A new flavonol glucoside from the aerial parts of Sida glutinosa.

Phytochemical investigation on the dried aerial parts of Sida glutinosa has led to the isolation of a new flavonol glucoside, glutinoside (1), along with seven known compounds, 24(28)-dehydromakisterone A (2), 1,2,3,9-tetrahydropyrrolo[2,1-b]-quinazolin-3-amine (3), docosanoic acid, 1-triacontanol, campesterol, stigmasterol, and ß-sitosterol. The structures of these compounds were elucidated by means of extensive spectroscopic techniques as well as GC/MS analysis (for sterols) and comparison with the literature data. All these seven known compounds are reported from this plant for the first time.

Iridoid glucosides from Wendlandia tinctoria roots.

A new iridoid glucoside, 8-O-(E)-caffeoylmussaenosidic acid (1), together with ixoside (2), was isolated from the roots of Wendlandia tinctoria. The structure of the new compound was established on the basis of detailed spectroscopic (2D NMR) and chemical analysis.

Naturally occurring triterpenoid saponins.

Naturally occurring new triterpenoid saponins reported from mid-1996 to March, 2007 are reviewed including their physical constants and plant sources, and are compiled in Table 1. New saponins are arranged in Table 1 on the basis of the skeletal structures of their aglycones, e.g., oleanane type, ursane type, lupane type, hopane type, taraxastane type, cycloartane type, lanostane type, tirucallane type, dammarane type, cucurbitane type, and holostane type. The known triterpenoid saponins and prosapogenins of the new saponins, the biological and pharmacological activities of which were published during 1996-2007, are also reviewed together with their plant sources listed in Table 2 according to the skeletal structures of their aglycones in the same fashion as in Table 1. The plant and animal sources of both new and known bioactive triterpenoid saponins are collected in Table 3 in alphabetical order. The biological and pharmacological activities such as antiallergic, antiatherosclerosis and antiplatelet, antibacterial, anticomplementary, antidiabetic, contraceptive, antifungal, anti-inflammatory, antileishmanial, antimalarial/antiplasmodial, anti-obesity, anti-proliferative, antipsoriatic, antispasmodic, antisweet, antiviral, cytotoxic/antitumor, detoxication, gastroprotective, haemolytic, hepatoprotective, immunomodulatory, anti-enzyme, anti-osteoporotic, insecticidal, insulin-like, membrane-porosity, molluscicidal, neuropharmacological, anti-endothelial dysfunction, snake venom antidote, and sweet activities of these saponins or derived prosapogenins are discussed briefly after Table 3.

Iridoid glucosides from leaves and stem barks of Parkia javanica.

Two new iridoid glucosides, javanicosides A (1) and B (2) along with the known compounds, ursolic acid and beta-sitosterol were isolated from the leaf and stem bark of Parkia javanica and the structures were established on the basis of detailed spectroscopic analysis (MS, 1D, and 2D NMR experiments). The new compounds were identified as 8-O-p-hydroxybenzoyl-6'-O-p-coumaroyl-mussaenosidic acid (1) and 7-O-E-3,4-dimethoxycinnamoyl-6'-O-beta-D-glucopyranosylloganic acid (2).

Enantioselective total synthesis of atpenin A5.

Enantioselective total synthesis of atpenin A5, a potent mitochondrial complex II (succinate-ubiquinone oxidoreductase) inhibitor, has been achieved by a convergent approach through a coupling reaction between 5-iodo-2,3,4,6-tetraalkoxypyridine and a side-chain aldehyde. The two key segments were synthesized through ortho-metalation/boronation with (MeO)3B/oxidation with mCPBA, ortho-iodination, halogen dance reaction, Sharpless epoxidation and regioselective epoxide-opening reaction. This synthetic study resulted in the revision of the earlier reported 1H-NMR data of the natural atpenin A5 and the confirmation of the stereochemical assignment.

Total synthesis of amidepsine B and revision of its absolute configuration.

The total synthesis of (-)-amidepsine B, a potent diacylglycerol acyltransferase inhibitor, has been achieved. This synthetic study resulted in the revision of the previously assigned stereostructure of the natural amidepsine B and determined the absolute configuration.

