Sugar Moiety Research Articles

Govanosides C-F, unprecedented steroidal saponins with rare sugars from rhizomes of Trillium govanianum and their antagonistic effects on acetylcholinesterase

Four previously undescribed steroidal saponins named govanosides C-F (1–4) and nine known compounds (5–13) were isolated from the rhizomes of Trillium govanianum Wall. ex D.Don. Govanosides C-E contained a rare sugar moiety i.e., 6-deoxy allose, while govanoside F has acetylated rhamnose moiety in its glycan part. Also, this is the first report on the isolation of feruloyl sucrose derivatives (11–12) and (E)-4-hydroxy-dodec-2-enedioic acid (13) from the Trillium genus. The structure of isolated compounds was deduced using 1D and 2D NMR, HRESIMS, LC-MS/MS, GC–MS, and saccharide linkage analysis. Steroidal scaffold isolates (1–10) were evaluated for their antagonistic effects on acetylcholinesterase inhibitory activity. Govanoside C (1) significantly inhibited acetylcholinesterase (IC50: 2.38 μM). Molecular docking experiments have also been performed to depict the molecule’s interaction and binding free energy with acetylcholinesterase.

A conserved family of immune effectors cleaves cellular ATP upon viral infection

During viral infection, cells can deploy immune strategies that deprive viruses of molecules essential for their replication. Here, we report a family of immune effectors in bacteria that, upon phage infection, degrade cellular adenosine triphosphate (ATP) and deoxyadenosine triphosphate (dATP) by cleaving the N-glycosidic bond between the adenine and sugar moieties. These ATP nucleosidase effectors are widely distributed within multiple bacterial defense systems, including cyclic oligonucleotide-based antiviral signaling systems (CBASS), prokaryotic argonautes, and nucleotide-binding leucine-rich repeat (NLR)-like proteins, and we show that ATP and dATP degradation during infection halts phage propagation. By analyzing homologs of the immune ATP nucleosidase domain, we discover and characterize Detocs, a family of bacterial defense systems with a two-component phosphotransfer-signaling architecture. The immune ATP nucleosidase domain is also encoded within diverse eukaryotic proteins with immune-like architectures, and we show biochemically that eukaryotic homologs preserve the ATP nucleosidase activity. Our findings suggest that ATP and dATP degradation is a cell-autonomous innate immune strategy conserved across the tree of life.

Combinatorics-based chemical characterization and bioactivity comparison of different parts of traditional Chinese medicinal plants through LC-Q-TOF-MS/MS, multivariate statistical analysis and bioassay: Marsdenia tenacissima as an example

Marsdenia tenacissima is a traditional Chinese medicinal plant used for treating cancer, and its main medicinal part is the stem. Considering the resource shortage of M. tenacissima, it is of great significance to improve its utilization efficiency. Steroids and caffeoylquinic acids, the two main components of M. tenacissima, are composed of several basic structures. Based on this rule, a novel strategy of combinatorics-based chemical characterization was proposed to analyze the constituents of roots, stems and leaves of M. tenacissima. Combinatorics was used to generate a compound library for structure alignment, which has the advantages of wide coverage and high specificity. Steroids are composed of four basic parts: core skeleton (C), substituent at position 11 (A), substituent at position 12 (B) and sugar moiety (S). Based on combinatorics, a compound library consisting of 1080 steroids was generated. Diagnostic neutral loss has been used to effectively predict the substituents at position 11 and 12 of steroids, including acetyl, 2-methylpropionyl, tigloyl, 2-methylbutyryl and benzoyl. As a result, 131, 131 and 99 components were detected from the roots, stems and leaves of M. tenacissima, respectively. Principal component analysis (PCA) was used to analyze the differences of roots, stems and leaves, and orthogonal partial least squares-discriminant analysis (OPLS-DA) was further applied to find differential components. Tenacissoside H, a critical indicator component for quality evaluation of the stem, has been proved to be a differential component between roots and stems. Notably, the relative content of tenacissoside H in the roots was significantly higher than that in the stems. The bioactivity comparison showed that roots, stems and leaves of M. tenacissima had similar scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. However, their α-glucosidase inhibitory activity was ranked as leaves > stems > roots. Therefore, besides stems, the other parts of M. tenacissima have potential medicinal value. This study not only helps to develop the resource of M. tenacissima, but also provides a paradigm for the research of other similar medicinal plants.

