Rotundic Acid Protects against Metabolic Disturbance and Improves Gut Microbiota in Type 2 Diabetes Rats

The synergism of Lactobacillaceae, inulin, polyglucose, and aerobic exercise ameliorates hyperglycemia by modulating the gut microbiota community and the metabolic profiles in db/db mice

This study aimed to assess the impact of Lactobacillaceae (L or H represents a low or high dose), inulin (I), and polydextrose (P) combined with aerobic exercise (A) on the composition of the gut microbiota and metabolic profiles in db/db mice. After a 12-week intervention, LIP, LIPA, and HIPA groups exhibited significant improvements in hyperglycemia, glucose tolerance, insulin resistance, inflammatory response, and short-chain fatty acid (SCFA) and blood lipid levels compared to type 2 diabetes mice (MC). After treatment, the gut microbiota composition shifted favorably in the treatment groups which significantly increased the abundance of beneficial bacteria, such as Bacteroides, Blautia, Akkermansia, and Faecalibaculum, and significantly decreased the abundance of Proteus. Metabolomics analysis showed that compared to the MC group, the contents of 5-hydroxyindoleacetic acid, 3-hydroxysebacic acid, adenosine monophosphate (AMP), xanthine and hypoxanthine were significantly decreased, while 3-ketosphinganine, sphinganine, and sphingosine were significantly increased in the LIP and LIPA groups, respectively. Additionally, LIP and LIPA not only improved sphingolipid metabolism and purine metabolism pathways but also activated AMP-activated protein kinase to promote β-oxidation by increasing the levels of SCFAs. Faecalibaculum, Blautia, Bacteroides, and Akkermansia exhibited positive correlations with sphingosine, 3-ketosphinganine, and sphinganine, and exhibited negative correlations with hypoxanthine, xanthine and AMP. Faecalibaculum, Blautia, Bacteroides, and Akkermansia may have the potential to improve sphingolipid metabolism and purine metabolism pathways. These findings suggest that the synergism of Lactobacillaceae, inulin, polydextrose, and aerobic exercise provides a promising strategy for the prevention and management of type 2 diabetes.

Rotundic acid improves nonalcoholic steatohepatitis in mice by regulating glycolysis and the TLR4/AP1 signaling pathway

BACKGROUND

Steatosis and inflammation are the hallmarks of nonalcoholic steatohepatitis (NASH). Rotundic acid (RA) is among the key triterpenes of Ilicis Rotundae Cortex and has exhibited multipronged effects in terms of lowering the lipid content and alleviating inflammation. The study objective is to systematically evaluate the potential mechanisms through which RA affects the development and progression of NASH.

METHODS

Transcriptomic and proteomic analyses of primary hepatocytes isolated from the control, high-fat diet-induced NASH, and RA treatment groups were performed through Gene Ontology analysis and pathway enrichment. Hub genes were identified through network analysis. Integrative analysis revealed key RA-regulated pathways, which were verified by gene and protein expression studies and cell assays.

RESULTS

Hub genes were identified and enriched in the Toll-like receptor 4 (TLR4)/activator protein-1 (AP1) signaling pathway and glycolysis pathway. RA reversed glycolysis and attenuated the TLR4/AP1 pathway, thereby reducing lipid accumulation and inflammation. Additionally, lactate release in L-02 cells increased with NaAsO2-treated and significantly decreased with RA treatment, thus revealing that RA had a major impact on glycolysis.

CONCLUSIONS

RA is effective in lowering the lipid content and reducing inflammation in mice with NASH by ameliorating glycolysis and TLR4/AP1 pathways, which contributes to the existing knowledge and potentially sheds light on the development of therapeutic interventions for patients with NASH.

