Effect of oral sebacic Acid on postprandial glycemia, insulinemia, and glucose rate of appearance in type 2 diabetes

Dicarboxylic acids counteract the metabolic effects of a Western diet by boosting energy expenditure

Obesity has reached pandemic proportion not only in the West but also in other countries around the world; it is now one of the leading causes of death worldwide. A Western diet is rich in saturated fats and provides more calories than necessary, contributing to the rise of the obesity rate. It also promotes the development of liver steatosis, insulin resistance, hyperglycemia, and hyperlipidemia. In this issue of the JCI, Goetzman and colleagues describe the effects of consuming dicarboxylic acids (DAs) as an alternative source of dietary fat. The 12-carbon dicarboxylic acid (DC12) was administered to mice at 20% of their daily caloric intake for nine weeks in place of triglycerides. Notably, the change in diet increased the metabolic rate, reduced body fat, reduced liver fat, and improved glucose tolerance. These findings highlight DAs as useful energy nutrients for combatting obesity and treating various metabolic disorders.

Medium-chain dicarboxylic acids: chemistry, pharmacological properties, and applications in modern pharmaceutical and cosmetics industries

Succinic (SUA), glutaric (GLA), pimelic (PA), suberic (SUBA), adipic (ADA), azelaic (AZA), and sebacic acids (SA) make up the majority of medium-chain dicarboxylic acids (MCDAs) with chain lengths of C4-C10, and are widely utilised in the chemical, food, textile, pesticide, pharmaceutical, and liquid crystal sectors. The MCDAs' two carboxyl groups provide them with an incredibly broad variety of applications. The focus of significant scientific research now is on the increasingly varied pharmacological effects of MCDAs. However, only a few studies have compared the biological characteristics of MCDAs in the contemporary pharmaceutical and cosmetic sectors and thoroughly examined the most recent research and marketing initiatives for MCDAs. This review's objective is to offer a thorough analysis of academic works on MCDAs, to assess the usefulness of these substances' chemical-pharmacological properties for use in the contemporary pharmaceutical and cosmetic industries, and to investigate the direction of their possible applications in these two disciplines. In addition, this review investigates how these compounds are metabolised in the human body.

Dietary dicarboxylic acids provide a non-storable alternative fat source that protects mice against obesity

Dicarboxylic fatty acids are generated in the liver and kidney in a minor pathway called fatty acid ω-oxidation. The effects of consuming dicarboxylic fatty acids as an alternative source of dietary fat have not been explored. Here, we fed dodecanedioic acid, a 12-carbon dicarboxylic (DC12), to mice at 20% of daily caloric intake for nine weeks. DC12 increased metabolic rate, reduced body fat, reduced liver fat, and improved glucose tolerance. We observed DC12-specific breakdown products in liver, kidney, muscle, heart, and brain, indicating that oral DC12 escaped first-pass liver metabolism and was utilized by many tissues. In tissues expressing the "a" isoform of acyl-CoA oxidase-1 (ACOX1), a key peroxisomal fatty acid oxidation enzyme, DC12 was chain shortened to the TCA cycle intermediate succinyl-CoA. In tissues with low peroxisomal fatty acid oxidation capacity, DC12 was oxidized by mitochondria. In vitro, DC12 was catabolized even by adipose tissue and was not stored intracellularly. We conclude that DC12 and other dicarboxylic acids may be useful for combatting obesity and for treating metabolic disorders.

Differential effect of gastric bypass versus sleeve gastrectomy on insulinotropic action of endogenous incretins

OBJECTIVE

Prandial hyperinsulinemia after Roux-en-Y gastric bypass surgery (GB), and to lesser degree after sleeve gastrectomy (SG), has been attributed to rapid glucose flux from the gut and increased insulinotropic gut hormones. However, β-cell sensitivity to exogenous incretin is reduced after GB. This study examines the effect of GB versus SG on prandial glycemia and β-cell response to increasing concentrations of endogenous incretins.

METHODS

Glucose kinetics, insulin secretion rate (ISR), and incretin responses to 50-g oral glucose ingestion were compared between ten nondiabetic participants with GB versus nine matched individuals with SG and seven nonoperated normal glucose tolerant control individuals (CN) with and without administration of 200 mg of sitagliptin.

