Synthesis of flaccidoside II, a bidesmosidic triterpene saponin isolated from Chinese folk medicine Di Wu

A total synthesis of flaccidoside II, 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-xylopyranosyloleanolic acid 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside, isolated from Chinese folk medicine Di Wu, has been accomplished from building blocks isopropyl 2-O-acetyl-3,4-di-O-benzoyl-1-thio-beta-D-xylopyranoside, 2,3,4-tri-O-benzoyl-alpha-L-rhamnopyranosyl trichloroacetimidate, oleanolic acid trityl ester, ethyl 2,3-di-O-acetyl-6-O-benzoyl-1-thio-beta-D-glucopyranoside and 4-methoxyphenyl 2,3,4-tri-O-acetyl-beta-D-glucopyranoside. The use of a partially protected thioglycosyl donor significantly simplified the synthesis of the target saponin.     

Synthesis of stryphnoside A, a triterpene saponin isolated from the pericarps of Stryphnodendron fissuratum

Stryphnoside A, α-l-rhamnopyranosyl 3β-O-[α-l-arabinopyranosyl-(1→4)-β-d-xylopyranosyl-(1→2)-β-d-glucopyranosyl]-2α-hydroxyolean-12-en-28-oate, has been synthesized in 11 steps in 15% overall yield starting from the naturally abundant oleanolic acid. Condensation of a partially protected glucopyranosyl donor and 2α,3β-dihydroxyolean-12-en-28-oic acid derivative using inverse glycosylation procedure has significantly simplified the target saponin synthesis. Stryphnoside A exhibited weak cytotoxic activities against tumor cells HeLa, A549, and HepG2 with IC₅₀ at mM level.     

Synthesis of alpha-lactosyl-(1-->3)-L-glycero-alpha-D-manno-heptopyranoside, a partial oligosaccharide structure expressed within the lipooligosaccharide produced by Neisseria gonorrhoeae strain 15253.

The glycosyl donor, hepta-O-benzyl-beta-lactosyl trichloroacetimidate (4) was prepared by treating hepta-O-benzyl-lactose with trichloroacetonitrile in the presence of potassium carbonate. The acceptor, methyl 2-O-benzyl-4,6-O-benzylidene-7,8-dideoxy-alpha-D-manno-oct-7-enopyranoside (8) was synthesized by hydrolysis of a 3,4-butane diacetal of methyl L-glycero-alpha-D-manno-oct-enopyranoside and subsequent benzylidenation. Glycosidation of the donor 4 with the acceptor 8 in 1,4-dioxane using Me(3)SiOTf as a promoter for 1 h at room temperature gave methyl (2,3,4,6-tetra-O-benzyl-beta-D-galactopyranosyl)-(1-->4)-(2,3,6-tri-O-benzyl-alpha-D-glucopyranosyl)-(1-->3)-2-O-benzyl-4,6-O-benzylidene-7,8-dideoxy-alpha-D-manno-oct-7-enopyranoside (9) as a major product (59%). The oct-enopyranoside moiety of the trisaccharide 9 was converted to a heptopyranoside (80%) by oxidative cleavage with OsO(4)-NaIO(4) and subsequent reduction. Hydrogenolysis of the resulting trisaccharide and subsequent acetylation gave the peracetate of alpha-lactosyl-(1-->3)-Hep. Deacetylation of the peracetate afforded the title trisaccharide.     

Synthesis of two trisaccharides related to the triterpenoid saponins isolated from Solanum lycocarpum

Chemical synthesis of two trisaccharides related to the triterpenoid saponins isolated from Solanum lycocarpum from commercially available d-Glc, d-Gal and l-Rha have been achieved by following concise and high-yielding route. The target trisaccharide 1 has been made by following a bis-glycosylation approach that has minimized the protecting group manipulations up to great extent. The trisaccharides have been synthesized in the form of their p-methoxyphenyl (OMP) glycosides to leave the scope for further glycoconjugates formation by the selective removal of the OMP glycoside and trichloroacetimidate chemistry. La(OTf)₃ has been used successfully as the promoter for the NIS mediated activation of thioglycosides.     