Fingerprint of sophorolipids based on ultra-high performance liquid chromatography-charged aerosol detection

Sophorolipids are secondary metabolites produced during fermentation by nonpathogenic yeasts. These molecules are amphiphilic and consist of a hydrophilic sophora sugar moiety and a hydrophobic hydroxylated fatty acid. Based on their degree of esterification, sophorolipids can be divided into the acid and lactone types. Sophorolipids are highly promising biosurfactants with good antibacterial, antiviral, and other biological activities. Moreover, they are characterized by mildness, low toxicity, and environmental friendliness. However, their composition is quite complex, and effective methods for their quality evaluation are lacking. Since sophorolipids do not absorb ultraviolet (UV) light, common UV detectors are unsuitable for fingerprint establishment. In this study, we first selected a charged aerosol detector (CAD) to establish the ultra-high performance liquid chromatography (UHPLC) fingerprint of sophorolipids. The detector had high sensitivity, good reproducibility, and excellent suitability for the detection of substances with no or weak ultraviolet absorption. We then evaluated the similarities between 17 batches of sophorolipid samples. The samples were extracted by ultrasound for 10 min in 80% ethanol aqueous solution at a liquid-solid ratio of 10∶1 (mL/g) and then separated on a Thermo Fisher Scientific Hypersil Gold chromatographic column (150 mm×2.1 mm, 1.9 μm). Separation was performed using acetonitrile-0.01% (v/v) formic acid aqueous solution as the mobile phase via gradient elution. The flow rate was 0.2 mL/min, and the column temperature was 40 ℃. The CAD was used under the following conditions: power function of 1.0, data rate of 5 Hz, filter constant of 3.6, and evaporation temperature of 45 ℃. The chromatograms and retention times of the sophorolipids were compared, and 16 common peaks with strong responses, good resolutions, and stable retention times were selected as characteristic peaks. Oleic acid was chosen as the reference peak because it achieved good separation and a strong chromatographic response in all batches of samples. UHPLC-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) was used to identify chromatographic peaks in the sophorolipid fingerprints. The results were combined with the retention time rule of the sophorolipids, leading to their identification based on matching with the results of the primary database, the precise relative molecular mass and fragmentation rule of secondary fragments, a self-built database, and the PubChem database. Sixteen compounds were identified, including eight acid sophorolipids, six lactone sophorolipids, and two aliphatic acids. The results of precision, repeatability, and 24 h stability tests indicated that the relative standard deviations (RSDs) of the retention times and peak areas of the 15 characteristic peaks relative to the control peak (oleic acid) were less than 3.0% (n=6). Seventeen batches of sophorolipid samples were analyzed, and the similarity values of all fingerprints were found to be 0.965 or higher. Little differences in chemical composition were observed among the different batches of sophorolipid samples, and the quality of the sophorolipids was relatively consistent. The fingerprint established in this study is stable and reliable; it can be used for the quality evaluation of sophorolipids and lays a solid foundation for future research on production technology and the development and utilization of sophorolipids. The successful application of a universal CAD to the fingerprint establishment of sophorolipids also provides a reliable solution for the fingerprint establishment of substances with no or weak ultraviolet absorption.

Host susceptibility and structural and immunological insight of S proteins of two SARS-CoV-2 closely related bat coronaviruses