RESULTS

Fasting glucose and hormonal levels were similar among three groups. Increasing plasma concentrations of endogenous incretins by two- to three-fold diminished prandial glycemia and increased β-cell secretion in all three groups (p < 0.05), but insulin secretion per insulin sensitivity (i.e., disposition index) was increased only in GB (p < 0.05 for interaction). However, plot of the slope of ISR (from premeal to peak values) versus plasma glucagon-like peptide-1 concentration was smaller after GB compared with SG and CN.

CONCLUSIONS

After GB, increasing incretin activity augments prandial β-cell response whereas the β-cell sensitivity to increasing plasma concentrations of endogenous incretin is diminished.

Sebacic Acid as a Potential Age-Related Biomarker of Liver Aging: Evidence Linking Mice and Human

The aging process is complicated and involves diverse organ dysfunction; furthermore, the biomarkers that are able to reflect biological aging are eagerly sought after to monitor the system-wide decline associated with the aging process. To address this, we performed a metabolomics analysis using a longitudinal cohort study from Taiwan (N = 710) and established plasma metabolomic age using a machine learning algorithm. The resulting estimation of age acceleration among the older adults was found to be correlated with HOMA-insulin resistance. In addition, a sliding window analysis was used to investigate the undulating decrease in hexanoic and heptanoic acids that occurs among the older adults at different ages. A comparison of the metabolomic alterations associated with aging between humans and mice implied that ω-oxidation of medium-chain fatty acids was commonly dysregulated in older subjects. Among these fatty acids, sebacic acid, an ω-oxidation product produced by the liver, was significantly decreased in the plasma of both older humans and aged mice. Notably, an increase in the production and consumption of sebacic acid within the liver tissue of aged mice was observed, along with an elevation of pyruvate-to-lactate conversion. Taken together, our study reveals that sebacic acid and metabolites of ω-oxidation are the common aging biomarkers in both humans and mice. The further analysis suggests that sebacic acid may play an energetic role in supporting the production of acetyl-CoA during liver aging, and thus its alteration in plasma concentration potentially reflects the aging process.

Mitigation of Insulin Resistance by Natural Products from a New Class of Molecules, Membrane-Active Immunomodulators

Insulin resistance (IR), accompanied by an impaired cellular glucose uptake, characterizes diverse pathologies that include, but are not limited to, metabolic disease, prediabetes and type 2 diabetes. Chronic inflammation associated with deranged cellular signaling is thought to contribute to IR. The key molecular players in IR are plasma membrane proteins, including the insulin receptor and glucose transporter 4. Certain natural products, such as lipids, phenols, terpenes, antibiotics and alkaloids have beneficial effects on IR, yet their mode of action remains obscured. We hypothesized that these products belong to a novel class of bioactive molecules that we have named membrane-active immunomodulators (MAIMs). A representative MAIM, the naturally occurring medium chain fatty acid ester diethyl azelate (DEA), has been shown to increase the fluidity of cell plasma membranes with subsequent downstream effects on cellular signaling. DEA has also been shown to improve markers of IR, including blood glucose, insulin and lipid levels, in humans. The literature supports the notion that DEA and other natural MAIMs share similar mechanisms of action in improving IR. These findings shed a new light on the mechanism of IR mitigation using natural products, and may facilitate the discovery of other compounds with similar activities.

The biochemistry and physiology of long-chain dicarboxylic acid metabolism

Mitochondrial β-oxidation is the most prominent pathway for fatty acid oxidation but alternative oxidative metabolism exists. Fatty acid ω-oxidation is one of these pathways and forms dicarboxylic acids as products. These dicarboxylic acids are metabolized through peroxisomal β-oxidation representing an alternative pathway, which could potentially limit the toxic effects of fatty acid accumulation. Although dicarboxylic acid metabolism is highly active in liver and kidney, its role in physiology has not been explored in depth. In this review, we summarize the biochemical mechanism of the formation and degradation of dicarboxylic acids through ω- and β-oxidation, respectively. We will discuss the role of dicarboxylic acids in different (patho)physiological states with a particular focus on the role of the intermediates and products generated through peroxisomal β-oxidation. This review is expected to increase the understanding of dicarboxylic acid metabolism and spark future research.

Insulinotropic effect of endogenous incretins is greater after gastric bypass than sleeve gastrectomy despite diminished beta-cell sensitivity to plasma incretins

BACKGROUND/AIMS

Prandial hyperinsulinemia after Roux-en Y gastric bypass surgery (GB), and to lesser degree after sleeve gastrectomy (SG), has been attributed to rapid glucose flux from the gut and increased insulinotropic gut hormones. However, β-cell sensitivity to exogenous incretin is markedly reduced after GB. This study examines the effect of GB versus SG on prandial glycemia and β-cell response to increasing concentrations of endogenous incretins.

