Cucurbitane Glucosides from the Crude Extract of Siraitia grosvenorii with Moderate Effects on PGC-1α Promoter Activity

Recent Advances in the Distribution, Chemical Composition, Health Benefits, and Application of the Fruit of Siraitia grosvenorii

The fruits of Siraitia grosvenorii (S. grosvenorii) have attracted a lot of scientific interest as part of the current healthy diet. S. grosvenorii has diverse health-promoting effects, including antioxidant, anti-inflammatory, antimicrobial, respiratory modulation, metabolic modulation, antitumor, and neuroprotective effects, as well as gastrointestinal function modulation. As a plant resource, S. grosvenorii has broad application prospects, which promotes the development of the horticultural industry. Moreover, Mogroside has attracted much attention as an important active ingredient of S. grosvenorii. This review provides an in-depth exploration of the distribution, chemical composition, health benefits, and application of S. grosvenorii, particularly Mogroside. This comprehensive exploration highlights the important therapeutic potential of S. grosvenorii, prompting further research into its applications. As value-added functional ingredients, S. grosvenorii and its constituents have significant potential for disease prevention and are widely used in the development of food and health supplements.

A comprehensive review of Siraitia grosvenorii (Swingle) C. Jeffrey: chemical composition, pharmacology, toxicology, status of resources development, and applications

Siraitia grosvenorii (Swingle) C. Jeffrey (S. grosvenorii), a perennial indigenous liana from the Cucurbitaceae family, has historically played a significant role in southern China's traditional remedies for various ailments. Its dual classification by the Chinese Ministry of Health for both medicinal and food utility underscores its has the potential of versatile applications. Recent research has shed light on the chemical composition, pharmacological effects, and toxicity of S. grosvenorii. Its active ingredients include triterpenoids, flavonoids, amino acids, volatile oils, polysaccharides, minerals, vitamins, and other microconstituents. Apart from being a natural sweetener, S. grosvenorii has been found to have numerous pharmacological effects, including alleviating cough and phlegm, preventing dental caries, exerting anti-inflammatory and anti-allergic effects, anti-aging and anti-oxidative, hypoglycemic, lipid-lowering, anti-depression, anti-fatigue, anti-schizophrenic, anti-Parkinson, anti-fibrotic, and anti-tumor activities. Despite its versatile potential, there is still a lack of systematic research on S. grosvenorii to date. This paper aims to address this gap by providing an overview of the main active components, pharmacological efficacy, toxicity, current status of development and application, development dilemmas, and strategies for intensive exploitation and utilization of S. grosvenorii. This paper aims to serve as a guide for researchers and practitioners committed to exploiting the biological resources of S. grosvenorii and further exploring its interdisciplinary potential.

Focus on Mitochondrial Respiratory Chain: Potential Therapeutic Target for Chronic Renal Failure

The function of the respiratory chain is closely associated with kidney function, and the dysfunction of the respiratory chain is a primary pathophysiological change in chronic kidney failure. The incidence of chronic kidney failure caused by defects in respiratory-chain-related genes has frequently been overlooked. Correcting abnormal metabolic reprogramming, rescuing the "toxic respiratory chain", and targeting the clearance of mitochondrial reactive oxygen species are potential therapies for treating chronic kidney failure. These treatments have shown promising results in slowing fibrosis and inflammation progression and improving kidney function in various animal models of chronic kidney failure and patients with chronic kidney disease (CKD). The mitochondrial respiratory chain is a key target worthy of attention in the treatment of chronic kidney failure. This review integrated research related to the mitochondrial respiratory chain and chronic kidney failure, primarily elucidating the pathological status of the mitochondrial respiratory chain in chronic kidney failure and potential therapeutic drugs. It provided new ideas for the treatment of kidney failure and promoted the development of drugs targeting the mitochondrial respiratory chain.

