Digestion and absorption of Siraitia grosvenori triterpenoids in the rat

Mogroside V prevents ethanol-induced hangover and liver damage by reducing oxidative stress, steatosis and inflammation

Excessive alcohol consumption is a leading cause of alcohol-associated liver disease (ALD). Previous studies presented Mogroside V (MV) have protective effects on against nonalcoholic fatty liver disease. however, the effects of MV on ethanol-induced hangover and liver damage remains to be elucidated. Herein, we investigated the potential effects of MV in relieving hangover and mitigating liver injury induced by ethanol. MV significantly reduced blood ethanol, liver histological alterations and serum ALT, AST、TG levels in ethanol-treated mice. Moreover, MV accelerates alcohol metabolism by inhibiting the upregulation of CYP2E1 induced by ethanol, while enhancing the activity of ADH and ALDH, as well as upregulating the expression of ADH1 and ALDH2. MV mitigates oxidative stress by decreased hepatic malondialdehyde (MDA) levels, restored glutathione (GSH)、superoxide dismutase (SOD) and catalase (CAT) content in ethanol-induced mice. Mechanistically, MV activated the p-AMPK/SREBP-1/FASN pathway to decreased hepatic lipid accumulation and alleviated steatosis. Additionally, MV promoted nuclear translocation of Nrf-2 to attenuates oxidative stress and suppressed TLR4/MyD88/NF-κB signaling pathway to reduce Inflammatory responses triggered by ethanol in mice. In summary, this study highlights mogroside V's hangover relieving effect and its protective effects against ethanol-related liver damage through its lipid metabolism regulation, antioxidative action and anti-inflammatory properties. These results suggest that mogroside V could be developed as a potential therapeutic agent against ethanol-induced liver damage.

Non-nutritive sweeteners in food-drug interactions: An overview of current evidence

Food-drug interactions occur when the presence of foods interferes with the absorption, distribution, metabolism, or excretion of pharmaceuticals. Specific compounds within foods, like certain phytochemicals from grapefruit, have been known to precipitate food-drug interactions for decades, leading to guidance from physicians and pharmacists about patients' dietary restrictions while taking certain drugs. Although approved by the Food and Drug Administration, high-intensity non-nutritive sweeteners (NNS) share qualities with drugs that suggest the potential for similar interactions. In this minireview, we have reviewed 5 of the most popular NNS, including saccharin, aspartame, acesulfame potassium, sucralose, and stevia, and detail their drug-like qualities, regulatory status, pharmacokinetics, and primary research articles containing evidence of NNS interacting with drug absorption, distribution, metabolism, and excretion. Although studies varied widely in concentration ranges for NNS, model systems, and methods, all NNS included in this review were found to have known interactions with mediators of absorption, distribution, metabolism, and excretion from studies conducted after their Food and Drug Administration approval or generally recognized as safe designation. We have highlighted essential gaps in the literature and recommend the scientific community actively research NNS as food additives that may interact with drugs. SIGNIFICANCE STATEMENT: Food-drug interactions are a growing concern in Western societies where polypharmacy and ultraprocessed foods and beverages are increasingly common. High-intensity non-nutritive sweeteners bear structural similarities to pharmaceuticals, and evidence suggests they interact with mediators of drug pharmacokinetics. This minireview highlights the interactions uncovered thus far and serves as a call to action for the scientific community to establish rigorous, consistent testing that will enable updated safety guidelines for consumers.

Mogroside V ameliorates astrocyte inflammation induced by cerebral ischemia through suppressing TLR4/TRADD pathway

Inflammation and oxidative stress are pivotal factors in the onset and progression of secondary injury following cerebral ischemia-reperfusion (I/R). Mogroside V (MV), a primary active compound of Siraitia grosvenorii, exhibits significant anti-inflammatory and antioxidant properties. However, its specific effects in cerebral ischemia remain unclear. In this study, we evaluated the neuroprotective effects of MV in a model of focal cerebral ischemia. Male C57BL/6J mice were subjected to middle cerebral artery occlusion/reperfusion (MCAO/R) as an in vivo model of cerebral ischemia-reperfusion injury (CIRI), while U87 cells were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to simulate CIRI in vitro. MV administration was found to reduce mortality, infarct volume, cerebral edema, and alleviate neurological deficits in these I/R mice. Furthermore, MV mitigated cerebral I/R injury by decreasing oxidative stress markers, such as reactive oxygen species (ROS) and malondialdehyde (MDA), while enhancing superoxide dismutase (SOD) levels. Gene Set Enrichment Analysis (GSEA) of the KEGG pathway revealed that most differentially expressed genes (DEGs) were involved in the Toll-like receptor/NF-κB/TNF/apoptosis signaling pathway. These findings were confirmed by real-time PCR, western blotting, immunohistochemistry, and immunofluorescence co-localization which demonstrated that MV reduced astrocyte inflammatory responses by inhibiting cytokine secretion associated with the TLR4/TRADD pathway. Additionally, MV protected neurons from apoptosis, as supported by TUNEL, Nissl, and HE staining. In conclusion, MV attenuates astrocyte inflammation and exerts neuroprotective effects following cerebral I/R injury, likely through suppression of the TLR4/TRADD signaling pathway.

The dynamic distribution patterns and lung targeting efficiency in rats of 9 bioactive components in Siraitia grosvenorii

ETHNOPHARMACOLOGICAL RELEVANCE

Siraitia grosvenorii (S. grosvenorii) is a traditional herbal medicine employed for the prevention of lung diseases. Mogrosides and flavonoids are postulated to be the principal active components. Nevertheless, the dynamic distribution of its active components in vivo and the amount of accumulation in the lung target tissue remain indistinct.

AIM OF THE STUDY

This study investigates the dynamic distribution patterns of 9 bioactive components within the extract of S. grosvenorii in rat blood, heart, liver, spleen, lung, and kidney, along with its pulmonary targeting.

MATERIALS AND METHODS

The blood, heart, liver, spleen, lung, and kidney samples of rats were obtained at diverse time points after oral administration of S. grosvenorii decotion, and a UPLC-MS/MS method was developed to determine the contents of 9 bioactive components (Siamenoside I, Grosvenorine, 11-O-Mogroside V, Mogroside II-E, Mogroside III-E, Mogroside IV-A, Mogroside V, Mogroside VI and Kaempferitrin) within the samples. The concentration-time curves of each component in each sample were plotted and the pharmacokinetic parameters were computed.

