Sugars with nitrogen in the ring isolated from the leaves of Morus bombycis

Expression of Recombinant Human α-Glucosidase in HEK293 Cells

In mammals, intestinal α-glucosidase exists as a maltase-glucoamylase complex (MGAM) and a sucrase-isomaltase complex (SI). In this study, we transiently expressed human MGAM and SI in human embryonic kidney 293 (HEK293) cells. At pH 6.0 and 37 °C, the MGAM-expressing HEK293 cells extract (MGE) exhibited maltase, glucoamylase, and isomaltase activities but not sucrase activity, whereas the SI-expressing HEK293 cells extract (SIE) exhibited sucrase, isomaltase, and maltase activities but not glucoamylase activity. The apparent Km value of the MGE for maltose hydrolysis was 14-26% of that of the SIE for maltose, sucrose, and isomaltose hydrolysis. The respective apparent Vmax values of the MGE and SIE for sucrose and isomaltose hydrolysis were 0% and 6% and 10% and 42% of those for maltose hydrolysis. These results indicated that the maltase activities of MGAM and SI were higher than those of sucrase and isomaltase.

Efficient synthesis for each of the eight stereoisomers of the iminosugars lentiginosine and 1,4-dideoxy-1,4-imino-D-arabinitol (DAB)

Herein, we describe the efficient, diastereoselective syntheses of the iminosugars 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) 1b, lentiginosine 3a, and the seven stereoisomers of each of these iminosugars starting from 4-benzoyl-6-deoxy-6-iodoglycopyranosides 47 with yields ranging from 38 % to 68 % for the DAB and isomers 1a-1h and from 44 % to 89 % for the lentiginosine and isomers 3a-3h. We also report the syntheses of the eight stereoisomers of the 4-benzoyl-6-deoxy-6-iodoglycopyranosides 47 from commercially available sugars. Key to the iminosugar syntheses is a single multistep reaction that converts the 4-benzoyl-6-deoxy-6-iodoglycopyranosides 47 to a vinyl pyrrolidine through a one-pot zinc mediated reductive elimination, followed by a reductive amination and finally an intramolecular nucleophilic substitution. Strategic selection of the amine utilized in the reductive amination and the functionalization of the intermediate carbon-carbon double bond provides access to a vast array of iminosugars.

Structures, activities, and putative biosynthetic pathways of characteristic polyphenolic compounds from Morus plants: A review

Morus plants played a pivotal role in ancient Chinese sericulture and silk production, which served as critical components of economy and culture. Besides, many parts of mulberry trees, including roots, leaves, stems, and fruits, hold various medicinal value, and have been utilized in traditional medicine for thousands of years. The chemical composition of mulberry has been reported in many literatures, while the characteristic compounds have not been systematically summarized. In this review, we focused on the polyphenolic compounds in mulberry, including flavonoids, 2-arylbenzofurans, and Diels-Alder (D-A) adducts, and summarized their structural features, structure-activity relationships, and potential biosynthetic pathways. The results revealed a characteristic class of 2'-hydroxylated flavonoids and stilbenes which played an important role in the biosynthesis of downstream 2-arylbenzofurans and D-A adducts in mulberry but had been overlooked by most studies. The prenylated modifications of different compounds were also discussed and their function as precursors of D-A adducts was emphasized. We also describe the effects of different modifications on biological activities. Besides, the chemical composition of Morus was most similar to that of Artocarpus in the Moraceae family in that they had almost identical characteristic compounds. Finally, a putative total biosynthetic pathway of D-A adducts in mulberry was proposed based on structure derivation and combination of verified reactions. This review contributes to the understanding of the biological activity and biosynthesis of the characteristic components of Morus plants.

Use of human Caco-2 cells and HPAE-PAD for α-glucosidase assay

To measure α-glucosidase activity, rat intestinal acetone powder is commonly used as a source of α-glucosidase, and the mutarotase-glucose oxidase (GOD) methods commonly used to quantitate glucose produced by enzymatic hydrolysis of the substrates. In this study, we compared human Caco-2 cell extracts with rat intestinal acetone powder extracts. We also compared high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD) with the mutarotase-GOD method. The sensitivity of HPAE-PAD was higher than that of mutarotase-GOD. The glucose concentration quantified by HPAE-PAD was similar to that quantified using the mutarotase-GOD method. In the maltase reaction, 1-deoxynojirimycin (1-DNJ) exerted a more potent inhibitory effect on human enzymes than on rat enzymes. This order was reversed during the sucrase reaction. These results suggested that the combined use of Caco-2 cell extracts and HPAE-PAD is advantageous for use in α-glucosidase-related basic research.

