Karel Ubik

Volatiles from stink bug, Graphosoma lineatum (L.) and from green shield bug, Palomena prasina (L.), (Heteroptera: Pentatomidae).

Keywords: Scent glands; defense substances; n-alkanes; furanones; 2-alkenals; 2-alkenyl acetates; 2-decenols

Study of the biotransformation of a potential benzo[c]fluorene antineoplastic using high-performance liquid chromatography with high-speed-scanning ultraviolet detection

As the sum of benfluron metabolites found was only a part of the total amount applied, a search for undiscovered metabolites was undertaken in the extracts from isolated rat hepatocytes and in the bile and perfusate in the experiments with an isolated perfused rat liver. To identify the metabolites, high-performance liquid chromatography with UV spectral analysis was used, as benfluron derivatives exhibit characteristic absorption spectra. Administration of known metabolites to experimental animals and selective induction of certain metabolic pathways led to the finding of new metabolites and of the respective conjugates. Fast atom bombardment-mass spectrometry analysis was used to identify the newly found metabolites and conjugates.

Dracophane, a metacyclophane derivative from the resin of Dracaena cinnabari Balf.

Dracophane, a novel structural derivative of metacyclophane, was isolated from the resin of Dracaena cinnabari Balf. The structure of this compound was determined by spectroscopic methods to be 3,12,21-trihydroxy-1,10,19-tris(4-hydroxyphenyl)-5,14,23-trimethoxy[3.3.3]metacyclophane.

An expedient synthesis of [16,16,17-2H3)-epitestosterone via a one pot deuteration and reduction of the 17-ketone followed by epimerization of a deuterated alcohol

The 17-Oxo group in androstane derivatives was reduced by sodium in deuterium oxide to [17-2H]-17β-alcohol. The 17β-tosyloxy group of 4 was found to be stable under the conditions of the i-steroid rearrangement The SN2 reaction of 17β tosylate 6 with potassium nitrite yielded the 17α alcohol 7 without the loss of deuterium.

Sterols in the termite Nasutitermes rippertii

Abstract The components of the mixture of free sterols isolated from the termite Nasutitermes rippertii have been identified. Androst-5-en-3β-ol, 5ξ-androstan-3β-ol, pregn-5-en-3β-ol, 17ξ-isopropylandrost-5-en-3β-ol, and 1ξ-isopropyl-5ξ-androstan-3β-ol have been found to constitute the minor components. Furthermore, the proportion of sterols in particular castes of these termites has been determined.