RESULTS

The AUC0→∞ and Cmax of 9 bioactive components in lung tissue were conspicuously higher than those in heart, liver, spleen, and kidney. For instance, the AUC0→∞ of Mogroside V in lung tissue was 7.20-55.54 times higher than that in blood and other tissues, and the Cmax in lung tissue was 3.315-96.70 times higher than that in blood and other tissues. The lung target efficiency of 9 bioactive components ranged from 1.885 to 15.80, indicating that the active components of S. grosvenorii exerting pharmacological effects are highly concentrated in the lung target tissue. The Tmax of 9 bioactive components in blood was within the range of 10.20-100.2 min, while the Tmax of the heart and liver was 20 min. The Tmax of all the components in the lung was 50 min, while the Tmax of the spleen and kidney was from 80 to 100 min, suggesting that 9 bioactive components entered the blood rapidly and then distributed to the heart and liver in large quantities, before entering the lung tissue in large quantities and eventually distributing to the spleen and kidney. The elimination half-life (T1/2) of the majority of 9 bioactive components was less than 1 h, and the MRT of most of them was less than 3 h.

CONCLUSIONS

S. grosvenorii is a naturally lung-targeted herbal medicine, and the clinical administration ought to be based on pharmacokinetic parameters such as Tmax, Cmax, AUC0→∞, T1/2, and MET0→∞ in lung tissue for designing a precise, rigorous, and rational administration plan.

Radiolabeling of Siamenoside I with Carbon-14

The synthesis of radiolabeled [25-14C]-siamenoside I following a synthetic route developed using unlabeled materials is disclosed. The synthesis features an early stage labeling of the mogrol's C25 via an oxidative cleavage-reconstruction strategy and regioselective glycosylations directed by protecting group manipulations. This route provided access to adequate amounts of [25-14C]-siamenoside I for in vivo ADME and PK studies.

A review of the state of sweeteners science: the natural versus artificial non-caloric sweeteners debate. Stevia rebaudiana and Siraitia grosvenorii into the spotlight

The rapid increase in the worldwide prevalence of obesity and certain non-communicable diseases (NCDs), such as: cardiovascular diseases, cancers, chronic respiratory diseases, and diabetes, has been mainly attributed to an excess of sugar consumption. Although the potential benefits of the synergetic use of sweeteners have been known for many years, recent development based on synthesis strategies to produce sucrose-like taste profiles is emerging where biocatalyst approaches may be preferred to produce and supply specific sweetener compounds. From a nutritional standpoint, high-intensity sweeteners have fewer calories than sugars while providing a major sweet potency, placing them in the spotlight as valuable alternatives to sugar. Due to the modern world awareness and incidence of metabolic diseases, both food research and growing markets have focused on two generally regarded as safe (GRAS) groups of compounds: the sweet diterpenoid glycosides present on the leaves of Stevia rebaudiana and, more recently, on the cucurbitane triterpene glycosides present on the fruits of Siraitia grosvenorii. In spite of their flavor advantages, biological benefits, including: antidiabetic, anticancer, and cardiovascular properties, have been elucidated. The present bibliographical review dips into the state-of-the-art of sweeteners and their role in human health as sugar replacements, as well as the biotransformation methods for steviol gylcosides and mogrosides apropos of enzymatic technology to update and locate the discoveries to date in the scientific literature to help boost the continuity of research efforts of the ongoing sweeteners.

Siraitia grosvenorii As a Homologue of Food and Medicine: A Review of Biological Activity, Mechanisms of Action, Synthetic Biology, and Applications in Future Food

Siraitia grosvenorii (SG), also known as Luo Han Guo or Monk fruit, boasts a significant history in food and medicine. This review delves into SG's historical role and varied applications in traditional Chinese culture, examining its phytochemical composition and the health benefits of its bioactive compounds. It further explores SG's biological activities, including antioxidant, anti-inflammatory, and antidiabetic properties and elucidates the mechanisms behind these effects. The review also highlights recent synthetic biology advances in enhancing the production of SG's bioactive compounds, presenting new opportunities for broadening their availability. Ultimately, this review emphasizes SG's value in food and medicine, showcasing its historical and cultural importance, phytochemistry, biological functions, action mechanisms, and the role of synthetic biology in its sustainable use.

Mogrol stimulates G-protein-coupled bile acid receptor 1 (GPBAR1/TGR5) and insulin secretion from pancreatic β-cells and alleviates hyperglycemia in mice

Target identification is a crucial step in elucidating the mechanisms by which functional food components exert their functions. Here, we identified the G-protein-coupled bile acid receptor 1 (GPBAR1, also known as TGR5) as a target of the triterpenoid mogrol, a class of aglycone mogroside derivative from Siraitia grosvenorii. Mogrol, but not mogrosides, activated cAMP-response element-mediated transcription in a TGR5-dependent manner. Additionally, mogrol selectively activated TGR5 but not the other bile acid-responsive receptors (i.e., farnesoid X receptor, vitamin D receptor, or muscarinic acetylcholine receptor M3). Several amino acids in TGR5 (L71A2.60, W75AECL1, Q77AECL1, R80AECL1, Y89A3.29, F161AECL2, L166A5.39, Y240A6.51, S247A6.58, Y251A6.62, L262A7.35, and L266A7.39) were found to be important for mogrol-induced activation. Mogrol activated insulin secretion under low-glucose conditions in INS-1 pancreatic β-cells, which can be inhibited by a TGR5 inhibitor. Similar effects of mogrol on insulin secretion were observed in the isolated mouse islets. Mogrol administration partially but significantly alleviated hyperglycemia in KKAy diabetic mice by increasing the insulin levels without affecting the β-cell mass or pancreatic insulin content. These results suggest that mogrol stimulates insulin secretion and alleviates hyperglycemia by acting as a TGR5 agonist.

Post-Ripening and Key Glycosyltransferase Catalysis to Promote Sweet Mogrosides Accumulation of Siraitia grosvenorii Fruits

Sweet mogrosides are not only the primary bioactive ingredient in Siraitia grosvenorii fruits that exhibit anti-tussive properties and expectorate phlegm, but they are also responsible for the fruit's sweetness. Increasing the content or proportion of sweet mogrosides in Siraitia grosvenorii fruits is significant for improving their quality and industrial production. Post-ripening is an essential step in the post-harvest processing of Siraitia grosvenorii fruits, but the underlying mechanism and condition of post-ripening on Siraitia grosvenorii quality improvement need to be studied systematically. Therefore, this study analyzed the mogroside metabolism in Siraitia grosvenorii fruits under different post-ripening conditions. We further examined the catalytic activity of glycosyltransferase UGT94-289-3 in vitro. The results showed that the post-ripening process of fruits could catalyze the glycosylation of bitter-tasting mogroside IIE and III to form sweet mogrosides containing four to six glucose units. After ripening at 35 °C for two weeks, the content of mogroside V changed significantly, with a maximum increase of 80%, while the increase in mogroside VI was over twice its initial amount. Furthermore, under the suitable catalytic condition, UGT94-289-3 could efficiently convert the mogrosides with less than three glucose units into structurally diverse sweet mogrosides, i.e., with mogroside III as the substrate, 95% of it can converted into sweet mogrosides. These findings suggest that controlling the temperature and related catalytic conditions may activate UGT94-289-3 and promote the accumulation of sweet mogrosides. This study provides an effective method for improving the quality of Siraitia grosvenorii fruits and the accumulation of sweet mogrosides, as well as a new economical, green, and efficient method for producing sweet mogrosides.