Synthesis of a tetrasaccharide related to the O-antigen from Azospirillum lipoferum SR65

Concise synthesis of a tetrasaccharide repeating unit of the LPS isolated from Azospirillum lipoferum SR65 has been accomplished through suitable protecting group manipulations and stereoselective glycosylation starting from commercially available l-rhamnose and d-glucose. The target oligosaccharide in the form of its p-methoxyphenyl glycoside is suitable for further glycoconjugate formation via selective cleavage of the OMP glycoside. Plant growth-promoting bacteria (PGPB) of genus Azospirillum plays important roles in the growth and development of plants. The interaction between the roots of the plants and the microbes is governed by the cell surface carbohydrate polymers (CPS, LPS, etc.). The present synthetic-based study elucidates aspects of plant-microbe interaction and future biofertiliser design.     

Isolation,reactivity, pharmacological activities and total synthesis of hispanolone and structurally related diterpenes from Labiatae plants

Hispanolone is a furolabdane diterpene isolated from Ballota hispanica, whose natural product chemistry has been summarized and updated here, including several aspects associated with the isolation, structure determination, hemisynthesis, total synthesis, and pharmacology, and related hispanolone diterpenoids that have attracted the interest of different laboratories from diverse perspective and expertise in the last forty-two years.     

Synthesis of a set of sulfated and/or phosphorylated oligosaccharide derivatives from the carbohydrate-protein linkage region of proteoglycans

The synthesis of a set of various sulfoforms and/or phosphoforms as 7-methoxy-2-naphthyl glycosides of beta-D-Xylp, beta-D-Galp-(1-->4)-beta-D-Xylp, and beta-D-Galp-(1-->3)-beta-D-Galp-(1-->4)-beta-D-Xylp, structures encountered in the common carbohydrate-protein linkage region of proteoglycans, is reported for the first time. These molecules will serve as probes for systematic studies of the substrate specificity of the glycosyltransferases involved in the early steps of the biosynthesis of proteoglycans. A straightforward divergent preparation was achieved using key intermediates, which were designed as common precursors.     

Inhibition of the oligosaccharides extracted from Morinda officinalis,a Chinese traditional herbal medicine,on the corticosterone induced apoptosis in PC12 cells

The mechanisms of the antidepressant action of the oligosaccharides (P(6)) extracted from Morinda Officinalis were studied. By flow cytometry analysis, treatment of PC12 cells with corticosterone (Cort) induced apoptosis in a concentration and time dependent manner. The highest percentage of apoptotic cells accumulated to 27.85 +/- 9.2% following pretreatment with Cort 10 microM for 5 d. In agarose gel electrophoresis of DNA, the sample obtained from PC12 cells pretreated with Cort 10 microM for 5 d showed a typical ladder pattern suggesting that Cort increased the DNA fragmentation significantly. Furthermore, the ultrastructure of Cort-treated cells displayed typical apoptosis-like morphological changes including fragmented chromatin accumulation to the inside of nucleolus membrane with a shape like crescent moon or ring, nuclear fragmentation or apoptotic body. In the presence of P(6), or tricyclic antidepressant desipramine (DIM), the apoptosis induced by Cort in the three measurements above was significantly inhibited. These results indicate that DIM or P(6) antagonize the apoptosis induced by Cort in PC12 cells, which may be one of the cellular mechanisms of their antidepressant effects.     

Case report: The effect of a Chinese herbal medicine,BG-104 in two HIV positive hemophiliacs

The BG-104, a Chinese herbal medicine, has been reported to restore decreased plasma superoxide scavenging activity.This report showedin vivo effect of BG-104 on two patients with hemophilia A infected with human immunodeficiency virus by infusions of the concentrated Factor VIII. Both patients, showed a peripheral CD4⁺ T-lymphocytopenia for more than half a year. BG-104 was administered daily and follow-up observations were continued for 3 years. The number of CD4⁺ T-lymphocytes remained relatively constant during BG-104 treatment without disease progression.Abbreviations CD cluster differentiation - HIV human immunodeficiency virus - IgG immunoglobulin G - CDC Center of disease control - MoAb monoclonal antibody     