The bat coronaviruses (CoV) BANAL-20-52 and BANAL-20-236 are two newly identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) closely related coronaviruses (SC2r-CoV) and the genome of BANAL-20-52 shares the highest homology with SARS-CoV-2. However, the risk of their potential zoonotic transmission has not been fully evaluated. Here, we determined their potential host susceptibility among 13 different bat species and 26 different animal species, and found that both might have extensive host ranges, indicating high zoonotic transmission potential. We also determined the cryo-EM structures of BANAL-20-52 and BANAL-20-236 S proteins at pH 5.5 and the complex of BANAL-20-236 S1 and Rhinolophus affinis ACE2, and found that both trimeric S proteins adopt all three receptor binding domains (RBDs) in “closed” conformation and are more compact than SARS-CoV-2. Strikingly, the unique sugar moiety at N370 of bat SC2r-CoVs acts like a “bolt” and crosses over two neighboring subunits, facilitating the S proteins in the locked conformation and underpinning the architecture stability. Removal of the glycosylation at N370 by a T372A substitution substantially enhances virus infectivity but becomes highly sensitive to trypsin digestion at pH 5.5, a condition roughly mimicking the insectivorous bat’s stomach digestion. In contrast, WT S proteins of SC2r-CoVs showed considerable resistance to trypsin digestion at pH 5.5, indicating that the highly conserved T372 in bat CoVs might result from the selective advantages in stability during the fecal-oral transmission over A372. Moreover, the results of cross-immunogenicity among S proteins of SARS-CoV-2, BANAL-20-52, and BANAL-20-236 showed that A372 pseudoviruses are more sensitive to anti-S sera than T372, indicating that immune evasion might also play a role in the natural selection of T372 over A372 during evolution. Finally, residues 493 and 498 of the S protein affect host susceptibility, and residue 498 also influences the immunogenicity of the S protein. Together, our findings aid a better understanding of the molecular basis of CoV entry, selective evolution, and immunogenicity and highlight the importance of surveillance of susceptible hosts of these viruses to prevent potential outbreaks.

Molecular Aspects of C-glycosides: Interactive Analysis of C-linked Compounds With the SGLT2 Molecular Model.

Interaction analysis between modeled human sodium/glucose cotransporter 2 (hSGLT2) and antidiabetic C-glycoside drugs, such as canagliflozin, dapagliflozin, ipragliflozin, empagliflozin, tofogliflozin, and luseogliflozin was performed. The hSGLT2 was modeled using the X-ray data of Vibrio parahaemolyticus SGLT2 (protein data bank ID=2XQ2) as a template. Conformational analyses of C-glycosides were performed using CAChe-Conflex. Interactive analyses between hSGLT2 and C-glycosides were performed using Molegro Virtual Docker. Canagliflozin interacted with hSGLT2 via Asn75, Ser287, Lys321 and Gln457 Dapagliflozin interacted with six amino acids (Arg46, Arg49, Ile76, Ser78, Met216 and Ser393). Ipragliflozin (Ala69, Met596 and Gln600), empagliflozin (Ser78, Gly79, Lys154, Asp158 and Ser393), tofogliflozin (Arg49, Met216, Ala389, Ser392 and Ser393), and luseogliflozin (Arg49, Ser74, Ser78, Gly79, His80, Lys154, Asp158 and Ser393) interacted with hSGLT2 via the amino acids described in the parentheses. The binding mode of each C-glycoside drug to hSGLT2 was different, and structural features of each compound were revealed. The reactive base points of C-glycosides were the sugar moiety, with the sugar structure being important for hSGLT2 inhibitory action.

Synthesis and Evaluation of Saponins with All-Nitrogenated Sugars

AbstractSaponins exhibit multiple biological and pharmacological activities, and the sugar moiety of saponins is known to play a crucial role in bioactivity. In this report, we focus on the synthesis and evaluation of saponins with all-nitrogenated sugar (ANS), in which all oxygen atoms are replaced with nitrogen atoms. OSW-1 derivative-, cholesterol-, and diosgenin-ANS glycosides are synthesized by glycosylation with ANS in the presence of TMSOTf. As a result, the OSW-1 mimic, with ANS, exhibits good cytotoxic activity (IC50 = 7.31 μM) and induces apoptosis.

Recent Developments in the Design of New Water-Soluble Boron Dipyrromethenes and Their Applications: An Updated Review.

Boron-dipyrromethene (BODIPY) and its derivatives play an important role in the area of organic fluorophore chemistry. Recently, the water-soluble boron-dipyrromethene dyes have increasingly received interest. The structural modification of the BODIPY core by incorporating different neutral and ionic hydrophilic groups makes it water-soluble. The important hydrophilic groups, such as quaternary ammonium, sulfonate, oligoethylene glycol, dicarboxylic acid, and sugar moieties significantly increase the solubility of these dyes in water while preserving their photophysical properties. As a result, these fluorescent dyes are utilized in aqueous systems for applications such as chemosensors, cell imaging, anticancer, biolabeling, biomedicine, metal ion detection, and photodynamic treatment. This review covers the most current developments in the design and synthesis of water-soluble BODIPY derivatives and their wide applications since 2014.

