Lactulose Assay Kit

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00:03 Introduction & Kit Description
00:24  Process
01:12    Principle
02:55   Reagent Preparation
04:24   Sample Preparation
21:45    Enzymatic Determination Reaction
29:12    Calculations
30:42   ISO Method 11285:2004

Lactulose Assay Kit K-LACTUL Scheme
Reference code: K-LACTUL
SKU: 700004308

50 assays per kit

Content: 50 assays per kit
Shipping Temperature: Ambient
Storage Temperature: Short term stability: 2-8oC,
Long term stability: See individual component labels
Stability: > 2 years under recommended storage conditions
Analyte: Lactulose
Assay Format: Spectrophotometer
Detection Method: Absorbance
Wavelength (nm): 340
Signal Response: Increase
Linear Range: 0.65 to 65 µg of lactulose per “Enzymatic Determination Reaction
Limit of Detection: 4.8 mg/L
Reaction Time (min): ~ 120 min
Application examples: Milk, dairy products and foods containing milk.
Method recognition: Novel method

The Lactulose Assay Kit is suitable for the specific, rapid and sensitive measurement and analysis of lactulose in milk and milk-based samples. Reagents included in this kit may also be prepared for use in the procedure described by ISO Method 11285:2004.

Check out our other monosaccharide and disaccharide assay kits.

Scheme-K-LACTUL LACTUL Megazyme

  • Twice the sensitivity of traditional hexokinase based lactulose methods 
  • Very cost effective 
  • All reagents stable for > 2 years after preparation 
  • Mega-Calc™ software tool is available from our website for hassle-free raw data processing 
  • Standard included
Certificate of Analysis
Safety Data Sheet
FAQs Assay Protocol Data Calculator Validation Report

Gut microbiota-derived 3-phenylpropionic acid promotes intestinal epithelial barrier function via AhR signaling.

Hu, J., Chen, J., Xu, X., Hou, Q., Ren, J. & Yan, X. (2023). Microbiome, 11(1), 1-23.

Background: The intestinal epithelial barrier confers protection against the intestinal invasion by pathogens and exposure to food antigens and toxins. Growing studies have linked the gut microbiota to the intestinal epithelial barrier function. The mining of the gut microbes that facilitate the function of intestinal epithelial barrier is urgently needed. Results: Here, we studied a landscape of the gut microbiome of seven pig breeds using metagenomics and 16S rDNA gene amplicon sequencing. The results indicated an obvious difference in the gut microbiome between Congjiang miniature (CM) pigs (a native Chinese breed) and commercial Duroc × [Landrace × Yorkshire] (DLY) pigs. CM finishing pigs had stronger intestinal epithelial barrier function than the DLY finishing pigs. Fecal microbiota transplantation from CM and DLY finishing pigs to germ-free (GF) mice transferred the intestinal epithelial barrier characteristics. By comparing the gut microbiome of the recipient GF mice, we identified and validated Bacteroides fragilis as a microbial species that contributes to the intestinal epithelial barrier. B. fragilis-derived 3-phenylpropionic acid metabolite had an important function on the enhancement of intestinal epithelial barrier. Furthermore, 3-phenylpropionic acid facilitated the intestinal epithelial barrier by activating aryl hydrocarbon receptor (AhR) signaling. Conclusions: These findings suggest that manipulation of B. fragilis and 3-phenylpropionic acid is a promising strategy for improving intestinal epithelial barrier.

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β-Galactosidase from Exiguobacterium acetylicum: cloning, expression, purification and characterization.

Aburto, C., Castillo, C., Cornejo, F., Arenas-Salinas, M., Vásquez, C., Guerrero, C., Arenas, F., Illanes. A., & Vera, C. (2019). Bioresource Technology, 277, 211-215.

The main goal of this work was to evaluate the performance of β-galactosidase from Exiguobacterium acetylicum MF03 in both hydrolysis and transgalactosylation reactions from different substrates. The enzyme gene was expressed in Escherichia coli BL21 (DE3), sequenced, and subjected to bioinformatic and kinetic assessment. Results showed that the enzyme was able to hydrolyze lactulose and o-nitrophenyl-β-d-galactopyranoside, but unable to hydrolyze lactose, o-nitrophenyl-β-d-glucopyranoside, butyl- and pentyl-β-d-galactosides. This unique and novel substrate specificity converts the E. acetylicum MF03 β-galactosidase into an ideal catalyst for the formulation of an enzymatic kit for lactulose quantification in thermally processed milk. This is because costly steps to eliminate glucose (resulting from hydrolysis of lactose when a customary β-galactosidase is used) can be avoided.

