Programmable one-pot synthesis of heparin pentasaccharides enabling access to regiodefined sulfate derivatives

Microwave-assisted synthesis of highly sulfated mannuronate glycans as potential inhibitors against SARS-CoV-2

Algae-based marine carbohydrate drugs are typically decorated with negative ion groups such as carboxylate and sulfate groups. However, the precise synthesis of highly sulfated alginates is challenging, thus impeding their structure-activity relationship studies. Herein we achieve a microwave-assisted synthesis of a range of highly sulfated mannuronate glycans with up to 17 sulfation sites by overcoming the incomplete sulfation due to the electrostatic repulsion of crowded polyanionic groups. Although the partially sulfated tetrasaccharide had the highest affinity for the receptor binding domain (RBD) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant, the fully sulfated octasaccharide showed the most potent interference with the binding of the RBD to angiotensin-converting enzyme 2 (ACE2) and Vero E6 cells, indicating that the sulfated oligosaccharides might inhibit the RBD binding to ACE2 in a length-dependent manner.

Thiourea-Cu(OTf)2/NIS-synergistically promoted stereoselective glycoside formation with 2-azidoselenoglycosides or thioglycosides as donors

A novel promoter system for glycosylation is described. A catalytic amount of thiourea and Cu(OTf)2 together with a slight excess of N-iodosuccinimide synergistically promotes glycosylation at room temperature. The combination of reagents applies to some 2-azidoselenoglycoside and thioglycoside donors. A wide range of alcoholic acceptors underwent smooth conversion to O-(2-azido)glycosides with good stereoselectivities. In addition, the value of this method has been highlighted by its convenient operation and outstanding functional group compatibility.

Production of different molecular weight glycosaminoglycans with microbial cell factories

Glycosaminoglycans (GAGs) are naturally occurring acidic polysaccharides with wide applications in pharmaceuticals, cosmetics, and health foods. The diverse biological activities and physiological functions of GAGs are closely associated with their molecular weights and sulfation patterns. Except for the non-sulfated hyaluronan which can be synthesized naturally by group A Streptococcus, all the other GAGs such as heparin and chondroitin sulfate are mainly acquired from animal tissues. Microbial cell factories provide a more effective platform for the production of structurally homogeneous GAGs. Enhancing the production efficiency of polysaccharides, accurately regulating the GAGs molecular weight, and effectively controlling the sulfation degree of GAGs represent the major challenges of developing GAGs microbial cell factories. Several enzymatic, metabolic engineering, and synthetic biology strategies have been developed to tackle these obstacles and push forward the industrialization of biotechnologically produced GAGs. This review summarizes the recent advances in the construction of GAGs synthesis cell factories, regulation of GAG molecular weight, and modification of GAGs chains. Furthermore, the challenges and prospects for future research in this field are also discussed.

Rational Design and Expedient Synthesis of Heparan Sulfate Mimetics from Natural Aminoglycosides for Structure and Activity Relationship Studies

Heparan sulfate (HS) contains variably repeating disaccharide units organized into high- and low-sulfated domains. This rich structural diversity enables HS to interact with many proteins and regulate key signaling pathways. Efforts to understand structure-function relationships and harness the therapeutic potential of HS are hindered by the inability to synthesize an extensive library of well-defined HS structures. We herein report a rational and expedient approach to access a library of 27 oligosaccharides from natural aminoglycosides as HS mimetics in 7-12 steps. This strategy significantly reduces the number of steps as compared to the traditional synthesis of HS oligosaccharides from monosaccharide building blocks. Combined with computational insight, we identify a new class of four trisaccharide compounds derived from the aminoglycoside tobramycin that mimic natural HS and have a strong binding to heparanase but a low affinity for off-target platelet factor-4 protein.

d-Glucuronate and d-Glucuronate Glycal Acceptors for the Scalable Synthesis of d-GlcN-α-1,4-d-GlcA Disaccharides and Modular Assembly of Heparan Sulfate

Reported herein is a scalable chemical synthesis of disaccharide building blocks for heparan sulfate (HS) oligosaccharide assembly. The use of d-glucuronate-based acceptors for dehydrative glycosylation with d-glucosamine partners is explored, enabling diastereoselective synthesis of appropriately protected HS disaccharide building blocks (d-GlcN-α-1,4-d-GlcA) on a multigram scale. Isolation and characterization of key donor (1,2 glycal)- and acceptor (ortho-ester, anhydro)-derived side products ensure methodology improvements to reduce their formation; protecting the d-glucuronate acceptor at the anomeric position with a para-methoxyphenyl unit proves optimal. We also introduce glycal uronate acceptors, showing them to be comparative in reactivity to their pyranuronate counterparts. Taken together, this gram-scale access offers the capability to explore the iterative assembly of defined HS sequences containing the d-GlcN-α-1,4-d-GlcA repeat, highlighted by completing this for two tetrasaccharide syntheses.

