1
|
Cai J, Yuan X, Kong Y, Hu Y, Li J, Jiang S, Dong C, Ding K. Chemical approaches for the stereocontrolled synthesis of 1,2-cis-β-D-rhamnosides. Chin J Nat Med 2023; 21:886-901. [PMID: 38143103 DOI: 10.1016/s1875-5364(23)60408-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Indexed: 12/26/2023]
Abstract
In carbohydrate chemistry, the stereoselective synthesis of 1,2-cis-glycosides remains a formidable challenge. This complexity is comparable to the synthesis of 1,2-cis-β-D-mannosides, primarily due to the adverse anomeric and Δ-2 effects. Over the past decades, to attain β-stereoselectivity in D-rhamnosylation, researchers have devised numerous direct and indirect methodologies, including the hydrogen-bond-mediated aglycone delivery (HAD) method, the synthesis of β-D-mannoside paired with C6 deoxygenation, and the combined approach of 1,2-trans-glycosylation and C2 epimerization. This review elaborates on the advancements in β-D-rhamnosylation and its implications for the total synthesis of tiacumicin B and other physiologically relevant glycans.
Collapse
Affiliation(s)
- Juntao Cai
- Henan Polysaccharide Research Center, Henan Key Laboratory of Chinese Medicine for Polysaccharides and Drugs Research, Academy of Chinese Medical Sciences, Henan University of Chinese Medicine, Zhengzhou 450046, China.
| | - Xin Yuan
- Henan Polysaccharide Research Center, Henan Key Laboratory of Chinese Medicine for Polysaccharides and Drugs Research, Academy of Chinese Medical Sciences, Henan University of Chinese Medicine, Zhengzhou 450046, China
| | - Yuanfang Kong
- College of Pharmacy, Henan University of Chinese Medicine, Zhengzhou 450046, China
| | - Yulong Hu
- Henan Polysaccharide Research Center, Henan Key Laboratory of Chinese Medicine for Polysaccharides and Drugs Research, Academy of Chinese Medical Sciences, Henan University of Chinese Medicine, Zhengzhou 450046, China
| | - Jieming Li
- Henan Polysaccharide Research Center, Henan Key Laboratory of Chinese Medicine for Polysaccharides and Drugs Research, Academy of Chinese Medical Sciences, Henan University of Chinese Medicine, Zhengzhou 450046, China
| | - Shiqing Jiang
- Henan Polysaccharide Research Center, Henan Key Laboratory of Chinese Medicine for Polysaccharides and Drugs Research, Academy of Chinese Medical Sciences, Henan University of Chinese Medicine, Zhengzhou 450046, China; Department of Oncology, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou 450000, China.
| | - Chunhong Dong
- Henan Polysaccharide Research Center, Henan Key Laboratory of Chinese Medicine for Polysaccharides and Drugs Research, Academy of Chinese Medical Sciences, Henan University of Chinese Medicine, Zhengzhou 450046, China.
| | - Kan Ding
- Henan Polysaccharide Research Center, Henan Key Laboratory of Chinese Medicine for Polysaccharides and Drugs Research, Academy of Chinese Medical Sciences, Henan University of Chinese Medicine, Zhengzhou 450046, China; Carbohydrate-Based Drug Research Center, CAS Key Laboratory of Receptor Research, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| |
Collapse
|
2
|
Ryu B, Park EJ, Doan TP, Cho HM, An JP, Pham TLG, Pham HTT, Oh WK. Heliciopsides A-E, Unusual Macrocyclic and Phenolic Glycosides from the Leaves of Heliciopsis terminalis and Their Stimulation of Glucose Uptake. Pharmaceuticals (Basel) 2022; 15:1315. [PMID: 36355487 PMCID: PMC9695999 DOI: 10.3390/ph15111315] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 10/10/2022] [Accepted: 10/21/2022] [Indexed: 11/26/2023] Open
Abstract
Ten phenolic constituents, including three new macrocyclic glycosides (1-3), a new phenolic glycoside (5), a new biphenyl glycoside (6), and five known compounds (4, 7-10), were isolated from a 70% MeOH extract of the leaves of Heliciopsis terminalis by liquid chromatography-tandem mass spectrometry (LC-MS/MS)-guided molecular networking. The chemical structures of new compounds 1-3, 5 and 6 were established based on comprehensive spectroscopic data analysis, including 1D and 2D NMR and HRESIMS techniques. All isolated compounds (1-10) were evaluated for their stimulation of glucose uptake in differentiated 3T3-L1 adipocytes using 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-d-glucose (2-NBDG) as a fluorescent glucose analog. Compounds 3, 6 and 8 showed stimulatory effects on the uptake of 2-NBDG in 3T3-L1 adipocyte cells. Among them, compounds 3 and 6 activated the AMPK signaling pathway in differentiated C2C12 myoblasts.
