Total Syntheses and Cytotoxic Evaluations of Cryptolactones A1, A2, B1, B2, and Their Derivatives.

The cryptolactones A1, A2, B1, and B2 isolated from a Cryptomyzus sp. aphid were synthesized via the Mukaiyama aldol reaction and olefin metathesis. Their antipodes and derivatives were also synthesized by the same strategy to investigate structure-activity relationships. These compounds exhibited cytotoxic activity against human promyelocytic leukemia HL-60 cells with IC50 values of 2.1-42 µM.

The Novel Lipid-Lowering Drug D-47 Ameliorates Hepatic Steatosis and Promotes Brown/Beige-Like Change of White Adipose Tissue in db/db Mice.

D-47 is a newly developed solid dispersion of the arginine salt of (S)-(+)-4-[1-(4-tert-butylphenyl)-2-oxo-pyrrolidin-4-yl]methoxybenzoic acid (S-2E), which inhibits sterol and fatty acid synthesis. D-47 was recently shown to lower the serum level and hepatic content of both triglyceride and cholesterol in a rabbit model of familial hypercholesterolemia. We here investigated the effects of D-47 on dyslipidemia and hepatic steatosis in comparison with those of bezafibrate in the db/db mouse model of obesity. Treatment of db/db mice with D-47 or bezafibrate for 14 days lowered the serum triglyceride concentration without affecting that of cholesterol. D-47, but not bezafibrate, almost completely eliminated lipid droplets in hepatocytes and markedly lowered the triglyceride content of the liver in these mice. The two agents induced similar changes in the hepatic expression of genes including those related to ß-oxidation or fatty acid synthesis. D-47 however significantly reduced the mass of white adipose tissue and up-regulated the expression of genes related to energy expenditure, mitochondrial function, fatty acid oxidation or lipolysis in this tissue, indicating that D-47 induced the brown/beige adipocyte-like change in white adipose tissue, whereas bezafibrate had no such effects. Treatment of 3T3-L1 adipocytes with D-47 provoked the expression of genes related to mitochondrial function, fatty acid oxidation or lipolysis. Our data have thus shown that D-47 ameliorated hypertriglyceridemia and hepatic steatosis in an animal model of obesity, and they suggest that this latter effect might be mediated through the change of adipose tissue characteristics.

A role of uroleuconaphins, polyketide red pigments in aphid, as a chemopreventor in the host defense system against infection with entomopathogenic fungi.

Four red polyketide pigments, uroleuconaphins A1 (1) and B1 (2) and their glucosides 3 and 4, were isolated from the red goldenrod aphid Uroleucon nigrotuberculatum. Although these red pigments exist only as glucosides 3 and 4 in the intact insect body, 3 and 4 convert instantly to aglycones 1 and 2 at death. Pigments 1 and 2 inhibited the growth of Lecanicillium sp. (Ascomycota: Cordycipitaceae) and 1, 2, and 3 were active against Conidiobolus obscurus (Entomophthoromycota; Entomophthorales); these fungal species are pathogenic. We therefore regard aphid pigments 1-4 as chemopreventive agents that aid in the resistance of infection by entomopathogenic fungi at the level of the individual aphid and/or at the species level.

Ameliorating effects of D-47, a newly developed compound, on lipid metabolism in an animal model of familial hypercholesterolemia (WHHLMI rabbits).

Improvements induced in lipid metabolism in the liver by D-47, a newly developed compound, were examined herein. WHHLMI rabbits, an animal model of hypercholesterolemia and coronary atherosclerosis, was fed D-47-supplemented chow for 5 weeks at a dose of 30mg/kg. Lipid concentration were assayed using enzymatic methods. Plasma lipoproteins were fractionated with an ultracentrifuge. mRNA expression was analyzed with real-time PCR. Lipidome analyses of lipoproteins were performed using supercritical fluid chromatography mass spectrometry. In the D-47-treated group, serum lipid levels decreased by 23% for total cholesterol and by 40% for triglycerides. These reductions were mainly attributed to decreases in the VLDL fraction. Compared with the control, in the D-47 group, lipid contents in the liver were decreased by 22% in cholesterol and by 69% in triglycerides, and fat accumulation was decreased by 57% in pericardial fat and by 17% in mesenteric fat. In lipidome analyses of VLDL fraction, lysophosphatidylcholine, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylethanolamine plasmalogen, sphingomyelin, and ceramide were decreased by the D-47 treatment. mRNA expression in the liver was 51% lower for FAS and 24% lower for MTP, but 5.9- and 5.1-fold higher for CYP7A1 and CPT-1, respectively, in the D-47 group than in the control. mRNA expression was 72%, 64%, and 36% higher for LPL, CTP-1, and PPARγ, respectively, in mesenteric fat in the D-47 group. D-47 is a potent lipid-lowering compound that uses a different mechanism of action from that of statins. It has potential as a compound in the treatment of steatohepatitis and metabolic syndrome.