METHODS

Glucose kinetics, insulin secretion rate (ISR), and incretin responses to 50-gram oral glucose ingestion were compared between 10 non-diabetic subjects with GB versus 9 matched individuals with SG and 7 non-operated normal glucose tolerant controls (CN) on two days with and without administration of 200 mg sitagliptin.

RESULTS

Fasting glucose and hormonal levels were similar among 3 groups. Increasing plasma concentrations of endogenous incretins by 2-3-fold diminished post-OGTT glycemia and increased β-cell secretion in all 3 groups (p<0.05), but insulin secretion per insulin sensitivity (i.e., disposition index) was increased only in GB (p<0.05 for interaction). As a result, sitagliptin administration led to hypoglycemia in 3 of 10 GB. Yet, plot of the slope of ISR versus the increase in endogenous incretin concentration was smaller after GB compared to both SG and CN.

CONCLUSION

Augmented glycemic-induced β-cell response caused by enhanced incretin activity is unique to GB and not shared with SG. However, the β-cell sensitivity to increasing concentrations of endogenous incretin is smaller after bariatric surgery, particularly after GB, compared to non-operated controls, indicating a long-term adaptation of gut-pancreas axis after these procedures.

HIGHLIGHTS

What is known?: Glycemic effects of gastric bypass (GB) and sleeve gastrectomy (SG) is attributed to rapid nutrient flux and enhanced insulinotropic effects of gut hormones but β-cell sensitivity to exogenous GLP-1 or GIP is diminished after GB. What the present findings add?: Post-OGTT β-cell sensitivity to enhanced endogenous incretins by DPP4i is markedly reduced in bariatric subjects versus non-operated controls, and yet insulin secretory response (disposition index) is increased leading to hypoglycemia in GB and not SG. Significance?: Blunted sensitivity to GLP-1 may represent β-cell adaptation to massive elevation in GLP-1 secretion following bariatric surgery to protect against hypoglycemia.The differential effect of enhanced concentrations of incretins on post-OGTT insulin response (disposition index) among GB versus SG highlights a distinct adaptive process among the two procedures.Augmented insulinotropic effects of gut hormones on postprandial insulin secretory response after GB despite a reduced beta-cell sensitivity to plasma concentrations of GLP-1 makes a case for non-hormonal mechanisms of GLP-1 action after GB.Better understanding of long-term effects of bariatric surgery on gut-pancreas axis activity is critical in development of GLP-1-based strategies to address glucose abnormalities (both hyperglycemia and hypoglycemia) in these settings.

Bamboo shoot dietary fiber alleviates gut microbiota dysbiosis and modulates liver fatty acid metabolism in mice with high-fat diet-induced obesity

Introduction

Obesity is a common nutritional disorder characterized by an excessive fat accumulation. In view of the critical role of gut microbiota in the development of obesity and metabolic diseases, novel dietary therapies have been developed to manage obesity by targeting the gut microbiome. In this study, we investigated anti-obesity effects of bamboo shoot dietary fiber (BSDF) and the potential mechanisms.

Methods

After 12 weeks of intervention with BSDF in high-fat mice, we detected obesity-related phenotypic indicators, and made transcriptomic analysis of liver tissue. Then we analyzed the changes of gut microbiota using 16S rRNA gene sequencing, explored the effect of BSDF on gut microbiota metabolites, and finally verified the importance of gut microbiota through antibiotic animal model.

Results and discussion

We found that BSDF was effective in reducing lipid accumulation in liver and adipose tissue and alleviating dyslipidemia and insulin resistance. Liver transcriptome analysis results showed that BSDF could improve lipid metabolism and liver injury by modulating peroxisome proliferator-activated receptor (PPAR) and fatty acid metabolic pathways. The 16S rRNA gene sequencing analysis of gut microbiota composition showed that BSDF significantly enriched beneficial bacteria such as Bifidobacterium, Akkermansia, Dubosiella, and Alloprevotella. Analysis of fecal metabolomics and gut microbiota metabolites revealed that BSDF increased the levels of several short-chain fatty acids and enriched bile acids, which may be important for improving lipid metabolism. Notably, the obesity-related metabolic disorders were abrogated after the abrogation of gut microbiota, suggesting that gut microbiota is a key factor in the beneficial effects of BSDF.