Identification of unprecedented purine-containing compounds, the zingerines, from ginger rhizomes (Zingiber officinale Roscoe) using a phase-trafficking approach

Three unprecedented purine-containing compounds, named [6]-, [8]-, and [10]-zingerines as they are 5-(6-amino-9H-purin-9-yl) analogs of [6]-, [8]-, and [10]-gingerols, respectively, were isolated from a methanolic extract of ginger rhizomes using a phase trafficking-based method that utilizes solid phase reagents allowing for fast and selective simultaneous separation of basic, acidic, and neutral components of natural products extracts.     

Tasiamide F,a potent inhibitor of cathepsins D and E from a marine cyanobacterium

In search of novel protease inhibitors with therapeutic potential, our efforts exploring the marine cyanobacterium Lyngbya sp. have led to the discovery of tasiamide F (1), which is an analogue of tasiamide B (2). The structure was elucidated using a combination of NMR spectroscopy and mass spectrometry. The key structural feature in 1 is the presence of the Phe-derived statine core, which contributes to its aspartic protease inhibitory activity. The antiproteolytic activity of 1 and 2 was evaluated in vitro against cathepsins D and E, and BACE1. Tasiamide F (1) displayed IC₅₀ values of 57 nM, 23 nM, and 0.69 μM, respectively, indicating greater selectivity for cathepsins over BACE1 compared with tasiamide B (2). Molecular docking experiments were carried out for compounds 1 and 2 against cathepsins D and E to rationalize their activity towards these proteases. The dysregulated activities of cathepsins D and E have been implicated in cancer and modulation of immune responses, respectively, and these proteases represent potential therapeutic targets.     

Highly selective antibacterial activity of novel alkyl quinolone alkaloids from a Chinese herbal medicine, Gosyuyu (Wu-Chu-Yu), against Helicobacter pylori in vitro

To elucidate the antibacterial activity of Gosyuyu, the crude extract from the fruit of Evodia rutaecarpa, a Chinese herbal medicine, has been fractionated chromatographically, and each fraction was assayed for antibacterial activity against Helicobacterpylori (H. pylori) in vitro. As the result, a single spot having marked antibacterial activity against H. pylori was obtained and the chemical structure was analyzed. The isolated compound was revealed to be a novel alkyl quinolone alkaloid based on the solubility, IR spectra, NMR analysis and mass spectrometric data after purification by TLC of silica. We compared the antimicrobial activity of this compound with that of other antimicrobial agents and examined susceptibility of various intestinal pathogens. As the result, the new quinolone compounds obtained from Gosyuyu extracts were found to be a mixture of two quinolone alkaloids, 1-methyl-2-[(Z)-8-tridecenyl]-4-(1H)-quinolone and 1-methyl-2-[(Z)-7-tridecenyl]-4-(1H)-quinolone (MW: 339), reported previously. The minimum inhibitory concentration (MIC) of these compounds against reference strains and clinically isolated H. pylori strains were less than 0.05 microg/ml, which was similar to the MIC of amoxicillin and clarithromycin that are used worldwide for the eradication of H. pylori, clinically. Furthermore, it was noted that the antimicrobial activity of these compounds was highly selective against H. pylori and almost non-active against other intestinal pathogens. The above results showed that these alkyl methyl quinolone (AM quinolones) alkaloids were useful for the eradication of H. pylori without affecting other intestinal flora.     

Synthesis of the non-peptidic snail toxin 6-bromo-2-mercaptotryptamine dimer (BrMT)2, its lower and higher thio homologs and their ability to modulate potassium ion channels

The first synthesis of the non-peptidic snail toxin 6-bromo-2-mercaptotryptamine dimer (BrMT)₂ is described, along with the preparation of its lower and higher thio homologs. The synthetic (BrMT)₂ and its derivatives reported herein are all capable of slowing the activation of the K_v1.1 potassium ion channel. Only the monosulfide variant shows significant slowing of the deactivation process. This synthetic strategy can now be applied to creating a more extensive set of compounds that vary in the length of the linker connecting the two monomers, the substituents on the indole ring core, and terminal amine.     