Isolation and total syntheses of cytotoxic cryptolactones A1, A2, B1, and B2: α,ß-unsaturated δ-lactones from a Cryptomyzus sp. aphid.

The cryptolactones A1, A2, B1, and B2, which are α,ß-unsaturated δ-lactones, were isolated from a Cryptomyzus sp. aphid. The structures were established by 1-D and 2-D NMR spectra and CI-HRMS. Their absolute configurations were determined with the Kusumi-Mosher method, combined with asymmetric total syntheses. The syntheses were accomplished with the Mukaiyama aldol reaction and olefin metathesis, which utilized the second-generation Grubbs catalyst for the key steps. These compounds exhibited cytotoxic activity against human promyelocytic leukemia HL-60 cells with IC50 values of 0.97-5.3 µM.

Viridaphin A1 glucoside, a green pigment possessing cytotoxic and antibacterial activity from the aphid Megoura crassicauda.

A green pigment, viridaphin A1 glucoside (1), was isolated from the green aphid Megoura crassicauda. One- and two-dimensional NMR spectrometric analyses of 1 and its aglycone established the structure as an octacyclic compound. Viridaphin A1 glucoside exhibited cytotoxicity against HL-60 human tumor cells with an IC50 of 23 µM and antibacterial activity against Bacillus subtilis NBRC 3134 with a minimum inhibitory concentration of 10.0 µg/mL. These results suggested that aphid pigments may protect aphids from invasive species, including viruses and bacteria.

Symbiotic bacterium modifies aphid body color.

Color variation within populations of the pea aphid influences relative susceptibility to predators and parasites. We have discovered that infection with a facultative endosymbiont of the genus Rickettsiella changes the insects' body color from red to green in natural populations. Approximately 8% of pea aphids collected in Western Europe carried the Rickettsiella infection. The infection increased amounts of blue-green polycyclic quinones, whereas it had less of an effect on yellow-red carotenoid pigments. The effect of the endosymbiont on body color is expected to influence prey-predator interactions, as well as interactions with other endosymbionts.

A practical total synthesis of (+)-antimycin A9.

(+)-Antimycin A9 (AA9) isolated from a cultured broth of Streptomyces sp. K01-0031 was synthesized via an asymmetric aldol reaction using Oppolzer's sultam as a chiral auxiliary.

Pigments from Uroleucon nigrotuberculatum induce apoptosis in HL60 human leukemia cells, implicating intracellular oxidative stress and activation of caspases.

Two pigmented compounds from Uroleucon nigrotuberculatum, uroleuconaphin-B(1) [corrected] (H427) and uroleuconaphin-A(1) [corrected] (H373), significantly diminished the cell viability of HL60 cells with IC50 of 10 microM and 30 microM, respectively, in an 18 h-dye uptake assay. Both H427 and H373 augmented the levels of intracellular reactive oxygen species (ROS) and induced apoptosis as demonstrated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling analysis. ROS augmentation by both H427 and H373 was inhibited by N-acetylcysteine (NAC) and alpha-tocopherol. The apoptosis induced by H427 was inhibited efficiently with NAC and caspase-8 inhibitor but less efficiently with alpha-tocopherol and caspase-9 inhibitor. These findings suggested that these pigments have pro-apoptotic activities via oxidative stress.

2-(1,3-Dioxan-2-yl)ethylsulfonyl group: a new versatile protecting and activating group for amine synthesis.

[reaction: see text] 2-(1,3-Dioxan-2-yl)ethylsulfonyl (Dios) chloride was synthesized and used as a new versatile sulfonating agent for amines. Primary and secondary amines were sulfonated very easily in excellent yields with Dios chloride. N-Nonsubstituted and N-monosubstituted Dios-amides, activated amines, were alkylated satisfactorily under new Mitsunobu conditions utilizing (cyanomethylene)tributylphosphorane (CMBP). The Dios group is very stable under basic and reductive conditions and is removed by heating in a hot aqueous solution of trifluoroacetic acid.

Preparation of (Cyanomethylene)tributylphosphorane: a new mitsunobu-type reagent.

(Cyanomethylene)tributylphosphorane (CMBP), which promoted the alkylation of various nucleophiles (HA) with alcohols (ROH) to give RA (Mitsunobu-type reaction), was prepared in two steps starting from chloroacetonitrile.

Preparation of (cyanomethylene)trimethylphosphorane as a new Mitsunobu-type reagent.

(Cyanomethylene)trimethylphosphorane (CMMP) mediates Mitsunobu-type reactions, which are a versatile method for the alkylation of various nucleophiles (HA) with alcohols (ROH) to give RA. CMMP is quite effective for the reaction of carbon nucleophiles whose pK(a) value are higher than 13. CMMP, which is very sensitive to air and moisture, was synthesized in two steps starting from chloroacetonitrile.