Biosynthetic pathways and related genes regulation of bioactive ingredients in mulberry leaves

Mulberry leaves are served not only as fodder for silkworms but also as potential functional food, exhibiting nutritional and medical benefits due to the complex and diverse constituents, including alkaloids, flavonoids, phenolic acids, and benzofurans, which possess a wide range of biological activities, such as anti-diabete, anti-oxidant, anti-inflammatory, and so on. Nevertheless, compared with the well-studied phytochemistry and pharmacology of mulberry leaves, the current understanding of the biosynthesis mechanisms and regulatory mechanisms of active ingredients in mulberry leaves remain unclear. Natural resources of these active ingredients are limited owing to their low contents in mulberry leaves tissues and the long growth cycle of mulberry. Biosynthesis is emerging as an alternative means for accumulation of the desired high-value compounds, which can broaden channels for their large-scale green productions. Therefore, this review summarizes the recent research advance on the correlative key genes, enzyme biocatalytic reactions and biosynthetic pathways of valuable natural ingredients (i.e. alkaloids, flavonoids, phenolic acids, and benzofurans) in mulberry leaves, thereby offering important insights for their further biomanufacturing.

Clinical potential and mechanistic insights of mulberry (Morus alba L.) leaves in managing type 2 diabetes mellitus: Focusing on gut microbiota, inflammation, and metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Natural herbs are gradually gaining recognition for their efficacy and safety in preventing diabetes and improving quality of life. Morus alba L. is a plant widely grown in Asia and is a traditional Chinese herb with a long history of use. Furthermore, several parts of Morus alba L. have been found to have significant health benefits. In particular, mulberry (Morus alba L.) leaves (ML) have been shown in human and animal studies to be promising hypoglycemic agents that can reduce or prevent glucolipid metabolism disorders caused by imbalances in the gut microbiota, inflammation, and oxidative stress and have demonstrated significant improvements in glucose metabolism-related markers, effectively lowering blood glucose, and reducing hyperglycemia-induced target organ damage.

AIM OF THE STUDY

This review briefly summarizes the methods for obtaining ML's bioactive components, elaborates on the clinical potential of the relevant components in managing type 2 diabetes mellitus (T2DM), and focuses on the therapeutic mechanisms of gut microbiota, inflammation, oxidative stress, and metabolism, to provide more inspiration and directions for future research in the field of traditional natural plants for the management of T2DM and its complications.

MATERIALS AND METHODS

Research on ML and its bioactive components was mainly performed using electronic databases, including PubMed, Google Scholar, and ScienceNet, to ensure the review's quality. In addition, master's and doctoral theses and ancient documents were consulted.

RESULTS

In clinical studies, we found that ML could effectively reduce blood glucose, glycated hemoglobin, and homeostasis model assessment of insulin resistance in T2DM patients. Furthermore, many in vitro and in vivo experiments have found that ML is involved in various pathways that regulate glucolipid metabolism and resist diabetes while alleviating liver and kidney damage.

CONCLUSIONS

As a potential natural anti-diabetic phytomedicine, an in-depth study of ML can provide new ideas and valuable references for applying traditional Chinese medicine to treat T2DM. While continuously exploring its clinical efficacy and therapeutic mechanism, the extraction method should be optimized to improve the efficacy of the bioactive components. in addition, further research on the dose-response relationship of drugs to determine the effective dose range is required.

Enzymatic transformation of esculetin as a potent class of α-glucosidase inhibitors

A rapid and simple enzymatic transformation of the representative coumarin esculetin (1) with polyphenol oxidase originating from Agaricus bisporus afforded five new oxidized metabolites, esculetinins A (2), B (3), C (4), D (5), and E (6), together with the known compound isoeuphorbetin (7). The structures of the oligomerized transformation products were established on the basis of spectroscopic interpretations. The esculetin oligomers 2 and 3 revealed highly enhanced inhibitory activities against α-glucosidase, with IC₅₀ values of 0.7 ± 0.1 and 2.3 ± 0.3μM, respectively, as compared to the original esculetin. Kinetic analysis also exhibited that the two new potent metabolites 2 and 3 have competitive modes of action.