Collapse
Affiliation(s)
- Byeol Ryu
- Korea Bioactive Natural Material Bank, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 08826, Korea
| | - Eun-Jin Park
- Korea Bioactive Natural Material Bank, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 08826, Korea
| | - Thi-Phuong Doan
- Korea Bioactive Natural Material Bank, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 08826, Korea
| | - Hyo-Moon Cho
- Korea Bioactive Natural Material Bank, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 08826, Korea
| | - Jin-Pyo An
- Korea Bioactive Natural Material Bank, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 08826, Korea
| | | | - Ha-Thanh-Tung Pham
- Department of Botany, Hanoi University of Pharmacy, Hanoi 000084, Vietnam
| | - Won-Keun Oh
- Korea Bioactive Natural Material Bank, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 08826, Korea
| |
Collapse
|
3
|
A thermostable glycosyltransferase from Paenibacillus polymyxa NJPI29: recombinant expression, characterization, and application in synthesis of glycosides. 3 Biotech 2021; 11:314. [PMID: 34109099 DOI: 10.1007/s13205-021-02855-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 05/19/2021] [Indexed: 10/21/2022] Open
Abstract
Glycosylation is a prominent biological mechanism, affecting the structural and functional diversity of many natural products. In this study, a novel thermostable uridine diphosphate-dependent glycosyltransferase gene PpGT1 was cloned from Paenibacillus polymyxa NJPI29 and recombinantly expressed in B. subtilis WB600. The purified PpGT1 had a molecular weight of 45 kDa, as estimated using SDS-PAGE. The PpGT1 could catalyze the glycosylation of vanillic acid, methyl vanillate, caffeic acid, cinnamic alcohol, and ferulic acid. Moreover, PpGT1 possessed good thermostability and retained 80% of its original activity even after 12 h of incubation at 45 °C. In addition, PpGT1 remained stable within a neutral to alkaline pH range as well as in the presence of metal ions. The synthesis of methyl vanillate 4-O-β-D-glucoside by purified PpGT1 reached a yield 3.58 mM in a system with pH 8.0, 45 °C, 12 mM UDP-Glc, and 4 mM methyl vanillate. 3D-structure-based amino acid sequence alignments revealed that the catalytic residues and C-terminated PSPG motif were conserved. These unusual properties indicated that PpGT1 is a candidate UGT for valuable natural product industrial applications. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s13205-021-02855-z.
Collapse
|
4
|
Adhikari SB, Chen A, Wang G. Synthesis of Carbohydrate Based Macrolactones and Their Applications as Receptors for Ion Recognition and Catalysis. Molecules 2021; 26:3394. [PMID: 34205128 PMCID: PMC8199946 DOI: 10.3390/molecules26113394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/20/2021] [Accepted: 05/24/2021] [Indexed: 01/23/2023] Open
Abstract
Glycomacrolactones exhibit many interesting biological properties, and they are also important in molecular recognitions and for supramolecular chemistry. Therefore, it is important to be able to access glycomacrocycles with different sizes and functionality. A new series of carbohydrate-based macrocycles containing triazole and lactone moieties have been designed and synthesized. The synthesis features an intramolecular nucleophilic substitution reaction for the macrocyclization step. In this article, the effect of some common sulfonate leaving groups is evaluated for macrolactonization. Using tosylate gave good selectivity for monolactonization products with good yields. Fourteen different macrocycles have been synthesized and characterized, of which eleven macrocycles are from cyclization of the C1 to C6 positions of N-acetyl D-glucosamine derivatives and three others from C2 to C6 cyclization of functionalized D-glucosamine derivatives. These novel macrolactones have unique structures and demonstrate interesting anion binding properties, especially for chloride. The macrocycles containing two triazoles form complexes with copper sulfate, and they are effective ligands for copper sulfate mediated azide-alkyne cycloaddition reactions (CuAAC). In addition, several macrocycles show some selectivity for different alkynes.