Pharmacological Activities of Mogrol: Potential Phytochemical against Different Diseases

Recently, mogrol has emerged as an important therapeutic candidate with multiple potential pharmacological properties, including neuroprotective, anticancer, anti-inflammatory, antiobesity, antidiabetes, and exerting a protective effect on different organs such as the lungs, bone, brain, and colon. Pharmacokinetic studies also highlighted the potential of mogrol as a therapeutic. Studies were also conducted to design and synthesize the analogs of mogrol to achieve better activities against different diseases. The literature also highlighted the possible molecular mechanism behind pharmacological activities, which suggested the role of several important targets, including AMPK, TNF-α, and NF-κB. These important mogrol targets were verified in different studies, indicating the possible role of mogrol in other associated diseases. Still, the compilation of pharmacological properties, possible molecular mechanisms, and important targets of the mogrol is missing in the literature. The current study not only provides the compilation of information regarding pharmacological activities but also highlights the current gaps and suggests the precise direction for the development of mogrol as a therapeutic against different diseases.

Enhancing the Antioxidant Ability of Momordica grosvenorii Saponin to Resist Gastrointestinal Stresses via Microcapsules of Sodium Alginate and Chitosan and Its Application in Beverage

Momordica grosvenorii saponin (MGS), as a promising dietary supplement with remarkable biological properties, has poor stability under acidic conditions and thus hinders its application in functional foods. In this study, capsules of chitosan and sodium alginate were successfully prepared to enhance the stability of MGS. The optimized parameters for preparing MGS capsules were established. Sodium alginate of 20.8 mg/mL and triplication of MGS powder were added to chitosan of 4 mg/mL and calcium chloride of 10 mg/mL at a volume ratio of 3:1, stirring at 1000 r/min for 30 min to form the capsules. In this case, the fresh particles averaged 1687 μm with an encapsulation efficiency (EE) of 80.25% MGS. The capsule tolerated acidic environments better, and in vitro MGS could be controlled to release in a stimulated gastrointestinal tract system. The antioxidant activity and delayed release of MGS could be achieved by microencapsulation of chitosan/sodium alginate. Moreover, one drink containing 19 mg/mL MGS was successfully developed for the fruit.

Culturing Important Plants for Sweet Secondary Products under Consideration of Environmentally Friendly Aspects

Some sweet tasting plant secondary metabolites are non-caloric or low nutritive compounds that have traditional use in food formulations. This mini-review focuses on conventional and advanced cultivation regimes of plants that accumulate sweet tasting or sweet taste modulating secondary metabolites of potential economic importance, in particular mogrosides (Siraitia grosvenorii), phyllodulcin (Hydrangea macrophylla), glycyrrhizin (Glycyrrhiza glabra), steviol glycosides (Stevia grosvenorii), and rubusoside (Rubus suavissimus). Consequential obstacles during the cultivation of Hydrangea macrophylla cultivars outside their natural habitat in a protected cultivation environment are addressed. Culturing at non-habitat locations facilitates short transportation routes of plant material for processing, which can be a key to an economically and environmentally compatible usage. The biosynthetic pathways, as far as known, are shortly mentioned. The proved or hypothetical degradation pathways of the compounds to minimalize environmental contamination are another focal point.

A Combined Transcriptomic and Proteomic Approach to Reveal the Effect of Mogroside V on OVA-Induced Pulmonary Inflammation in Mice

Mogroside V is a bioactive ingredient extracted from the natural food Siraitia grosvenorii which possesses functions that stimulate lung humidification and cough relief activities, but its underlying mechanisms were rarely studied. To estimate its potential protective effect on ovalbumin (OVA)-induced pulmonary inflammation and understand its system-wide mechanism, integrated omics was applied in this study. Mogroside V effectively reduced the levels of IgE, TNF-α, and IL-5 in OVA-induced mice. The results of RNA-seq and data-independent acquisition proteomics approach revealed that 944 genes and 341 proteins were differentially expressed in the normal control group (NC) and ovalbumin-induced control group (OC) and 449 genes and 259 proteins were differentially expressed between the OC and the group treated with 50 mg/kg mogroside V (MV). After a combined analysis of the transcriptome and the proteome, 93 major pathways were screened, and we discovered that mogroside V exerts an anti-inflammation effect in the lung via NF-κB and JAK-STAT, both of which are among the signaling pathways mentioned above. In addition, we found that the key regulatory molecules (Igha, Ighg1, NF-κB, Jak1, and Stat1) in the two pathways were activated in inflammation and inhibited by mogroside V. Thus, mogroside V may be the main bioactivity component in S. grosvenorii that exerts lung humidification and cough relief effects.

The pharmacokinetic profiles of mogrosides in T2DM rats

ETHNOPHARMACOLOGICAL RELEVANCE

Luohanguo (LHG) extract major contenting mogrosides, as a nonnutritive sweetener, has been reported to exert a hypoglycemic effect on diabetic patients and animals. As the pharmacokinetics and pharmacodynamics of drugs were changed with diabetes, it may lead to the different pharmacological of mogrosides between diabetic and normal subjects.

AIMS OF THE STUDY

To characterise the pharmacokinetic profiles of mogrosides in T2DM rats.

STUDY DESIGN AND METHODS

High-fat diet and streptozocin induced type 2 diabetic mellitus rats were used to investigate the pharmacokinetic behavior of mogroside V and mogrosides IIIA₁, IIA₁, and IA₁ after T2DM rats orally administrated with mogroside V and 1-3 glucose residues' mogrosides, respectively. The validated convenient UPLC-QTOF/MS and UPLC-MS/MS methods were established to use in the pharmacokinetic studies of mogrosides in normal and T2DM rats. Additionally, the expression of the intestinal tight junction protein zonula occludens-1 (ZO-1) was also detected by immunohistochemical analysis, which assessed the function of passive intestinal permeability in T2DM rats.