Evaluation of mulberry leaves’ hypoglycemic properties and hypoglycemic mechanisms

The effectiveness of herbal medicine in treating diabetes has grown in recent years, but the precise mechanism by which it does so is still unclear to both medical professionals and diabetics. In traditional Chinese medicine, mulberry leaf is used to treat inflammation, colds, and antiviral illnesses. Mulberry leaves are one of the herbs with many medicinal applications, and as mulberry leaf study grows, there is mounting evidence that these leaves also have potent anti-diabetic properties. The direct role of mulberry leaf as a natural remedy in the treatment of diabetes has been proven in several studies and clinical trials. However, because mulberry leaf is a more potent remedy for diabetes, a deeper understanding of how it works is required. The bioactive compounds flavonoids, alkaloids, polysaccharides, polyphenols, volatile oils, sterols, amino acids, and a variety of inorganic trace elements and vitamins, among others, have been found to be abundant in mulberry leaves. Among these compounds, flavonoids, alkaloids, polysaccharides, and polyphenols have a stronger link to diabetes. Of course, trace minerals and vitamins also contribute to blood sugar regulation. Inhibiting alpha glucosidase activity in the intestine, regulating lipid metabolism in the body, protecting pancreatic -cells, lowering insulin resistance, accelerating glucose uptake by target tissues, and improving oxidative stress levels in the body are some of the main therapeutic properties mentioned above. These mechanisms can effectively regulate blood glucose levels. The therapeutic effects of the bioactive compounds found in mulberry leaves on diabetes mellitus and their associated molecular mechanisms are the main topics of this paper’s overview of the state of the art in mulberry leaf research for the treatment of diabetes mellitus.

Investigation on Antioxidant Activity and Different Metabolites of Mulberry (Morus spp.) Leaves Depending on the Harvest Months by UPLC-Q-TOF-MS with Multivariate Tools

The changes in active components in mulberry leaves harvested in different months and their antioxidant activities were investigated. Ultra-high-performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) with multivariate statistical tools was used to investigate the chemical constituents in the extracts of mulberry leaves. The results indicated that mulberry leaves were rich in phenolic acids, flavonoids, organic acids, and fatty acid derivatives. In addition, 25 different compounds were identified in the different batches of mulberry leaves. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity was measured to evaluate the in vitro antioxidant activities of mulberry leaves. Among the four batches, batch A, harvested in December, exhibited the strongest DPPH radical-scavenging activity, while batch B, harvested in March, showed the weakest activity. This was related to the total phenolic content in the mulberry leaves of each batch. The optimal harvest time of mulberry leaves greatly influences the bioactivity and bioavailability of the plant.

Exosome-like nanoparticles from Mulberry bark prevent DSS-induced colitis via the AhR/COPS8 pathway

Bark protects the tree against environmental insults. Here, we analyzed whether this defensive strategy could be utilized to broadly enhance protection against colitis. As a proof of concept, we show that exosome-like nanoparticles (MBELNs) derived from edible mulberry bark confer protection against colitis in a mouse model by promoting heat shock protein family A (Hsp70) member 8 (HSPA8)-mediated activation of the AhR signaling pathway. Activation of this pathway in intestinal epithelial cells leads to the induction of COP9 Constitutive Photomorphogenic Homolog Subunit 8 (COPS8). Utilizing a gut epithelium-specific knockout of COPS8, we demonstrate that COPS8 acts downstream of the AhR pathway and is required for the protective effect of MBELNs by inducing an array of anti-microbial peptides. Our results indicate that MBELNs represent an undescribed mode of inter-kingdom communication in the mammalian intestine through an AhR-COPS8-mediated anti-inflammatory pathway. These data suggest that inflammatory pathways in a microbiota-enriched intestinal environment are regulated by COPS8 and that edible plant-derived ELNs may hold the potential as new agents for the prevention and treatment of gut-related inflammatory disease.

Cyclisations and Strategies for Stereoselective Synthesis of Piperidine Iminosugars

This personal account focuses on synthesis of polyhydroxylated piperidines, a subset of compounds within the iminosugar family. Cyclisations to form the piperidine ring include reductive amination, substitution via amines, iminium ions and cyclic nitrones, transamidification (N-acyl transfer), addition to alkenes, ring contraction and expansion, photoinduced electron transfer, multicomponent Ugi reaction and ring closing metathesis. Enantiomerically pure piperidines are obtained from chiral pool precursors (e. g. sugars, amino acids, Garner's aldehyde) or asymmetric reactions (e. g. epoxidation, dihydroxylation, aminohydroxylation, aldol, biotransformation). Our laboratory have contributed cascades based on reductive amination from glycosyl azide precursors as well as Huisgen azide-alkene cycloaddition. The latter's combination with allylic azide rearrangement has given substituted piperidines, including those with quaternary centres adjacent to nitrogen.

