Evaluation of Betulinic Acid Derivatives as PET Tracers for Hypoxia-Induced Carbonic Anhydrase IX (CA IX) Expression.

Non-invasive visualisation of the expression of hypoxia-related proteins, such as carbonic anhydrase IX (CA IX), by positron emission tomography (PET) could provide important information on the oxygenation status of tumours. Since betulinic acid derivatives bind specifically to CA IX the aim of the study was the development betulinic acid-based Ga-labelled PET tracers and to evaluate the hypoxia detecting properties in vitro and in vivo. The binding of betulinic acid (B-DOTA) and betulinyl-3-sulfamate (BS-DOTA) was assessed in two rat tumour cell lines (AT1 prostate and Walker-256 mammary carcinomas).

In the Mists of a Fungal Metabolite: An Unexpected Reaction of 2,4,5-Trimethoxyphenylglyoxylic Acid.

The reactions of phenylglyoxylic acids during the synthesis and biological evaluation of fungal metabolites led to the discovery of hitherto unknown compounds with a -quinone methide (-QM) structure. The formation of these -QMs using C-labelled starting materials revealed a key-step of this reaction being a retro-Friedel-Crafts alkylation.

Transformation of asiatic acid into a mitocanic, bimodal-acting rhodamine B conjugate of nanomolar cytotoxicity.

Based on their biological activity natural products continue to represent optimal lead structures for the development of novel drug candidates. We focused on the syntheses of several derivatives of the triterpene asiatic acid and on the evaluation of their cytotoxic activity in a photometric sulforhodamin B assay. Especially, benzamide 2 and rhodamine B conjugate 11 show a distinct cytotoxicity for several human tumor cell lines, e.

The ancient CYP716 family is a major contributor to the diversification of eudicot triterpenoid biosynthesis.

Triterpenoids are widespread bioactive plant defence compounds with potential use as pharmaceuticals, pesticides and other high-value products. Enzymes belonging to the cytochrome P450 family have an essential role in creating the immense structural diversity of triterpenoids across the plant kingdom. However, for many triterpenoid oxidation reactions, the corresponding enzyme remains unknown.

Rhodamine B conjugates of triterpenoic acids are cytotoxic mitocans even at nanomolar concentrations.

Triterpenoic acids 1-6 exhibited very low or no cytotoxicity at all, but their corresponding 2,3-di-O-acetyl-piperazinyl amides 13-18 showed low EC values for several human tumor cell lines. Their cytotoxicity, however, was also high for the non-malignant mouse fibroblasts NIH 3T3. A significant improvement was achieved by preparing the rhodamine B derivatives 19-24.