Officinatrione: an unusual (17S)-17,18-seco-lupane skeleton,and four novel lupane-type triterpenoids from the roots of Taraxacum officinale

Novel 5 lupane-type of triterpenois, i.e., 3β-acetoxy-18α,19α-epoxylupan-21β-ol (1), 18α,19α-epoxy-21β-hydroxylupan-3-one (2), lup-18-ene-3,21-dione (3), lupa-18,21-dien-3β-yl acetate (4), and (17S)-17,18-seco-lup-19(21)-ene-3,18,22-trione (5), named officinatrione, as well as 16 known compounds from the roots of Taraxacum officinale collected in Takatsuki city, Osaka, Japan. Of the above compounds, 5 was the first lupane-type triterpene, of which the D-ring was open to form a nine-membered ring. Compounds 2 and 5 exhibited moderate cytotoxic activities against L1210 cell line (IC₅₀ 10.5 and 10.1 μM).     

Synthesis and spectral properties of ruthenium(II) complexes based on 2,2′-bipyridines modified by a perylene chromophore

Five new 2,2′-bipyridines functionalized with a perylene or a perylenediimide moiety were synthesized and the corresponding heteroleptic ruthenium(II) complexes ([Ru(bpy)₂(L)](PF₆)₂; bpy = 2,2′-bipyridyl, L = perylene-substituted bpy ligand) were prepared. The UV–vis spectra of the ruthenium(II) complexes showed red-shifted and intense absorption bands derived from the conjugated structure of the new ligands.     

Design of sugar–oligonucleotide conjugates installed gold nanoparticle for effective delivery to hepatic parenchymal cells

A novel oligonucleotide delivery system that is based on oligonucleotide–nanoparticle conjugates has been described. Installed oligonucleotides were modified with the carbohydrate at the 3′ terminus, accordingly, constructed nanoparticles display clustered carbohydrates on their outer layer for the targeted delivery of oligonucleotides. The method for the construction of ligand-functionalized nanoparticle was simple and reproducible. The stability of the nanoparticles displaying clustered carbohydrates greatly increased in serum compared to nanoparticles without carbohydrates. In order to investigate the targetability of oligonucleotide–nanoparticle conjugates into primary hepatic parenchymal cells, freshly isolated rat hepatocytes were incubated with nanoparticles and the amount of internalized gold nanoparticles was evaluated by an inductively coupled plasma mass spectroscopy analysis. Nanoparticles displaying clustered carbohydrates internalized more efficiently than nanoparticles without carbohydrate modifications. In particular, the cellular uptakes of oligonucleotide-conjugated gold nanoparticle increased 1.7 ～2.0-fold by galactose modification. Competition assay revealed that clustered galactose enhanced the internalization of the nanoparticle into primary hepatic parenchymal cells by a receptor-mediated process.

Preparation of various Janus composite particles with two components differently combined

Janus composite particles with a combination of organic and inorganic substances were synthesized by soap-free emulsion polymerization in which an amphoteric initiator of 2,2′-azobis[N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was employed to introduce a polystyrene (PSt) lobe onto silica cores surface-modified with 3-methacryloxypropyltrimethoxy silane (MPTMS). Thermogravimetric analysis and X-ray photoelectron spectroscopy were used to characterize the surface-modified silica particles and showed that a small amount of MPTMS introduced onto the surface of silica particles could successfully prepare SiO₂–PSt Janus particles. The oxide part of SiO₂–PSt Janus particles obtained with the polymerization was further surface-modified with 3-aminopropyltriethoxysilane (APS) to introduce positively charged amino groups on the silica surface. The silica surface modified with APS was covered with gold by electroless deposition in which a gold precursor of auric chloride was reduced with ascorbic acid in the presence of polyvinylpyrrolidone. The electroless deposition of gold successfully produced Janus particles with a combination of gold and PSt surfaces. Furthermore, dissolution of the polymer component of the Au–PSt Janus particles in tetrahydrofuran led to another Janus type of particles with an inorganic combination of Au and SiO₂.     

Direct Synthesis of 1,4‐Diols from Alkenes by Iron‐Catalyzed Aerobic Hydration and C?H Hydroxylation

Various 1,4‐diols are easily accessible from alkenes through iron‐catalyzed aerobic hydration. The reaction system consists of a user‐friendly iron phthalocyanine complex, sodium borohydride, and molecular oxygen. Furthermore, the effect of additional ligands on the iron complex was examined for a model reaction. The second hydroxy group is installed by direct C(sp³) H oxygenation, which is based on a [1,5] hydrogen shift process of a transient alkoxy radical that is formed by formal hydration of the olefin.     

Neomacrophorin I,II, and III,novel drimenyl cyclohexanes with hydroxylated butanoates from Trichoderma sp. 1212-03

Neomacrophorins I (1), II (2), and III (3) were isolated from the culture broth of Trichoderma sp. 1212-03, which was collected at Shirakami Mountainous area in Japan. Structural analyses disclosed that these resemble known macrophorins but possess axial-hydroxy group at C3 as well as different side chains at C7′. These are diastereomeric forms of macrophorins for 5′,6′-epoxide functionality. The NMR analyses suggested their relative configurational relationship between the C1–C15 drimene and C1′–C7′ epoxyquinone moieties. ECD spectral discussions verified them particularly for C5′,C6′-epoxyquinone (1), C5′,C6′-epoxysemiquinone (2 and 3), and 2″,3″-dihydroxybutanoate moiety in 1 and 2. The configuration of C3″-stereocenter of 3 was determined by chiral GC–MS after converting into methyl (S)-3″-hydroxybutanoate by basic of 3 methanolysis. Biological assays disclosed that 1 induces hyphal branching of Cochliobolus miyabeanus as well as cytotoxicity against human colorectal cancer COLO 201.     

Structure of tecophilin,a tri-caffeoylanthocyanin from the blue petals of Tecophilaea cyanocrocus, and the mechanism of blue color development

The pigment, tecophilin, in blue flowers of Tecophilaea cyanocrocus was isolated and the structure was determined to be 3-O-(6-O-α-l-rhamnopyranosyl-β-d-glucopyranosyl)-7-O-(6-O-(4-O-(2-O-(4-O-β-d-glucopyranosyl-(E)-caffeoyl)-6-O-(4-O-β-d-glucopyranosyl-(E)-caffeoyl)-β-d-glucopyranosyl)-(E)-caffeoyl)-β-d-glucopyranosyl)delphinidin. The reproduction experiment of the same color as petals according to the results of chemical analysis and measurement of vacuolar pH of blue cells clarified that the blue color solely develops by tecophilin without interaction of metal ions nor co-pigments. ¹H NMR analysis and CD spectrum indicate the co-existence of clockwise intermolecular self-association of the delphinidin nuclei and intramolecular π–π stacking between the chromophore and caffeoyl residues to derive bathochromic shift of the absorption spectrum and stabilize the color by preventing hydration reaction.     

Enantioselective Total Synthesis of Pinnaic Acid and Halichlorine

The enantioselective total synthesis of the bioactive marine natural products pinnaic acid and halichlorine is reported in detail. Our total synthesis features the construction of the five‐membered ring and C9 and C13 stereogenic centers through a palladium‐catalyzed trimethylenemethane [3+2] cyclization; the installation of the nitrogen atom through a regioselective Beckmann rearrangement of a poorly reactive ketone; the stereoselective cyclization of the spiro ring through a four‐step, one‐pot hydrogenation–cyclization; and efficient connection of the sterically hindered lower chain through a reduced‐pressure cross olefin metathesis reaction.