Palmitoylethanolamide counteracts high-fat diet-induced gut dysfunction by reprogramming microbiota composition and affecting tryptophan metabolism

Obesity is associated with gastrointestinal (GI) tract and central nervous system (CNS) disorders. High-fat diet (HFD) feeding-induced obesity in mice induces dysbiosis, causing a shift toward bacteria-derived metabolites with detrimental effects on metabolism and inflammation: events often contributing to the onset and progression of both GI and CNS disorders. Palmitoylethanolamide (PEA) is an endogenous lipid mediator with beneficial effects in mouse models of GI and CNS disorders. However, the mechanisms underlining its enteroprotective and neuroprotective effects still need to be fully understood. Here, we aimed to study the effects of PEA on intestinal inflammation and microbiota alterations resulting from lipid overnutrition. Ultramicronized PEA (30 mg/kg/die per os) was administered to HFD-fed mice for 7 weeks starting at the 12th week of HFD regimen. At the termination of the study, the effects of PEA on inflammatory factors and cells, gut microbial features and tryptophan (TRP)-kynurenine metabolism were evaluated. PEA regulates the crosstalk between the host immune system and gut microbiota via rebalancing colonic TRP metabolites. PEA treatment reduced intestinal immune cell recruitment, inflammatory response triggered by HFD feeding, and corticotropin-releasing hormone levels. In particular, PEA modulated HFD-altered TRP metabolism in the colon, rebalancing serotonin (5-HT) turnover and reducing kynurenine levels. These effects were associated with a reshaping of gut microbiota composition through increased butyrate-promoting/producing bacteria, such as Bifidobacterium, Oscillospiraceae and Turicibacter sanguinis, with the latter also described as 5-HT sensor. These data indicate that the rebuilding of gut microbiota following PEA supplementation promotes host 5-HT biosynthesis, which is crucial in regulating intestinal function.

A comprehensive review of the novel therapeutic targets for the treatment of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is characterized by structural and functional abnormalities in the myocardium affecting people with diabetes. Treatment of DCM focuses on glucose control, blood pressure management, lipid-lowering, and lifestyle changes. Due to limited therapeutic options, DCM remains a significant cause of morbidity and mortality in patients with diabetes, thus emphasizing the need to develop new therapeutic strategies. Ongoing research is aimed at understanding the underlying molecular mechanism(s) involved in the development and progression of DCM, including oxidative stress, inflammation, and metabolic dysregulation. The goal is to develope innovative pharmaceutical therapeutics, offering significant improvements in the clinical management of DCM. Some of these approaches include the effective targeting of impaired insulin signaling, cardiac stiffness, glucotoxicity, lipotoxicity, inflammation, oxidative stress, cardiac hypertrophy, and fibrosis. This review focuses on the latest developments in understanding the underlying causes of DCM and the therapeutic landscape of DCM treatment.

A systematic review: Botany, phytochemistry, traditional uses, pharmacology, toxicology, quality control and pharmacokinetics of Ilex rotunda Thunb

ETHNOPHARMACOLOGICAL RELEVANCE

Ilex rotunda Thunb. (I. rotunda) is an Ilex species of Aquifoliaceae, widely distributed in East Asia. Its dried bark is commonly used as a medicinal part in the field of traditional Chinese medicine (TCM), named Ilicis Rotundae Cortex. This medicinal plant is commonly used for clearing heat and removing toxin, draining dampness and relieving pain in TCM to treat tonsillitis, acute gastroenteritis, gastric and duodenal ulcer, rheumatism, traumatic injury, and so on. It also has significant development value on lipid-lowering, hepatoprotection and anti-inflammation, but the potential mechanism needs to be further explored.

AIM OF THE REVIEW

More and more medicinal substances are being discovered in I. rotunda with multiple biological activities, which help to advance the ethno-pharmacological research in I. rotunda. However, to date there is a lack of a systematic summary of research progress on I. rotunda. This review aims to provide a critical summary of the current studies on I. rotunda. The progress in research on botany, phytochemistry, traditional uses, pharmacology, toxicology, quality control and pharmacokinetics of the plant is discussed. It hopes to provide useful references and guidance for the future directions of research on I. rotunda.

MATERIALS AND METHODS

Studies of I. rotunda were collected via Google Scholar and Baidu Scholar, PubMed, ScienceDirect, SciFinder, Web of Science, China National Knowledge Infrastructure (CNKI), WANFANG DATA and libraries. Some local books, official websites, PhD or MS's dissertations were also included. The literature cited in this review covered the period from 1956 to January 2022.