RESULTS

The results showed that for rats treated with mogroside V, its metabolite mogroside IIIA₁ has a significant increase (p < 0.05) in maximum plasma concentration (C_max, 163.80 ± 25.56 ng/mL) and area under the plasma concentration (AUC_0-t, 2327.44 ± 474.63 h·ng/mL) in T2DM rats compared with in normal rats. The mean residence time (MRT_0-t, 12.04 ± 0.97 h) of mogroside V showed a significant decrease (p < 0.05) in T2DM rats. However, the mogrosides IIIA₁, IIA₁and IA₁ showed no statistical differences in the normal and T2DM rats after administered with 1-3 glucose residues' mogrosides. Furthermore, the expression level of ZO-1 in the duodenum and colon of T2DM rats were downregulated.

CONCLUSION

The pharmacokinetic profiles of mogroside V and its metabolite mogroside IIIA₁ in T2DM rats and normal rats showed some difference, it might be affected by the metabolic changes in the pathological state of T2DM.

Research progress of pharmacological effects of Siraitia grosvenorii extract

OBJECTIVES

To summarise the ingredients of Luo Han Guo extract and the different pharmacological activity of the different ingredients. Find and evaluate the research value of Luo Han Guo extract as a therapeutic drug.

KEY FINDINGS

Siraitia grosvenorii is a fruit native to China and has many years of medicinal history. Because of its low-calorie and sugar-free properties, it is approved as a sweetener substitute in foods for obese and diabetic patients. Experiments have shown that this sweetener is non-toxic. This article summarises much literature on S. grosvenorii extracts, briefly introduces their chemical composition and metabolic distribution and summarises the possible pharmacological effects of each S. grosvenorii extract. Siraitia grosvenorii extract has anti-diabetic, anti-tumour, anti-inflammatory, antioxidant, neuroprotective and lipogenic inhibitory effects. These pharmacological activities suggest the medicinal value of S. grosvenorii.

SUMMARY

Luo Han Guo extract is a low-calorie, non-toxic substance, and its pharmacological activity and its potential medicinal properties support its further utilisation and research.

Artificial Sweeteners: History and New Concepts on Inflammation

Since the introduction of artificial sweeteners (AS) to the North American market in the 1950s, a growing number of epidemiological and animal studies have suggested that AS may induce changes in gut bacteria and gut wall immune reactivity, which could negatively affect individuals with or susceptible to chronic inflammatory conditions such as inflammatory bowel disease (IBD), a disorder that has been growing exponentially in westernized countries. This review summarizes the history of current FDA-approved AS and their chemical composition, metabolism, and bacterial utilization, and provides a scoping overview of the disease mechanisms associated with the induction or prevention of inflammation in IBD. We provide a general outlook on areas that have been both largely and scarcely studied, emerging concepts using silica, and describe the effects of AS on acute and chronic forms of intestinal inflammation.

High-Yield Synthesis of Transglycosylated Mogrosides Improves the Flavor Profile of Monk Fruit Extract Sweeteners

Luo Han Guo fruit extract (Siraitia grosvenorii), mainly composed of mogroside V (50%), could be considered a suitable alternative to free sugars; however, its commercial applications are limited by its unpleasant off-notes. In the present work, a central composite design method was employed to optimize the transglycosylation of a mogroside extract using cyclodextrin glucosyltransferases (CGTases) from three different bacteriological sources (Paenibacillus macerans, Geobacillus sp., and Thermoanaerobacter sp.) considering various experimental parameters such as maltodextrin and mogroside concentration, temperature, time of reaction, enzymatic activity, and pH. Product structures were determined by liquid chromatography coupled to a diode-array detector (LC-DAD), liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Sensory analysis of glucosylated mogrosides showed an improvement in flavor attributes relevant to licorice flavor and aftereffect. Consequently, an optimum methodology was developed to produce new modified mogrosides more suitable when formulating food products as free sugar substitutes.

Comparative In vitro metabolism of purified mogrosides derived from monk fruit extracts

Mogrosides are the primary components responsible for the sweet taste of Monk fruit which is derived from Siraitia grosvenorii (Swingle), a herbaceous plant native to southern China. Many mogrosides have been identified from Monk fruit extract, but the major sweetness component of Monk fruit by mass is mogroside V, comprising up to 0.5% of the dried fruit weight. Recent pharmacokinetic studies indicate that the parent mogrosides undergo minimal systemic absorption following ingestion and hydrolysis by digestive enzymes and/or intestinal flora and are excreted as mogrol (i.e., the aglycone) and its mono- and diglucosides. The objective of this study was to demonstrate whether individual mogrosides, are metabolized to a common and terminal deglycosylated metabolite, mogrol. An in vitro assay was conducted with pooled human male and female intestinal fecal homogenates (HFH) using mogrosides IIIe, mogroside V, siamenoside I, and isomogroside V at two concentrations over a 48 h period. The results show that various mogrosides that differ in the linkages and number of glucose units attached to a common cucurbitane backbone, share a common metabolic fate, and are metabolized within 24 h to mogrol. Aside from an apparent difference in the initial rate of deglycosylation between mogrosides at higher concentrations, no apparent difference in the rate of deglycosylation was observed between the male and female HFH. Given the similar structures of these mogrosides and a shared metabolic fate to mogrol, the study provides support for a reasonably conservative approach to assess safety based on bridging safety data from an individual mogroside (i.e., Mogroside V) to other mogrosides, and the establishment of a group Acceptable Daily Intake (ADI), rather than individual ADI's for mogrosides.

Siraitia grosvenorii Residual Extract Attenuates Atopic Dermatitis by Regulating Immune Dysfunction and Skin Barrier Abnormality

Atopic dermatitis is a persistent inflammatory skin disorder. Siraitia grosvenorii fruits (monk fruit or nahangwa in Korean, NHG) are used as a natural sweetener and as a traditional medicine for the treatment of asthma and bronchitis. We evaluated the activity of S. grosvenorii residual extract (NHGR) on allergic inflammation of atopic dermatitis in a Dermatophagoides farinae mite antigen extract (DfE)-treated NC/Nga murine model and in vitro. Oral administration of NHGR significantly reduced epidermal hyperplasia and inflammatory cell infiltration in the skin lesions of DfE-induced atopic dermatitis, as well as the dermatitis severity score. NHGR reduced serum immunoglobulin E levels. Splenic concentrations of IFN-γ, interleukin (IL)-4, IL-5, and IL-13 were reduced by NHGR administration. Immunohistofluorescence staining showed that NHGR administration increased the protein levels of claudin-1, SIRT1, and filaggrin in atopic dermatitis skin lesions. In addition, NHGR inhibited the phosphorylation of mitogen-activated protein kinases and decreased filaggrin and chemokine protein expression in TNF-α/IFN-γ-induced human keratinocytes. Moreover, NHGR also inhibited histamine in mast cells. The quantitative analysis of NHGR revealed the presence of grosvenorine, kaempferitrin, and mogrosides. These results demonstrate that NHGR may be an efficient therapeutic agent for the treatment of atopic dermatitis.