A comprehensive review on the production, pharmacokinetics and health benefits of mulberry leaf iminosugars: Main focus on 1-deoxynojirimycin, d-fagomine, and 2-O-ɑ-d-galactopyranosyl-DNJ

Mulberry leaves are rich in biologically active compounds, including phenolics, polysaccharides, and alkaloids. Mulberry leaf iminosugars (MLIs; a type of polyhydroxylated alkaloids), in particular, have been gaining increasing attention due to their health-promoting effects, including anti-diabetic, anti-obesity, anti-hyperglycemic, anti-hypercholesterolemic, anti-inflammatory, and gut microbiota-modulatory activities. Knowledge regarding the in vivo bioavailability and bioactivity of MLIs are crucial to understand their role and function and human health. Therefore, this review is aimed to comprehensively summarize the existing studies on the oral pharmacokinetics and the physiological significance of selected MLIs (i.e.,1-deoxynojirimycin, d-fagomine, and 2-O-ɑ-d-galactopyranosyl-DNJ). Evidence have suggested that MLIs possess relatively good uptake and safety profiles, which support their prospective use for oral intake; the therapeutic potential of these compounds against metabolic and chronic disorders and the underlying mechanisms behind these effects have also been studied in in vitro and in vivo models. Also discussed are the biosynthetic pathways of MLIs in plants, as well as the agronomic and processing factors that affect their concentration in mulberry leaves-derived products.

Inhibitory effect of Morus australis leaf extract and its component iminosugars on intestinal carbohydrate-digesting enzymes

α-Amylase and α-glucosidase are central enzymes involved in the digestion of carbohydrates. α-Glucosidase includes maltase-glucoamylase and sucrase-isomaltase. We have previously performed the kinetic analysis of the inhibitory effects of powdered or roasted Morus australis leaf extract and its component iminosugars, such as 1-deoxynojirimycin (1-DNJ), fagomine, and 2-O-α-d-galactopyranosyl deoxynojirimycin (GAL-DNJ) on the activity of maltase. In this study, we analyzed the inhibitory effects of the aforementioned compounds against α-amylase, glucoamylase, sucrase, and isomaltase. At pH 6.0 and 37 °C, each leaf extract sample inhibited glucoamylase, sucrase, and isomaltase but not α-amylase. 1-DNJ and fagomine showed weak α-amylase inhibitory activity while GAL-DNJ exhibited none. 1-DNJ showed a strong glucoamylase, sucrase, and isomaltase inhibitory potential. The inhibitory potential against these three enzymes was 18-500 and 1500-3000-fold higher in the case of 1-DNJ than that observed in the case of fagomine and GAL-DNJ, respectively. We also observed that the indigestible dextrin could considerably inhibit α-amylase. When the powdered M. australis leaf extract was blended with indigestible dextrin, the mixture inhibited α-amylase, as well as maltase, glucoamylase, sucrase, and isomaltase. These results suggest that the ingestion of the leaf extract blended with indigestible dextrin might have the potential to efficiently suppress the postprandial blood glucose level increase.

Kinetic analysis of inhibition of α-glucosidase by leaf powder from Morus australis and its component iminosugars

Abbreviations

1-DNJ: 1-deoxynojirimycin; GAL-DNJ: 2-O-α-D-galactopyranosyl-DNJ

Anti-diabetic potential of plant alkaloids: Revisiting current findings and future perspectives

Diabetes mellitus (DM) is a chronic metabolic disease which causes millions of death all over the world each year, and its incidence is on increase. The most prevalent form, type 2 DM, is characterized by insulin resistance and β-cell dysfunction, whereas type 1 DM is due to insulin deficiency as a result of β-cell destruction. Various classes of synthetic drugs have been developed to regulate glucose homeostasis and combat the development of late-diabetic complications. However, several of these chemical agents are either sub-optimal in their effect and/or may have side effects. Biologically, alkaloids unveiled a wide range of therapeutic effects including anti-diabetic properties. The chemical backbones of these compounds have the potential to interact with a wide range of proteins involved in glucose homeostasis, and thus they have received increasing attention as reliable candidates for drug development. This review sets out to investigate the anti-diabetic potential of plant alkaloids (PAs), and therefore, scientific databases were comprehensively screened to highlight the biological activity of 78 PAs with a considerable anti-diabetic profile. There are not enough clinical data available for these phytochemicals to follow their fingerprint in human, but current studies generally recommending PAs as potent α-glucosidase inhibitors. Except for some classes of monoterpene alkaloids, other compounds showed similar features as well as the presently available anti-diabetic drugs such as amino sugars and other relevant drugs. Moreover, the evidence suggests that PAs have the potential to be used as alternative additives for the treatment of DM, however, further in vitro and in vivo studies are needed to validate these findings.

Supplementation ofBacillus amyloliquefaciensAS385 culture broth powder containing 1-deoxynojirimycin in a high-fat diet altered the gene expressions related to lipid metabolism and insulin signaling in mice epididymal white adipose tissue

Supplementation ofBacillus amyloliquefaciensAS385 culture broth powder in high-fat diet restored adiposity, glucose tolerance and insulin sensitivity in mice.

