New compounds from the seeds of Embelia ribes Burm

Phytochemical investigation of the seeds of Embelia ribes Burm. resulted in the isolation of three new compounds identified as 3-(4"-hydroxyoctadecanyloxy)-p-quinonyl-5-methylene-8-(10-pentanyloxy)-p-quinone (embelinol) (1), n-pentacosanyl-n-nonadeca-7'-en-9'-alpha-ol-1'-oate (embeliaribyl ester) (2) and 1,2,4,5-tetrahydroxy 3-undecanyl benzene (embeliol) (3) along with the known compound 2,5-dihydroxy-3-undecyl-2,5-cyclohexadiene-1,4-dione (embelin) (4). Their structures have been established on the basis of spectral data analyses and chemical reactions.

Determination of amphetamine, methamphetamine and desmethyldeprenyl in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry

A sensitive and specific assay for the quantitative determination of amphetamine, methamphetamine and desmethyldeprenyl in human plasma specimens is described. Electron capture/negative ion chemical ionization gas chromatography/mass spectrometry is used to determine the extracted plasma concentrations of the three target compounds as their N-heptafluorobutyryl derivatives. Quantitation is performed by stable isotope dilution using d6-amphetamine and d6-methamphetamine as internal standards. Selected ion monitoring of the [M-HF]- ions of both the analytes and internal standards results in minimum quantifiable limits of 0.10 ng ml-1 for both amphetamine and methamphetamine and 0.25 ng ml-1 for desmethyldeprenyl. Excellent linearity (r = 0.998) up to at least 5.00 ng ml-1 is demonstrated.

The state of the pores in functioning sieve plates

Electron microscopy of Helianthus stem and Saxifraga sarmentosa stolon after first plunging the material into boiling water indicates that the natural condition of the sieve plate pores is to be plugged fairly compactly with slime substance. Electron microscopy of pre-wilted plants demonstrates the same thing. These and other arguments indicate that the slime-filled condition of the pores is not an artifact induced by enzyme action or turgor release, nor is it a consequence of rapid translocation of slime; it is the natural state. This conclusion, very damaging to the pressure-flow hypothesis, is favourable to the electroosmotic theory.