CaM kinase phosphatase (CaMKP/PPM1F/POPX2) is specifically inactivated through gallate-mediated protein carbonylation.

CaMK phosphatase (CaMKP/PPM1F/POPX2) is a Mn2+-dependent, calyculin A/okadaic acid-insensitive Ser/Thr protein phosphatase that belongs to the PPM family. CaMKP is thought to be involved in regulation of not only various protein kinases, such as CaM kinases and p21-activated protein kinase, but also of cellular proteins regulated by phosphorylation. A large-scale screening of a chemical library identified gallic acid and some of its alkyl esters as novel CaMKP inhibitors highly specific to CaMKP. Surprisingly, they caused specific carbonylation of CaMKP, leading to its inactivation. Under the same conditions, no carbonylation nor inactivation was observed when PPM1A, which is affiliated with the same family as CaMKP, and λ-phosphatase were used. The carbonylation reaction was inhibited by SH compounds such as cysteamine in a dose-dependent manner with a concomitant decrease in CaMKP inhibition by ethyl gallate. The pyrogallol structure of gallate was necessary for the gallate-mediated carbonylation of CaMKP. Point mutations of CaMKP leading to impairment of phosphatase activity did not significantly affect the gallate-mediated carbonylation. Ethyl gallate resulted in almost complete inhibition of CaMKP under the conditions where the carbonylation level was nearly identical to that of CaMKP carbonylation via metal-catalyzed oxidation with ascorbic acid/FeSO4, which resulted in only a partial inhibition of CaMKP. The gallate-mediated carbonylation of CaMKP absolutely required divalent cations such as Mn2+, Cu2+, Co2+ and Fe2+, and was markedly enhanced by a phosphopeptide substrate. When MDA-MB-231 cells transiently expressing CaM kinase I, a CaMKP substrate, were treated by ethyl gallate, significant enhancement of phosphorylation of CaM kinase I was observed, suggesting that ethyl gallate can penetrate into cells to inactivate cellular CaMKP. All the presented data strongly support the hypothesis that CaMKP undergoes carbonylation of its specific amino acid residues by incubation with alkyl gallates and the divalent metal cations, leading to inactivation specific to CaMKP.

Isolation of Fluorescent Benzoxazines with Neuroprotective Activity from the Olive Weevil Pimelocerus perforatus.

The weevil Pimelocerus perforatus poses a serious pest problem for olive cultivation in Japan. Two new racemic fluorescent benzoxazines, designated as pimeforazine A ((±)-1) and pimeforazine B ((±)-2), were successfully isolated from P. perforatus. Their structures, including the absolute configurations of their resolved enantiomers, were determined using spectroscopic methods, single-crystal X-ray diffraction, and electronic circular dichroism calculations. The neuroprotective activity of the isolated compounds was evaluated against hydrogen peroxide-induced cellular damage in SH-SY5Y human neuroblastoma cells. Compounds (±)-1 and (±)-2 exhibited neuroprotective effects.

Crotofolane-Type Diterpenoids: Crotocascarins R-V, Rearranged Trinorcrotofolane: Crotocascarin δ and a Phorbol Derivative from the Leaves of Croton cascarilloides.

Five new crotofolanes, named crotocascarins R-V (1-5), one rearranged trinorcrotofolane, crotocascarin δ, and one phorbol derivative were isolated from the EtOAc-soluble fraction of the MeOH extract of the leaves of Croton cascarilloides. Crotocascarins R (1), T (3), and U (4) possessed isobutyric acid as an acyl moiety and crotocascarin B (2) an acetyl group, whereas crotocascarin V (5) was elucidated to be a hydroxylated compound of crotocascarin K at the 9-position. Crotocascarin δ (6) was a trinor rearranged crotofolane with a tertiary hemiketal functional group at the 8-position. The absolute configuration of the 8-position was determined by the comparison of the experimental electronic circular dichroism (ECD) spectrum and calculated ECD spectra. Compound 7 was a phorbol ester derivative with a peroxide functional group. The fatty acid attached at the 12-position was found to be a single species-i.e., lauric acid (C-12)-from the evidence of the mass spectral data.

Isolation of Three New Diterpenes from Dodonaea viscosa.