A green chemical oligomerization of phloroglucinol induced by plasma as novel α-glucosidase inhibitors

A new facile method was developed for simple green synthesis of methylene-bridged phloroglucinol oligomers using nonthermal dielectric barrier discharge (DBD) plasma in methanolic solution. The chemical structures of these newly generated oligomers 2-5 were determined by interpretation of the spectroscopic data, and the inhibitory activity toward α-glucosidase of all isolates was evaluated. The unusual phloroglcuinol pentamer 5 connected by four methylene linkages showed a much higher potential inhibitory effect against α-glucosidase than the other generated oligomers 2-4 and appeared to be a promising lead for development as a potential antidiabetic agent. Abbreviations: T2DM, type2 diabetes mellitus; DBD, dielectric barrier discharge; HPLC, high-performance liquid chromatography; IC50, 50% inhibition concentration; NMR, nuclear magnetic resonance; FABMS, fastatom bombardment mass spectrometry.

Study of the effect of the herbal composition SR2004 on hemoglobin A1c, fasting blood glucose, and lipids in patients with type 2 diabetes mellitus

Background

Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by raised blood glucose levels and peripheral insulin resistance. It is an increasingly prevalent global healthcare concern. Conventional treatment options are limited and in this context, there is renewed interest in evaluating the clinical and biological effects of traditional therapies. We assess the effect of a new herbal composition SR2004 on the hemoglobin A1c (HbA1c), fasting blood glucose, and lipid profiles of patients with T2DM.

Methods

This is a single center, unblinded, prospective interventional study conducted in Israel. The composition SR2004 includes Morus alba, Artemisia dracunculus, Urtica dioica, Cinnamomum zeylanicum, and Taraxacum officinale. One hundred and nineteen patients with diagnosed T2DM were enrolled and received SR2004 in addition to their usual medications. HbA1c, fasting blood glucose, and lipid profiles at 12 weeks were compared with baseline. In addition, the tolerability and side effects of SR2004 were recorded.

Results

One hundred and three patients completed 12 weeks of follow-up (87%) and were included in the results. At 12 weeks, HbA1c reduced from 9.0% to 7.1% (22%; p < 0.0001), mean blood glucose decreased from 211 mg/dL to 133 mg/dL (37% reduction; p < 0.0001), mean total cholesterol to 185 mg/dL (13% reduction; p < 0.01) and mean serum triglycerides to160 mg/dL (a reduction of 40% from baseline; p < 0.001). Twelve patients (12%) had no response with SR2004 supplementation. In addition, of thirteen patients who took insulin at baseline, five required only oral hypoglycemics and another five reduced their daily insulin requirements by 30% at 12 weeks. Clinical observations included improvements in vasculopathy, including reversal of established retinopathic changes in two patients.

No major adverse effects were observed, with minor abdominal symptoms reported in sixteen patients (16%).

Conclusion

SR2004 supplementation significantly reduced HbA1c, blood glucose, and lipids with good tolerability and no observed adverse interactions with conventional medications. Some interesting findings relating to the reversal of microvascular phenomena warrant further research to elucidate the mechanisms of action of this novel composition.

1-Deoxynojirimycin: Sources, Extraction, Analysis and Biological Functions

1-Deoxynojirimycin (DNJ), a natural polyhydroxylated piperidine alkaloid, is attracting growing attention due to its important biological functions. This paper introduces the discovery and origins of DNJ, its extraction, purification, and physiological functions in the treatment of diabetes. The mechanisms of DNJ in the inhibition of fat accumulation and tumor cell metastasis are also discussed. In addition, the prospects and challenges of DNJ for practical production are proposed. This work aims to provide technical advice on obtaining DNJ and a fuller understanding of its biological activities.

Plasma-Induced Degradation of Quercetin Associated with the Enhancement of Biological Activities

Nonthermal plasma is a promising technology to improve the safety and to extend the shelf-life of various minimally processed foods. However, research on plasma-induced systemic degradation related to changes in chemical structure and biological activity is still very limited. In this study, the enhancement of biological activity and the mechanism of degradation of the most common type of flavonol, quercetin, induced by a dielectric barrier discharge (DBD) plasma were investigated. Quercetin is dissolved in methanol and exposed to nonthermal DBD plasma for 5, 10, 20, and 30 min. The quercetin treated with the plasma for 20 min showed rapidly increased α-glucosidase inhibitory and radical scavenging activities compared to those of parent quercetin. The structures of the degradation products 1-3 from the quercetin treated with the plasma for 20 min were isolated and characterized by interpretation of their spectroscopic data. Among the generated products, (±)-alphitonin (1) exhibited significantly improved antidiabetic and antioxidant properties compared to those of the parent quercetin. The antidiabetic and antioxidant properties were measured by α-glucosidase inhibition and 1,1-diphenyl-2-picrylhydrazyl radical scavenging assays. These results suggested that structural changes in quercetin induced by DBD plasma might be attributable to improving the biological activity.