Status of the application of exogenous enzyme technology for the development of natural plant resources

Exogenous enzymes are extraneous enzymes that are not intrinsic to the subject. The exogenous enzyme industry has been rapidly developing recently. Successful application of recombinant DNA amplification, high-efficiency expression, and immobilization technology to genetically engineered bacteria provides a rich source of enzymes. Amylase, cellulase, protease, pectinase, glycosidase, tannase, and polyphenol oxidase are among the most widely used such enzymes. Currently, the application of exogenous enzyme technology in the development of natural plant resources mainly focuses on improving the taste and flavor of the product, enriching the active ingredient contents, deriving and transforming the structure of a chosen compound, and enhancing the biological activity and utilization of the functional ingredient. In this review, we discuss the application status of exogenous enzyme technology for the development of natural plant resources using typical natural active ingredients from plant, such as resveratrol, steviosides, catechins, mogrosides, and ginsenosides, as examples, to provide basis for further exploitation and utilization of exogenous enzyme technology.

Encapsulation of β-Glucosidase within PVA Fibers by CCD-RSM-Guided Coelectrospinning: A Novel Approach for Specific Mogroside Sweetener Production

Siamenoside I is a rare mogroside in Siraitia grosvenorii Swingle and has become one of the target ingredients in natural sweetener production. However, the complex structure of siamenoside I has hindered its production in various ways. Here, a yeast cell that produces a specific β-glucosidase for siamenoside I conversion from mogroside V was constructed, and the enzymes were coelectrospun with poly(vinyl alcohol) followed by phenylboronic acid cross-linking to provide potential usage in the batch production process of Siamenoside I. A central composite design (CCD)-response surface methodology (RSM) was used to find the optimum coelectrospinning parameters. The pH stability and sodium dodecyl sulfate tolerance increased for the entrapped enzymes, and positive correlations between the fiber diameter and enzymatic activity were confirmed. The batch process showed an average siamenoside I production rate of 118 ± 0.08 mg L^-1 h^-1 per gram of fiber. This is the first research article showing specific siamenoside I production on enzyme-loaded electrospun fibers.

Anti-hyperglycemic and anti-hyperlipidemic effects of a special fraction of Luohanguo extract on obese T2DM rats

ETHNOPHARMACOLOGICAL RELEVANCE

Luohanguo (LHG), a traditional Chinese medicine, could clear heat, moisten the lung, soothe the throat, restore the voice, and lubricate intestine and open the bowels. LHG has been utilized for the treatment of sore throats and hyperglycemia in folk medicine as a homology of medicine and food. The hypoglycemic pharmacology of LHG has attracted considerable attention, and mogrosides have been considered to be active ingredients against diabetes mellitus. We have found that these mogrosides could be metabolized into their secondary glycosides containing 1-3 glucose residues in type 2 diabetes mellitus (T2DM) rats in previous studies. These metabolites may be the antidiabetic components of LHG in vivo. Thus far, no reports have been found on reducing blood glucose of mogrosides containing 1-3 glucose residues.

AIMS OF THE STUDY

The aim of this study was to confirm that mogrosides containing 1-3 glucose residues were the active components of LHG for antidiabetic effects and to understand their potential mechanisms of action.

MATERIALS AND METHODS

First, the special fraction of mogrosides containing 1-3 glucose residues was separated from a 50% ethanol extract of LHG, and the chemical components were identified by ultra-performance liquid chromatography (UPLC) and named low-polar Siraitia grosvenorii glycosides (L-SGgly). Second, the antidiabetic effects of L-SGgly were evaluated by HFD/STZ-induced (high-fat diet and streptozocin) obese T2DM rats by indexing fasting blood glucose (FBG), fasting insulin (FINS), and insulin resistance, and then compared with other fractions in the separation process. The changes in serum lipid levels were also detected. Finally, possible mechanisms of antidiabetic activity of L-SGgly were identified as increasing GLP-1 levels and activating liver AMPK in T2DM rats.

RESULTS

The chemical analysis of L-SGgly showed that they contain 11-oxomogroside V, mogroside V, mogroside III, mogroside IIE, mogroside IIIA₁, mogroside IIA₁, and mogroside IA₁, respectively. The total content of the mogrosides in L-SGgly was 54.4%, including 15.7% mogroside IIA₁ and 12.6% mogroside IA₁. L-SGgly showed excellent effects on obese T2DM rats compared with the other fractions of LHG extract, including significantly reducing the levels of FBG (p < 0.001) and modifying insulin resistance (p < 0.05). Meanwhile, they could significantly decrease the content of triglyceride (p < 0.01), total cholesterol (p < 0.01), low-density lipoprotein cholesterol (p < 0.01) and free fatty acid (p < 0.001) and increase the content of high-density lipoprotein cholesterol (p < 0.001) in serum of T2DM rats. Moreover, L-SGgly can significantly increase (p < 0.01) GLP-1 levels and decrease (p < 0.01) IL-6 levels in T2DM rat serum. AMPK-activating activity in T2DM rats was also upregulated by L-SGgly, but no statistical significance was shown.

CONCLUSION

L-SGgly, fractions separated from LHG extract, were verified to have obvious anti-hyperglycemic and anti-hyperlipidemic effects on T2DM rats. Furthermore, L-SGgly regulated insulin secretion in T2DM rats by increasing GLP-1 levels. These findings provide an explanation for the antidiabetic role of LHG.

Safety of use of Monk fruit extract as a food additive in different food categories

The EFSA Panel on Food Additives and Flavourings (FAF) provides a scientific opinion on the safety of Monk fruit extract proposed for use as a new food additive in different food categories. Monk fruit extracts are prepared by water extraction of the fruits of Siraitia grosvenorii. Cucurbitane glycosides, mogrosides, are the main components of the S. grosvenorii fruit and mogroside V is the main mogroside in the Monk fruit extract. Mogroside V is absorbed to some extent and is systemically bioavailable. Monk fruit extract containing 25% and 55% mogroside V were negative in the bacterial reverse mutation assay and did not induce structural and/or numerical chromosomal damage. However, the Panel noted that the in vitro toxicity studies including study with metabolic activation were not sufficiently informative to evaluate the genotoxic potential of the metabolites generated after microbial metabolism, including the aglycone. The effects on the testis observed in a 90‐day study with monk fruit extract‐52% mogroside V cannot be dismissed and the adversity of these effects cannot be ruled out. No effects on parental, reproductive or development toxicity were observed in a reproductive and developmental screening study in rats. For male animals, the time of exposure did not cover the full length of spermatogenesis and, therefore, a longer term study at higher doses would be needed to clarify the effects on testes observed in the 90‐day study. No maternal and developmental toxicity was observed. Considering the systemic availability of mogroside V, the effects observed in the rat subchronic study and following the principles of EFSA Guidance on food additives evaluation, data from chronic/carcinogenicity toxicity testing would have been warranted. Exposure to mogroside V was calculated based on the proposed use levels. The Panel concluded that toxicity database on Monk fruit extract is insufficient to conclude on the safety of the use of Monk fruit extract as a food additive.