Daucosterol confers protection against T-2 toxin induced blood-brain barrier toxicity through the PGC-1α-mediated defensive response in vitro and in vivo

T-2 toxin is a common environmental pollutant and contaminant in food and animal feed that represents a great challenge to human and animal' health throughout the world. Using natural compounds to prevent the detrimental effects of T-2 toxin represents an attractive strategy. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is a critical regulator in various cellular processes. Recently, PGC-1α activation has been reported to confer protection against neurological injuries. We aimed to identify a potent PGC-1α activator from plants as a chemopreventive compound and to demonstrate the efficacy of the compound in attenuating T-2 toxin-induced blood-brain barrier (BBB) toxicity. We identified daucosterol, which binds directly to the 71-74 (-1100 to -1000 bp) position of the second promoter of human PGC-1α by hydrogen bonding. An in vitro and in vivo T-2 toxin induced BBB injury model revealed that this compound can protect against this injury by increasing transepithelial/transendothelial electrical resistance, reducing sodium fluorescein (NaF) infiltration and increasing the expression of tight junction-related proteins (zonula occludens-1 (ZO-1), occludin (OCLN), claudin-5 (CLDN5)) expression. In conclusion, we identified daucosterol as representing a novel of PGC-1α activators and illustrated the mechanism of specific binding site. Furthermore, we have demonstrated the feasibility of using natural compounds targeting PGC-1α as a therapeutic approach to protect humans from environmental insults that may occur daily such as lipopolysaccharide.

A Review of the Phytochemistry and Pharmacology of the Fruit of Siraitia grosvenorii (Swingle): A Traditional Chinese Medicinal Food

Siraitia grosvenorii (Swingle) C. Jeffrey ex Lu et Z. Y. Zhang is a unique economic and medicinal plant of Cucurbitaceae in Southern China. For hundreds of years, Chinese people have used the fruit of S. grosvenorii as an excellent natural sweetener and traditional medicine for lung congestion, sore throat, and constipation. It is one of the first species in China to be classified as a medicinal food homology, which has received considerable attention as a natural product with high development potential. Various natural products, such as triterpenoids, flavonoids, amino acids, and lignans, have been released from this plant by previous phytochemical studies. Phar- macological research of the fruits of S. grosvenorii has attracted extensive attention, and an increasing number of extracts and compounds have been demonstrated to have antitussive, expectorant, antiasthmatic, antioxidant, hypoglycemic, immunologic, hepatoprotective, antibacte- rial, and other activities. In this review, based on a large number of previous studies, we summarized the related research progress of the chemical components and pharmacological effects of S. grosvenorii, which provides theoretical support for further investigation of its biological functions and potential clinical applications.

Macrocephatriolides A and B: Two Guaianolide Trimers from Ainsliaea macrocephala as PTP1B Inhibitors and Insulin Sensitizers

Macrocephatriolides A and B (1 and 2), two novel guaiane-type sesquiterpene lactone trimers possessing unique linkage patterns, were identified from the whole plant of Ainsliaea macrocephala. The trimeric architecture of 1 features a cyclohexene linkage and a methylene bridge, which were presumably constructed from three constitutive monomers via a Diels-Alder cycloaddition and a Michael addition, respectively. The three monomers of 2 were tethered by a 1,2-ethanediyl and a methylene linkage at the same time. Their complex structures were established by extensive analysis of spectroscopic data inclusive of band-selective CT-HSQC and CT-HMBC and time-dependent density functional theory (TDDFT) ECD calculations. Compound 2 showed potent inhibition against protein tyrosine phosphatase 1B (PTP1B) with an IC₅₀ value of 26.26 ± 0.88 μM but not compound 1. In the kinetic study, compound 2 was disclosed as a competitive inhibitor of PTP1B with a K_i value of 16.34 ± 4.72 μM. In insulin-stimulated C2C12 myotubes, compound 2 dose-dependently enhanced glucose uptake by activating the insulin signaling pathway. Compound 2 might represent a new scaffold of insulin sensitizers.

Regulating the gut microbiota and SCFAs in the faeces of T2DM rats should be one of antidiabetic mechanisms of mogrosides in the fruits of Siraitia grosvenorii

ETHNOPHARMACOLOGICAL RELEVANCE

The Siraitia grosvenorii fruits extract (SG, in which mogrosides are the main components), considered as a non-nutritional sweetener, has an antidiabetic effect. Our previous studies have confirmed that an extract of mogrosides being rich in triterpene glycosides with 1-3 glucosyl residues, designated as low-polar S. grosvenorii glycosides (L-SGgly), had a significant antidiabetic effect. However, whether the mechanism through impacting on gut microbiota to exert the antidiabetic effect of mogrosides remains unclear.

AIMS OF THE STUDY

To explore the potential mechanism of mogrosides (SG and L-SGgly) on gut microbiota and faecal metabolites in the treatment of diabetes.