Synthesis, from cellobiose, of a trisaccharide closely related to the GlcNAc----GlcA----GlcN segment of the antithrombin-binding sequence of heparin

O-(2-Deoxy-2-sulfamido-6-O-sulfo-alpha-D-glucopyranosyl)-(1----4)- O-(beta-D- glucopyranosyluronic acid)-(1----4)-1,6-anhydro-2-deoxy-2-sulfamido-6-O-sulfo-beta-D-gl ucopyranose pentasodium salt (14) was synthesized as a heparin-related oligosaccharide. The glycosyl acceptor (derived from cellobiose) and a glycosyl donor, 6-O-acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl bromide, were coupled in the presence of mercuric bromide and molecular sieves 4A to afford a 69% yield of fully protected trisaccharide, namely, O-(6-O-acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl)-(1 ----4)- O-(methyl 2,3-di-O-benzyl-beta-D-glucopyranosyluronate)-(1----4)-3-O-acetyl- 1,6-anhydro-2 - azido-2-deoxy-beta-D-glucopyranose (10), which was converted into the partially sulfated trisaccharide 14. Compound 10 also underwent acetolysis to afford the glycosyl acetate, for further elongation of the glycosyl chain.     

Synthesis of methyl glycoside derivatives of tri- and penta-saccharides related to the antithrombin III-binding sequence of heparin, employing cellobiose as a key starting-material

Two key synthons for the title pentasaccharide derivative, methyl O-(methyl 2-O-benzoyl-3-O-benzyl-alpha-L-idopyranosyluronate)-(1----4)-6-O-acetyl- 2-azido - 3-O- benzyl-2-deoxy-beta-D-glucopyranoside and O-(methyl 2,3-di-O-benzyl-4-O- chloroacetyl-beta-D-glucopyranosyluronate)-(1----4)-3,6-di-O-acetyl-2-az ido-2- deoxy-alpha-D- glucopyranosyl bromide, were prepared from a common starting material, cellobiose. They were coupled to give a tetrasaccharide derivative that underwent O-dechloroacetylation to the corresponding glycosyl acceptor. Its condensation with the known 6-O-acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl bromide afforded a 77% yield of suitably protected pentasaccharide, methyl O-(6-O- acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl)-(1----4)- O- (methyl 2,3- di-O-benzyl-beta-D-glucopyranosyluronate)-(1----4)-O-(3,6-di-O-acetyl-2- azido-2 - deoxy-alpha-D-glucopyranosyl)-(1----4)-O-(methyl 2-O-benzoyl-3-O-benzyl-alpha-L- idopyranosyluronate)- (1----4)-6-O-acetyl-2-azido-3-O-benzyl-2-deoxy-beta-D-glucopyranoside. Sequential deprotection and sulfation gave the decasodium salt of methyl O-(2- deoxy-2-sulfamido-6-O-sulfo-alpha-D-glucopyranosyl)-(1----4)-O-(be ta-D- glucopyranosyl-uronic acid)-(1----4)-O-(2-deoxy-2-sulfamido-3,6-di-O-sulfo-alpha-D-gluco pyranosyl)- (1----4)-O-(2-O-sulfo-alpha-L-idopyranosyluronic acid)-(1----4)-2-deoxy-2- sulfamido-6-O- sulfo-beta-D-glucopyranoside (3). In a similar way, the trisaccharide derivative, the hexasodium salt of methyl O-(2-deoxy-2-sulfamido-6-O-sulfo-alpha-D- glucopyranosyl)- (1----4)-O-(beta-D-glucopyranosyluronic acid)-(1----4)-2-deoxy-2-sulfamido-3,6- di-O- sulfo-alpha-D-glucopyranoside (4) was synthesized from methyl O-(6-O-acetyl-2- azido- 3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl)-(1----4)-O-(methyl 2,3-di-O- benzyl-beta- D-glucopyranosyluronate)-3,6-di-O-acetyl-2-azido-2-deoxy-alpha-D- glucopyranoside. The pentasaccharide 3 binds strongly to antithrombin III with an association constant almost equivalent to that of high-affinity heparin, but the trisaccharide 4 appears not to bind.     