An investigation into the methanol extracts obtained from the stems of Dodonaea viscosa led to the isolation of one nor-clerodane diterpene (1) and two labdane diterpenes (2, 3), as well as 17 known compounds (4-20). The structures of these compounds were elucidated based on chemical and spectral evidence. The stereochemical structure of the nor-clerodane diterpene was confirmed via its circular dichroism spectrum and calculated electronic circular dichroism spectrum. Isolated compounds were evaluated for their inhibitory effects on collagenase and tyrosinase. Since 5,7,4'-trihydroxy-3'-(4-hydroxy-3-methylbutyl)-5'-(3-methylbut-2-enyl)-3,6-dimethoxyflavone (9) showed collagenase inhibitory activity and scopoletin (12) had significant tyrosinase inhibitory activity, they were considered to be good candidates for cosmetic agents.

Assignment of Absolute Configuration of Bromoallenes by Vacuum-Ultraviolet Circular Dichroism (VUVCD).

A new application of vacuum-ultraviolet circular dichroism (VUVCD), which enables the measurement of CD spectra in the vacuum-ultraviolet region (140-200 nm), for the assignment of the absolute configurations of bromoallenes is described. Bromoallene moieties are found in natural products obtained from many marine organisms. To date, the absolute configuration of bromoallenes has been assigned almost exclusively with Lowe's rule, which is based on specific rotation. However, exceptions to Lowe's rule have been reported arising from the presence of other substituents with large specific rotations. For the unambiguous assignment of the absolute configuration of the bromoallene moiety with its characteristic absorption wavelength at 180-190 nm due to the π-π* transition, VUVCD was applied to four pairs of bromoallene diastereomers prepared by modifying the synthetic scheme of omaezallene. The VUVCD spectra clearly showed positive or negative Cotton effects around 180-190 nm according to the configuration of the bromoallene employed, revealing the potential of VUVCD for determining absolute stereochemistry.

Asaroidoxazines from the Roots of Asarum asaroides Induce Apoptosis in Human Neuroblastoma Cells.

Plants in the family Aristolochiaceae contain phenanthrene skeleton-containing chemical constituents that exhibit nephrotoxic, carcinogenic, mutagenic, anti-inflammatory, and cytotoxic effects. Two new phenanthrene-containing 1,2-oxazin-6-ones, designated as asaroidoxazine A (1) and asaroidoxazine B (2), and a known aristolactam, 5-methoxyaristololactam I (3), were isolated from the roots of Asarum asaroides. The structures of compounds 1 and 2 were determined using spectroscopic methods and X-ray crystallography. Treatment of SH-SY5Y human neuroblastoma cells with 1 µM of asaroidoxazine A (1) induced nuclear condensation as well as caspase-3/7 activation, indicating that this compound is a strong apoptosis inducer in neuronal cells. This is the first report of apoptosis induction by phenanthrene-containing oxazines.

Natural dolapyrrolidone: Isolation and absolute stereochemistry of a substructure of bioactive peptides.

During the course of our chemical analysis of the hydrophilic fractions from marine cyanobacterium Moorena producens, we have isolated natural dolapyrrolidone (Dpy, 1), a natural pyrrolidone derived from phenylalanine, for the first time as a single compound. Compound 1, with an (S)-l absolute stereochemistry, was previously identified as a substructure that is common among several bioactive natural peptides. Surprisingly, the absolute stereochemistry of the isolated natural 1, determined through total synthesis, was (R)-d. This result was unambiguously determined by HPLC analysis using a chiral stationary column by comparing the retention times of the natural 1 and authentic samples of synthetic enantiomers. To verify the unexpected result, the absolute stereochemistry of the natural 1 was confirmed by X-ray crystallographic analysis of Pt-complex derivative using the synthetic enantiomer.

Tetradehydrohalicyclamine B, a new proteasome inhibitor from the marine sponge Acanthostrongylophora ingens.

A new halicyclamine derivative, tetradehydrohalicyclamine B (1), was isolated from the marine sponge Acanthostrongylophora ingens, along with halicyclamine B (2) as proteasome inhibitors. Compound 1 is the second example found to have a pyridinium ring in the halicyclamine family. Although the relative configuration of 2 was previously determined by X-ray crystallographic analysis, here we determined the absolute configuration of 2 by ECD experiment. Compounds 1 and 2 inhibited the constitutive proteasome as well as the immunoproteasome. The inhibitory activities of 2 were 4- to 10-fold more potent than those of 1.

Altercrasins A⁻E, Decalin Derivatives, from a Sea-Urchin-Derived Alternaria sp.: Isolation and Structural Analysis Including Stereochemistry.