A Stereoselective Synthesis of 4′‐α‐Fluoro‐methyl Carbocyclic Nucleoside Analogs

AbstractThe 4′ position modifications in carbocyclic nucleosides have not been investigated much as potential antiviral agents. Due to the higher ring strain and torsion of the cyclopentyl carbocyclic ring, it is not easy to carry out the modification at the 4′ position. Therefore, there is a need for a procedure that may tackle the synthesis of 4′ position substituted carbocyclic pentyl ring. In this communication, a stereoselective synthesis of 4′‐α‐fluoro‐methyl carbocyclic nucleosides has been reported. A stereoselective synthesis of the 4‐α‐fluoro‐methyl carbocyclic sugar moiety (16) was carried out via carbocyclic ketone 1. The oxidation of the 5‐methyl hydroxy of 9 followed by the aldol condensation gave a diol 11, which via selective protection followed by selective fluorination, yielded a MOM‐protected 4‐α‐fluoro‐methyl carbocyclic ring (16). Compound 16 served as a key intermediate for the synthesis of purines (21&24) and pyrimidine (28&31) nucleosides. The described synthesis may be utilized to construct the various 4′ position modified carbocyclic nucleos(t)ides for an elaborated structure‐activity relationship (SAR) as an antiviral and anticancer agent.

Synthesis of novobiocin derivatives and evaluation of their antigonococcal activity and pharmacokinetics

Gonorrhea has become a serious problem because the number of infected people is increasing and the multi-drug resistance of the causative bacteria, Neisseria gonorrhoeae, is progressing. To develop novel drugs against resistant N. gonorrhoeae, we focused on the antibiotic novobiocin (1). This natural product has a different mechanism of action from existing drugs for gonorrhea, which may make it effective against resistant strains. Actually, it was applied to resistant N. gonorrhoeae, and moderate antibacterial activity was confirmed. Based on this result, we investigated the development of an antigonococcal drug with 1 as the lead compound. The pharmacophore is thought to be the noviose sugar moiety, especially around the 3′-position, so we derivatized this part in order to improve antibacterial activity. As a result, we found that 5 with an methylpyrrole ester structure have a very potent antibacterial activity. This derivative also showed excellent antigonococcal activity against resistant strains in vitro, however it has poor water solubility and pharmacokinetics because it is the acidic lipid-soluble compound. Therefore, we considered introduction of a basic substituent into the molecule would result in an amphoteric compound with improved water solubility, and we investigated further derivatization. As a result of synthesizing various derivatives, we found 47 containing imidazole with strong antigonococcal activity and greatly improved water solubility. This derivative has also improved metabolism and blood concentration in vivo, and is expected to be orally absorbed. Based on these results, we believe that 47 is a very promising anti-gonococcal lead compound and has great potential for further development.

Seed coat composition in black and white soybean seeds with differential water permeability.

The seed coat composition of white (JS 335) and black (Bhatt) soybean (Glycine max (L.) Merr) having different water permeability was studied. Phenols, tannins and proteins were measured, as well as trace elements and metabolites in the seed coats. The seed coat of Bhatt was impermeable and imposed dormancy, while that of JS 335 was permeable and seeds exhibited imbibitional injury. Bhatt seed coats contained comparatively higher concentrations of phenols, tannins, proteins, Fe and Cu than those of JS 335. Metabolites of seed coats of both genotypes contained 164 compounds, among which only 14 were common to both cultivars, while the remaining 79 and 71 compounds were unique to JS 331 and Bhatt, respectively. Phenols are the main compounds responsible for seed coat impermeability and accumulate in palisade cells of Bhatt, providing impermeability and strength to the seed coat. JS 335 had more cracked seed coats, mainly due to their lower tannin content. Alkanes, esters, carboxylic acids and alcohols were common to both genotypes, while cyclic thiocarbamate (1.07%), monoterpene alcohols (1.07%), nitric esters (1.07%), phenoxazine (1.07%) and sulphoxide (1.07%) compounds were unique to the JS 335 seed coat, while aldehydes (2.35%), amides (1.17%), azoles (1.17%) and sugar moieties (1.17%) were unique to Bhatt seed coats. This study provides a platform for isolation and understanding of each identified compound for its function in seed coat permeability.