Design, synthesis and biological evaluation of mogrol derivatives as a novel class of AMPKα2β1γ1 activators

Adenosine monophosphate-activated protein kinase (AMPK) has been considered as a promising drug target for its regulation in both glucose and lipid metabolism. Mogrol was originally identified from high throughput screening as a small molecule activator of AMPK subtype α2β1γ1. In order to enhance its potency on AMPK and summarize the structure-activity relationships, a series of mogrol derivatives were designed, synthesized and evaluated in pharmacological AMPK activation assays. The results showed that the amine derivatives at the 24-position can improve the potency. Among them, compounds 3 and 4 exhibited the best potency (EC₅₀: 0.15 and 0.14 μM) which was 20 times more potent than mogrol (EC₅₀: 3.0 μM).

Mogroside V protects porcine oocytes from in vitro ageing by reducing oxidative stress through SIRT1 upregulation

Postovulatory ageing compromises oocyte quality and subsequent development in various manners. We aimed to assay the protective effects of mogroside V on porcine oocyte quality during in vitro ageing and explore the related causes. We observed that mogroside V can effectively maintain normal oocyte morphology and early embryo development competence after prolonged culture for 24 h. Moreover, mogroside V can markedly reduce reactive oxygen species (ROS) levels, alleviate spindle formation and chromosome alignment abnormalities, improve mitochondrial contents, adenosine triphosphate (ATP) levels and the membrane potential (ΔΨm), and reduce early apoptosis in aged oocytes. We examined the molecular changes and found that SIRT1 expression was decreased in in vitro aged oocytes but was maintained by exposure to mogroside V. However, when SIRT1 was successfully inhibited by the specific inhibitor EX-527, mogroside V could not reduce ROS levels or alleviate abnormal spindle organization and chromosome misalignment. In summary, our results demonstrated that mogroside V can alleviate the deterioration of oocyte quality during in vitro ageing, possibly by reducing oxidative stress through SIRT1 upregulation.

Siraitia grosvenorii residual extract attenuates ovalbumin-induced lung inflammation by down-regulating IL-4, IL-5, IL-13, IL-17, and MUC5AC expression in mice

BACKGROUND

Siraitia grosvenorii fruits are used in traditional medicine to treat cough, sore throat, bronchitis, and asthma.

PURPOSE

This study aimed to investigate the anti-inflammatory and anti-asthmatic effects of S. grosvenorii residual extract (SGRE) on ovalbumin (OVA)-induced asthma in mice.

METHODS

Asthma was induced in BALB/c mice by systemic sensitization to OVA, followed by intratracheal, intraperitoneal, and aerosol allergen challenges. SGRE was orally administered for four weeks. We investigated the effects of SGRE on airway hyper-responsiveness, OVA-specific IgE production, histological analysis of lung and trachea, immune cell phenotyping, Th1/Th2 cytokine production in bronchoalveolar lavage fluid (BAL) fluid and splenocytes, and gene expression in the lung.

RESULTS

SGRE ameliorated OVA-driven airway hyper-responsiveness, serum IgE production, and histopathological changes in the lung and trachea. SGRE reduced the total number of cells in the lung and BAL, the total number of lymphocytes, neutrophils, monocytes, and eosinophils in the lung and BAL, the absolute number of CD4+/CD69+ T cells in the lung, and the absolute number of CD4+/CD8+ T cells and CD11b+/Gr-1+ granulocytes in the lung and BAL. SGRE also reduced Th2 cytokines (IL-4, IL-5, and IL-13) and increased the Th1 cytokine IFN-γ in the BAL fluid and supernatant of splenocyte cultures. SGRE decreased the OVA-induced increase of IL-13, TARC, MUC5AC, TNF-α, and IL-17 expression in the lung.

CONCLUSION

SGRE exerts anti-asthmatic effects via the inhibition of Th2 and Th17 cytokines and the increase of Th1 cytokines, suggesting that SGRE may be a potential therapeutic agent for allergic lung inflammation, such as asthma.

Mogroside V inhibits LPS-induced COX-2 expression/ROS production and overexpression of HO-1 by blocking phosphorylation of AKT1 in RAW264.7 cells

Momordica grosvenori is a valuable edible plant with medicinal purposes, and it is widely used in medicated diets and traditional Chinese medicine in Asia. Mogroside V (MV), the main bioactive component from M. grosvenori, is commonly used as a natural sweetener. M. grosvenori extracts have been reported to exert potent anti-inflammatory property, however the underlying molecular mechanism still remains unknown. In the present study, the biological effect of MV in inflammation was investigated in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The ELISA and western blot analysis results showed that MV significantly inhibited LPS-induced prostaglandin E2 (PGE2) production and cyclooxygenase-2 (COX-2) expression. MV markedly decreased the phosphorylation of IκB-α, increased IκB-α, and reduced nuclear p-65 and C/EBPδ. Furthermore, MV attenuated LPS-induced phosphorylation of MAPKs and AKT1, and only the phosphorylation status of AKT1 was found to be consistent with the expression trend of COX-2. Moreover, MV reduced ROS level and restored overexpressed HO-1 and AP-1 to basal level, which can be markedly reversed by AKT1 inhibitor LY294002. These results revealed that AKT1 plays a key role in LPS-induced COX-2 expression, and acts as a mediator to keep the redox balance in LPS-stimulated RAW264.7 cells. MV exerts anti-inflammatory property by blocking AKT1-mediated NF-κB and C/EBPδ activation, ROS generation and AP-1/ HO-1 expression. Therefore, the present study indicated that MV has a significant chemopreventive effect on the inflammatory lesions and suggested that AKT1 is a potential specific target of MV for relieving inflammation.