Efficient platform for synthesizing comprehensive heparan sulfate oligosaccharide libraries for decoding glycosaminoglycan-protein interactions

Glycosaminoglycans (GAGs) are abundant, ubiquitous carbohydrates in biology, yet their structural complexity has limited an understanding of their biological roles and structure-function relationships. Synthetic access to large collections of well defined, structurally diverse GAG oligosaccharides would provide critical insights into this important class of biomolecules and represent a major advance in glycoscience. Here we report a new platform for synthesizing large heparan sulfate (HS) oligosaccharide libraries displaying comprehensive arrays of sulfation patterns. Library synthesis is made possible by improving the overall synthetic efficiency through universal building blocks derived from natural heparin and a traceless fluorous tagging method for rapid purification with minimal manual manipulation. Using this approach, we generated a complete library of 64 HS oligosaccharides displaying all possible 2-O-, 6-O- and N-sulfation sequences in the tetrasaccharide GlcN-IdoA-GlcN-IdoA. These diverse structures provide an unprecedented view into the sulfation code of GAGs and identify sequences for modulating the activities of important growth factors and chemokines.

Glycosaminoglycans: What Remains To Be Deciphered?

Glycosaminoglycans (GAGs) are complex polysaccharides exhibiting a vast structural diversity and fulfilling various functions mediated by thousands of interactions in the extracellular matrix, at the cell surface, and within the cells where they have been detected in the nucleus. It is known that the chemical groups attached to GAGs and GAG conformations comprise "glycocodes" that are not yet fully deciphered. The molecular context also matters for GAG structures and functions, and the influence of the structure and functions of the proteoglycan core proteins on sulfated GAGs and vice versa warrants further investigation. The lack of dedicated bioinformatic tools for mining GAG data sets contributes to a partial characterization of the structural and functional landscape and interactions of GAGs. These pending issues will benefit from the development of new approaches reviewed here, namely (i) the synthesis of GAG oligosaccharides to build large and diverse GAG libraries, (ii) GAG analysis and sequencing by mass spectrometry (e.g., ion mobility-mass spectrometry), gas-phase infrared spectroscopy, recognition tunnelling nanopores, and molecular modeling to identify bioactive GAG sequences, biophysical methods to investigate binding interfaces, and to expand our knowledge and understanding of glycocodes governing GAG molecular recognition, and (iii) artificial intelligence for in-depth investigation of GAGomic data sets and their integration with proteomics.

Development of a new heparan sulfate proteoglycan (HSPG) chromolith LC column to study the pH dependence binding of peptide vaccines to HSPG and role of human serum albumin on its binding

Heparan sulfate proteoglycan (HSPG) expressed on immune cell surface participate in antitumor T-cell responses generated in the acidic lymph node (LN) microenvironment. In this work, HSPG was immobilized for the first time on a HPLC chromolith support for studying the effect of extra cellular acidosis in LNs on the binding to HSPG of two peptide vaccines (universal cancer peptide UCP2 and UCP4). This home-made HSPG column enabling to work at high flow-rates, was resistance to change in pH, had a long - life time, an excellent repeatability and negligible non-specific binding sites. The performance of this affinity HSPG column was confirmed by the evaluation of recognition assay for a series of known ligand of HSPG. It was shown that at 37 °C, the UCP2 binding to HSPG versus pH described a sigmoidal shape while UCP4 remained relatively constant in the pH range 5.0-7.5 and lower than the one of UCP2. By the use of an HSA HPLC column, it was shown at 37 °C and in acidic conditions a loss of affinity of UCP2 and UCP4 to HSA. It was demonstrated that upon UCP2/HSA binding, the protonation of the histidine residue in the cluster R(arg) Q(Gln) Hist (H) of the UCP2 peptide allowed to expose more favorably than UCP4 its polar and cationic groups to the negative net charge of HSPG on immune cells. Acidic pHs led to the protonation of the UCP2 residue histidine by flipping the His switch to the on position with a concomitant increase in affinity for the negative net charge of HSPG confirming that UCP2 was more immunogenic than UCP4. As well this HSPG chromolith LC column developed in this work could be used in the feature for other protein - HSPG binding studies or for a separative mode.