Selectivity of pyripyropene derivatives in inhibition toward acyl-CoA:cholesterol acyltransferase 2 isozyme.

Selectivity of 96 semisynthetic derivatives prepared from fungal pyripyropene A, originally isolated as a potent inhibitor of acyl-CoA:cholesterol acyltransferase (ACAT), toward ACAT1 and ACAT2 isozymes was investigated in the cell-based assay using ACAT1- and ACAT2-expressing CHO cells. Eighteen derivatives including PR-71 (7-O-isocaproyl derivative) showed much more potent ACAT2 inhibition (IC50: 6.0 to 62 nM) than pyripyropene A (IC50: 70 nM). Among them, however, natural pyripyropene A showed the highest selectivity toward ACAT2 with a selectivity index (SI) of >1000, followed by PR-71 (SI, 667).

Total synthesis of salinosporamide A.

The total synthesis of salinosporamide A has been achieved through enzymatic desymmetrization, diastereoselective aldol reaction, intramolecular aldol reaction, and intermolecular Reformatsky-type reaction followed by 1,4-reduction as key reactions.

Iridoid glucoside and sterol galactoside from Mussaenda macrophylla.

A new iridoid glucoside, 6-epi-barlerin, and a new unusual sterol galactoside along with beta-sitosterol were isolated from the stem bark of Mussaenda macrophylla. The structures were established on the basis of the spectral and chemical evidence.

Naturally occurring secoiridoids and bioactivity of naturally occurring iridoids and secoiridoids. A review, part 2.

Naturally occurring new secoiridoids published during 1994-2005 are reviewed with available physical and spectral data: mp, [alpha](D), UV, IR, (1)H- and (13)C-NMR and plant source. The works on biological and pharmacological activity of naturally occurring iridoids and secoiridoids reported during 1998-2005 are also reviewed. Bioactivities like antiallergic, antiarthritis, antibacterial, anticancer, anticoagulant, anticomplement, antifungal, antiinflammatory, antioxidative, antiprotozoal, antispasmodic, antiviral, immunomodulatory, neuroprotective, nerve growth factor potentiating and wound healing activities are highlighted.

Total synthesis of borrelidin.

The total synthesis of borrelidin has been achieved. The best feature of our synthetic route is macrocyclization at C11-C12 for the construction of an 18-membered ring after esterification between two segments. A detailed examination of the macrocyclization led us to the samarium(II) iodide-mediated intramolecular Reformatsky-type reaction as the most efficient synthetic approach. The two key segments were synthesized through regioselective methylation, directed hydrogenation, stereoselective Reformatsky-type reaction, and MgBr2.Et2O-mediated chelation-controlled allylation.

Naturally occurring iridoids. A review, part 1.

A compilation of new naturally occurring iridoid glycosides, iridoid aglycones, iridoid derivatives and bis-iridoids reported during 1994-2005 is provided with available physical and spectral data: mp, [alpha]D, UV, IR, 1H- and 13C-NMR as well as natural source with family and references. 418 compounds with 202 references are cited.

Iridoid glucosides from Wendlandia tinctoria roots.

Four new iridoid glucosides, 5-dehydro-8-epi-adoxosidic acid, 5-dehydro-8-epi-mussaenoside, 10-O-dihydroferuloyldeacetyldaphylloside, and wendoside, together with one known iridoid glucoside, 8-epi-mussaenoside, beta-D-glucose, D-mannitol and beta-sitosterol have been isolated from the roots of Wendlandia tinctoria. On the basis of chemical and spectral analyses, the structures of new iridoid glucosides have been elucidated.

Preparation of 7-Halo-indoles by Thallation of N-formylindoline and their attempted use for synthesis of the right-hand segment of chloropeptin.

7-Substituted (Cl, Br, I) indoles were synthesized by using thallation of N-formylindoline as a key reaction. Two precursor tripeptides for the right-hand segment of chloropeptin were synthesized by using (R)-7'-iodo and 7'-bromotryptophans derived from each 7-substituted indole (I, Br) obtained by the above procedure.

Antimicrobial C-glucoside from aerial parts of Diospyros nigra.

