Semi-synthesis and Crystal Structure of Sophoridine N-oxide

Sophoridine N-oxide was synthesized and characterized by 1H-NMR,EI-MS,IR and elemental analysis,together with X-ray single-crystal diffraction analysis,and its crystal structure was reported for the first time.The crystal belongs to the orthorhombic system,space group P212121 with a = 8.321（2）,b = 15.650（3）,c = 24.352（5） ,V = 3171.1（11） 3,Z = 8,Dc = 1.258 g/cm3,λ（CuKα） = 1.54178,F（000） = 1440,the final R = 0.0351 and wR = 0.0970.The crystal structure shows Sophoridine N-oxide crystallizes with two host molecules of similar conformation and four water solvent molecules in the asymmetric unit.In the crystal structure,intermolecular O-H…O hydrogen bonds link the constituent molecules into a 2D layer structure,which further extends to a 3D supramolecular architecture via Van der Waals interactions and intermolecular O-H…O hydrogen bonds.

Regioselective protection of 10-deacetylbaccatin Ⅲ and semi-synthesis of paclitaxel

Semi-synthesis of paclitaxel was achieved in four steps from 10-deacetylbaccatin HI （10-DAB HI）. The key steps are the regioselective protection at the hydroxyl group at C-7 of 10-DAB HI, using 1,1′-thiocarbonyldiimidazole as a selective reagent, and the deprotection of the protected paclitaxel with a mixture of p-toluenesulfonic acid and 0.1 mol/L aqueous hydrochloride.

SEMI-SYNTHESIS OF TRIPTONIDE

A compound.triptonide showed and antifertil has been semi-synthesized from triptolide in 97% yield with chromic acid in one step.

Semi-synthesis of Ubiquitin-propargylamide for identifying deubiquitinase targeting inhibitors

Ubiquitin-propargylamide(Ub-PA) is one of the most widely used activity-based probe to measure the activity of deubiquitinases(DUBs) and help validate DUBs targeting inhibitors. However, current synthetic route of Ub-PA is cumbersome. In this work, we report a novel semi-synthetic strategy to prepare Ub-PA in large-scale. Biochemical assays prove that semi-synthetic Ub-PA is an effective probe in identifying DUBs targeting inhibitors.

Semi-synthesis of mangiferin-7-O-β-D-glucuronide

Mangiferin is a natural plant polyphenol with a structure of xanthone C-glycoside and it displays a wide spectrum of pharmacological activities. Investigation of the metabolites of mangiferin is valuable in studying the mechanisms of its various pharmacological properties and developing novel drugs from the mangiferin derivatives. Among the metabolites of mangiferin, mangiferin-7-O-β-D-glucuronide has been reported as the phase Ⅱ metabolite of mangiferin. Herein we described the first semi-synthesis of mangiferin-7-O-β-D-glucuronide with the natural product mangiferin as the starting material. In this work, we adopted several regioselective protection procedures to distinguish the different hydroxyl groups in the structure of mangiferin, and we accomplished the glycosylation under the phase-transfer catalysis conditions. In this method, we efficiently synthesized the glucuronide derivative of mangiferin in 10 steps with highly regioselective protection.

Semi-synthesis of biotin-bearing activity-based ubiquitin probes through sequential enzymatic ligation,N-S acyl transfer and aminolysis reaction

Activity-based Ubiquitin probes(Ub-ABPs)carrying a reporter group have emerged as effective tools for the investigation of deubiquitinating enzymes(DUBs),such as studying the molecular mechanism of DUBs,profiling new DUBs.But so far,the synthesis of commonly used biotin-bearing Ub-ABPs is a technical challenge.Here,we report a one-pot semi-synthetic strategy for the acquiring of Ub-ABPs carrying a biotin tag through sequential enzymatic ligation,N-S acyl transfer and aminolysis reaction without any purification steps.These probes enable to capture the different family of DUBs for enrichment and immunoblotting using the attached biotin tag.

Insertion of unnatural metal ligand in the heme pocket of nitrophorin through protein semi-synthesis:Toward biomimicking binuclear active sites

Herein,we report a semi-synthetic strategy affording a nitrophorin 2(NP2)variant with a N,N'-bis(2-pyridylmethyl)amine(Dpa)ligand as sidechain selectively installed at position 27,which was assembled from a synthetic peptide thioester bearing the Dpa ligand and an expressed protein segment via native chemical ligation.The semi-synthetic NP2 was able to accept the natural heme b cofactor and the Dpa ligand was able to bind Cu(Ⅱ)/Fe(Ⅲ)ions,leading to heteronuclear active site.

An asymmetric catalytic multi-component reaction enabled the green synthesis of isoserine derivatives and semi-synthesis of paclitaxel

Paclitaxel(Taxol^(@))as a cornerstone of chemotherapy remains in high demand.The semi-synthesis of paclitaxel via coupling of Taxus leaf-produced baccatin III and manually synthesized isoserine(C-13 side chain)is one of the solutions to avoid environmental damage caused by the sacrifice of the whole Taxus brevifolia.A green synthesis of the C-13 side chain is pivotal to the green production of paclitaxel.We herein report a green synthesis of isoserine derivatives and the semi-synthesis of paclitaxel via a straightforward assembly of isoserines based on an Rh2(TPA)3(OAc)/CPA1 co-catalyzed asymmetric multi-component reaction of ethyl diazoacetate,triethyl silanol and N-(anthrancen-9-ylmethyl)benzaldimine.The method is featured by improved atom economy,effective mass yield,and environmental factors compared to our previous racemic method and BMS company's semi-synthesis method.And the method allows for rapid access to paclitaxel derivatives with varied C-13 side chains.

