Simultaneous determination of D-lactic acid and 3-hydroxybutyric acid in rat plasma using a column-switching HPLC with fluorescent derivatization with 4-nitro-7-piperazino-2,1,3-benzoxadiazole (NBD-PZ)

A highly sensitive method for the determination of D-lactic acid and 3-hydroxybutyric acid (3-HB) in rat plasma was developed using high-performance liquid chromatography with octadecylsilica (ODS) connected to a chiral column. At first, (D + L)-lactic acid and 3-HB in the plasma were derivatized with a fluorescent reagent, 4-nitro-7-piperazino-2,1,3-benzoxadiazole (NBD-PZ), separated on the ODS column and determined fluorimetrically at 547 nm with 491 nm of excitation wavelength. During the separation step on the ODS, the peak fraction of (D + L)-lactate derivative was introduced directly to a phenylcarbamoylated beta-cyclodextrin chiral column by changing the flow of the eluent via a six-port valve. Then, D-lactate derivative was separated enantiomerically from the L-lactate derivative, and the enantiomeric ratio was determined from the chromatogram. Intra- and inter-day accuracy values for the determination of D-lactic acid in 10 microL of rat plasma were 97.8-109.2 and 98.4-109.9%, and those for 3-HB were 99.8-108.4 and 99.8-103.8%, respectively. The intra- and inter-day precision values were within 4.6 and 5.1% for D-lactic acid, and 2.7 and 2.4% for 3-HB, respectively. The detection limits for D-lactic acid and 3-HB were approximately 2.0 and 0.04 microM, respectively (signal-to-noise ratio 3). The proposed method was applied to the plasma of diabetic rats induced by intraperitoneal administration of streptozotocin, and the significant increases of both D-lactic acid and 3-HB concentrations were observed in the diabetic rats as compared to the normal rats.     

Five new subspicatins and noreremophilane from Paraseneciopetasitoides collected in China

Five new 1β-angeloyloxyeremophilanolides (subspicatins H-L) and 1β-angeloyloxytetranoreremophilanone (norsubspicatin A), were isolated from the EtOAc extracts of Parasenecio petasitoides and their structures established on the basis of spectroscopic analyses. They are biogenetically mutually related to each other and represent a new category in the Parasenecio group. These findings suggest that there is diversity in this species, too.     

Twelve new compounds from Ligularia melanothyrsa; isolation of melanothyrsins A–E,normelanothyrsin A,and other eremophilane sesquiterpenoids

Twelve new compounds, namely, five melanothyrsins A–E (1α-angeloyloxyeremophilenolides), normelanothyrsin A (1α-angeloyloxynoreremophilenone), and six other eremophilane-type compounds, have been isolated from Ligularia melanothyrsa Hand.-Mazz. (Asteraceae), collected in the Sichuan Province of China. Six of the compounds have a 1α-angeloyloxy moiety, while the other six have no functional group at the C-1 position. The absolute configuration was also determined using CD spectra. This is the first chemical study of compounds isolated from this species.     

A cytotoxic substance from Sangre de Grado

Taspine has been isolated as a cytotoxic substance from Sangre de Grado, sap of Croton palanostigma (Euphorbiaceae), by bioassay guided fractionation. The cytotoxicity (IC50) of taspine was found to be 0.39 microgram/ml against KB cells and 0.17 microgram/ml against V-79 cells.     

Limit Theorem for Controlled Backward SDEs and Homogenization of Hamilton–Jacobi–Bellman Equations

We prove a convergence theorem for a family of value functions associated with stochastic control problems whose cost functions are defined by backward stochastic differential equations. The limit function is characterized as a viscosity solution to a fully nonlinear partial differential equation of second order. The key assumption we use in our approach is shown to be a necessary and sufficient assumption for the homogenizability of the control problem. The results generalize partially homogenization problems for Hamilton–Jacobi–Bellman equations treated recently by Alvarez and Bardi by viscosity solution methods. In contrast to their approach, we use mainly probabilistic arguments, and discuss a stochastic control interpretation for the limit equation.     

Stereoselective synthesis of (±)-palitantin

Stereoselective synthesis of (±)-palitantin has been completed.     

Stereoselective synthesis of (±)-senepoxyde and (±)-crotepoxide1

Stereoselective synthesis of (±)-senepoxyde and (±) crotepoxide is described starting from 2-hydroxymethyl-1, 4-benzoquinone through the retro-Diels-Alder reaction.     

Synthesis of pyrenocine A and B

From 5-acetyl-4-hydroxy-6-methyl-α-pyrone, two phytotoxins, pyrenocine A and B, were synthesized and erroneous β-pyrone structure of the starting compound was corrected on the basis of spectroscopic data.