STUDY DESIGN AND METHODS

In this study, the effects of SG and L-SGgly on gut microbiota and faecal endogenous metabolites were explored by sequencing the 16S rRNA V3-V4 region of gut microbiota, and detecting with gas chromatography-mass spectrometry (GC-MS) and liquid chromatography quadrupole time-of-flight MS (LC-Q-TOF/MS), respectively. In particular, correlation analyses revealed how these influences affect the anti-hyperglycaemic effect, to give the underlying antidiabetic mechanisms of the mogrosides in S. grosvenorii fruits.

RESULTS

After a 14-day treatment with SG and L-SGgly for type 2 diabetes mellitus (T2DM) rats induced by a high-fat diet (HFD) and streptozotocin (STZ), the disordered gut microbiota in the faeces of T2DM rats were recovered. At the same time, the short-chain fatty acids (SCFAs) concentration significantly increased and the deoxycholic acid and 1β-hydroxycholic acid content decreased in the faeces of T2DM rats. Moreover, correlation analyses provided the evidences that gut microbiota and its metabolites could be the target for exerting the anti-hyperglycaemic effects of SG and L-SGgly. Especially, Elusimicrobium, Lachnospiraceae_UCG-004, acetate, butyrate, and 1β-hydroxycholic acid would be the potential dominant bacteria and biomarkers for SG and L-SGgly in reducing the blood glucose and insulin resistance of T2DM rats.

CONCLUSION

It is the first time that a mechanism of targeting on gut microbiota for the antidiabetic effect of mogrosides in S. grosvenorii fruits has been proposed.

Prediction of the sweetening effect of Siraitia grosvenorii (luo han guo) fruits by two-dimensional quantitative NMR

During the last decade, dried fruits of Siraitia grosvenorii (luo han guo), also known as monk fruit, have become popular food ingredients. Luo han guo extracts, which are promoted as non-caloric natural sweeteners, are now incorporated into dietary supplements, soft drinks, and energy shakes. The compounds responsible for the sweetening effect are glycosylated cucurbitane-type triterpenoids, the so-called mogrosides. However, of the more than 40 known mogroside compounds, only 11-α-hydroxy-mogrosides exhibit a sweetening effect, whereas the other triterpenoids are non- or bitter-tasting. We have used two-dimensional quantitative NMR to determine selectively the content of 11-α-hydroxy-mogrosides in these dried fruits and thus to predict their sweetening potential. Homonuclear (H,H COSY) and heteronuclear (HSQC) methods were developed, validated, and compared. Both techniques were found suitable for the quality control of luo han guo fruits and extracts, the COSY experiment being advantageous with regard to accuracy, precision, and limit of quantification.

Structure-Dependent Activity of Plant-Derived Sweeteners

Human sensation for sweet tastes and the thus resulting over-consumption of sugar in recent decades has led to an increasing number of people suffering from caries, diabetes, and obesity. Therefore, a demand for sugar substitutes has arisen, which increasingly has turned towards natural sweeteners over the last 20 years. In the same period, thanks to advances in bioinformatics and structural biology, understanding of the sweet taste receptor and its different binding sites has made significant progress, thus explaining the various chemical structures found for sweet tasting molecules. The present review summarizes the data on natural sweeteners and their most important (semi-synthetic) derivatives until the end of 2019 and discusses their structure–activity relationships, with an emphasis on small-molecule high-intensity sweeteners.

Unraveling Plant Natural Chemical Diversity for Drug Discovery Purposes

The screening and testing of extracts against a variety of pharmacological targets in order to benefit from the immense natural chemical diversity is a concern in many laboratories worldwide. And several successes have been recorded in finding new actives in natural products, some of which have become new drugs or new sources of inspiration for drugs. But in view of the vast amount of research on the subject, it is surprising that not more drug candidates were found. In our view, it is fundamental to reflect upon the approaches of such drug discovery programs and the technical processes that are used, along with their inherent difficulties and biases. Based on an extensive survey of recent publications, we discuss the origin and the variety of natural chemical diversity as well as the strategies to having the potential to embrace this diversity. It seemed to us that some of the difficulties of the area could be related with the technical approaches that are used, so the present review begins with synthetizing some of the more used discovery strategies, exemplifying some key points, in order to address some of their limitations. It appears that one of the challenges of natural product-based drug discovery programs should be an easier access to renewable sources of plant-derived products. Maximizing the use of the data together with the exploration of chemical diversity while working on reasonable supply of natural product-based entities could be a way to answer this challenge. We suggested alternative ways to access and explore part of this chemical diversity with in vitro cultures. We also reinforced how important it was organizing and making available this worldwide knowledge in an "inventory" of natural products and their sources. And finally, we focused on strategies based on synthetic biology and syntheses that allow reaching industrial scale supply. Approaches based on the opportunities lying in untapped natural plant chemical diversity are also considered.