The unique activity of saponin: Induction of cytotoxicity in HTLV-1 infected cells

Infection with the retrovirus human T-cell leukemia virus type 1 (HTLV-1) sometimes causes diseases that are difficult to cure. To find anti-HTLV-1 natural compounds, we opted to screen using the HTLV-1-infected T-cell line, MT-2. Based on our results, an extract of the pulp/seeds of Akebia quinata Decaisne fruit killed MT-2 cells but did not affect the Jurkat cell line that was not infected with virus. To determine the active ingredients, seven saponins with one-six sugar moieties were isolated from A. quinata seeds, and their activities against the two cell lines were examined. Both cell lines were killed in a similar manner by Akebia saponins A and B. Further, Akebia saponins D, E, PK and G did not exhibit cytotoxicity. Akebia saponin C had a similar activity to the extract found in the screening. This compound was found to enhance Gag aggregation, induce the abnormal cleavage of Gag, suppress virion release, and preferentially kill HTLV-1 infected cells; however, their relationship remains elusive. Our findings may lead to the development of new therapies for infectious diseases based on the removal of whole-virus-infected cells.

Gradation control in the hydrodynamic diameters of mixed glycan-aglycan glycovesicles

Abstract Glycovesicles mimic synthetic cell membrane surfaces and aid to delineate intricate, weak carbohydrate–protein interactions. In this report, the dependence of the hydrodynamic diameters in relation to the molar fractions of carbohydrate moieties in the mixed polydiacetylene (PDA) glycovesicles is evaluated. The glycovesicles are constituted with diacetylene monomers of varying molar fractions of carbohydrate moieties and the hydrodynamic diameters are assessed without and with polymerization of the vesicles. A strong dependence of the hydrodynamic diameter of glycovesicles is seen as a function of the molar fractions and the nature of the sugar moiety being either mono- or disaccharide. A monotonous increase in the hydrodynamic diameters of the glycovesicles occurs with the increase in mole fractions of the sugar monomer lipids. Upon polymerization, the hydrodynamic diameters reduce for the vesicles with lower mole fractions of sugar monomer, whereas the reverse occurs for glycovesicles possessing higher mole fractions. Disaccharide glycovesicles possess higher hydrodynamic diameters than monosaccharide-containing vesicles. Ligand–lectin interactions were probed with lactose disaccharide-containing glycovesicles with tetrameric peanut agglutinin lectin, from which an increase in the hydrodynamic diameters is observed, as the mole fraction of sugar monomer is increased in the PDA-glycovesicles.

Bacillus licheniformis: A Producer of Antimicrobial Substances, including Antimycobacterials, Which Are Feasible for Medical Applications.

Bacillus licheniformis produces several classes of antimicrobial substances, including bacteriocins, which are peptides or proteins with different structural composition and molecular mass: ribosomally synthesized by bacteria (1.4-20 kDa), non-ribosomally synthesized peptides and cyclic lipopeptides (0.8-42 kDa) and exopolysaccharides (>1000 kDa). Different bacteriocins act against Gram-positive or Gram-negative bacteria, fungal pathogens and amoeba cells. The main mechanisms of bacteriocin lytic activity include interaction of peptides with membranes of target cells resulting in structural alterations, pore-forming, and inhibition of cell wall biosynthesis. DNase and RNase activity for some bacteriocines are also postulated. Non-ribosomal peptides are synthesized by special non-ribosomal multimodular peptide synthetases and contain unnatural amino acids or fatty acids. Their harmful effect is due to their ability to form pores in biological membranes, destabilize lipid packaging, and disrupt the peptidoglycan layer. Lipopeptides, as biosurfactants, are able to destroy bacterial biofilms. Secreted polysaccharides are high molecular weight compounds, composed of repeated units of sugar moieties attached to a carrier lipid. Their antagonistic action was revealed in relation to bacteria, viruses, and fungi. Exopolysaccharides also inhibit the formation of biofilms by pathogenic bacteria and prevent their colonization on various surfaces. However, mechanism of the harmful effect for many secreted antibacterial substances remains unknown. The antimicrobial activity for most substances has been studied in vitro only, but some substances have been characterized in vivo and they have found practical applications in medicine and veterinary. The cyclic lipopeptides that have surfactant properties are used in some industries. In this review, special attention is paid to the antimycobacterials produced by B. licheniformis as a possible approach to combat multidrug-resistant and latent tuberculosis. In particular, licheniformins and bacitracins have shown strong antimycobacterial activity. However, the medical application of some antibacterials with promising in vitro antimycobacterial activity has been limited by their toxicity to animals and humans. As such, similar to the enhancement in the antimycobacterial activity of natural bacteriocins achieved using genetic engineering, the reduction in toxicity using the same approach appears feasible. The unique capability of B. licheniformis to synthesize and produce a range of different antibacterial compounds means that this organism can act as a natural universal vehicle for antibiotic substances in the form of probiotic cultures and strains to combat various types of pathogens, including mycobacteria.