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Hepatoprotective effect of Lentinus edodes mycelia fermented formulation against alcoholic liver injury in rats.

Chung, W. S., Wang, J. H., Bose, S., Park, J. M., Park, S. O., Lee, S. J., Jeon. S. & Kim, H. (2015). Journal of Food Biochemistry, 39(3), 251-262.

The hepatoprotective effects of fermented black rice bran extracts (FF1 and FF2: black rice bran fermented by Lentinus edodes derived from mycelium supplemented with soybean or Hovenia dulcis) and their associated mechanisms were evaluated. In an in vitro experiment, FFs caused significant amelioration of the metabolic function of rat hepatocytes treated with NH4Cl. In addition, administration of FFs to rats with chronic liver injury induced by 12-week continual alcohol consumption resulted in significant restoration of body weight shrinkage, notable attenuation of excessive aspartate aminotransferase, alkaline phosphatase and endotoxin in serum, malondialdehyde in liver and the lactulose/mannitol ratio in urine. Furthermore, FF1 or FF2 also caused significant downregulation of gene expression of several critical inflammatory mediators (interleukin-6, tumor necrosis factor-alpha, cyclooxygenase-2 and inducible nitric oxide synthase). Histopathological findings also indicated that FFs reduced inflammation, necrosis and fatty infiltration in liver tissue. Taken together, FFs exert hepatoprotective effects through anti-inflammatory and anti-lipid peroxidative properties and regulation of intestinal permeability.

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Evaluation of furosine, lactulose and acid-soluble β-lactoglobulin as time temperature integrators for whipping cream samples at retail in Austria.

Boitz, L. I. & Mayer, H. K. (2015). International Dairy Journal, 50, 24-31.

Three heat load indicators, i.e., furosine, lactulose and acid-soluble β-lactoglobulin, were determined in whipping cream samples purchased from Austrian market (n = 33), as well as commercial samples obtained directly from one Austrian dairy company (one brand, n = 25). Furosine contents were 47.8 ± 14.0, 72.2 ± 36.6, and 172.5 ± 17.7 mg 100 g−1 protein, and β-lactoglobulin contents were 143 ± 91, 195 ± 150, and 89 ± 31 mg L−1 for retailed pasteurised, extended shelf life (ESL), and ultra-high temperature (UHT) cream samples, respectively. Lactulose concentrations (analysed enzymatically) were 29 ± 10, 56 ± 41, and 201 ± 24 mg L−1 for pasteurised, ESL and UHT cream samples, respectively. Linear correlation obtained for furosine and lactulose concentrations indicated that these indicators can reliably assess the heat load of pasteurised, ESL and UHT cream samples, whereas β-lactoglobulin was definitely not appropriate to discriminate between these heating categories.

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Flos Lonicera Ameliorates Obesity and Associated Endotoxemia in Rats through Modulation of Gut Permeability and Intestinal Microbiota.

Wang, J. H., Bose, S., Kim, G. C., Hong, S. U., Kim, J. H., Kim, J. E. & Kim, H. (2014). PloS One, 9(1), e86117.

Background and Aims: Increasing evidence has indicated a close association of host-gut flora metabolic interaction with obesity. Flos Lonicera, a traditional herbal medicine, is used widely in eastern Asia for the treatment of various disorders. The aim of this study was to evaluate whether unfermented or fermented formulations of Flos Lonicera could exert a beneficial impact to combat obesity and related metabolic endotoxemia. Methods: Obesity and metabolic endotoxemia were induced separately or together in rats through feeding a eight-week high fat diet either alone (HFD control group) or in combination with a single LPS stimulation (intraperitoneal injection, 0.75 mg/kg) (LPS control group). While, the mechanism of action of the Lonicera formulations was explored in vitro using RAW 264.7 and HCT 116 cell lines as models. Results: In cell-based studies, treatment with both unfermented Flos Lonicera (UFL) and fermented Flos Lonicera (FFL) formulations resulted in suppression of LPS-induced NO production and gene expression of vital proinflammatory cytokines (TNF-α, COX-2, and IL-6) in RAW 264.7 cells, reduced the gene expression of zonula occludens (ZO)-1 and claudin-1, and normalized trans epithelial electric resistance (TEER) and horseradish peroxidase (HRP) flux in LPS-treated HCT-116 cells. In an animal study, treatment of HFD as well as HFD+LPS groups with UFL or FFL resulted in a notable decrease in body and adipose tissue weights, ameliorated total cholesterol, HDL, triglyceride, aspartate transaminase and endotoxin levels in serum, reduced the urinary lactulose/mannitol ratio, and markedly alleviated lipid accumulation in liver. In addition, exposure of HFD as well as HFD+LPS groups with UFL or FFL resulted in significant alteration of the distribution of intestinal flora, especially affecting the population of Akkermansia spp. and ratio of Bacteroidetes and Firmicutes. Conclusion: This evidence collectively demonstrates that Flos Lonicera ameliorates obesity and related metabolic endotoxemia via regulating distribution of gut flora and gut permeability.