Protecting group enabled stereocontrolled approach for rare-sugars talose/gulose via dual-ruthenium catalysis

We herein report a convenient and highly stereocontrolled approach for rare and vital ᴅ-talo and ᴅ-gulo sugars directly from economical ᴅ-galactal through dual ruthenium-catalysis. The stereo-divergent strategy involves Ru(III)Cl₃-catalyzed Ferrier glycosylation of ᴅ-galactal to give 2,3-unsaturated ᴅ-galactopyranoside, further selective functionalization of C-4 and C-6 position with diverse protecting groups and dihydroxylation with Ru(VIII)O₄ generated in situ providing access to talo/gulo isomers. The α-anomeric stereoselectivity and syn-diastereoselectivity in glycosylation-dihydroxylation steps have been predominantly achieved by judicious selection of stereoelectronically diverse protecting groups. The synthetic utility of the dual-ruthenium catalysis was demonstrated for efficiently assembling the ᴅ-talose and/or ᴅ-gulose sugars in natural products and bioactive scaffolds.

Design and Synthesis of 6-O-Phosphorylated Heparan Sulfate Oligosaccharides to Inhibit Amyloid β Aggregation

Dysregulation of amyloidogenic proteins and their abnormal processing and deposition in tissues cause systemic and localized amyloidosis. Formation of amyloid β (Aβ) fibrils that deposit as amyloid plaques in Alzheimer's disease (AD) brains is an earliest pathological hallmark. The polysulfated heparan sulfate (HS)/heparin (HP) is one of the non-protein components of Aβ deposits that not only modulates Aβ aggregation, but also acts as a receptor for Aβ fibrils to mediate their cytotoxicity. Interfering the interaction between HS/HP and Aβ could be a therapeutic strategy to arrest amyloidosis. Here we have synthesized the 6- O -phosphorylated HS/HP oligosaccharides and reported their competitive effects on the inhibition of HP-mediated Aβ fibril formation in vitro using a thioflavin T fluorescence assay and a tapping mode atomic force microscopy.

Developments in the Chemical Synthesis of Heparin and Heparan Sulfate

Heparin and heparan sulfate represent key members of the glycosaminoglycan family of carbohydrates and underpin considerable repertoires of biological importance. As such, their efficiency of synthesis represents a key requirement, to further understand and exploit the H/HS structure-to-biological function axis. In this review we focus on chemical approaches to and methodology improvements for the synthesis of these essential sugars (from 2015 onwards). We first consider advances in accessing the heparin-derived pentasaccharide anticoagulant fondaparinux. This is followed by heparan sulfate targets, including key building block synthesis, oligosaccharide construction and chemical sulfation techniques. We end with a consideration of technological improvements to traditional, solution-phase synthesis approaches that are increasingly being utilised.

Progress and challenges in the synthesis of sequence controlled polysaccharides

The sequence, length and substitution of a polysaccharide influence its physical and biological properties. Thus, sequence controlled polysaccharides are important targets to establish structure-properties correlations. Polymerization techniques and enzymatic methods have been optimized to obtain samples with well-defined substitution patterns and narrow molecular weight distribution. Chemical synthesis has granted access to polysaccharides with full control over the length. Here, we review the progress towards the synthesis of well-defined polysaccharides. For each class of polysaccharides, we discuss the available synthetic approaches and their current limitations.

Automated Quantification of Hydroxyl Reactivities: Prediction of Glycosylation Reactions

The stereoselectivity and yield in glycosylation reactions are paramount but unpredictable. We have developed a database of acceptor nucleophilic constants (Aka) to quantify the nucleophilicity of hydroxyl groups in glycosylation influenced by the steric, electronic and structural effects, providing a connection between experiments and computer algorithms. The subtle reactivity differences among the hydroxyl groups on various carbohydrate molecules can be defined by Aka, which is easily accessible by a simple and convenient automation system to assure high reproducibility and accuracy. A diverse range of glycosylation donors and acceptors with well-defined reactivity and promoters were organized and processed by the designed software program "GlycoComputer" for prediction of glycosylation reactions without involving sophisticated computational processing. The importance of Aka was further verified by random forest algorithm, and the applicability was tested by the synthesis of a Lewis A skeleton to show that the stereoselectivity and yield can be accurately estimated.

