Eugene M. Oltz

Preferential cytotoxicity on tumor cells by caffeic acid phenethyl ester isolated from propolis

The honeybee hive product, propolis, is a folk medicine employed for treating various ailments. Many important pharmaceutical properties have been ascribed to propolis, including anti-inflammatory, antiviral, immunostimulatory and carcinostatic activities. Propolis extracts have provided an active component identified as caffeic acid phenethyl ester (CAPE), which was readily prepared in one step. Differential cytotoxicity has been observed in normal rat/human versus transformed rat/human melanoma and breast carcinoma cell lines in the presence of CAPE.

Distribution of tunichrome and vanadium in sea squirt blood cells sorted by flow cytometry.

Specialized blood cells of many tunicates accumulate high concentrations of vanadium and phenolic peptide pigments called tunichromes (TC). In order to determine whether V and TC reside in the same cells,Ascidia nigra andAscidia ceratodes blood cell subpopulations were isolated by fluorescence-activated cell sorting (flow cytometry) and chemically analyzed. V was found in the spherical, gree/grey signet ring cells, and to a lesser degree in the mulberry-shaped, yellow/ green morula cells (MRs), whereas free TC was detected mainly in MRs.

RECENT APPLICATIONS OF CIRCULAR DICHROISM TO STRUCTURAL PROBLEMS, ESPECIALLY OLIGOSACCHARIDE STRUCTURES

First, a brief review of the exciton chirality method is given, with emphasis on practical aspects. This is followed by a case (mitomycin C) in which the interpretation of CD data is purposely carried out in a wavelength region where undesirable interchromophoric interaction is negligible. A new chromophore for coupled CD studies and the additivity relation in coupled CD is mentioned. Generalized schemes for carrying out micro— (p-) scale structural studies of oligosaccharides, namely identification of sugars and their glycosidic linkages, are described. The simple three-step sequence currently under study is based on the remarkable additivity relationship found in the coupled CD of pyranose p—methoxycarbonyl benzyl ethers. THE EXCITON CHIRALITY METHOD The chiral through—space interaction between two or more chromophores gives rise to circular dichroism (CD) curves with extrema of opposite signs (split CD curve). The basic theory of this phenomenon was developed in the 1930s by W. Kuhn (coupled oscillator theory, Ref. 1) and J.G. Kirkwood (group polarizability theory, Ref. 2). The application of the coupled oscillator method to various natural products, which we have termed the exciton chirality method (Refs. 3 & 4) , is in most cases straightforward. Together with the X—ray Bijvoet method, it enables one to determine the absolute configurations of organic compounds without reference to authentic cases; moreover, it can be used for a variety of other purposes besides absolute configurational studies as exemplified by the following attempts to devise microgram scale methods for determining glycosidic linkages in oligosaccharides. Several pertinent points of the exciton chirality method will first be briefly summarized (Refs. 3 & 4). When the symmetric p-substituted benzoate chromo— phore is close to a chiral center, the strong La or intramolecular charge transfer (CT) band gives rise to a CD Cotton effect (CE). In the case of the p—dimethylaminobenzoate (dma-OBz) of cholesterol (Fig. 1, ,), the 311 nm UV maximum gives rise to a single CE at 309 nm of moderate intensity. However, when two such chromophores are present in spatial proximity, either intramolecularly or intermolecularly, a through—space interaction takes place and this leads to a CD with extrema of opposite signs (a split CD) . In the 3,4-dibenzoate case shown, the CE at longer and shorter wavelengths (first and second CE) which have negative and positive signs, respectively, reflect the chirality or screwness between the two La electric transition moments. Despite the free rotation around the C-O bond connecting the OBz group to the

CD additivity in trichothecene benzoates: application as a microanalytical method for trichothecene characterization

Abstract The additivity relation in A values of split CD curves previously established with pyranose p-bromobenzoates was shown to be valid for p-bromobenzoates of the cage-like trichothecene system (which also possesses a primary hydroxyl group). This suggests that additivity is generally valid even for congested multichromophoric molecules. The relation has been integrated Into a new micro method for trichothecene characterization, which was applied to a new trichothecene from Fusarium sporotrichioides (MC-72083) at a sub- μg level.