Cyclopeptides from Polycarpon prostratum (Caryophyllaceae)

Two new cyclic peptides, polycarponin B and C (1, 2), were isolated from the whole plants of Polycarpon prostratum (Forssk.) Aschers. et Schwein. ex Aschers. By detailed spectroscopic analysis, their structures were determined as cyclo(-Gly(1)-Ile-Val(1)-Leu(1)-Val(2)-Gly(2)-Leu(2)-Pro) and cyclo(-Pro(1)-Thr-Leu(1)-Pro(2)-Pro(3)-Val-Leu(2)-Phe), respectively.

New Minor Cyclopeptides from Arenaria oreophila (Caryophyllaceae)

New minor cyclic peptides, named arenariphilin C 1 and arenariphilin D 2, were isolated from the whole plants of Arenaria oreophila （Caryophyllaceae）. Their structures were determined as cyclo（Pro^1-Pro2-Leu^1-Leu2-Phe-Ser-Gly-Thr） and cyclo （Ser-Cys） on the basis of spectroscopic data, especially by two-dimension NMR （2D NMR） technologies.

HETEROPHYLLIN-A AND B,TWO CYCLOPEPTIDES,FROM THE ROOTS OF PSEUDOSTELLARIA HETEROPHYLLA

Two cyclopeptides,heterophyllin A and B,have been isolated from the roots of Pseudostellaria heterophylla.Their structures were elucidated by chemical, spectroscopic,and enzymatic methods.

A New Cyclopeptide from Polycarpon prostratum

A new cyclic peptide named polycarponin A, was isolated from the whole plants of Polycarpon prostratum. Its structure was determined by detailed spectroscopic analysis.

Leiocyclocin A and B, Two Cyclopeptides from Goniothalamus leiocarpus

Two new cyclopeptides, leiocyclocin A (1); B (2), were isolated from the seeds of Goniothalanus leiocarpus. Their structures were elucidated by means of spectral and chemical methods.

A new cyclopeptide from Dianthus caryophyllus

A new cyclopeptide as well as a known cyclopeptide were isolated from the whole plants of Dianthus caryophyllus. Their structures were elucidated as cyclo （-Thr-Gly-Pro-Tyr-Phe-） （1） and cyclo （-Ala-Gly-Ser-IIe-Phe-Phe-） （2） by means of chemical and spectroscopic methods including MS, 1D and 2D NMR techniques.

An Efficient Synthesis of Cyclopeptides Bridged with Aliphatic-aryl Ether Bond

Based on the pseudo-dilution effect (PDE) on solid support, three cyclopeptides with an aliphatic-aryl ether bond as the bridge were synthesized via SN2 reaction between bromoacetylated at N-terminal and the phenol –OH group in C-terminal Tyr residue. All the products were obtained in good overall yields and characterized by related analytic data.

Cyclopeptides from Amanita exitialis

A new cyclic nonapeptide, amanexitide (1), along with the known cyclopeptides, a- and b-amanitins, was isolated from the fruiting bodies of Amanita exitialis, a newly described poisonous mushroom endemic to Guangzhou, Guangdong Province, China. Its amino acid composition and absolute configuration were determined by chemical degradation and derivatization followed by chiral GC analysis. Its amino acid sequence was elucidated by extensive analysis of ESIMS/MS and FTICRMS data. The occurrence of 1 in this mushroom is interesting because it has a structure closely related to antamanide, a cyclic decapeptide with antidote activity against amatoxins and phallotoxins, occurring in A. phalloides.

A New Cyclopeptide from Brachystemma calycinum

A new cyclopeptide, brachystemin A, has been isolated from the roots of Brachystemma calycinum. The structure was elucidated by spectral methods.

Squamin-A,Novel Cyclopeptide from Annona squamosa

A novel cyclopeptide, squamin-A has been isolated from the seeds of Annona squamosa Linn.. The structure was elucidated by extensive 2D-NMR, FABMS and amino acid analysis in combination with Marfey's reagents as cyclo-[l-prolyl-l-(S-oxo)-methionyl-l-tyrosyl-l-glycyl-tythreonyl-l-valyl-l-alanyl-l-isoleucyl].

Application of a new TLC chemical method for detection of cyclopeptides in plants

Cyclopeptides have been investigated phytochemically less often because until now there has not been a special chemical method to detect them. Since we found cyclopeptides in Pseudostellaria heterophylla (Caryophyllaceae) in 1991, we have gradually established a special chemical detection method for detecting cyclopeptides in plants, which induces a new thin layer chromatography (TLC) protosite reaction with ninhydrin reagent. With this method, our group isolated and determined 73 cyclopeptides from 17 plants which belong to 5 families and 14 genuses, they are from dicyclopeptides to undecacyclopeptides, including 68 new ones, and were determined based on spectral, chemical and enzymic methods, especially 2D NMR and FAB-MS. Meantime, with this method cyclopeptides can be distinguished from peptidic amides based on their behaviour in TLC.

Chemical Progress in Cyclopeptide-containing Traditional Medicines Cited in Chinese Pharmacopoeia

Plant cyclopeptides, cyclic compounds formed mainly by the peptidic bonds of 2--37 protein and non-protein amino acids （mainly L-amino acids） and found in higher plants, have been attractive for their extensive bioactivities and distinctive molecular architectures. During the last half century＇s study, about 500 cyclopeptides divided into eight types have been isolated from over 120 species, which belong to over 20 families and 60 genera. Some cyclopeptides showed potential anti-tumor, sedative, immunosuppressive, and uterotonic activities. In the Chinese Pharmacopoeia （CP, 2010 Version）, 23 species （14 families, 18 genera） containing cyclopeptides have been re- corded in the origins of 24 traditional Chinese medicines （TCMs）. Heterophyllin B （64）, first reported by us from Pseudostellaria heterophylla in 1993 was cited for the first time in CP as the standard substance of cyclopeptides for quality control. In this review, we highlight the progress in the chemical studies of these cyclopeptide-containing TCMs, in particular recent results in our group＇s publications.