Conclusion

Our study suggests that BSDF as a prebiotic supplement has the potential to improve obesity by improving gut microbiota and modulating host PPAR and fatty acid metabolic pathways.

Glucose Metabolism and Metabolomic Changes in Response to Prolonged Fasting in Individuals with Obesity, Type 2 Diabetes and Non-Obese People-A Cohort Trial

Metabolic regulation of glucose can be altered by fasting periods. We examined glucose metabolism and metabolomics profiles after 12 h and 36 h fasting in non-obese and obese participants and people with type 2 diabetes using oral glucose tolerance (OGTT) and intravenous glucose tolerance testing (IVGTT). Insulin sensitivity was estimated by established indices and mass spectrometric metabolomics was performed on fasting serum samples. Participants had a mean age of 43 ± 16 years (62% women). Fasting levels of glucose, insulin and C-peptide were significantly lower in all cohorts after 36 h compared to 12 h fasting (p < 0.05). In non-obese participants, glucose levels were significantly higher after 36 h compared to 12 h fasting at 120 min of OGTT (109 ± 31 mg/dL vs. 79 ± 18 mg/dL; p = 0.001) but insulin levels were lower after 36 h of fasting at 30 min of OGTT (41.2 ± 34.1 mU/L after 36 h vs. 56.1 ± 29.7 mU/L; p < 0.05). In contrast, no significant differences were observed in obese participants or people with diabetes. Insulin sensitivity improved in all cohorts after 36 h fasting. In line, metabolomics revealed subtle baseline differences and an attenuated metabolic response to fasting in obese participants and people with diabetes. Our data demonstrate an improved insulin sensitivity after 36 h of fasting with higher glucose variations and reduced early insulin response in non-obese people only.

Royal jelly fatty acids downregulate ANGPTL8 expression through the decrease in HNF4α protein in human hepatoma HepG2 cells

Royal jelly (RJ) intake has been reported to be effective for reducing serum lipids; however, the mechanism is not fully understood. Angiopoietin-like protein 8 (ANGPTL8), a secreted protein, plays a key role in lipid metabolism. In this study, we investigated the effects of specific fatty acids included in RJ (RJ fatty acids), such as 10-hydroxy-2-decenoic acid, 10-hydroxydecanoic acid, and sebacic acid (SA), on expression of ANGPTL8 in human hepatoma HepG2 cells. SA markedly reduced the expression of ANGPTL8. Reporter assay revealed that SA suppressed ANGPTL8 promoter activity. In addition, we identified a functional binding site of hepatocyte nuclear factor-4α (HNF4α), a liver-enriched transcription factor, in the ANGPTL8 promoter. SA reduced the levels of HNF4α protein and the binding of HNF4α to the ANGPTL8 promoter. Moreover, siRNA knockdown of HNF4α suppressed the expression of ANGTPL8 mRNA. Taken together, we conclude that SA downregulates ANGPTL8 expression via the decrease in HNF4α protein.

Effects of Acute and Chronic Resistance Exercise on the Skeletal Muscle Metabolome

Resistance training promotes metabolic health and stimulates muscle hypertrophy, but the precise routes by which resistance exercise (RE) conveys these health benefits are largely unknown. Aim: To investigate how acute RE affects human skeletal muscle metabolism. Methods: We collected vastus lateralis biopsies from six healthy male untrained volunteers at rest, before the first of 13 RE training sessions, and 45 min after the first and last bouts of RE. Biopsies were analysed using untargeted mass spectrometry-based metabolomics. Results: We measured 617 metabolites covering a broad range of metabolic pathways. In the untrained state RE altered 33 metabolites, including increased 3-methylhistidine and N-lactoylvaline, suggesting increased protein breakdown, as well as metabolites linked to ATP (xanthosine) and NAD (N1-methyl-2-pyridone-5-carboxamide) metabolism; the bile acid chenodeoxycholate also increased in response to RE in muscle opposing previous findings in blood. Resistance training led to muscle hypertrophy, with slow type I and fast/intermediate type II muscle fibre diameter increasing by 10.7% and 10.4%, respectively. Comparison of post-exercise metabolite levels between trained and untrained state revealed alterations of 46 metabolites, including decreased N-acetylated ketogenic amino acids and increased beta-citrylglutamate which might support growth. Only five of the metabolites that changed after acute exercise in the untrained state were altered after chronic training, indicating that training induces multiple metabolic changes not directly related to the acute exercise response. Conclusion: The human skeletal muscle metabolome is sensitive towards acute RE in the trained and untrained states and reflects a broad range of adaptive processes in response to repeated stimulation.