In order to find out the seeds of antitumor agents, we focused on potential bioactive materials from marine-derived microorganisms. Marine products include a number of compounds with unique structures, some of which may exhibit unusual bioactivities. As a part of this study, we studied metabolites of a strain of Alternaria sp. OUPS-117D-1 originally derived from the sea urchin Anthocidaris crassispina, and isolated five new decalin derivatives, altercrasins A-E (1-5). The absolute stereostructure of altercrasins A (1) had been decided by chemical transformation and the modified Mosher's method. In this study, four decalin derivatives, altercrasins B-E (2-5) were purified by silica gel chromatography, and reversed phase high-performance liquid chromatography (RP HPLC), and their structures were elucidated on the basis of 1D and 2D nuclear magnetic resonance (NMR) spectroscopic analyses. The absolute configuration of them were deduced by the comparison with 1 in the NMR chemical shifts, NOESY correlations, and electronic circular dichroism (ECD) spectral analyses. As a result, we found out that compound pairs of 1/2 and 4/5 were respective stereoisomers. In addition, their cytotoxic activities using murine P388 leukemia, human HL-60 leukemia, and murine L1210 leukemia cell lines showed that 4 and 5 exhibit potent cytotoxicity, in especially, the activity of 4 was equal to that of 5-fluorouracil.

Lasianosides A-E: New Iridoid Glucosides from the Leaves of Lasianthus verticillatus (Lour.) Merr. and Their Antioxidant Activity.

The genus Lasianthus (Rubiaceae) consists of approximately 180 species, of which the greatest species diversity is found in tropical Asia. Some of the Lasianthus species have been used in folk medicine to treat tinnitus, arthritis, fever, and bleeding. Lasianthus verticillatus (Lour.) Merr. (Syn. Lasianthus trichophlebus auct. non Hemsl.) is a shrub, branchlets terete about 1.5-3 m in height. This paper studies the chemical composition of the leaves of L. verticillatus for the first time, which resulted in the isolation of five undescribed iridoid glucosides, lasianosides A-E (1-5), together with three known compounds (6-8). The undescribed structures of isolated compounds (1-5) were characterized by physical and spectroscopic data analyses, including one-dimensional (1D) and two-dimensional (2D) NMR, IR, UV, and high-resolution electrospray ionization mass spectra (HR-ESI-MS). Furthermore, the electronic circular dichroism data determined the absolute configurations of the new compounds. The free radical scavenging properties of isolated compounds was assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, and their cytotoxicity was assessed toward human lung cancer cell line A549 by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Among the isolated compounds, 3 and 4 displayed potent radical scavenging activities with IC50 values of 30.2 ± 1.8 and 32.0 ± 1.2 µM, which were comparable to that of Trolox (29.2 ± 0.39 µM), respectively, while 5 possessed moderate activity with an IC50 value of 46.4 ± 2.3 µM. None of the isolated compounds exerted cytotoxicity against human cell line A549. As a result, lasianosides C, D, and E have the potential to be non-toxic safe antioxidant agents.

Di(1-naphthyl) methanol ester of carboxylic acids for absolute stereochemical determination.

The absolute stereochemistry of chiral carboxylic acids is determined as a di(1-naphthyl)methanol ester derivative. Computational scoring of conformations favoring either P or M helicity of the naphthyl groups, capable of exciton-coupled circular dichroic coupling, leads to a predicted stereochemistry for the derivatized carboxylic acids.

Sulfated Purine Alkaloid Glycosides from the Pupal Case Built by the Bruchid Beetle Bruchidius dorsalis Inside the Seed of Gleditsia japonica.

Three new sulfated isoguanine alkaloid glycosides, designated as saikachinoside A monosulfate (1), saikachinoside A disulfate (2), and locustoside B disulfate (3), have been isolated from the pupal case of the wild bruchid seed beetle Bruchidius dorsalis (Chrysomelidae, Bruchinae) infesting the seed of Gleditsia japonica Miq. (Fabaceae). Their structures were determined by spectroscopic methods and the inhibitory activity of 2 and 3 against acid phosphatase was evaluated.

Spontaneous emulsification and self-propulsion of oil droplets induced by the synthesis of amino acid-based surfactants.

It is well known that oil droplets in or on water exhibit spontaneous movement induced by surfactants, and this self-propulsion is regarded as an important factor in droplet-based models for a living cell. We report here an oil-droplet system spontaneously producing amino acid-based surfactants, which are then utilized for the droplets' self-propulsion. Thus this system is an active system capable of producing the fuel for the propulsion by itself, which can be used as a conceptual model for cell metabolism.

Cyclohelminthol X, a Hexa-Substituted Spirocyclopropane from Helminthosporium velutinum yone96: Structural Elucidation, Electronic Circular Dichroism Analysis, and Biological Properties.