Targeted isolation of antitubercular cycloheptapeptides and an unusual pyrroloindoline-containing new analog,asperpyrroindotide A,using LC–MS/MS-based molecular networking

Further insights on the secondary metabolites of a soft coral-derived fungus Aspergillus versicolor under the guidance of MS/MS-based molecular networking led to the isolation of seven known cycloheptapeptides,namely,asperversiamides A–C(1–3)and asperheptatides A–D(4–7)and an unusual pyrroloindoline-containing new cycloheptapeptide,asperpyrroindotide A(8).The structure of 8 was elucidated by comprehensive spectroscopic data analysis,and its absolute configuration was determined by advanced Marfey’s method.The semisynthetic transformation of 1 into 8 was successfully achieved and the reaction conditions were optimized.Additionally,a series of new derivatives(10−19)of asperversiamide A(1)was semi-synthesized and their anti-tubercular activities were evaluated against Mycobacterium tuberculosis H37Ra.The preliminary structure−activity relationships revealed that the serine hydroxy groups and the tryptophan residue are important to the activity.

Construction of acetyl-CoA and DBAT hybrid metabolic pathway for acetylation of 10-deacetylbaccatin Ⅲ to baccatin Ⅲ

10-DeacetylbaccatinⅢ(10-DAB)C10 acetylation is an indispensable procedure for Taxol semi-synthesis,which often requires harsh conditions.10-DeacetylbaccatinⅢ-10-β-O-acetyltransferase(DBAT)catalyzes the acetylation but acetyl-CoA supply remains a key limiting factor.Here we refactored the innate biosynthetic pathway of acetyl-CoA in Escherichia coli and obtained a chassis with acetyl-CoA productivity over three times higher than that of the host cell.Then,we constructed a microbial cell factory by introducing DBAT gene into this chassis for efficiently converting 10-DAB into baccatinⅢ.We found that baccatinⅢcould be efficiently deacetylated into 10-DAB by DBAT with CoASH and K+under alkaline condition.Thus,we fed acetic acid to the engineered strain both for serving as a substrate of acetyl-CoA biosynthesis and for alleviating the deacetylation of baccatinⅢ.The fermentation conditions were optimized and the baccatinⅢtiters reached 2,3 and 4.6 g/L,respectively,in a 3-L bioreactor culture when 2,3 and 6 g/L of 10-DAB were supplied.Our study provides an environmentfriendly approach for the large scale 10-DAB acetylation without addition of acetyl-CoA in the industrial Taxol semi-synthesis.The finding of DBAT deacetylase activity may broaden its application in the structural modification of pharmaceutically important lead compounds.

Hypericin: chemical synthesis and biosynthesis

Hypericin is one of the most important phenanthoperylene quinones extracted mainly from plants of the genus Hypericum belonging to the sections Euhypericum and Campylosporus of Keller's classification. Widespread attention to the antiviral and anti-tumor properties of hypericin has spurred investigations of the chemical synthesis and biosynthesis of this unique compound. However, the synthetic strategies are challenging for organic and biological chemists. In this review, specific significant advances in total synthesis, semi-synthesis, and biosynthesis in the past decades are summarized.

Simultaneous capture of ISG15 conjugating and deconjugating enzymes using a semi-synthetic ISG15-Dha probe

ISG15 is a ubiquitin-like(Ubl) protein attached to substrate proteins by ISG15 conjugating enzymes whose dysregulation is implicated in a multitude of disease processes, but the probing of these enzymes remains to be accomplished. Here, we describe the development of a new activity-based probe ISG15-Dha(dehydroalanine) through protein semi-synthesis. In vitro crosslinking and cell lysate proteomic profiling experiments showed that this probe can sequentially capture ISG15 conjugating enzymes including E1 enzyme UBA7, E2 enzyme UBE2L6, E3 enzyme HERC5, the previously known ISG15 deconjugating enzyme(USP18), as well as some other enzymes(USP5 and USP14) which we additionally confirmed to impart deISGylation activity. Collectively, ISG15-Dha provides a new tool that can simultaneously capture ISG15 conjugating and deconjugating enzymes for biochemical or pharmacological studies.

Synthesis of Ras proteins and their application in biofunctional studies

Approximately 30% of human cancers are associated with RAS mutation. Ras proteins on the plasma membrane regulate a plenty of important cellular processes. The post-translational modifications(PTMs)of Ras proteins like lipidation and methylation are crucial for their correct cellular localization and biological function. Hence, obtaining Ras proteins with different kinds of modifications is the necessary prerequisite to investigate their biological properties at molecular level. In this review, we mainly summarize the developed strategies including chemical total synthesis, biosynthesis and semi-synthesis for producing Ras proteins with modifications and their application in biological studies.

An Efficient Semi-Synthetic Method to Construct Docetaxel via Sterically Crowded Linear Side Chain Esterification

An efficient semi-synthetic method was developed to construct docetaxel 1 by using N,N-di-Boc protected lin- ear isoserine derivative 5 as the side chain source, in which, bulky protecting group on the nitrogen atom blocked C-2＇ position and prohibited unavoidable racemization in previous studies.