Collapse
Affiliation(s)
| | | | - Guijun Wang
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529, USA; (S.B.A.); (A.C.)
| |
Collapse
|
5
|
Prabhakar Reddy D, Yu B. Total Synthesis of Macrocyclic Dysoxylactam A. Chem Asian J 2020; 15:2467-2469. [PMID: 32667142 DOI: 10.1002/asia.202000482] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/12/2020] [Indexed: 02/06/2023]
Abstract
The total synthesis of dysoxylactam A, a novel 17-membered macrolactam with potent multi-drug-resistant reversing activities, has been achieved, starting from 4-pentene-1-al in a longest linear sequence of 17 steps and 9.5% overall yield. The key transformations consist of iterative aldol and ring-closing metathesis reactions for the construction of the stereochemically enriched polypropionate scaffold and the macrocycle, respectively.
Collapse
Affiliation(s)
- D Prabhakar Reddy
- Innovation Research Institute of Traditional Chinese Medicine, Shanghai University of Traditional Chinese Medicine, 1200 Cai Lun Road, Shanghai, 201203, China.,State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China
| | - Biao Yu
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China.,School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Sub-lane Xiangshan, Hangzhou, 310024, China
| |
Collapse
|
6
|
Affiliation(s)
- Dapeng Zhu
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry; Chinese Academy of Sciences, 345 Lingling Road; Shanghai 20032 China
| | - Biao Yu
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry; Chinese Academy of Sciences, 345 Lingling Road; Shanghai 20032 China
| |
Collapse
|
7
|
Peng D, Lin X, Jiang L, Huang J, Zeng G, Deng X, Zhou Y. Five macrocyclic glycosides from Schoenoplectus tabernaemontani. Nat Prod Res 2018; 33:427-434. [PMID: 29600732 DOI: 10.1080/14786419.2018.1455195] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Macrocyclic glycosides with unique 22-membered dimeric lactone skeleton, are rare occurring natural products. There are only ten compounds reported so far. Herein we reported the isolation and characterisation of five macrocyclic glycosides from Schoenoplectus tabernaemontani, including three new compounds (Schoenopolide A-C, 1-3) and two known ones, Berchemolide (4) and Clemoarmanoside B (5). Their structures were established on the basis of extensive analysis of spectroscopic data. In addition, the anti-oxidative activity of Berchemolide (4) against H2O2-induced of renal tubular epithelial (HK-2) cells was also evaluated.