Silver-assisted gold-catalyzed formal synthesis of the anticoagulant Fondaparinux pentasaccharide

Clinically approved anti-coagulant Fondaparinux is safe since it has zero contamination problems often associated with animal based heparins. Fondaparinux is a synthetic pentasaccharide based on the antithrombin-binding domain of Heparin sulfate and contains glucosamine, glucuronic acid and iduronic acid in its sequence. Here, we show the formal synthesis of Fondaparinux pentasaccharide by performing all glycosidations in a catalytic fashion for the first time to the best of our knowledge. Designer monosaccharides were synthesized avoiding harsh reaction conditions or reagents. Further, those were subjected to reciprocal donor-acceptor selectivity studies to guide [Au]/[Ag]-catalytic glycosidations for assembling the pentasaccharide in a highly convergent [3 + 2] or [3 + 1 + 1] manner. Catalytic and mild activation during glycosidations that produce desired glycosides exclusively, scalable route to the synthesis of unnatural and expensive iduronic acid, minimal number of steps and facile purifications, shared use of functionalized building blocks and excellent process efficiency are the salient features.

Sequential activation of thioglycosides enables one-pot glycosylation

This review describes recent developments in relative reactivity value (RRV) controlled sequential glycosylation, pre-activation based iterative glycosylation, and sulfoxide activation initiated one-pot glycosylation.

Synthetic Carbohydrate Chemistry and Translational Medicine

The importance of post-translational glycosylation in protein structure and function has gained significant clinical relevance recently. The latest developments in glycobiology, glycochemistry, and glycoproteomics have made the field more manageable and relevant to disease progression and immune-response signaling. Here, we summarize the current progress in glycoscience, including the new methodologies that have led to the introduction of programmable and automatic as well as large-scale enzymatic synthesis, and the development of glycan array, glycosylation probes, and inhibitors of carbohydrate-associated enzymes or receptors. These novel methodologies and tools have facilitated our understanding of the significance of glycosylation and development of carbohydrate-derived medicines that bring the field to the next level of scientific and medical significance.

Programmable One-Pot Synthesis of Heparin Pentasaccharide Fondaparinux

The clinically approved Fondaparinux (Arixtra) has been used for the treatment of deep vein thrombosis and acute pulmonary embolism since 2002 and is considered to be better than the low-molecular weight heparin in terms of anticoagulation response, duration of action, and biosafety. However, the synthetic methods previously developed for its manufacture are relatively complicated, thus restricting its extensive use. We report here a potentially scalable and programmable one-pot synthesis of Fondaparinux using the [1,2,2] strategy and designed thioglycosides with well-defined reactivity as building blocks.

Trisaccharide Sulfate and Its Sulfonamide as an Effective Substrate and Inhibitor of Human Endo-O-sulfatase-1

Human endo-O-sulfatases (Sulf-1 and Sulf-2) are extracellular heparan sulfate proteoglycan (HSPG)-specific 6-O-endosulfatases, which regulate a multitude of cell-signaling events through heparan sulfate (HS)-protein interactions and are associated with the onset of osteoarthritis. These endo-O-sulfatases are transported onto the cell surface to liberate the 6-sulfate groups from the internal d-glucosamine residues in the highly sulfated subdomains of HSPGs. In this study, a variety of HS oligosaccharides with different chain lengths and N- and O-sulfation patterns via chemical synthesis were systematically studied about the substrate specificity of human Sulf-1 employing the fluorogenic substrate 4-methylumbelliferyl sulfate (4-MUS) in a competition assay. The trisaccharide sulfate IdoA2S-GlcNS6S-IdoA2S was found to be the minimal-size substrate for Sulf-1, and substitution of the sulfate group at the 6-O position of the d-glucosamine unit with the sulfonamide motif effectively inhibited the Sulf-1 activity with IC₅₀ = 0.53 μM, K_i = 0.36 μM, and K_D = 12 nM.