RESULTS

Analysis of the literature indicates that I. rotunda is a potentially valuable herbal medicine for the therapeutic of various diseases. To date, 120 compounds were found and identified in I. rotunda, mainly including triterpenoids, phenylpropanoids, etc. Modern pharmacological studies also found that the plant has the activities of protecting the cardiovascular system, lowering lipids and protecting the liver, as well as being an anti-inflammatory, anti-tumor and antibacterial.

CONCLUSIONS

This review summarizes the results from current studies of I. rotunda. However, the current explanation seems insufficient and unsatisfactory, in terms of the relationships between the traditional uses and the modern pharmacological activities, the mechanisms and the material basis. Thus, a critical and comprehensive evaluation is necessary to explore its future research prospects and development direction.

Chalcone-1-Deoxynojirimycin Heterozygote Reduced the Blood Glucose Concentration and Alleviated the Adverse Symptoms and Intestinal Flora Disorder of Diabetes Mellitus Rats

Chalcone-1-deoxynojirimycin heterozygote (DC-5), a novel compound which was designed and synthesized in our laboratory for diabetes treatment, showed an extremely strong in vitro inhibitory activity on α-glucosidase in our previous studies. In the current research, its potential in vivo anti-diabetic effects were further investigated by integration detection and the analysis of blood glucose concentration, blood biochemical parameters, tissue section and gut microbiota of the diabetic rats. The results indicated that oral administration of DC-5 significantly reduced the fasting blood glucose and postprandial blood glucose, both in diabetic and normal rats; meanwhile, it alleviated the adverse symptoms of elevated blood lipid level and lipid metabolism disorder in diabetic rats. Furthermore, DC-5 effectively decreased the organ coefficient and alleviated the pathological changes of the liver, kidney and small intestine of the diabetic rats at the same time. Moreover, the results of 16S rDNA gene sequencing analysis suggested that DC-5 significantly increased the ratio of Firmicutes to Bacteroidetes and improved the disorder of gut microbiota in diabetic rats. In conclusion, DC-5 displayed a good therapeutic effect on the diabetic rats, and therefore had a good application prospect in hypoglycemic drugs and foods.

Preclinical Studies of Natural Products Targeting the Gut Microbiota: Beneficial Effects on Diabetes

Diabetes mellitus (DM) is a serious metabolic disease characterized by persistent hyperglycemia, with a continuously increasing morbidity and mortality. Although traditional treatments including insulin and oral hypoglycemic drugs maintain blood glucose levels within the normal range to a certain extent, there is an urgent need to develop new drugs that can effectively improve glucose metabolism and diabetes-related complications. Notably, accumulated evidence implicates that the gut microbiota is unbalanced in DM individuals and is involved in the physiological and pathological processes of this metabolic disease. In this review, we introduce the molecular mechanisms by which the gut microbiota contributes to the development of DM. Furthermore, we summarize the preclinical studies of bioactive natural products that exert antidiabetic effects by modulating the gut microbiota, aiming to expand the novel therapeutic strategies for DM prevention and management.

Intestinal absorption mechanism of rotundic acid: Involvement of P-gp and OATP2B1

ETHNOPHARMACOLOGICAL RELEVANCE

Ilicis Rotundae Cortex (IRC), the dried barks of Ilex rotunda Thunb. (Aquifoliaceae), has been used for the prevention or treatment of colds, tonsillitis, dysentery, and gastrointestinal diseases in folk medicine due to its antibacterial and anti-inflammatory effects. However, there is no report about the intestinal absorption of major compounds that support traditional usage.

AIM OF STUDY

Considering the potential of rotundic acid (RA) - major biologically active pentacyclic triterpenes found in the IRC, this study was purposed to uncover the oral absorption mechanism of RA using in situ single-pass intestinal perfusion (SPIP) model, in vitro cell models (Caco-2, MDCKII-WT, MDCKII-MDR1, MDCKII-BCRP, and HEK293-OATP2B1 cells) and in vivo pharmacokinetics studies in rats.

MATERIALS AND METHODS

The molecular properties (solubility, lipophilicity, and chemical stability) and the effects of principal parameters (time, compound concentrations, pH, paracellular pathway, and the different intestinal segments) were analyzed by liquid chromatography-tandem mass spectrometry. The susceptibility of RA to various inhibitors, such as P-gp inhibitor verapamil, BCRP inhibitor Ko143, OATP 2B1 inhibitor rifampicin, and absorption enhancer EGTA were assessed.