Collapse
Affiliation(s)
- Dian Peng
- a Xiangya School of Pharmaceutical Sciences, Central South University , Changsha , China
| | - Xiaolin Lin
- b Hunan Provincial Key Laboratory of Metabolic Bone Diseases, Department of Endocrinology and Metabolism, The Second XiangYa Hospital, Central South University , Changsha , China
| | - Lin Jiang
- c Xiangya International Academy of Translat-ional Medicine, Central South University , Changsha , China
| | - Juan Huang
- d Hunan Children's Hospital , Changsha , China
| | - Guangyao Zeng
- a Xiangya School of Pharmaceutical Sciences, Central South University , Changsha , China
| | - Xu Deng
- a Xiangya School of Pharmaceutical Sciences, Central South University , Changsha , China
| | - Yingjun Zhou
- a Xiangya School of Pharmaceutical Sciences, Central South University , Changsha , China
| |
Collapse
|
8
|
Despras G, Hain J, Jaeschke SO. Photocontrol over Molecular Shape: Synthesis and Photochemical Evaluation of Glycoazobenzene Macrocycles. Chemistry 2017; 23:10838-10847. [DOI: 10.1002/chem.201701232] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Guillaume Despras
- Otto Diels Institute of Organic Chemistry; Christiana Albertina University of Kiel; Otto-Hahn-Platz 3/4 24118 Kiel Germany
| | - Julia Hain
- Otto Diels Institute of Organic Chemistry; Christiana Albertina University of Kiel; Otto-Hahn-Platz 3/4 24118 Kiel Germany
| | - Sven Ole Jaeschke
- Otto Diels Institute of Organic Chemistry; Christiana Albertina University of Kiel; Otto-Hahn-Platz 3/4 24118 Kiel Germany
| |
Collapse
|
9
|
Traboni S, Bedini E, Iadonisi A. Solvent-Free One-Pot Diversified Protection of Saccharide Polyols Via Regioselective Tritylations. ChemistrySelect 2017. [DOI: 10.1002/slct.201701033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Serena Traboni
- Department of Chemical Sciences; University of Naples Federico II; Via Cinthia 4 I-80126 Naples Italy
| | - Emiliano Bedini
- Department of Chemical Sciences; University of Naples Federico II; Via Cinthia 4 I-80126 Naples Italy
| | - Alfonso Iadonisi
- Department of Chemical Sciences; University of Naples Federico II; Via Cinthia 4 I-80126 Naples Italy
| |
Collapse
|
10
|
Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012. MASS SPECTROMETRY REVIEWS 2017; 36:255-422. [PMID: 26270629 DOI: 10.1002/mas.21471] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 01/15/2015] [Indexed: 06/04/2023]
Abstract
This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.
Collapse
Affiliation(s)
- David J Harvey
- Department of Biochemistry, Oxford Glycobiology Institute, University of Oxford, Oxford, OX1 3QU, UK
| |
Collapse
|
11
|
Tu XY, Liu MZ, Wei H. Recent progress on cyclic polymers: Synthesis, bioproperties, and biomedical applications. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/pola.28051] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Xiao-Yan Tu
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, and College of Chemistry and Chemical Engineering, Lanzhou University; Lanzhou Gansu 730000 China
| | - Ming-Zhu Liu
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, and College of Chemistry and Chemical Engineering, Lanzhou University; Lanzhou Gansu 730000 China
| | - Hua Wei
- State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, and College of Chemistry and Chemical Engineering, Lanzhou University; Lanzhou Gansu 730000 China
| |
Collapse
|
12
|
Xie J, Bogliotti N. Synthesis and applications of carbohydrate-derived macrocyclic compounds. Chem Rev 2014; 114:7678-739. [PMID: 25007213 DOI: 10.1021/cr400035j] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Juan Xie
- PPSM, Institut d'Alembert, ENS Cachan, CNRS, UMR 8531 , 61 av. Président Wilson, F-94235 Cachan Cedex, France
| | | |
Collapse
|
13
|
Luo Q, Wang SM, Lu Q, Luo J, Cheng YX. Identification of compounds from the water soluble extract of Cinnamomum cassia barks and their inhibitory effects against high-glucose-induced mesangial cells. Molecules 2013; 18:10930-43. [PMID: 24013407 PMCID: PMC6270337 DOI: 10.3390/molecules180910930] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 08/21/2013] [Accepted: 08/27/2013] [Indexed: 11/16/2022] Open
Abstract
The difficulty of diabetic nephropathy (DN) treatment makes prevention the best choice. Cinnamomum cassia barks, known as Chinese cinnamon or Chinese cassia, is one of the most popular natural spices and flavoring agents in many parts of the World. Since previous reports indicated that Chinese cinnamon extract could be used for the treatment of diabetes, we proposed that this spice may be beneficial for the prevention of DN. However, the responsible compounds need to be further identified. In this study, we isolated three new phenolic glycosides, cinnacassosides A–C (1-3), together with fifteen known compounds from the water soluble extract of Chinese cinnamon. The structures of the new compounds were identified by comprehensive spectroscopic evidence. Eleven compounds (6-9, 11, 13-18) were isolated from this spice for the first time, despite extensive research on this species in the past, which added new facets for the chemical profiling of this spice. These isolates were purposely evaluated for their inhibitory effects on IL-6 and extracellular matrix production in mesangial cells which are definitely implicated in DN. The results showed that compounds 4-8 could inhibit over secretion of IL-6, collagen IV and fibronectin against high-glucose-induced mesangial cells at 10 µM, suggesting that Chinese cinnamon could be used as a functional food against DN.