Two new cyclopeptides from stellaria yunnanensis

In the previous papers, we reported the isolation and structural elucidation of three new cyclopeptides, namely stellarin A, B and C, from the fresh roots of stellaria yunnanensis Franch. In a continued study on this plant, other two new cyclopeptides named stellarin D(1) and E(2) were obtained and their structures were established to be cyclo (Gly-Tyr-Leu-Phe-Pro-Ile-Pro)(1), cyclo(Gly-Ile-Pro-Tyr-Ile-Ala-Ala)(2), respectively.

Stellarins F and G, two new cyclopeptides from Stellaria yunnanensis

In the previous papers, we reported the structural elucidation of stellarins A-E, five new cyclopeptides from the fresh roots of Stellaria yunnanensis Franch. Further chemical study on this plant led to the isolation of two other new cyclopeptide named stellarins F(1) and G(2). By a combination of 2D-NMR, enzymatic degradation and FABMS, their structures were established to by cyclo(Gly-Ala-Gly-Ser-Pro-Trp-Phe-Pro) and cyclo(Gly-Ala-Tyr-Leu-Ala), respectively.

Enzymatic cyclization of linear peptide to plant cyclopeptide heterophyllin B

The crude enzyme (PH-1) isolated from Pseudostellaria heterophylla by ourgroup has catalyzed enzymatic cyclization of linear peptideNH_2-Gly^1-Gly^2-Leu-Pro-Pro-Pro-lle-Phe-COOH (4) into cyclopeptide heterophyllin B (HB) from plantfor the first time. To ensure this reaction, some analytical methods including TLC, HPLC, MS, NMR,and ^(13)C labeling were used to prove that the reaction of substrate 4 sharing residue ofNH-Phe-Gly-CO was successful.

A pair of cyclopeptide epimers from the seeds of Celosia argentea

Two cyclopeptides, celogentin L(1) and its epimer lyciumin A(2) were firstly isolated from Celosia argentea L.. The planar structures of the two compounds were fully determined by spectroscopic data, including 1 D-, 2 D-NMR, and HR-ESI/MS. The absolute configurations of amino acid components were assigned via chiral-phase HPLC analyses after acid hydrolysis. Furthermore, the configuration of C-N linkage at the glycine Cα was elucidated by extensive analyses of 2 D-NMR and comparison of the experimental and calculated electronic circular dichroism(ECD) spectra. Cytotoxicity of the two compounds against human alveolar epithelial A549, hepatocellular carcinoma Hep G2, and cervical cancer Hela cell lines was assayed. Although both of them were inactive in these cells, the present findings add new facets for the chemistry of Celosia argentea.

Two New Cyclopeptides from Podocarpus nagi

Two new cyclopeptides, nagitides A and B, were isolated from the stem bark ofPodoearpus nagi. Their struc- tures were elucidated on the basis of NMR experiments including IH-IH COSY, HSQC, HMBC, ROESY, etc. This is the first report of cyclopeptides separated from this plant.

Novel Cyclopeptide Bolaamphiphile for Constructing Supramolecular Nanotubes

A novel dicyclopeptide-based bolaamphiphile was synthesized.The hydrophilic cyclopeptide fragments were linked to an alkyl chain 1,6-bis(maleimido)hexane,which acted as a hydrophobic spacer.The transmission electron microscopy (TEM) observation indicated that the cyclopeptide bolaamphiphile (CPB) self-assembled into the nanotubes with a thickness of about 3 nm.Based on the optimized molecular conformation obtained via MM2 method,the length of CPB was demonstrated to be around 4 nm,implying that the nanotubes were single-walled.Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD) analysis showed that the cyclopeptides in CPB mainly acted as the hydrophilic headgroups,rather than providing the well-ordered hydrogen bonding interaction responsible for β-sheet conformation.To investigate the special self-assembly behavior of CPB,the single cyclopeptide (CP) without the connection of the linker was synthesized.Further investigation indicated that the CP molecules can not form tubular structures but nanofibers.

Structure of Cyclopeptide C10 in Solution

Two dimensional 1H NMR techniques were used to determine the solution structure of C10, a cyclopeptide synthesized in the laboratory. Complete proton resonance assignments were obtained using 2 D DQF COSY, TOCSY, and NOESY experiments. The cross peak volumes in the NOESY spectra were used to calculate the C10 structure. The conformation showed that the four side chains of the lysine residues faced the same side of the cyclopeptide ring.

银柴胡化学成分的研究

银柴胡为石竹科植物披针叶叉歧繁缕(Stellaria dichotoma L.var.lancenlata Bge.)的干燥根。主产宁夏,具有清热凉血之功效。我们从银柴胡中分离得到九种化合物。其中银柴胡环肽A及B为两个首次发现的新化合物。银柴胡根用甲醇提取,回收甲醇后悬浮于水中,用乙醚及正丁醇萃取。乙醚和正丁醇提取物再分别上硅胶柱,用氯仿-甲醇洗脱得到九个化合物。经理化常数测定(与标准品对照)气相层析及光谱方法鉴定了七种已知成分,分别为α-菠甾醇(α-spinasterol)(1)。