RESULTS

RA was a compound with low water solubility (12.89 μg/mL) and strong lipophilicity (LogP = 4.1). RA was considered stable in all media during the SPIP and transport studies. The SPIP and cell experiments showed RA was moderate absorbed in the intestines and exhibited time, concentration, pH, and segment-dependent permeability. In addition, results from the cell model, in situ SPIP model as well as the in vivo pharmacokinetics studies consistently showed that verapamil, rifampicin, and EGTA might have significant effect on the intestinal absorption of RA.

CONCLUSION

The mechanisms of intestinal absorption of RA might involve multiple transport pathways, including passive diffusion, the participation of efflux (i.e., P-gp) and influx (i.e., OATP2B1) transporters, and paracellular pathways.

Understanding the mechanism underlying the anti-diabetic effect of dietary component: a focus on gut microbiota

Diabetes has become one of the biggest non-communicable diseases and threatens human health worldwide. The management of diabetes is a complex and multifaceted process including drug therapy and lifestyle interventions. Dietary components are essential for both diabetes management and health and survival of trillions of the gut microbiota (GM). Herein, we will discuss the relationship between diets and GM, the mechanism linking diabetes and gut dysbiosis, and the effects of dietary components (nutrients, phytochemicals, probiotics, food additives, etc.) on diabetes from the perspective of modulating GM. The GM of diabetic patients differs from that of health individuals and GM disorder contributes to the onset and maintenance of diabetes. Studies in humans and animal models consolidate that dietary component is a key regulator of diabetes and increasing evidence suggests that the alteration of GM plays a salient role in dietary interventions for diabetes. Given that diabetes is a major public health issue, especially that diabetes is linked with a high risk of mortality from COVID-19, this review provides compelling evidence for that targeting GM by dietary components is a promising strategy, and offers new insights into potential preventive or therapeutic approaches (dietary and pharmacological intervention) for the clinical management of diabetes.

Diaphragma juglandis extracts modifies the gut microbiota during prevention of type 2 diabetes in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The diaphragma juglandis (DJ) comes from the wooden septum in the core of Juglans regia L, also known as the walnut septum. In Iranian traditional medicine, walnut distraction wood was widely used in the treatment of diabetes. However, there is a lack of research data on the mechanism of DJ against diabetes.

AIM OF THE STUDY

To explore the protective effect of diaphragma juglandis extract (DJE) on type 2 diabetic rats and the hypoglycemic mechanism of DJE.

MATERIAL AND METHODS

Supplemented DJE and fed a high-fat diet for five weeks, and then injected low-dose STZ, successfully induced type 2 diabetic rats. Collected rat serum, liver, pancreas and feces to determine the biochemical parameters of serum and liver, analyze the pathological damages of pancreas and liver, and measure the changes of gut microbes in feces.

RESULTS

DJE could inhibit the metabolic abnormalities of T2DM by improving insulin resistance, abnormal lipid metabolism, liver damage, oxidative stress, and reducing inflammation. DJE significantly held fasting blood glucose, glycosylated serum protein, serum low density lipoprotein, high density lipoprotein, oral glucose tolerance test, nitric oxide, superoxide dismutase and catalase, serum and liver triglycerides, total cholesterol, aspartate aminotransferase, alanine aminotransferase, malondialdehyde, lipopolysaccharide, fasting insulin and tumor necrosis factor-α and prevented the pathological damage of pancreas and liver. The 16SrRNA gene sequencing results showed that DJE intercepted the disorders of the fecal gut microbes, mainly including Lactobacillaceae, Rikenella, Pygmaiobacter, Oscillospiraceae and Klebsiella. Spearman correlation analysis showed that the changes of gut microbes were closely relative with biochemical parameters.

CONCLUSION

DJE might prevent type 2 diabetes and its complications and hold up the disorders of gut microbes.