A new C-alkylglucoside, diospyrodin [beta-1C-(1'S*,2'R*,3'R*,4'S*-1',2',3',4',5'-pentahydroxypentyl)-glucopyranoside] (1) has been isolated as its nonaacetate from the leaves and stems of Diospyros nigra. Its structure was elucidated on the basis of chemical and spectral properties and a single crystal X-ray analysis. It showed antimicrobial activity against Gram-positive and Gram-negative bacteria.

Identification of inorganic anions by gas chromatography/mass spectrometry.

Inorganic anions were identified by using gas chromatography/mass spectrometry (GC/MS). Derivatization of the anions was achieved with pentafluorobenzyl p-toluenesulphonate (PFB-Tos) as the reaction reagent and a crown ether as a phase transfer catalyst. When PFB-Br was used as the reaction reagent, the retention time of it was close to those of the derivatized inorganic anions and interfered with the analysis. In contrast, the retention time of PFB-Tos differed greatly from the PFB derivatives of the inorganic anions and the compounds of interest could be detected without interference. Although the PFB derivatives of SO4, S2O3, CO3, ClO4, and ClO3 could not be detected, the derivatives of F, Cl, Br, I, CN, OCN, SCN, N3, NO3, and NO2 were detected using PFB-Tos as the derivatizing reagent. The inorganic anions were detectable within 30 ng approximately, which is of sufficient sensitivity for use in forensic chemistry. Accurate mass number was measured for each PFB derivative by high-resolution mass spectrometry (HRMS) within a measurement error of 2 millimass units (mmu), which allowed determination of the compositional formula from the mass number. In addition, actual analysis was performed successively by our method using trial samples of matrix.

Synthesis of linear tripeptides for right-hand segments of complestatin.

This paper concerns a synthetic study of the right-hand segment of complestatin, an inhibitor of gp120-CD4 receptor. The effective synthesis of four important precursors for the right-hand segment of complestatin is described. Two of them are the precursor tripeptides for macrolactamization to the right-hand segment of complestatin at the last step and the other two are the precursor tripeptides for ring-closing reaction using Suzuki and Stille coupling, respectively, to the right-hand segment of complestatin at the last step. These compounds and the synthetic procedure will serve for both the synthesis of the right-hand segment and total synthesis of complestatin in the near future. In addition, consideration of the smooth acidic isomerization of complestatin to chloropeptin was carried out by density functional theory (DFT) calculation.

Application of intramolecular 1,3-dipolar cyclic addition of azide and olefin; construction of (pyrrolidine-2-ylidene)glycinate and glycinamides.

Oxopropyl E-(pyrrolidine-2-ylidene)glycinamide (5c) and allyl E-(pyrrolidine-2-ylidene)glycinate (5d) were effectively synthesized from 2,3,5-tri-O-benzyl-4-O-tert-butyldimethylsilyl(TBDMS)-D-arabinal (7) using intramolecular 1,3-dipolar cyclic reaction of azide and olefin as a key reaction. These results proved this cyclic reaction should be applicable for the synthesis of various (pyrrolidine-2-ylidene)glycinate and glycinamide. In addition, the development of a synthetic route for the precursor of an unsaturated cyclic dehydro amino acid involved in azinomycins (carzinophilin) using relating glycinate, methyl E-(pyrrolidine-2-ylidene)glycinate (5a) was described.

Preparative monohydroxyflavanone syntheses and a protocol for gas chromatography-mass spectrometry analysis of monohydroxyflavanones.

We describe a facile efficient, and preparative approach for monohydroxyflavanone syntheses. Using this protocol, a hydroxyl is regio-selectively introduced at one carbon of a flavanone A- or B-ring per synthesis. The seven possible isomers were each synthesized from the corresponding monomethoxymethoxylated 2'-hydroxychalcones in acidic solution. These monohydroxyflavanones were characterized using a gas chromatography-mass spectrometry (GC-MS) system that incorporated a DB-5 capillary column. Ours is the first report of a preparative synthetic method during which a single hydroxyl can be selectively added to a flavanone A- or B-ring at any position. We are also the first to develop a procedure that separates the seven isomers by GC and characterizes the mass spectra of the isomers. Both the synthetic method and the GC-MS conditions may become important tools during future flavanone metabolism and oxidation studies.