Potential biomarkers identified in plasma of patients with gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a common complication during pregnancy. Looking for reliable diagnostic markers for early diagnosis can reduce the impact of the disease on the fetus OBJECTIVE: The present study is designed to find plasma metabolites that can be used as potential biomarkers for GDM, and to clarify GDM-related mechanisms METHODS: By non-target metabolomics analysis, compared with their respective controls, the plasma metabolites of GDM pregnant women at 12-16 weeks and 24-28 weeks of pregnancy were analyzed. Multiple reaction monitoring (MRM) analysis was performed to verify the potential marker RESULTS: One hundred and seventy-two (172) and 478 metabolites were identified as differential metabolites in the plasma of GDM pregnant women at 12-16 weeks and 24-28 weeks of pregnancy, respectively. Among these, 40 metabolites were overlapped. Most of them are associated with the mechanism of diabetes, and related to short-term and long-term complications in the perinatal period. Among them, 7 and 10 differential metabolites may serve as potential biomarkers at the 12-16 weeks and 24-28 weeks of pregnancy, respectively. By MRM analysis, compared with controls, increased levels of 17(S)-HDoHE and sebacic acid may serve as early prediction biomarkers of GDM. At 24-28 weeks of pregnancy, elevated levels of 17(S)-HDoHE and L-Serine may be used as auxiliary diagnostic markers for GDM CONCLUSION: Abnormal amino acid metabolism and lipid metabolism in patients with GDM may be related to GDM pathogenesis. Several differential metabolites identified in this study may serve as potential biomarkers for GDM prediction and diagnosis.

Circulating short and medium chain fatty acids are associated with normoalbuminuria in type 1 diabetes of long duration

A substantial number of subjects with Type 1 Diabetes (T1D) of long duration never develop albuminuria or renal function impairment, yet the underlying protective mechanisms remain unknown. Therefore, our study included 308 Joslin Kidney Study subjects who had T1D of long duration (median: 24 years), maintained normal renal function and had either normoalbuminuria or a broad range of albuminuria within the 2 years preceding the metabolomic determinations. Serum samples were subjected to global metabolomic profiling. 352 metabolites were detected in at least 80% of the study population. In the logistic analyses adjusted for multiple testing (Bonferroni corrected α = 0.000028), we identified 38 metabolites associated with persistent normoalbuminuria independently from clinical covariates. Protective metabolites were enriched in Medium Chain Fatty Acids (MCFAs) and in Short Chain Fatty Acids (SCFAs) and particularly involved odd-numbered and dicarboxylate Fatty Acids. One quartile change of nonanoate, the top protective MCFA, was associated with high odds of having persistent normoalbuminuria (OR (95% CI) 0.14 (0.09, 0.23); p < 10-12). Multivariable Random Forest analysis concordantly indicated to MCFAs as effective classifiers. Associations of the relevant Fatty Acids with albuminuria seemed to parallel associations with tubular biomarkers. Our findings suggest that MCFAs and SCFAs contribute to the metabolic processes underlying protection against albuminuria development in T1D that are independent from mechanisms associated with changes in renal function.

The mitochondrial-derived peptide MOTS-c is a regulator of plasma metabolites and enhances insulin sensitivity

MOTS‐c is an exercise mimetic and improves insulin sensitivity in aged and diet‐induced obese mice. Although plasma markers are good markers for the metabolic condition, whether MOTS‐c changes plasma markers in diet‐induced obese mice has not been examined. Here, we used an unbiased metabolomics approach to examine the effect of MOTS‐c on plasma markers of metabolic dysfunction. We found that three pathways – sphingolipid metabolism, monoacylglycerol metabolism, and dicarboxylate metabolism – were reduced in MOTS‐c–injected mice. Interestingly, these pathways are upregulated in obese and T2D models. MOTS‐c improves insulin sensitivity and increases beta‐oxidation to prevent fat accumulation in DIO mice through these pathways. These results provide us a better understanding of the mechanism of how MOTS‐c improves insulin sensitivity and reduces the body weight and fatty liver and opens a new venue for further study.