Collapse
Affiliation(s)
- Qi Luo
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
- College of Pharmaceutical Sciences, Dali University, Dali 671002, Yunnan, China
| | - Shu-Mei Wang
- College of Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, Guangdong, China
| | - Qing Lu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
| | - Jie Luo
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
| | - Yong-Xian Cheng
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China
- College of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 610075, Sichuan, China
- Authors to whom correspondence should be addressed; E-Mail: ; Tel./Fax: +86-871-6522-3048
| |
Collapse
|
14
|
Li Y, Mo H, Lian G, Yu B. Revisit of the phenol O-glycosylation with glycosyl imidates, BF3·OEt2 is a better catalyst than TMSOTf. Carbohydr Res 2012; 363:14-22. [DOI: 10.1016/j.carres.2012.09.025] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 09/27/2012] [Accepted: 09/29/2012] [Indexed: 01/03/2023]
|
15
|
Yu B, Sun J, Yang X. Assembly of naturally occurring glycosides, evolved tactics, and glycosylation methods. Acc Chem Res 2012; 45:1227-36. [PMID: 22493991 DOI: 10.1021/ar200296m] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glycosylation of proteins and lipids is critical to many life processes. Secondary metabolites (or natural products), such as flavonoids, steroids, triterpenes, and antibiotics, are also frequently modified with saccharides. The resulting glycosides include diverse structures and functions, and some of them have pharmacological significance. The saccharide portions of the glycosides often have specific structural characteristics that depend on the aglycones. These molecules also form heterogeneous "glycoform" mixtures where molecules have similar glycosidic linkages but the saccharides vary in the length and type of monosaccharide unit. Thus, it is difficult to purify homogeneous glycosides in appreciable amounts from natural sources. Chemical synthesis provides a feasible access to the homogeneous glycosides and their congeners. Synthesis of a glycoside involves the synthesis of the aglycone, the saccharide, the connection of these two parts, and the overall manipulation of protecting groups. However, most synthetic efforts to date have focused on the aglycones, treating the attachment of saccharides onto the aglycones as a dispensable topic. The synthesis of the aglycone and the synthesis of the saccharide belong to two independent categories of chemistry, and different types of the aglycones and saccharides pose as specific synthetic subjects in their own disciplines. The only reaction that integrates the broad chemistry of glycoside synthesis is the glycosidic bond formation between the saccharide and the aglycone. Focusing on this glycosylation reaction in this Account, we string together our experience with the synthesis of the naturally occurring glycosides. We briefly describe the synthesis of 18 glycosides, including glycolipids, phenolic glycosides, steroid glycosides, and triterpene glycosides. Each molecule represents a prototypical structure of a family of the natural glycosides with interesting biological activities, and we emphasize the general tactics for the synthesis of these diverse structures. We provide a rationale for four tactics for the synthesis of glycosides, based on the stage at which the glycosidic bond is formed between the saccharide and the aglycone. This choice of tactic determines the success or failure of a synthesis, and the flexibility and the overall efficiency of the synthesis as well. Toward the synthesis of heterogeneous glycoform mixtures, we discuss successive and random glycosylation reactions. Finally, we have developed two new glycosylation protocols that address the challenges in the glycosylation of aglycones that are poorly nucleophilic, extremely acid labile, or extremely electrophilic. One of these new protocols takes advantage of glycosyl trifluoroacetimidate donors, and a second protocol uses gold(I)-catalyzed glycosylation with glycosyl ortho-alkynylbenzoate donors.
Collapse
Affiliation(s)
- Biao Yu
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences
| | - Jiansong Sun
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences
| | - Xiaoyu Yang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences
| |
Collapse
|
16
|
|