and peripheral blood fructose concentrations to >1 and 0.1 mm, respectively, are now associated with numerous diseases and syndromes. The role of the fructose transporters GLUT5 and GLUT2 in causing, contributing to or exacerbating these diseases is not well known. GLUT5 expression seems extremely low in neonatal intestines, and limited absorptive capacities for fructose may explain the high incidence of malabsorption in infants and cause problems in adults unable to upregulate GLUT5 levels to match fructose concentrations in the diet. GLUT5- and GLUT2-mediated fructose effects on intestinal electrolyte transporters, hepatic uric acid metabolism, as well as renal and cardiomyocyte function, may play a role in fructose-induced hypertension. Likewise, GLUT2 may contribute to the development of non-alcoholic fatty liver disease by facilitating the uptake of fructose. Finally, GLUT5 may play a role in the atypical growth of certain cancers and fat tissues. We also highlight research areas that should yield information needed to better understand the role of these GLUTs in fructose-induced diseases.