Guanghui Zong

Synthesis and anti-fungal activity of seven oleanolic acid glycosides.

In order to develop potential anti-fungal agents, seven glycoconjugates composed of α-L-rhamnose, 6-deoxy-α-L-talose, β-D-galactose, α-D-mannose, β-D-xylose-(1→4)-6-deoxy-α-L-talose, β-D-galactose-(1→4)-α-L-rhamnose, β-D-galactose-(1→3)-β-D-xylose-(1→4)-6-deoxy-α-L-talose as the glycone and oleanolic acid as the aglycone were synthesized in an efficient and practical way using glycosyl trichloroacetimidates as donors. The structures of the new compounds were confirmed by MS, 1H-NMR and 13C- NMR. Preliminary studies based on means of mycelium growth rate, indicated that all the compounds possess certain fungicidal activity against Sclerotinia sclerotiorum (Lib.) de Bary, Rhizoctonia solani Kuhn, Botrytis cinerea Pers and Phytophthora parasitica Dast.

Design, Synthesis and Bioactivity of Novel Glycosylthiadiazole Derivatives

A series of novel glycosylthiadiazole derivatives, namely 2-phenylamino-5-glycosyl-1,3,4-thiadiazoles, were designed and synthesized by condensation between sugar aldehydes A/B and substituted thiosemicarbazide C followed by oxidative cyclization by treating with manganese dioxide. The original fungicidal activities results showed that some title compounds exhibited excellent fungicidal activities against Sclerotinia sclerotiorum (Lib.) de Bary and Pyricularia oryzae Cav, especially compounds F-5 and G-8 which displayed better fungicidal activities than the commercial fungicide chlorothalonil. At the same time, the preliminary studies based on the Elson-Morgan method indicated that many compounds exhibited some inhibitory activity toward glucosamine-6-phosphate synthase (GlmS). The structure-activity relationships (SAR) are discussed in terms of the effects of the substituents on both the benzene and the sugar ring.

Efficient synthesis of a 6-deoxytalose tetrasaccharide related to the antigenic O-polysaccharide produced by Aggregatibacter actinomycetemcomitans serotype c.

Concise synthesis of a 6-deoxy-alpha-L-talose tetrasaccharide, 6-deoxy-alpha-L-Talp-(1-->3)-6-deoxy-alpha-L-Talp-(1-->2)-6-deoxy-alpha-L-Talp-(1-->3)-6-deoxy-alpha-L-Talp, the dimer of the disaccharide repeating unit of the OPS from Aggregatibacter actinomycetemcomitans serotype c, has been accomplished through suitable protecting group manipulations and stereoselective glycosylation starting from commercially available L-rhamnose. The target oligosaccharide in the form of its p-methoxyphenyl glycoside is suitable for further glycoconjugate formation via selective cleavage of this group.

Synthesis of the 6-deoxytalose-containing tri- and hexasaccharides of the O-antigen polysaccharide from Mesorhizobium huakuii IFO15243T

The synthesis of a trisaccharide and a hexasaccharide, the monomer and dimer of the repeating unit of O-antigen polysaccharide from Mesorhizobium huakuii IFO15243, has been accomplished through suitable protecting group manipulations and stereoselective glycosylation reactions starting from commercially available l-rhamnose. The target oligosaccharides in the form of their p-methoxyphenyl glycosides are suitable for further glycoconjugate formation via selective cleavage of this group.

Facile syntheses of the disaccharide repeating unit of the O-antigenic polysaccharide of Burkholderia pseudomallei strain 304b and its dimer and trimer.

A highly efficient strategy for the preparation of a disaccharide-repeating unit of the O-antigenic polysaccharide of Burkholderia pseudomallei strain 304b, and its dimer and trimer, has been developed through a regio- and stereoselective manner using p-methoxylphenyl 2,4,6-tri-O-benzoyl-α-D-glucopyranoside and 3-O-allyloxycarbonyl-2,4-di-O-benzoyl-6-deoxy-α-L-talopyranosyl trichloroacetimidate as the key synthons. The target molecules were equipped with a p-methoxylphenyl handle at the reducing terminus to allow for their further functionalization and attachment to a carrier protein.

Synthesis and plant growth regulation activity of α-d-ManpNAc-(1→2)-[α-L-Rhap-(1→3)-]α-L-Rhap-(1→4)-β-d-GlupNAc-(1→3)-α-L-Rhap, the repeating unit of O-antigen of Rhizobium trifolii 4s.

The synthesis of a pentasaccharide 2 containing acetamido-2-deoxy-d-glucose and acetamido-2-deoxy-d-mannose related to the cell wall polysaccharide of Rhizobium trifolii 4s has been achieved by a [2+3] approach from commercially available l-rhamnose, d-glucose, and d-glucosamine as the starting materials. The target molecule was equipped with a p-methoxylphenyl handle at the reducing terminus to allow for further glycoconjugate formation via selective cleavage of this group. The bioassay suggested that the synthetic pentasaccharide 2 can stimulate the growth of wheat coleoptile similarly to indole-3-acetic acid (IAA), and promote the wheat seedling development before winter by seed treatment at a concentration of 20mg/L.

Direct 2,3-O-isopropylidenation of α-D-mannopyranosides and the preparation of 3,6-branched mannose trisaccharides.

A highly efficient, regioselective method for the direct 2,3-O-isopropylidenation of α-d-mannopyranosides is reported. Treatment of various α-d-mannopyranosides with 0.12 equiv of the TsOH·H2O and 2-methoxypropene at 70 °C gave 2,3-O-isopropylidene-α-d-mannopyranosides directly in 80%~90% yields. Based on this method, a 3,6-branched α-d-mannosyl trisaccharide was prepared in 50.4% total yield using p-nitrophenyl 2,3-O-isopropylidene-α-d-mannopyranoside as the starting material.

Synthesis, fungicidal evaluation and 3D-QSAR studies of novel 1,3,4-thiadiazole xylofuranose derivatives

1,3,4-Thiadiazole and sugar-derived molecules have proven to be promising agrochemicals with growth promoting, insecticidal and fungicidal activities. In the research field of agricultural fungicide, applying union of active group we synthesized a new set of 1,3,4-thiadiazole xylofuranose derivatives and all of the compounds were characterized by 1H NMR and HRMS. In precise toxicity measurement, some of compounds exhibited more potent fungicidal activities than the most widely used commercial fungicide Chlorothalonil, promoting further research and development. Based on our experimental data, 3D-QSAR (three-dimensional quantitative structure-activity relationship) was established and investigated using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques, helping to better understand the structural requirements of lead compounds with high fungicidal activity and environmental compatibility.