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The effects of co-administration of probiotics with herbal medicine on obesity, metabolic endotoxemia and dysbiosis: A randomized double-blind controlled clinical trial.

Lee, S. J., Bose, S., Seo, J. G., Chung, W. S., Lim, C. Y. & Kim, H. (2013). Clinical Nutrition, 33(6), 973-981.

Backgrounds & aims: Probiotics help maintain balance in composition of the gut microbiota, and have been considered as a potential treatment for obesity. This study was conducted in order to assess the effects of probiotics when combined with herbal medicine in treatment of obesity. Probiotics were tested for the ability to modulate gut microbiota, gut permeability, and endotoxin level, which may have correlation with factors involved in obesity. Methods: A randomized, double-blind, placebo controlled study was conducted, in which patients with higher BMI (>25 kg/m2) and waist circumference (>85 cm) were enrolled and randomly assigned to receive Bofutsushosan with either probiotics or placebo capsules for a period of eight weeks. Assessment of body composition parameters, metabolic biomarkers, endotoxin level, gut permeability, and fecal bacteria in stool was performed at baseline and at week 8. The study was registered at the Clinical Research Information Service, approved by the Korea National Institute of Health (KCT0000386). Results: Although both groups showed a significant reduction in weight and waist circumference (p= 0.000), no significant differences in body composition and metabolic markers were observed. In correlation analysis, change in body composition showed positive correlation with endotoxin level (r= 0.441, p< 0.05 for BW; and r= 0.350, p< 0.05 for fat mass) and the population of gut Lactobacillus plantarum (r= 0.425, p< 0.05 for BW; and r= 0.407, p< 0.05 for BMI). The Gram negative bacterial population in gut also exhibited positive correlation with changes in body composition (WC) and total cholesterol level (r= 0.359, and 0.393, for the former and later parameters, respectively, p< 0.05 for both). While, the profile of gut Bifidobacterium breve population showed negative correlation with endotoxin level (r= −0.350, p< 0.05). Conclusions: Correlations between gut microbiota and change in body composition indicate that probiotics may influence energy metabolism in obesity. Correlation between endotoxin level and weight reduction indicates that probiotics may play an important role in prevention of endotoxin production, which can lead to gut microbiota dysbiosis associated with obesity.

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Assessment of gastrointestinal permeability by lactulose test in sheep after repeated indomethacin treatment.

Minuti, A., Ahmed, S., Trevisi, E., Piccioli-Cappelli, F., Bertoni, G. & Bani, P. (2013). Journal of Animal Science, 91(12), 5646-5653.

The aim of the study was to assess the small intestine permeability by using lactulose as a sugar probe and blood metabolites in sheep after a challenge with repeated indomethacin injections. According to a changeover design, 7 adult sheep (4 males and 3 females) were subjected to 4 intramuscular injections (every 12 h) of saline [control (CRT); 7 animals] or indomethacin (INDO; 7 animals). Two hours after the last injection, 30 g of lactulose were administered orally to both CTR and INDO. Blood samples were collected daily for the analysis of the metabolic profile and 5 samples were collected at 2-h intervals following lactulose ingestion to monitor changes in blood levels of lactulose as an index of intestinal permeability. The INDO challenge induced clinical symptoms such as lack of appetite, dullness, weakness, depression, and diarrhea with traces of blood in the feces. In INDO group, haptoglobin and ceruloplasmin increased (P < 0.01) after INDO challenge whereas a decrease (P< 0.05) of negative acute phase reactants (e.g., cholesterol, albumin, and paraoxonase) was observed. Reactive oxygen metabolites increased (P< 0.01) from 60 to 204 h after the INDO challenge start, with a decrease of vitamin E concentration from 12 (P< 0.01) to 132 h (P< 0.05). Blood lactulose concentrations were increased (P< 0.05) in INDO animals and the highest mean values (17.67 µg/mL in INDO vs. 0.17 µg/mL in CRT; P< 0.01) were observed 6 h after oral dosage of lactulose. These changes indicate that the INDO challenge led to severe inflammatory responses with oxidative stress by enhancing small intestinal permeability in sheep that allowed lactulose to enter in blood. The results of this experiment demonstrate that lactulose can be used as a probe to assess gastrointestinal permeability in adult ruminants to test the consequences of stressing conditions on animal welfare. For this purpose, the most suitable time for blood sampling is between 2 and 8 h after the oral dosage of lactulose.