White common bean extract remodels the gut microbiota and ameliorates type 2 diabetes and its complications: A randomized double-blinded placebo-controlled trial

OBJECTIVE

Excessive carbohydrate intake is a high risk factor for increased morbidity of type 2 diabetes (T2D). A novel regimen for the dietary care of diabetes that consists of a highly active α-amylase inhibitor derived from white common bean extract (WCBE) and sufficient carbohydrates intake was applied to attenuate T2D and its complications. Furthermore, the role of gut microbiota in this remission was also investigated.

METHODS

We conducted a 4-month randomized double-blinded placebo-controlled trial. During the intense intervention period, ninety subjects were randomly assigned to the control group (Group C) and WCBE group (Group W). Subjects in Group C were supplemented with 1.5 g of maltodextrin as a placebo. Subjects in Group W took 1.5 g of WCBE half an hour before a meal. Fifty-five participants continued the maintenance intervention receiving the previous dietary intervention whereas less frequent follow-up. The variation in biochemical, vasculopathy and neuropathy indicators and the structure of the fecal microbiota during the intervention was analyzed.

RESULT

Glucose metabolism and diabetic complications showed superior remission in Group W with a 0.721 ± 0.742% decline of glycosylated hemoglobin after 4 months. The proportion of patients with diabetic peripheral neuropathy (Toronto Clinical Scoring System, TCSS ≥ 6) was significantly lower in Group W than in Group C. Both the left and right sural sensory nerve conduction velocity (SNCV-left sural and SNCV-right sural) slightly decreased in Group C and slightly increased in Group W. Additionally, the abundances of Bifidobacterium, Faecalibacterium and Anaerostipes were higher in Group W, and the abundances of Weissella, Klebsiella, Cronobacter and Enterobacteriaceae_unclassified were lower than those in Group C at month 2. At the end of month 4, Bifidobacterium remained more abundant in Group W.

CONCLUSION

To our knowledge, this is the first report of improvement to diabetes complications by using a dietary supplement in such a short-term period. The enrichment of SCFA-producing bacteria might be responsible for the attenuation of T2D and its complications.

CLINICAL TRIAL REGISTRATION NUMBER

http://www.chictr.org.cn/edit.aspx?pid=23309&htm=4, identifier ChiCTR-IOR-17013656.

Fermented noni (Morinda citrifolia L.) fruit juice improved oxidative stress and insulin resistance under the synergistic effect of Nrf2/ARE pathway and gut flora in db/db mice and HepG2 cells

Oxidative stress interferes with blood glucose homeostasis, leading to insulin resistance (IR) and hyperglycemia, which eventually induces type 2 diabetes (T2DM). Fermented noni (Morinda citrifolia L.) fruit juice (FNJ) is...

Influence of verapamil on the pharmacokinetics of rotundic acid in rats and its potential mechanism

CONTEXT

Rotundic acid (RA), a plant-derived pentacyclic triterpene acid, has been reported to possess extensive pharmacological activities. The poor bioavailability limits its further development and potential clinic application.

OBJECTIVE

To clarify the potential mechanism for poor oral bioavailability.

MATERIALS AND METHODS

The single-dose pharmacokinetics of orally administered RA (10 mg/kg) in Sprague-Dawley rats without or with verapamil (25 or 50 mg/kg) were investigated. Additionally, MDCKII-MDR1 and Caco-2 cell monolayers, five recombinant human cytochrome P450 (rhCYP) enzymes (1A2, 2C8, 2C9, 2D6 and 3A4), and rat liver microsomes were also conducted to investigate its potential mechanism.

RESULTS

Verapamil could significantly affect the plasma concentration of RA. Co-administered verapamil at 25 and 50 mg/kg, the AUC_0-∞ increased from 432 ± 64.2 to 539 ± 53.6 and 836 ± 116 ng × h/mL, respectively, and the oral clearance decreased from 23.6 ± 3.50 to 18.7 ± 1.85 and 12.2 ± 1.85 L/h/kg, respectively. The MDCKII-MDR1 cell assay showed that RA might be a P-gp substrate. The rhCYPs experiments indicated that RA was mainly metabolized by CYP3A4. Additionally, verapamil could increase the absorption of RA by inhibiting the activity of P-gp, and slow down the intrinsic clearance of RA from 48.5 ± 3.18 to 12.0 ± 1.06 µL/min/mg protein.