Gene organization of oryzacystatin-II, a new cystatin superfamily member of plant origin, is closely related to that of oryzacystatin-I but different from those of animal cystatins

The gene structure of oryzacystatin-II, a new cystatin superfamily member of rice seed origin, was determined. It spans approximately 2.5 kbp and comprises 3 exons. The number of exons and the intron-breakpoints coincide with those of oryzacystatin-I, the first well-defined plant cystatin. However, no similar sequences were observed between the two oryzacystatin genes in 5'-upstream regulatory regions, even though both are expressed specifically during the ripening stage of rice seeds. The gene organization of these two plant cystatins is generally different from that of animal cystatins.     

Absolute configuration of fusarone, a new azaphilone from the endophytic fungus Fusarium sp. isolated from Melia azedarach, and of related azaphilones

A new azaphilone derivative, named fusarone (1), has been isolated from the ethyl acetate soluble extract of the fermentation broth of an endophytic fungus, Fusarium sp. LN-12, isolated from the leaves of Melia azedarach Linn. The structure of the new compound was established on the basis of extensive spectroscopic analysis, including 1D-NMR and 2D-NMR ((1) H-(1)H COSY, TOCSY, HSQC, HMBC, and NOESY) experiments. The absolute configurations of fusarone (1) and of a second related azaphilone were determined by means of electronic circular dichroism spectroscopy and optical rotation calculations.     

Anti-inflammatory and analgesic effects and molecular mechanisms of JCICM-6, a purified extract derived from an anti-arthritic Chinese herbal formula

The anti-inflammatory and anti-nociceptive effects and the molecular mechanisms of JCICM-6, a purified extract derived from an anti-arthritic Chinese herbal formula composed of Caulis Sinomenii, Aconiti laterralis Preparata, Rhizoma Curcumae longae, Radix Paeoniae albae, and Cortex Moutan, were examined for the first time. JCICM-6 was prepared using pharmaceutical extraction technology, purified by Amberlite XAD-7HP polymeric resin. Pharmacologically, in carrageenan-induced edema and carrageenan-evoked thermal hyperalgesia in paws of rats, the oral administration of JCICM-6 at dosages of 0.4, 0.8, and 1.6 g/kg demonstrated significant inhibition with a dose-dependent manner. Mechanistic studies showed that JCICM-6 effectively decreased the production of the pro-inflammatory cytokines of IL-6 and IL-1β and expression of COX-2 and iNOS proteins, and simultaneously elevated the level of anti-inflammatory cytokine IL-4 in the carrageenan-injected rat paw tissues and exudates. The positive reference drug, indomethacin at a dosage of 10 mg/kg, demonstrated inhibitory potency in both rat models, but it could not augment the production of IL-4, indicating JCICM-6 and indomethacin might possess different pharmacological properties and molecular mechanisms although both have anti-inflammatory and analgesic effects in rats. These results suggest that JCICM-6 would be a valuable candidate for further investigation as a new anti-arthritic drug.     

Synthesis of a D-rhamnose branched tetrasaccharide, repeating unit of the O-chain from Pseudomonas syringae pv. Syringae (cerasi) 435

The first synthesis of a d-rhamnose branched tetrasaccharide, corresponding to the repeating unit of the O-chain from Pseudomonas syringae pv. cerasi 435, as methyl glycoside is reported. The approach used is based on the synthesis of an opportune building-block, that is the methyl 3-O-allyl-4-O-benzoyl-alpha-D-rhamnopyranoside, which was then converted into both a glycosyl acceptor and two different protected glycosyl trichloroacetimidate donors. Successive couplings of these three compounds afforded the target oligosaccharide. The reported synthesis is also useful to perform the oligomerization of the repeating unit.