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The effect of intestinal permeability and endotoxemia on the prognosis of acute pancreatitis.

Koh, Y. Y., Jeon, W. K., Cho, Y. K., Kim, H. J., Chung, W. G., Chon, C. U., Oh, T. Y. & Shin, J. H. (2012). Gut and Liver, 6(4), 505-511.

Background/Aims: Early intestinal mucosal damage plays an important role in severe acute pancreatitis (AP). Previous studies have shown that intestinal permeability (IP), serum endotoxin and cytokines contribute to the early intestinal barrier dysfunction in AP. This study explored the predictive capacity of IP, endotoxemia and cytokines as prognostic indicators in AP patients. Methods: Eighty-seven AP patients were included in the study. The patients were classified into three groups according to the Balthazar computed tomography severity index (CTSI). We compared the biochemical parameters, including IP, serum endotoxin level and cytokine level among the three groups. The associations of IP with serum endotoxin, cytokines, CTSI, and other widely used biochemical parameters and scoring systems were also examined. Results: IP, serum endotoxin, interleukin (IL-6) and tumor necrosis factor (TNF)- α had a positive correlation with the CTSI of AP. Endotoxin, IL-6, TNF-α, CTSI, the Ranson/APACHE II score, the duration of hospital stay, complications and death significantly affect IP in the AP patients. Conclusions: We believe that IP with subsidiary measurements of serum endotoxin, IL-6 and TNF-α may be reliable markers for predicting the prognosis of AP. Further studies that can restore and preserve gut barrier function in AP patients are warranted.

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In vitro and in vivo protective effects of fermented preparations of dietary herbs against lipopolysaccharide insult.

Bose, S., Song, M. Y., Nam, J. K., Lee, M. J. & Kim, H. (2012). Food Chemistry, 134(2), 758-765.

Lipopolysaccharide (LPS) is known to produce endotoxic shock by triggering systemic inflammatory responses. Here, we evaluated the protective effects of three fermented/re-fermented herbs, Rhizoma Atractylodis Macrocephalae, Massa Medicata Fermentata, and Dolichoris Semen, in an LPS-mediated inflammatory insult, either individually in vitro using RAW264.7 cells or in combination in in vivo using rats. In general, each of the fermented herbs showed appreciable in vitro anti-inflammatory activity, although the degree of this activity varied with the herb used. Moreover, a mixture of fermented herbal extracts in combination with probiotics significantly attenuated the blood endotoxin and CRP levels, as well as the gut permeability, and significantly augmented the intestinal Lactobacillus spp. colonisation in LPS-treated rats. However, these effects were not observed following the administration of the corresponding mixture of unfermented herbal extracts. Thus, our results highlight the beneficial impacts of the use of fermented herb products with probiotics to combat LPS-mediated inflammatory insults.

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Evaluation of the in vitro and in vivo protective effects of unfermented and fermented Rhizoma coptidis formulations against lipopolysaccharide insult.

Bose, S., Jeon, S., Eom, T., Song, M. Y. & Kim, H. (2012). Food Chemistry, 135(2), 452-459.

Lipopolysaccharide (LPS) can produce endotoxic shock by triggering the systemic inflammatory response. Here, we evaluated the in vitro and in vivo protective effects of unfermented and fermented Rhizoma coptidis (RC and FRC, respectively) against LPS-insult. In general, RC suppressed the LPS-induced expression of key inflammatory mediators in RAW264.7 cells, in a dose-dependent manner. Notably, FRC at a 20 µg/ml dose in combination with the probiotic used for fermentation showed more potent in vitro anti-inflammatory activities than that exhibited by the corresponding dose of RC. Moreover, oral treatment with FRC in association with the probiotic, but not oral administration of RC, significantly attenuated blood endotoxin and C-reactive protein (CRP) levels, and gut permeability, and significantly augmented the intestinal population of Bifodobacterium spp. and Lactobacillus spp. in LPS-treated animals. Our results demonstrate the beneficial impact of fermented RC in combination with the associated probiotic in combating LPS-insult both in vitro and in vivo.

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Safety Information
Symbol : GHS05, GHS08
Signal Word : Danger
Hazard Statements : H314, H334, H360
Precautionary Statements : P201, P202, P260, P261, P264, P280, P284, P304+P340, P342+P311, P501
Safety Data Sheet
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