One-pot kinetic resolution–Mitsunobu reaction to access optically pure compounds, using silver salts in the substitution protocol

Racemic carbinols were converted to chirally pure acetates by a combination of one-pot, enzyme mediated KR and Mitsunobu reaction with metal acetates. Use of AoNO₃ or mixture with NaOAc gave excellent results. The protocol is further extended to introduce azide in place of acetate.

Uncovering the detailed mode of cleavage of heparinase I toward structurally defined heparin oligosaccharides

For a more insightful investigation into the specificity of bacterial heparinase I, a series of structurally well-defined heparin oligosaccharides was synthesized using a highly efficient chemoenzymatic strategy. Apart from the primary cleavage site, five glycosidic linkages of oligosaccharides with varying modifications to obtain secondary cleavage sites were degraded by a high concentration of heparinase I. The reactivity of linkages toward heparinase I was not entirely dependent on the 2-O-sulfated iduronic acid being cleaved or the neighboring 6-O-sulfated glucosamine residues, but it was dependent on higher degrees of sulfation of oligosaccharides and indispensable N-substituted glucosamine adjacent to the cleavable linkage. Moreover, the enzyme demonstrated less preferential cleavage toward glycosidic linkages containing glucuronic acid than those containing iduronic acid of the counterpart oligosaccharides. Biolayer interferometry revealed differences in reactivity that are not completely consistent with different affinities of substrates to enzyme. Our study presented accurate information on the cleavage promiscuity of heparinase I that is crucial for heparin depolymerization.

Expedient Synthesis of Core Disaccharide Building Blocks from Natural Polysaccharides for Heparan Sulfate Oligosaccharide Assembly

The complex sulfation motifs of heparan sulfate glycosaminoglycans (HS GAGs) play critical roles in many important biological processes. However, an understanding of their specific functions has been hampered by an inability to synthesize large numbers of diverse, yet defined, HS structures. Herein, we describe a new approach to access the four core disaccharides required for HS/heparin oligosaccharide assembly from natural polysaccharides. The use of disaccharides rather than monosaccharides as minimal precursors greatly accelerates the synthesis of HS GAGs, providing key disaccharide and tetrasaccharide intermediates in about half the number of steps compared to traditional strategies. Rapid access to such versatile intermediates will enable the generation of comprehensive libraries of sulfated oligosaccharides for unlocking the "sulfation code" and understanding the roles of specific GAG structures in physiology and disease.

Glycans in drug discovery

Glycans are key players in many biological processes. They are essential for protein folding and stability and act as recognition elements in cell-cell and cell-matrix interactions. Thus, being at the heart of medically relevant biological processes, glycans have come onto the scene and are considered hot spots for biomedical intervention. The progress in biophysical techniques allowing access to an increasing molecular and structural understanding of these processes has led to the development of effective therapeutics. Indeed, strategies aimed at designing glycomimetics able to block specific lectin-carbohydrate interactions, carbohydrate-based vaccines mimicking self- and non-self-antigens as well as the exploitation of the therapeutic potential of glycosylated antibodies are being pursued. In this mini-review the most prominent contributions concerning recurrent diseases are highlighted, including bacterial and viral infections, cancer or immune-related pathologies, which certainly show the great promise of carbohydrates in drug discovery.

Paramylon and synthesis of its ionic derivatives: Applications as pharmaceutical tablet disintegrants and as colloid flocculants

Paramylon, a high molecular weight polysaccharide, is a linear and unbranched (1 → 3)-β-d-glucan. Despite its numerous biological benefits, the poor aqueous solubility of crystalline paramylon is a drawback that has hampered some of its applications. In an effort to make this biomaterial amenable to practical uses, cationic and anionic paramylon derivatives were obtained. The degrees of substitution of both products were determined. The products were characterized by FT-IR spectrocopy, ESI mass spectrometry, ¹H, ¹³C and ¹H-¹³C NMR and SEM microscopy. These techniques confirmed the success of the substitution reactions. ¹H NMR analysis was used to develop alternative methods for an approximate estimation of the degree of substitution. ¹H-¹³C HSQC NMR spectra were assigned for both derivatives. New applications of native, cationic and anionic paramylon were found. Native paramylon showed similar performance as pharmaceutical tablet disintegrant than sodium croscarmellose. Cationic paramylon behavior as colloid flocculant was comparable with commercial cationic polyacrylamides. The anionic derivative could eventually be used in the formulation of matrix controlled release systems or as a suspending agent.