Five new resin glycosides, calyhedins XI-XV, from Calystegia hederacea.

Calystegia hederacea Wall. (Convolvulaceae) is a perennial herbaceous vine that grows widely in India and East Asia. All parts of this plant are used to treat various disorders such as menoxenia and gonorrhea. Four new resin glycosides, calyhedins XI (1)-XIV (4), were isolated from the rhizomes of C. hederacea. A new glycoside, calyhedin XV (5), was isolated from its leaves and stems. Alkaline hydrolysis of 1 and 2 furnished a new glycosidic acid, calyhedic acid G (1a), from 1 and a new acid, calyhedic acid H (2a), from 2 along with 2S-methylbutyric acid and 2R-methyl-3R-hydroxybutyric (2R,3R-nilic) acid. The structures of 1-5, 1a, and 2a were determined using MS and NMR spectral analyses. Compounds 1a and 2a had the same sugar moiety, β-D-glucopyranosyl-(1 → 6)-O-β-D-glucopyranosyl-(1 → 6)-O-β-D-glucopyranosyl-(1 → 3)-[O-β-D-glucopyranosyl-(1 → 3)-O-α-L-rhamnopyranosyl-(1 → 2)]-O-β-D-glucopyranosyl-(1 → 2)-β-D-fucopyranose, while their aglycones were 11S-dihydroxyhexadecanoic acid and 12S-dihydroxyhexadecanoic acid, respectively. These compounds are the first glycosidic acids, with fucose as the monosaccharide component obtained from the resin glycosides of C. hederacea. Compounds 1-5, comprising either 1a or 2a, were heptaglycosides with macrolactone structures, and their sugar moieties were partially acylated with 5mol of organic acids comprising 2S-methylbutyric, (E)-2-methylbut-2-enoic, and 2R,3R-nilic acids. Compounds 1 and 5 had 22-membered rings, while 2-4 had 28-membered rings. In addition, 1 and 5 exhibited cytotoxic activity against HL-60 human promyelocytic leukemia cells, comparable to that of the positive control cisplatin.

Evaluation of heterocyte glycolipids with a hexose sugar moiety for tracing terrestrial organic matter in the South China Sea

Heterocyte glycolipids (HGs) are biomarkers for N2-fixing heterocytous cyanobacteria (HCB). The hexose (hereafter C6) sugar moiety of HGs is produced by free-living HCB dominant in fresh and brackish waters, while the pentose moiety (hereafter C5) of HGs is found in endosymbiotic HCB associated with diatoms in tropical-subtropical marine waters. Therefore, C6 HGs detected in marine environments may indicate terrestrial organic matter (TOM) input, but this may be complicated by the fact that free-living HCB may be active over a wide salinity range. In this study, we evaluate C6 HGs and their fraction in total HGs, referred to as FHG, to trace TOM in the South China Sea (SCS) by analyzing a series of surface sediments from the Pearl River Estuary (PRE) to the open SCS, as well as suspended particular matters (SPM) in the euphotic zone of central SCS and a sediment core 17950-2 in the deep SCS. Our results showed that C6 HGs were abundant in the PRE sediments but almost absent in sediments or SPM from the northern shelf to the central SCS, leading us to conclude that free-living HCB producing C6 HGs are inactive in the modern ocean where salinity is >30. In the sediment core, C6 HGs and FHG showed a variation pattern similar to sea level changes during glacial-interglacial cycles, and the reconstructed sea surface salinity was above 32 throughout the cycles. Such a pattern was also evident in the records of branched to isoprenoid tetraether (BIT) index and detrital content from the same core. Thus, the modern distribution of C6 HGs and FHG, together with their downcore records in this study, demonstrates that C6 HGs and FHG are excellent for tracking TOM in tropical-subtropical marine environments.