Helminthosporium velutinum yone96 produces cyclohelminthol X (1), a unique hexa-substituted spirocyclopropane. Although its molecular formula and NMR spectral data resemble those of AD0157, being isolated from marine fungus Paraconiothyrium sp. HL-78-gCHSP3-B005, our detailed analyses disclosed a totally different structure. Chemical shift calculations and electronic circular dichroism spectral calculations were quite helpful to establish the structure, when those were performed based on density functional theory. The carbon framework of cyclohelminthols I-IV is found at the C1-C8 propenylcyclopentene substructure of 1. Thus, 1 is assumed to be biosynthesized by cyclopropanation between an oxidized form of cyclohelminthol IV and a succinic anhydride derivative 4. Cytotoxicity for two cancer cell lines and proteasome inhibition efficiency are measured.

Nabscessins A and B, Aminocyclitol Derivatives from Nocardia abscessus IFM 10029T.

Two new aminocyclitol amide derivatives, nabscessins A (1) and B (2), were isolated from the culture broth of a pathogenic actinomycete species, Nocardia abscessus IFM 10029T. The structures of nabscessins A and B were elucidated by spectral studies, and the compounds showed antifungal activity against Cryptococcus neoformans, with IC50 values of 32 and 16 µg/mL, respectively.

New Prenylated ortho-Dihydroxycoumarins from the Fruits of Ficus nipponica.

Two new prenylated ortho-dihydroxycoumarins, designated fipsomin (1) and fipsotwin (2), were isolated from the fruits of Ficus nipponica together with a known prenylated coumarin, apigravin (3). Their structures were established by spectroscopic data and X-ray crystallographic analysis. Compound 1 exhibited antibacterial activity against Bacillus subtilis with an MIC value of 61 µm, while 2 and 3 showed very weak activity.

Taichunamides: Prenylated Indole Alkaloids from Aspergillus taichungensis (IBT 19404).

Seven new prenylated indole alkaloids, taichunamides A-G, were isolated from the fungus Aspergillus taichungensis (IBT 19404). Taichunamides A and B contained an azetidine and 4-pyridone units, respectively, and are likely biosynthesized from notoamide S via (+)-6-epi-stephacidin A. Taichunamides C and D contain endoperoxide and methylsulfonyl units, respectively. This fungus produced indole alkaloids containing an anti-bicyclo[2.2.2]diazaoctane core, whereas A. protuberus and A. amoenus produced congeners with a syn-bicyclo[2.2.2]diazaoctane core. Plausible biosynthetic pathways to access these cores within the three species likely arise from an intramolecular hetero Diels-Alder reaction.

Computation-Assisted Structural Elucidation of Epoxyroussoeone and Epoxyroussoedione Isolated from Roussoella japanensis KT1651.

The structures of epoxyroussoenone (1) and epoxyroussoedione (3) isolated from a culture broth of Roussoella japanensis KT1651 were determined. Although NMR spectra provided insufficient structural information, computation of the theoretical chemical shifts with DFT EDF2/6-31G* enabled us to elucidate not only the planar structure, but also the relative configuration. Their ECD (electric circular dichroism) spectra suggested the absolute configurations, which were confirmed with time-dependent DFT calculations employing BHandHLYP/TZVP. The ECD calculations for other stereoisomers yielded obviously different spectral profiles, thus confirming the relative structures of 1 and 3.

Chiroptical molecular propellers based on hexakis(phenylethynyl)benzene through the complexation-induced intramolecular transmission of local point chirality.

We designed hexakis(phenylethynyl)benzene derivatives with a tertiary amide group on each blade to achieve a helically biased propeller arrangement through the complexation-induced intramolecular transmission of point chirality. A hydrogen-bonding ditopic guest was captured at two amide groups, and thus could pair two neighboring blades to form a supramolecular cyclic structure, in which an auxiliary chiral group associated with a blade acted as a chiral handle to control the helical bias, while the chiral auxiliary did not exert any helical influence on the dynamic helicity in the absence of a guest due to the high flexibility of each blade.

Roussoellols A and B, tetracyclic fusicoccanes from Roussoella hysterioides.

The structures of the tetracyclic fusicoccanes roussoellols A (1) and B (2) from Roussoella hysterioides KT1651 are described. NMR spectroscopic analyses involving NOESY experiments revealed that these molecules possessed unique bent structures that were supported by chemical derivatizations as well as chemical shift comparisons with theoretical shifts based on the density functional theory (DFT) at the EDF2/6-31G* level. Absolute configurations were established by the ECD couplet of positive chirality in both 1 and 2 at vacuum UV (VUV) region, which were further confirmed by successful reproduction of VUVCD spectra using theoretical calculations.