DISCUSSION AND CONCLUSIONS

These findings indicated that verapamil could significantly affect the pharmacokinetic profiles of RA in rats. It was demonstrated that P-gp and CYP3A were involved in the transport and metabolism of RA, which might contribute to the low oral bioavailability of RA.

Gut microbiota as a potential target for developing anti-fatigue foods

Fatigue has many negative effects on human health. As such, it is desirable to develop anti-fatigue foods and understand the mechanisms of their action. Based on a comprehensive review of the literature, this article discusses the important roles of gut microbiota in fatigue and anti-fatigue. Studies have shown that an increase in pathogenic bacteria and a decrease in beneficial bacteria co-exist when fatigue is present in both rodents and humans, whereas changes in gut microbiota were reported after intervention with anti-fatigue foods. The roles of gut microbiota in the activities of anti-fatigue foods can also be explained in the causes and the effects of fatigue. Among the causes of fatigue, the accumulation of lactic acid, decrease of energy, and reduction of central nervous system function were related to gut microbiota metabolism. Among the harmful effects of fatigue, oxidative stress, inflammation, and intestinal barrier dysfunction were related to gut microbiota dysbiosis. Furthermore, gut microbiota, together with anti-fatigue foods, can inhibit pathogen growth, convert foods into highly anti-oxidative or anti-inflammatory products, produce short-chain fatty acids, maintain intestinal barrier integrity, inhibit intestinal inflammation, and stimulate the production of neurotransmitters that regulate the central nervous system. Therefore, it is believed that gut microbiota play important roles in the activities of anti-fatigue foods and may provide new insights on the development of anti-fatigue foods.

Rotundic acid ameliorates non-alcoholic steatohepatitis via SREBP-1c/ SCD1 signaling pathway and modulating gut microbiota

Non-alcoholic steatohepatitis (NASH) is a devastating form of non-alcoholic fatty liver disease (NAFLD) with distinguished hallmarks of steatosis and inflammation. Rotundic acid (RA) is a natural pentacyclic triterpene compound extracted from the bank of Ilex rotunda Thunb with a wide range of biological activities. The aim of the study is to evaluate the pharmacological effect and action mechanism of RA on NASH in vitro and in vivo. RA has weak lipid lowering ability in rat primary hepatocytes, significantly decreases serum LDL level, hepatic TG and TC levels and lipid droplets, reduces NAS compared with the NASH group, and alleviates hepatic inflammation. RA also enhances the recovery of intestinal bacterial community and intestinal-derived short-chain fatty acid caused by high food diet (HFD). Further investigation shows that RA protects against HFD-induced NASH via downregulating the expression of SREBP-1c/SCD1 signaling pathway and improving gut microbiota. These findings imply that RA might be helpful for the alleviation of NASH.

Analysis of jejunum microbiota of HFD/STZ diabetic rats

Currently, several studies propose that the dominant intestinal bacteria are core flora. Besides keeping the homeostasis of the intestinal environment, the intestinal microflora also plays a role in body metabolism, production of some vitamins, and control of barrier function. The study aimed to investigate the jejunum microbiota in diabetic rats as well as it's the relationship with Ceftriaxone sodium-mediated gut dysbiosis, diabetic parameters, and intestinal permeability. Thirty-two Wistar rats (Male) were enrolled and divided into four groups (A, B, C, and D; N = 8). Subsequently, T2DM was induced in C and D groups by HFD/STZ model and then gut dysbiosis in B and D groups via intragastric administration of Ceftriaxone sodium for two weeks. The food-water intake, body weight, fasting blood glucose, plasma insulin, HOMA-IR, intestinal permeability, and jejunum microbiota and it's histology were investigated. In this study, T2DM was associated with a significant decrease in the richness and diversity of jejunum microbiota, elevation in the intestinal permeability, and higher abundance of some opportunistic pathogens. Ceftriaxone sodium-induced gut dysbiosis declined food-water intake, damagedthe villi of jejunum tissue, increased intestinal permeability, and affected the diversity of jejunum microbiota. In diabetic rats, Ceftriaxone sodium-mediated gut dysbiosis also declined the abundance of someSCFAs bacteria and raised the abundant of some opportunistic bacteria such as Staphylococcus_sciuri. Interestingly, we found that several bacteria were negatively correlated with HOMA-IR, fasting blood glucose, body weight, and intestinal permeability. Overall, the study highlighted the jejunum microflora alterations in HFD/STZ diabetic rats and assessed the effect of Ceftriaxone sodium-induced gut dysbiosis on diabetic parameters, jejunum microbiota and histology, and intestinal permeability, which are of potential for further studies.