Hydrolyzation of mogrosides: Immobilized β-glucosidase for mogrosides deglycosylation from Lo Han Kuo

An immobilized enzyme system for bioconversion of Lo Han Kuo (LHK) mogrosides was established. β-Glucosidase which was covalently immobilized onto the glass spheres exhibited a significant bioconversion efficiency from pNPG to pnitrophenol over other carriers. Optimum operational pH and temperature were determined to be pH 4 and 30°C. Results of storage stability test demonstrated that the glass sphere enzyme immobilization system was capable of sustaining more than 80% residual activity until 50 days, and operation reusability was confirmed for at least 10 cycles. The Michaelis constant (K m) of the system was determined to be 0.33 mM. The kinetic parameters, rate constant (K) at which Mogrosides conversion was determined, the τ 50 in which 50% of mogroside V deglycosylation/mogroside IIIE production was reached, and the τ complete of complete mogroside V deglycosylation/mogroside IIIE production, were 0.044/0.017 min-1, 15.6/41.1 min, and 60/120 min, respectively. Formation of the intermediates contributed to the kinetic differences between mogroside V deglycosylation and mogroside IIIE formation.

Glycemic impact of non-nutritive sweeteners: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND/OBJECTIVES

Nonnutritive sweeteners (NNSs) are zero- or low-calorie alternatives to nutritive sweeteners, such as table sugars. A systematic review and meta-analysis of randomized controlled trials was conducted to quantitatively synthesize existing scientific evidence on the glycemic impact of NNSs.

SUBJECTS/METHODS

PubMed and Web of Science databases were searched. Two authors screened the titles and abstracts of candidate publications. The third author was consulted to resolve discrepancies. Twenty-nine randomized controlled trials, with a total of 741 participants, were included and their quality assessed. NNSs under examination included aspartame, saccharin, steviosides, and sucralose. The review followed the PRISMA guidelines.

RESULTS

Meta-analysis was performed to estimate and track the trajectory of blood glucose concentrations over time after NNS consumption, and to test differential effects by type of NNS and participants' age, weight, and disease status. In comparison with the baseline, NNS consumption was not found to increase blood glucose level, and its concentration gradually declined over the course of observation following NNS consumption. The glycemic impact of NNS consumption did not differ by type of NNS but to some extent varied by participants' age, body weight, and diabetic status.

CONCLUSIONS

NNS consumption was not found to elevate blood glucose level. Future studies are warranted to assess the health implications of frequent and chronic NNS consumption and elucidate the underlying biological mechanisms.

Mogrol Derived from Siraitia grosvenorii Mogrosides Suppresses 3T3-L1 Adipocyte Differentiation by Reducing cAMP-Response Element-Binding Protein Phosphorylation and Increasing AMP-Activated Protein Kinase Phosphorylation

This study investigated the effects of mogrol, an aglycone of mogrosides from Siraitia grosvenorii, on adipogenesis in 3T3-L1 preadipocytes. Mogrol, but not mogrosides, suppressed triglyceride accumulation by affecting early (days 0–2) and late (days 4–8), but not middle (days 2–4), differentiation stages. At the late stage, mogrol increased AMP-activated protein kinase (AMPK) phosphorylation and reduced glycerol-3-phosphate dehydrogenase activity. At the early stage, mogrol promoted AMPK phosphorylation, inhibited the induction of CCAAT/enhancer-binding protein β (C/EBPβ; a master regulator of adipogenesis), and reduced 3T3-L1 cell contents (e.g., clonal expansion). In addition, mogrol, but not the AMPK activator AICAR, suppressed the phosphorylation and activity of the cAMP response element-binding protein (CREB), which regulates C/EBPβ expression. These results indicated that mogrol suppressed adipogenesis by reducing CREB activation in the initial stage of cell differentiation and by activating AMPK signaling in both the early and late stages of this process.

Metabolites of Siamenoside I and Their Distributions in Rats

Siamenoside I is the sweetest mogroside that has several kinds of bioactivities, and it is also a constituent of Siraitiae Fructus, a fruit and herb in China. Hitherto the metabolism of siamenoside I in human or animals remains unclear. To reveal its metabolic pathways, a high-performance liquid chromatography-electrospray ionization-ion trap-time of flight-multistage mass spectrometry (HPLC-ESI-IT-TOF-MSⁿ) method was used to profile and identify its metabolites in rats. Altogether, 86 new metabolites were identified or tentatively identified, and 23 of them were also new metabolites of mogrosides. In rats, siamenoside I was found to undergo deglycosylation, hydroxylation, dehydrogenation, deoxygenation, isomerization, and glycosylation reactions. Among them, deoxygenation, pentahydroxylation, and didehydrogenation were novel metabolic reactions of mogrosides. The distributions of siamenoside I and its 86 metabolites in rat organs were firstly reported, and they were mainly distributed to intestine, stomach, kidney, and brain. The most widely distributed metabolite was mogroside IIIE. In addition, eight metabolites were bioactive according to literature. These findings would help to understand the metabolism and effective forms of siamenoside I and other mogrosides in vivo.

In vitro AMPK activating effect and in vivo pharmacokinetics of mogroside V, a cucurbitane-type triterpenoid from Siraitia grosvenorii fruits

The aim of this study was to explore the anti-diabetic effects of mogroside V (MV) and its aglycone mogrol (MO), both isolated from the fruits of Siraitia grosvenorii Swingle, and to investigate the pharmacokinetic behaviors of MV and its metabolite MO in rats.

Exploring in vitro, in vivo metabolism of mogroside V and distribution of its metabolites in rats by HPLC-ESI-IT-TOF-MS(n)

Mogroside V, a cucurbitane-type saponin, is not only the major bioactive constituent of traditional Chinese medicine Siraitiae Fructus, but also a widely used sweetener. To clarify its biotransformation process and identify its effective forms in vivo, we studied its metabolism in a human intestinal bacteria incubation system, a rat hepatic 9000g supernatant (S9) incubation system, and rats. Meanwhile, the distribution of mogroside V and its metabolites was also reported firstly. Seventy-seven new metabolites, including 52 oxidation products formed by mono- to tetra- hydroxylation/dehydrogenation, were identified with the aid of HPLC in tandem with ESI ion trap (IT) TOF multistage mass spectrometry (HPLC-ESI-IT-TOF-MS(n)). Specifically, 14 metabolites were identified in human intestinal bacteria incubation system, 4 in hepatic S9 incubation system, 58 in faeces, 29 in urine, 14 in plasma, 34 in heart, 33 in liver, 39 in spleen, 39 in lungs, 42 in kidneys, 45 in stomach, and 51 in small intestine. The metabolic pathways of mogroside V were proposed and the identified metabolic reactions were deglycosylation, hydroxylation, dehydrogenation, isomerization, glucosylation, and methylation. Mogroside V and its metabolites were distributed unevenly in the organs of treated rats. Seven bioactive metabolites of mogroside V were identified, among which mogroside IIE was abundant in heart, liver, spleen and lung, suggesting that it may contribute to the bioactivities of mogroside V. Mogroside V was mainly excreted in urine, whereas its metabolites were mainly excreted in faeces. To our knowledge, this is the first report that a plant constituent can be biotransformed into more than 65 metabolites in vivo. These findings will improve understanding of the in vivo metabolism, distribution, and effective forms of mogroside V and congeneric molecules.