Tricarabrols A–C, three anti-inflammatory sesquiterpene lactone trimers featuring a methylene-tethered linkage from Carpesium faberi

Three anti-inflammatory trimeric compounds constructed from carabrol-type sesquiterpenoids through a methylene-tethered linkage were characterized from Carpesium faberi.

Mogroside V improves porcine oocyte in vitro maturation and subsequent embryonic development

Oocyte in vitro maturation (IVM) plays a pivotal role in in vitro embryo production. However, the efficiency of IVM is still low and needs to be further improved. In the present study, we evaluated the beneficial effects of mogroside V, an extract derived from Siraitia grosvenorii, on oocyte IVM. Porcine cumulus-oocyte complexes were cultured in IVM medium supplemented or not supplemented with mogroside V for 40 h. We found that mogroside V supplementation increased the percentage of oocyte first polar body extrusion and improved subsequent blastocyst formation after parthenogenetic activation. Furthermore, mogroside V reduced the levels of reactive oxygen species (ROS) and increased the mRNA expression of oxidative stress-related genes (SOD, CAT and SIRT1). Moreover, mogroside V supplementation enhanced the mitochondrial content, mtDNA copy number, mitochondrial membrane potential (ΔΨm), ATP generation, and the relative mRNA expression of mitochondria-related genes (PGC-1α and TFAM). In summary, our findings demonstrate that mogroside V supplementation reduces intracellular ROS levels and enhances mitochondrial function to promote porcine oocyte IVM.

Two New Cucurbitane Glycosides from the Fruits of Siraitia grosvenori

Two novel cucurbitane glycosides, named as 11-oxomogroside III A₁ and 7β-methoxy-mogroside V, along with sixteen known ones were isolated from the fruits of Siraitia grosvenori SWINGLE. The structures of the new compounds were characterized by chemical and extensive spectral methods.

Stigmastane-type steroids with unique conjugated Δ7,9(11) diene and highly oxygenated side chains from the twigs of Vernonia amygdalina

Veramyosides A-J, eleven undescribed stigmastane-type steroids, including one aglycone and ten glycosides, along with three known homologues were isolated from the twigs of Vernonia amygdalina Delile (compositae). All compounds featured a stigmastane-type steroid skeleton with a unique conjugated Δ^7,9(11) diene segment and highly oxygenated side chains with a γ-lactone or an α, β-unsaturated five-membered lactone ring. The structures of veramyosides A-J and their absolute configurations were unambiguously elucidated by HR-ESI-MS, extensive NMR spectroscopy, in situ dimolybdenum CD methods, modified Mosher's method, quantum chemical calculation of their ECD curves, and CD comparison methods on basis of their biogenetic pathway. In addition, all isolates were investigated for their effects on RXRα transcription, and their effects on the NF-κB signaling pathway were also evaluated.

New podolactones from the seeds of Podocarpus nagi and their anti-inflammatory effect

Podolactones are a class of structural diverse diterpenoid lactones, mainly isolated from the Podocarpus species. Several bioactivities have been disclosed for podolactones, including cytotoxicity and anti-atherosclerosis. In this study, the seeds of P. nagi were isolated by comprehensive chromatographic methods to obtain three new podolatones, named nagilactone B 1-O-β-D-glucoside (1), nagilactone N3 3-O-β-D-glucoside (2), and 2-epinagilactone B (3), as well as a known compound, nagilactone B (4). Their structures were determined by analyses of NMR and HRESIMS data. Compounds 1 and 2 significantly inhibited nitric oxide (NO) production on LPS-stimulated RAW264.7 macrophages, with IC₅₀ values of 0.18 ± 0.04 and 0.53 ± 0.03 μM, respectively. Indomethacin (IC₅₀ 4.21 ± 0.32 μM) was used as a positive control. Compound 1 suppressed the expression of inducible NO synthase (iNOS) in a concentration-dependent manner, mediating through inhibiting nuclear factor-κB (NF-κB) activity. This is the first report regarding the anti-inflammatory effect of podolactones, which could be potential anti-inflammatory agents.