Accumulation of Flavonoid Glycosides and UFGT Gene Expression in Mulberry Leaves (Morus alba L.) before and after Frost

In order to determine the molecular mechanism underlying the influence of frost on chemical changes in mulberry leaves, the UFGT activity, expression level, and accumulation of flavonoid glycosides in mulberry leaves (Morus alba L.) were studied. The expression of UFGT gene was investigated by quantitative real-time PCR (qRT-PCR) and the UFGT activity, accumulation of flavonoid glycosides was studied by high performance liquid chromatography. Then, the correlation between the expression level of UFGT, the UFGT activity, and the flavonoid glycosides accumulation with temperature was explored. The accumulation of isoquercitrin and astragalin is significantly positively correlated with UFGT gene expression and UFGT activity. On the contrary, the average temperature was significantly negatively correlated with the level of UFGT gene expression and UFGT activity. The results show that after frost, low temperature can induce the expression of UFGT gene in mulberry leaves, resulting in the accumulation of flavonoid glycosides.

The complete chloroplast genome sequence of Morus cathayana and Morus multicaulis, and comparative analysis within genus Morus L

Trees in the Morus genera belong to the Moraceae family. To better understand the species status of genus Morus and to provide information for studies on evolutionary biology within the genus, the complete chloroplast (cp) genomes of M. cathayana and M. multicaulis were sequenced. The plastomes of the two species are 159,265 bp and 159,103 bp, respectively, with corresponding 83 and 82 simple sequence repeats (SSRs). Similar to the SSRs of M. mongolica and M. indica cp genomes, more than 70% are mononucleotides, ten are in coding regions, and one exhibits nucleotide content polymorphism. Results for codon usage and relative synonymous codon usage show a strong bias towards NNA and NNT codons in the two cp genomes. Analysis of a plot of the effective number of codons (ENc) for five Morus spp. cp genomes showed that most genes follow the standard curve, but several genes have ENc values below the expected curve. The results indicate that both natural selection and mutational bias have contributed to the codon bias. Ten highly variable regions were identified among the five Morus spp. cp genomes, and 154 single-nucleotide polymorphism mutation events were accurately located in the gene coding region.

Potato plants with genetically engineered tropane alkaloid precursors

Solanum tuberosum tropinone reductase I reduced tropinone in vivo. Suppression of tropinone reductase II strongly reduced calystegines in sprouts. Overexpression of putrescine N -methyltransferase did not alter calystegine accumulation. Calystegines are hydroxylated alkaloids formed by the tropane alkaloid pathway. They accumulate in potato (Solanum tuberosum L., Solanaceae) roots and sprouting tubers. Calystegines inhibit various glycosidases in vitro due to their sugar-mimic structure, but functions of calystegines in plants are not understood. Enzymes participating in or competing with calystegine biosynthesis, including putrescine N-methyltransferase (PMT) and tropinone reductases (TRI and TRII), were altered in their activity in potato plants by RNA interference (RNAi) and by overexpression. The genetically altered potato plants were investigated for the accumulation of calystegines and for intermediates of their biosynthesis. An increase in N-methylputrescine provided by DsPMT expression was not sufficient to increase calystegine accumulation. Overexpression and gene knockdown of StTRI proved that S. tuberosum TRI is a functional tropinone reductase in vivo, but no influence on calystegine accumulation was observed. When StTRII expression was suppressed by RNAi, calystegine formation was severely compromised in the transformed plants. Under phytochamber and green house conditions, the StTRII RNAi plants did not show phenotypic alterations. Further investigation of calystegines function in potato plants under natural conditions is enabled by the calystegine deprived StTRII RNAi plants.