Absolute bioavailability, dose proportionality, and tissue distribution of rotundic acid in rats based on validated LC-QqQ-MS/MS method

Rotundic acid (RA), an ursane-type pentacyclic triterpene acid isolated from the dried barks of Ilex rotunda Thunb. (Aquifoliaceae), possesses diverse bioactivities. To further study its pharmacokinetics, a simple and sensitive liquid chromatography with triple quadrupole mass spectrometry (LC-QqQ-MS/MS) method was developed and validated to quantify RA concentration in rat plasma and tissue using etofesalamide as an internal standard (IS). Plasma and tissue samples were subjected to one-step protein precipitation. Chromatographic separation was achieved on a ZORBAX Eclipse XDB-C₁₈ column (4.6 mm × 50 mm, 5 μm) under gradient conditions with eluents of methanol:acetonitrile (1:1, V/V) and 5 mM ammonium formate:methanol (9:1, V/V) at 0.5 mL/min. Multiple reaction monitoring transitions were performed at m/z 487.30 → 437.30 for RA and m/z 256.10 → 227.10 for IS in the negative mode. The developed LC-QqQ-MS/MS method exhibited good linearity (2–500 ng/mL) and was fully validated in accordance with U.S. Food and Drug Administration bioanalytical guidelines. Dose proportionality and bioavailability in rats were determined by comparing pharmacokinetic data after single oral (10, 20, and 40 mg/kg) and intravenous (10 mg/kg) administration of RA. Tissue distribution was studied following oral administration at 20 mg/kg. The results showed that the absolute bioavailability of RA after administration at different doses ranged from 16.1% to 19.4%. RA showed good dose proportionality over a dose range of 10–40 mg/kg. RA was rapidly absorbed in a dose-dependent manner and highly distributed in the liver. In conclusion, this study is the first to systematically elucidate the absorption and distribution characteristics of RA in rats, which can provide additional information for further development and evaluation of RA in drug metabolism and pharmacokinetic studies.

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A simple, rapid, and sensitive LC-QqQ-MS/MS method was developed and validated for RA quantification in rat plasma and tissue.

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Absolute bioavailability of RA was calculated to range from 16.1% to 19.4%.

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Dose proportionality and tissue distribution of RA were assessed for in rats.

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RA showed good dose proportionality over a dose range of 10–40 mg/kg.

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RA was rapidly and extensively distributed and exhibited the highest concentration in the liver after oral administration.

Integrated metabolomics and gut microbiome to the effects and mechanisms of naoxintong capsule on type 2 diabetes in rats

Naoxintong Capsule (NXT) is a Traditional Chinese Medicine formulation which has been widely applied in treating cardiovascular and cerebrovascular diseases. Previous studies also reported the potential effects of NXT against diabetes and certain complications, yet its mechanisms remain largely obscured. Herein, in this study, we investigated the anti-diabetic effects of NXT as well as its potential mechanisms. Type 2 diabetes (T2D) was induced in rats by 10-week high-fat diet in companion with a low-dose streptozotocin injection. NXT was administrated for additional 8 weeks. The results showed that NXT exerted potent efficacy against T2D by alleviating hyperglycemia and hyperlipidemia, ameliorating insulin resistance, mitigating inflammation, relieving hypertension, and reducing myocardial injuries. To investigate its mechanisms, by integrating sequencing of gut microbiota and serum untargeted metabolomics, we showed that NXT could significantly recover the disturbances of gut microbiota and metabolic phenotypes in T2D rats. Several feature pathways, such as arachidonic acid metabolism, fatty acid β-oxidation and glycerophospholipid metabolism, were identified as the potential mechanisms of NXT in vivo. In summary, our study has comprehensively revealed the anti-diabetic effects of NXT which could be considered as a promising strategy for treating metabolic disorders, T2D and diabetic related complications in clinical practice.