Chemical synthesis of diglucosyl diacylglycerols utilizing glycosyl donors with stereodirecting cyclic silyl protective groups

Chemical syntheses of the bacterial diglucosyl diacylglycerols 1-heptadecanoyl-2-pentadecanoyl-3-O-[6-O-(β-d-glucopyranosyl)-β-d-glucopyranosyl]-sn-glycerol and 1-(cis-13-octadecenoyl)-2-palmitoyl-3-O-[2-O-(α-d-glucopyranosyl)-α-d-glucopyranosyl]-sn-glycerol are described. The syntheses feature the stereoselective construction of glycosidic linkages in glycosylation reaction by utilizing glycosyl donors with stereodirecting cyclic silyl protective groups. The 1,1,3,3-tetraisopropyldisiloxane-1,3-diyl (TIPDS) group was used for formation of the β-glycosidic linkage, while the di-tert-butylsilylene (DTBS) group was used for α-linkage formation. The silyl protective groups were chemoselectively cleavable without affecting acyl functionalities on the glycerol moiety and proved effective for the synthesis of diacylglycoglycerolipids.

An Efficient Modular One-Pot Synthesis of Heparin-Based Anticoagulant Idraparinux

Idraparinux is a fully O-sulfated α-methyl glycoside of heparin pentasaccharide motif known to interact with the antithrombin III domain and act as anticoagulant. The current most effective synthesis of Idraparinux is complicated and nonstereoselective, requiring numerous stepwise procedures with low yields. We report here an efficient modular one-pot synthesis of Idraparinux involving the use of a glycosyl phosphate with 6- O- tert-butyl diphenyl silyl group and a d-glucuronic acid-containing disaccharide thioglycoside with 6- O-acetyl group as donor building blocks for the α-directing one-pot glycosylations with an l-iduronic acid-containing disaccharide acceptor building block. The uronic acid was incorporated in a disaccharide module used in the one-pot synthesis to avoid the complicated late-stage installation of these acidic sugars. The one-pot synthesis of Idraparinux demonstrated here is an effective strategy and should be applicable to the modular assembly of other heparan sulfates with regiodefined sulfation pattern for functional study.

Advances in Chemical Synthesis of Fondaparinux

Fondaparinux (trade name Arixtra) is a safe and efficacious anticoagulant, and it is chemically related to low-molecular-weight heparins such as enoxaparin. Fondaparinux is a synthetic pentasaccharide, and its synthesis is difficult and expensive. The high cost of fondaparinux thwarts its extensive worldwide usage. Over the last two decades, several research groups and pharmaceutical companies have been interested in finding efficient and practical methods for its synthesis. The present review discusses those strategies and their pros and cons in a comparative account.

Oligosaccharide Synthesis and Translational Innovation

The translation of biological glycosylation in humans to the clinical applications involves systematic studies using homogeneous samples of oligosaccharides and glycoconjugates, which could be accessed by chemical, enzymatic or other biological methods. However, the structural complexity and wide-range variations of glycans and their conjugates represent a major challenge in the synthesis of this class of biomolecules. To help navigate within many methods of oligosaccharide synthesis, this Perspective offers a critical assessment of the most promising synthetic strategies with an eye on the therapeutically relevant targets.

Preactivation-based, iterative one-pot synthesis of anticoagulant pentasaccharide fondaparinux sodium

A one-pot, three-component synthetic strategy was designed to rapidly assemble fondaparinux, using a monosaccharide donor and two disaccharide acceptors.

Hierarchical and programmable one-pot synthesis of oligosaccharides

The programmable one-pot oligosaccharide synthesis method was designed to enable the rapid synthesis of a large number of oligosaccharides, using the software Optimer to search Building BLocks (BBLs) with defined relative reactivity values (RRVs) to be used sequentially in the one-pot reaction. However, there were only about 50 BBLs with measured RRVs in the original library and the method could only synthesize small oligosaccharides due to the RRV ordering requirement. Here, we increase the library to include 154 validated BBLs and more than 50,000 virtual BBLs with predicted RRVs by machine learning. We also develop the software Auto-CHO to accommodate more data handling and support hierarchical one-pot synthesis using fragments as BBLs generated by the one-pot synthesis. This advanced programmable one-pot method provides potential synthetic solutions for complex glycans with four successful examples demonstrated in this work.