Evaluation of a Standardized Extract from Morus alba against α-Glucosidase Inhibitory Effect and Postprandial Antihyperglycemic in Patients with Impaired Glucose Tolerance: A Randomized Double-Blind Clinical Trial

To evaluate the antihyperglycemic effect of a standardized extract of the leaves of Morus alba (SEMA), the present study was designed to investigate the α-glucosidase inhibitory effect and acute single oral toxicity as well as evaluate blood glucose reduction in animals and in patients with impaired glucose tolerance in a randomized double-blind clinical trial. SEMA was found to inhibit α-glucosidase at a fourfold higher level than the positive control (acarbose), in a concentration-dependent manner. Moreover, blood glucose concentration was suppressed by SEMA in vivo. Clinical signs and weight changes were observed when conducting an evaluation of the acute toxicity of SEMA through a single-time administration, with clinical observation conducted more than once each day. After administration of the SEMA, observation was for 14 days; all of the animals did not die and did not show any abnormal symptoms. In addition, the inhibitory effects of rice coated with SEMA were evaluated in a group of impaired glucose tolerance patients on postprandial glucose and a group of normal persons, and results showed that SEMA had a clear inhibitory effect on postprandial hyperglycemia in both groups. Overall, SEMA showed excellent potential in the present study as a material for improving postprandial hyperglycemia.

Effect of Wheat Flour Noodles with Bombyx mori Powder on Glycemic Response in Healthy Subjects

Recent trial results suggest that the consumption of a low glycemic index (GI) diet is beneficial in the prevention of high blood glucose levels. Identifying active hypoglycemic substances in ordinary foods could be a significant benefit to the management of blood glucose. It has been hypothesized that noodles with Bombyx mori powder are a low GI food. We evaluated GI and changes in postprandial glucose levels following consumption of those noodles and compared them with those following consumption of plain wheat flour noodles (control) and glucose (reference) in healthy subjects. Thirteen males (age: 34.2±4.5 years, body mass index: 23.2±1.1 kg/m2) consumed 75 g carbohydrate portions of glucose and the 2 kinds of noodle after an overnight fast. Capillary blood was measured at time 0 (fasting), 15, 30, 45, 60, 90, 120, and 180 min from the start of each food intake. The GI values were calculated by taking the ratio of the incremental area under the blood glucose response curve (IAUC) for the noodles and glucose. There was a significant difference in postprandial glucose concentrations at 30 and 45 min between the control noodles and the noodles with Bombyx mori powder: the IAUC and GI for the noodles with Bombyx mori powder were significantly lower than those for glucose and plain wheat flour noodles. The wheat flour noodles with Bombyx mori powder could help prevent an increase in postprandial glucose response and possibly provide an alternative to other carbohydrate staple foods for glycemic management.

Randomized, Double-Blinded, Double-Dummy, Active-Controlled, and Multiple-Dose Clinical Study Comparing the Efficacy and Safety of Mulberry Twig (Ramulus Mori, Sangzhi) Alkaloid Tablet and Acarbose in Individuals with Type 2 Diabetes Mellitus

Aims. To evaluate the efficacy and safety of mulberry twig alkaloid (SZ-A) tablet compared with acarbose in patients with type 2 diabetes. Methods. This clinical trial enrolled 38 patients who were randomized into two groups (SZ-A: 23; acarbose: 15) and were treated for 24 weeks. Patients and clinical trial staffs were masked to treatment assignment throughout the study. The primary outcome measures were glycated hemoglobin (HbA1c) and 1-hour and 2-hour postprandial and fasting plasma glucose levels from baseline to the end of treatment. Analysis included all patients who completed this study. Results. By the end of this study, HbA1c level in SZ-A group was decreased from baseline significantly (P < 0.001). No significant difference was found when compared with acarbose group (P = 0.652). Similarly, 1-hour and 2-hour postprandial plasma glucose levels in SZ-A group were decreased from baseline statistically (P < 0.05), without any significant differences compared with acarbose group (P = 0.748 and 0.558, resp.). The fasting plasma glucose levels were not significantly changed in both groups. One of 23 patients in SZ-A group (4.76%) and 5 of 15 patients in acarbose group (33.33%) suffered from gastrointestinal adverse events. Conclusions. Compared with acarbose, SZ-A tablet was effective and safe in glycemic control in patients with type 2 diabetes.

A novel α-glucosidase inhibitory constituent from Uncaria gambir

Bioactivity-guided fractionation of an aqueous methanolic extract of manufactured gambir product from Uncaria gambir with in vitro α-glucosidase inhibitory activity was performed to isolate a novel prenyl resorcinol derivative (1) together with seven known compounds, including two flavone glycosides (2, 3), three catechin analogues (4-6), and two simple phenolics (7, 8). Structures of the isolated compounds were determined by analysis of physical and spectroscopic data (NMR, UV, [α]D, and MS). All isolates were evaluated for in vitro α-glucosidase inhibitory activity. Among the compounds, novel compound 1, possessing an unprecedented spirocyclopropane ring in the molecule, showed the most potent α-glucosidase inhibitory activity in this assay. On the other hand, compounds 4 and 7 showed less potent inhibitory effects in this same bioassay, with half-maximal inhibitory concentration values of 17.3 ± 1.0 μM and 27.0 ± 0.9 μM, respectively.