Composition of Royal Jelly (RJ) and Its Anti-Androgenic Effect on Reproductive Parameters in a Polycystic Ovarian Syndrome (PCOS) Animal Model

Royal jelly (RJ) has been shown to contribute its positive effects upon imbalance in the reproductive system. However, it remains unknown as to whether RJ has an anti-androgenic effect on reproductive parameters in a polycystic ovarian syndrome (PCOS) animal model. Composition of RJ was assessed by phytochemical screening and the LC–MS method. Forty immature female rats (3 weeks, 40–50 g) were randomly divided into five groups (n = 8 per group), i.e., control, testosterone (T), T+100RJ (100 mg/kg/day), T+200RJ (200 mg/kg/day RJ), and T+400RJ (400 mg/kg/day RJ) groups. Hyperandrogenism was induced by daily subcutaneous injection of T propionate for 3 weeks, followed by oral RJ for 4 weeks. The T+200RJ group had a significantly higher follicle-stimulating hormone level, and significantly lower luteinizing hormone, testosterone, and estradiol levels in comparison to the T group. Malondialdehyde level and glutathione peroxidase activity were significantly lower, while total antioxidant capacity level was significantly higher in the T+200RJ group compared to the T group. Histologically, the T+200RJ group showed recovery of various stages of ovarian follicular development. RJ at 200 mg/kg/day for 4 weeks significantly improved reproductive parameters in PCOS rats partly due to its anti-androgenic effect through antioxidant action and probably due to modulation on estrogenic activity, which needs further study to evaluate its exact mechanism of action.

Extending Classification Algorithms to Case-Control Studies

Classification is a common technique applied to 'omics data to build predictive models and identify potential markers of biomedical outcomes. Despite the prevalence of case-control studies, the number of classification methods available to analyze data generated by such studies is extremely limited. Conditional logistic regression is the most commonly used technique, but the associated modeling assumptions limit its ability to identify a large class of sufficiently complicated 'omic signatures. We propose a data preprocessing step which generalizes and makes any linear or nonlinear classification algorithm, even those typically not appropriate for matched design data, available to be used to model case-control data and identify relevant biomarkers in these study designs. We demonstrate on simulated case-control data that both the classification and variable selection accuracy of each method is improved after applying this processing step and that the proposed methods are comparable to or outperform existing variable selection methods. Finally, we demonstrate the impact of conditional classification algorithms on a large cohort study of children with islet autoimmunity.

Effectiveness of royal jelly supplementation in glycemic regulation: A systematic review

BACKGROUND

Royal jelly (RJ) has been observed to have therapeutic properties in diabetic individuals, including the reduction of high blood sugar. This systematic review synthesized existing evidence to investigate the effectiveness of RJ supplementation in managing measures of blood glucose.

AIM

To determine the effectiveness of RJ supplementation on glycemic responses in healthy and non-insulin dependent diabetic adults, as well as animal models of diabetes.

METHODS

This was a systematic review employing the PRISMA strategy. Peer-reviewed, published articles were extracted from several databases using key words related to target population, intervention and outcome and hand-selected for inclusion. Included articles proceeded to data extraction phase, where information on target parameters and effectiveness of treatment was summarized. Following this, the risk of bias for each included study was evaluated. Then, the long-term and immediate effectiveness of RJ supplementation in glycemic control were assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) tool, which rates the quality of evidence.

RESULTS

Of 168 articles extracted from database searching, eighteen were included for analysis in this systematic review. Across the studies, studied populations, intervention styles and outcome measures were largely heterogeneous. Despite this, the results in studies indicate a general trend of positive effect of RJ in glycemic regulation in vitro and in vivo. Additionally, some dose-dependent glycemic effects were observed, along with some large effect sizes. The risk of bias for human and animal studies is generally low-unclear risk, although lack of blinding is a serious concern in both categories. Overall, as per the GRADE tool, the quality of evidence is low, and very low for long-term and immediate effectiveness of RJ, respectively. A major limitation affecting evidence quality is the heterogeneity among included studies. Fasting blood glucose and glucose clearance appear to be most affected by RJ supplementation.

CONCLUSION

Quality of evidence suggesting that RJ is an effective modulator of glycemic regulation is low for long-term effects of RJ, and very low for immediate effects.