Cucurbitane glycosides derived from mogroside IIE: structure-taste relationships, antioxidant activity, and acute toxicity

Mogroside IIE is a bitter triterpenoid saponin which is the main component of unripe Luo Han Guo fruit and a precursor of the commercially available sweetener mogroside V. In this study, we developed an enzymatic glycosyl transfer method, by which bitter mogroside IIE could be converted into a sweet triterpenoid saponin mixture. The reactant concentration, temperature, pH and buffer system were studied. New saponins with the α-glucose group were isolated from the resulting mixtures, and the structures of three components of the extract were determined. The structure-taste relationships of these derivatives were also studied together with those of the natural mogrosides. The number and stereoconfiguration of glucose groups present in the mogroside molecules were found to be the main factor to determine the sweet or bitter taste of a compound. The antioxidant and food safety properties were initially evaluated by their radical scavenging ability and via 7 day mice survival tests, respectively. The results showed that the sweet triterpenoid saponin mixture has the same favorable physiological and safety characteristics as the natural mogrosides.

Spontaneous vesicle formation from sodium salt of acidic sophorolipid and its application as a skin penetration enhancer

In this study, spontaneous vesicle formation from the sodium salt of acidic sophorolipid (SLNa) was observed, and its potential application as a skin penetration enhancer for triterpene glycosides extracted from the fruits of Siraitia grosvenorii Swingle was then investigated. Dynamic light scattering (DLS) measurements of the SLNa assemblies prepared by the gentle mixing of SLNa with water (1%) showed their hydrodynamic radius (Rh) to be 96.2 nm, and their structure was assigned to be vesicles by freeze-fracture electron microscopy (FF-TEM). DLS and FF-TEM also revealed that the size of the vesicles increased with an increase in the concentration of the triterpene glycosides, indicating that the triterpene glycosides were incorporated into the SLNa vesicles. The results of an in vitro skin permeation assay, after loading the SLNa vesicles on a 3D cultured skin model, showed that the amount of SLNa that penetrated though the skin model increased with time. It was also found that the amount of permeated mogroside, which is the main active component of triterpene glycosides, was significantly enhanced by the SLNa vesicle formulation. These results clearly demonstrated that spontaneously formed vesicles composed of the bolaamphiphile SLNa are useful for application as penetration enhancers for active ingredients such as mogroside V.

Antioxidant effect of mogrosides against oxidative stress induced by palmitic acid in mouse insulinoma NIT-1 cells

Excessive oxidative stress in pancreatic β cells, caused by glucose and fatty acids, is associated with the pathogenesis of type 2 diabetes. Mogrosides have shown antioxidant and antidiabetic activities in animal models of diabetes, but the underlying mechanisms remain unclear. This study evaluated the antioxidant effect of mogrosides on insulinoma cells under oxidative stress caused by palmitic acid, and investigated the underlying molecular mechanisms. Mouse insulinoma NIT-1 cells were cultured in medium containing 0.75 mM palmitic acid, mimicking oxidative stress. The effects of 1 mM mogrosides were determined with the dichlorodihydrofluorescein diacetate assay for intracellular reactive oxygen species (ROS) and FITC-Annexin V/PI assay for cell apoptosis. Expression of glucose transporter-2 (GLUT2) and pyruvate kinase was determined by semi-quantitative reverse-transcription polymerase chain reaction. Palmitic acid significantly increased intracellular ROS concentration 2-fold (P<0.05), and decreased expression of GLUT2 (by 60%, P<0.05) and pyruvate kinase (by 80%, P<0.05) mRNAs in NIT-1 cells. Compared with palmitic acid, co-treatment with 1 mM mogrosides for 48 h significantly reduced intracellular ROS concentration and restored mRNA expression levels of GLUT2 and pyruvate kinase. However, mogrosides did not reverse palmitic acid-induced apoptosis in NIT-1 cells. Our results indicate that mogrosides might exert their antioxidant effect by reducing intracellular ROS and regulating expression of genes involved in glucose metabolism. Further research is needed to achieve a better understanding of the signaling pathway involved in the antioxidant effect of mogrosides.

Biotransformation of mogrosides from Siraitia grosvenorii Swingle by Saccharomyces cerevisiae

Mogrosides are a group of triterpenoidal saponins from the fruit of Siraitia grosvenorii Swingle; they are intensely sweet and have consequently been used as a substitute for sugar by the food industry. The lack of efficient methods to produce specific mogrosides has hindered investigation of the relationship between their structure and bioactivity, e.g., down-regulation of blood glucose levels, anti-inflammation, and antiviral infection. Here, we attempt to selectively convert the major saponin mogroside V, a mogrol pentaglucoside, into mogroside III E, a triglucoside, via the β-glucosidases of the budding yeast Saccharomyces cerevisiae. We report that the β-glucopyranosyl and β-glucopyranosyl-(1→2)-β-d-glucopyranosyl attached on C-3 and -24 of mogrol, respectively, were resistant to hydrolysis by yeast β-d-glucosidases. We further screened 16 mutants bearing single defective glucanase or glucosidase genes, thereby demonstrating that Exg1 is a major enzyme of the initiation of mogroside V conversion. Deletion of the KRE6 gene unexpectedly facilitated the production of mogroside III E in yeast culture. This paper demonstrates that yeast knockout mutants are a valuable tool for saponin modification and for studying the specificity of glucosidase function.

Potential AMPK activators of cucurbitane triterpenoids from Siraitia grosvenorii Swingle

AMP-activated kinase (AMPK) as a key controller in the regulation of whole-body energy homeostasis, plays an important role in protecting the body from metabolic diseases. Recently, improved glucose, lipid utility and increased insulin sensitivity were observed on several diabetic rodent models treated with crude mogrosides isolated from the fruit of Siraitia grosvenorii Swingle, but the precise active compounds responsible for the anti-diabetic activity of this plant have not been clearly identified. In our current work, acid hydrolysis of crude mogrosides provided five new cucurbitane triterpenoids (1-4, 8), along with three known ones (5-7). The main aglycone mogrol (7) and compounds 4 and 8 were found to be potent AMPK activators in the HepG2 cell line. This result suggested AMPK activation by the mogroside aglycones 7 and 8 was proved to contribute at least partially to the anti-hyperglycemic and anti-lipidemic properties in vivo of S. grosvenorii.