Recent advances in synthesis of sugar and nucleoside coumarin conjugates and their biological impact

Naturally occurring coumarin and sugar molecules have a diverse range of applications along with superior biocompatibility. Coumarin, a member of the benzopyrone family, exhibits a wide spectrum of medicinal properties, such as anti-coagulant, anti-bacterial, anti-tumor, anti-oxidant, anti-cancer, anti-inflammatory and anti-viral activities. The sugar moiety functions as the central scaffold for the synthesis of complex molecules, attributing to their excellent biocompatibility, well-defined stereochemistry, benign nature and outstanding aqueous solubility. When the coumarin moiety is conjugated with the sugar or nucleoside molecule, the resulting conjugates exhibit significant biological properties.Due to the remarkable growth of such bioconjugates in the field of science over the last decade, owing to their future prospect as a potential bioactive core, an update to this area is very much needed. The present review focusses on the synthesis, characterization and the various therapeutic applications of coumarin conjugates, i.e., sugar and nucleoside coumarin conjugates along with their perspective for future research.

A review on applications of β-glucosidase in food, brewery, pharmaceutical and cosmetic industries

β-glucosidases hydrolyse glycosidic bonds to release non-reducing terminal glucosyl residues from glycosides and oligosaccharides via catalytic mechanisms. It is very well known that the β-glucosidase enzyme is used in biorefineries for cellulose degradation, where β-glucosidases is the rate-limiting enzyme for the final glucose production from cellobiose. The β-glucosidase enzyme is used as a catalyst in other industrial sectors, including pharmaceuticals, breweries, dairy, and food processing. With the aid of β-glucosidase enzymes, cyanogenic glycosides and plant glycosides are transformed into sugar moiety and aglycones. These aglycone compounds are employed as aromatic compounds in the food processing and brewing industries. They are also used as medications and dietary supplements based on their pharmacological qualities. Applications of aglycones and the microbiological sources of β-glucosidase in aglycone production have been discussed in this review.

Palladium-Catalyzed Cyanation of Nucleobases: Total Synthesis of Toyocamycin, Sangivamycin, and a Mycalisine A Precursor

AbstractInstallation of cyano group functionality onto nucleosides has always been a challenging task for chemists, and catalytic protocols developed for simple aryl substrates have, in most cases, failed to replicate their success when applied to nucleobase or sugar moieties of nucleosides. Given the importance of the cyano and amide functionalities in nucleoside chemistry, we herein disclose an efficient Pd-catalyzed cyanation protocol specifically applied to iodo nucleobases. Furthermore, the developed cyanation method has been explored for the synthesis of naturally occurring and bioactive nucleosides such as toyocamycin, sangivamycin, and a mycalisine A precursor.

Bacillinaphthin A: A New Naphthohydroquinone from the Endophyte Bacillus subtilis NPROOT3.

The present study explores the endophyte associated with the halophyte Salicornia brachiata for uncovering new biologically important compounds. Thus, HPLC-PDA guided chemical investigation of the ethyl acetate extract of the Bacillus subtilis NPROOT3 led to the isolation of a new compound named bacillinaphthin A (1) along with previously known rubinaphthin A (2). The structure of 2 was determined by a comparison of HR-ESI-MS, 1 H and 13 C nuclear magnetic resonances (NMR) with those of reported data, whereas the structure of new compound 1 was elucidated by interpretation of 1D- and 2D-NMR and MS data. Bacillinaphthin (1) and rubinaphthin (2) feature 1,4-dihydroxy-2-naphthoic acid derivatives which have been isolated herein for the first time from the genus Bacillus. Bacillinaphthin (1) is a new congener of 2 with an additional succinic acid side chain attached to the sugar moiety. Production of succinoglycan compounds was reported to regulate symbiosis, hence the isolation of 1 exhibits an example of chemical ecology between the halophyte and its endophyte. In silico tools were used to assess the bioactive potential of both isolated molecules.