Metabolism and pharmacokinetics of medium chain fatty acids after oral administration of royal jelly to healthy subjects

The unique fatty acids in royal jelly (RJ), 10-hydroxy-2-decenoic acid and 10-hydroxydecanoic acid are expected to be associated with many health benefits, but little is known on the pharmacokinetics and metabolism. The aim of this study is to confirm the metabolism and pharmacokinetics of RJ fatty acids in humans. Twelve volunteers received RJ capsules or enzyme treated RJ (ETRJ) capsules (800 mg). The other group received two doses of ETRJ tablets (800 mg and 1600 mg). Plasma samples were collected up to 12 h after the RJ intake and urine samples were collected within 24 h after ETRJ tablet consumption. The samples were analyzed by LC/MS/MS. A multivariate analysis of the RJ dose plasma samples detected 2-decenedioic acid (2-DA), sebacic acid (SA), and 3-hydroxysebacic acid (3-HSA) with significantly different intensities (P < 0.05) before and after RJ intake. The area under the concentration (AUC) of 2-DA, SA, and 3-HSA was 2500.05 ± 569.58, 322.57 ± 137.36, and 242.98 ± 58.36 ng h mL⁻¹, respectively. By enzyme treatment, the AUC of 2-DA, SA, and 3-HSA was significantly increased (P < 0.05). The values of AUC and urinary excretion of these metabolites were dose-dependent. The major RJ fatty acids were metabolized to dicarboxylate, absorbed into the circulation and their absorption increased by enzyme treatment. This study provides useful information that will support studies aimed at clarifying the identity of bioactive RJ constituents and their biological effect, and further the development of RJ.

The royal jelly fatty acids were metabolized to dicarboxylic acids, absorbed into the circulation and then excreted in the urine.

Toxicology of the aqueous extract from the flowers of Butea monosperma Lam. and it's metabolomics in yeast cells

Due to lack of scientific evidence for the safety of Butea monosperma (Fabaceae), our study aimed to carry out its toxicological profile and to identify its metabolic pattern in yeast cell. The effect of aqueous extract of B. monosperma flower on glucose uptake in yeast cell was evaluated through optimizing pH, temperature, incubation time, substrate concentration and kinetic parameters. Further, the metabolic pattern of extract as such and in yeast cell were analyzed by gas chromatography-mass spectrometry. Mice were administered aqueous extract up to 6000 and 4000 mg/kg for acute oral and intraperitoneal toxicity, respectively, while up to 4500 mg/kg for sub-acute oral toxicity (30 days). Elongation in the lag and log phase was observed in yeast cells supplemented with extract as compared to control. A maximum of 184.9% glucose uptake was observed whereas kinetic parameters (K_m and V_max) were 1.38 and 41.91 mol/s, respectively. Out of 75 metabolites found in the extract, 14 and 18 metabolites were utilized by yeast cell after 15 and 30 min of incubation, respectively. The LD₅₀ of extract administered through intraperitoneal route was estimated to be 3500 mg/kg. The extract did not elicit any significant difference (P ≥ 0.05) in weight gain, food consumption, water intake, hematological, biochemical parameters and histological changes as compared to the normal control. Results ascertained the safety of B. monosperma flower extract which can be explored as potential candidates for the development of anti-diabetic phytopharmaceuticals.

Mutations in the Na(+)/citrate cotransporter NaCT (SLC13A5) in pediatric patients with epilepsy and developmental delay

Mutations in the SLC13A5 gene that codes for the Na(+)/citrate cotransporter, NaCT, are associated with early onset epilepsy, developmental delay and tooth dysplasia in children. In the present study we identify additional SLC13A5 mutations in nine epilepsy patients from six families. To better characterize the syndrome, families with affected children answered questions about the scope of illness and treatment strategies. There are currently no effective treatments, but some anti-epileptic drugs targeting the GABA system reduce seizure frequency. Acetazolamide, a carbonic anhydrase inhibitor and atypical anti-seizure medication decreases seizures in 4 patients. In contrast to previous reports, the ketogenic diet and fasting produce worsening of symptoms. The effects of the mutations on NaCT transport function and protein expression were examined by transient transfections of COS-7 cells. There was no transport activity from any of the mutant transporters, although some of the mutant transporter proteins were present on the plasma membrane. The structural model of NaCT suggests that these mutations can affect helix packing or substrate binding. We tested various treatments, including chemical chaperones and low temperatures, but none improve transport function in the NaCT mutants. Interestingly, coexpression of NaCT and the mutants results in decreased protein expression and activity of the wild-type transporter, indicating functional interaction. In conclusion, our study has identified additional SLC13A5 mutations in patients with chronic epilepsy starting in the neonatal period, with the mutations producing inactive Na(+)/citrate transporters.