Concise synthesis of calystegines B2 and B3via intramolecular Nozaki-Hiyama-Kishi reaction

The key step in the concise syntheses of calystegine B2 and its C-2 epimer calystegine B3 was the construction of cycloheptanone 8via an intramolecular Nozaki-Hiyama-Kishi (NHK) reaction of 9, an aldehyde containing a Z-vinyl iodide. Vinyl iodide 9 was obtained by the Stork olefination of aldehyde 10, derived from carbohydrate starting materials. Calystegines B2 (3) and B3 (4) were synthesized from d-xylose and l-arabinose derivatives respectively in 11 steps in excellent overall yields (27% and 19%).

Identification and Determination of the Polyhydroxylated Alkaloids Compounds with α-Glucosidase Inhibitor Activity in Mulberry Leaves of Different Origins

Mulberry leaves have commonly been utilized in China as a herbal medicine for the treatment of diabetes for thousands of years. To evaluate the quality, an ultra-high performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC-Q-TOF/MS) method was developed for identification of polyhydroxylated alkaloids with α-glucosidase inhibitor activity in mulberry leaf. As a result, five alkaloid compounds were identified or tentatively characterized. Among them, the compound 1-deoxynojirimycin (DNJ) was selected as the most typical and active chemical marker and quantified using an improved high performance liquid chromatography (HPLC) normal phase coupled with evaporative light scattering detector (ELSD) method. The developed method was fully validated in terms of linearity, sensitivity, precision and repeatability, as well as recovery, and subsequently applied to evaluate twenty-nine batches of mulberry leaves from different collections. From the analytical data it was discovered that the average content of DNJ is 1.53 mg/g, while the total contents of DNJ in the 29 mulberry leaf sample ranged from 0.20 to 3.88 mg/g, which suggested remarkable differences, although it reached the highest levels in early August. These data may provide an important reference for the quality of mulberry leaves used as herbal medicine for the treatment of diabetes or as a material to obtain the DNJ of α-glucosidase inhibitor or as a functional food.

Effect of (D)-fagomine on excreted Enterobacteria and weight gain in rats fed a high-fat high-sucrose diet

OBJECTIVE

Becoming overweight has been related to elevated levels of Enterobacteriales in the gut. d-Fagomine is an iminosugar that has been shown to selectively agglutinate Enterobacteriales in vitro. The goal of this work is to establish whether d-fagomine exerts a similar effect in vivo and whether this has any downstream consequences on weight gain.

METHODS

The rats were fed a high-fat high-sucrose diet (HFHS) supplemented with d-fagomine (or not; for comparison) or a standard diet for 5 weeks. The levels of total bacteria, Enterobacteriales and Escherichia coli were determined in fecal samples by performing quantitative real-time polymerase chain reactions on DNA.

RESULTS

Whereas the total levels of bacteria were independent of the diet, rats fed HFHS (without d-fagomine) excreted significantly higher proportions of Enterobacteriales and E. coli than those fed a standard diet. The levels of Enterobacteriales and E. coli of the rats given HFHS with d-fagomine were similar to those of the rats fed a standard diet. Compared to the standard group, rats fed HFHS with d-fagomine gained significantly less weight (15.3%) than those fed HFHS (20.9%).

CONCLUSION

d-Fagomine reduces the amount of Enterobacteriales excreted by rats fed HFHS and this may help to avert becoming obese.

Draft genome sequence of the mulberry tree Morus notabilis

Human utilization of the mulberry–silkworm interaction started at least 5,000 years ago and greatly influenced world history through the Silk Road. Complementing the silkworm genome sequence, here we describe the genome of a mulberry species Morus notabilis. In the 330-Mb genome assembly, we identify 128 Mb of repetitive sequences and 29,338 genes, 60.8% of which are supported by transcriptome sequencing. Mulberry gene sequences appear to evolve ~3 times faster than other Rosales, perhaps facilitating the species’ spread worldwide. The mulberry tree is among a few eudicots but several Rosales that have not preserved genome duplications in more than 100 million years; however, a neopolyploid series found in the mulberry tree and several others suggest that new duplications may confer benefits. Five predicted mulberry miRNAs are found in the haemolymph and silk glands of the silkworm, suggesting interactions at molecular levels in the plant–herbivore relationship. The identification and analyses of mulberry genes involved in diversifying selection, resistance and protease inhibitor expressed in the laticifers will accelerate the improvement of mulberry plants.

Mulberry trees are the primary food source for silkworms, which are reared for the production of silk. In this study, He et al. present the draft genome sequence of Morus notabilis and find that it evolved significantly faster than other plants in the Rosales order.