Antimicrobial activity of untypical lipid compounds in the cuticular and internal lipids of four fly species

AIMS

This article describes the qualitative and quantitative analyses of untypical compounds in the cuticular and internal lipids of four dipteran species. For isolated compounds, antimicrobial activity against 18 reference strains of bacteria and fungi was determined.

METHODS AND RESULTS

In this study, gas chromatography (GC) combined with mass spectrometry (GC-MS) was used to analyse the surface and internal compounds of four fly species. Seven untypical compounds from both pre-imaginal and imaginal stages of examined insects were identified. Azelaic acid (AA) was the most abundant, while phenylacetic and phenylpropionic acids occurred in lower concentration. Minor quantities of sebacic acid, 2-methyl-2-hydroxybutanoic acid, tocopherol acetate and trace amounts of 2,4-decadienal were also detected. Tocopherol acetate was found only in cuticular lipids of Musca domestica larvae. Each compound was tested against several species of fungi and bacteria by determining minimal inhibitory concentration (MIC). Human pathogenic fungi were also investigated. Phenylpropionic acid showed the greatest antifungal activity. Bacterial strains were insensitive to the presence of identified compounds, apart from 2,4-decadienal which strongly inhibited bacterial growth.

CONCLUSIONS

This is the first time that the chemical composition and the antimicrobial activity of untypical compounds in the cuticular and internal lipids of four fly species has been analysed.

SIGNIFICANCE AND IMPACT OF THE STUDY

Determination of untypical compounds and their antimicrobial activity can effectively contribute to the knowledge concerning insect defence mechanisms.

Use of dicarboxylic acids in type 2 diabetes

Even-number, medium-chain dicarboxylic acids (DAs), naturally occurring in higher plants, are a promising alternative energy substrate. Unlike the homologous fatty acids, DAs are soluble in water as salts. They are β-oxidized, providing acetyl-CoA and succinyl-CoA, the latter being an intermediate of the tricarboxylic acid cycle. Sebacic acid and dodecanedioic acid, DAs with 10 and 12 carbon atoms respectively, provide 6.6 and 7.2 kcal g⁻¹ each; therefore, their energy density is intermediate between glucose and fatty acids. Dicarboxylic acids have been proved to be safe in both experimental animals and humans, and their use has recently been proposed in diabetes. Studies in animals and humans with type 2 diabetes showed that oral administration of sebacic acid improved glycaemic control, probably by enhancing insulin sensitivity, and reduced hepatic gluconeogenesis and glucose output. Moreover, dodecanedioic acid intake reduced muscle fatigue during exercise in subjects with type 2 diabetes, suggesting an improvement of energy utilization and 'metabolic flexibility'. In this article, we review the natural sources of DAs, their fate in animals and humans and their effect in improving glucose metabolism in type 2 diabetes.

Six weeks' sebacic acid supplementation improves fasting plasma glucose, HbA1c and glucose tolerance in db/db mice

AIM

To investigate the impact of chronic ingestion of sebacic acid (SA), a 10-carbon medium-chain dicarboxylic acid, on glycaemic control in a mouse model of type 2 diabetes (T2D).

METHODS

Three groups of 15 db/db mice were fed for 6 weeks either a chow diet (Ctrl) or a chow diet supplemented with 1.5 or 15% (SA(1.5%) and SA(15%) , respectively) energy from SA. Fasting glycaemia was measured once a week and HbA1c before and after supplementation. An oral glucose tolerance test (OGTT) was performed at the end of the supplementation. Gene expression was determined by transcriptomic analysis on the liver of the Ctrl and SA(15%) groups.

RESULTS

After 42 days of supplementation, fasting glycaemia and HbA1c were ∼70 and 25% lower in the SA(15%) group compared with the other groups showing a beneficial effect of SA on hyperglycaemia. During OGTT, plasma glucose area under the curve was reduced after SA(15%) compared with the other groups. This effect was associated with a tendency for an improved insulin response. In the liver, Pck1 and FBP mRNA were statistically decreased in the SA(15%) compared with Ctrl suggesting a reduced hepatic glucose output induced by SA.

CONCLUSION

Dietary supplementation of SA largely improves glycaemic control in a mouse model of T2D. This beneficial effect may be due to (i) an improved glucose-induced insulin secretion and (ii) a reduced hepatic glucose output.