Search

Background: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biyearly highlight commentary to describe trends in the field. Results: This commentary of highlights has resulted in 19 different topics selected by each member of the Editorial Board addressing a variety of aspects ranging from novel radiochemistry to first in man application of novel radiopharmaceuticals. Conclusion: Trends in radiochemistry and radiopharmacy are highlighted demonstrating the progress in the research field being the scope of EJNMMI Radiopharmacy and Chemistry. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Mono- and tetrakis(aminomethyl)-substituted resorcinarene-based cavitands 1 and 2 and their clathrates 1 2·THF and 2·(THF)2 were investigated by FTIR spectroscopy and thermogravimetric analysis. Both hosts form stable clathrates with THF both in solution and in the solid state. Major intra- and intermolecular interactions could be identified and located by the use of vibrational spectroscopy. In all cases, dynamic cyclic intramolecular hydrogen bonds between the amino groups and neighbouring ether bridges are observable.

By comparison of the fully assigned vibrational spectra obtained for resorcarene-based cavitands 2a and 2b, their clathrates with toluene and ethanol respectively, and free guest molecules, good structural models for the clathrates could be obtained merely based on Fourier transform infrared data. Using this novel technique, various different interactions between the host and guest in the solid state as well as the orientation of the included guest could be identified. In the case of cavitand 2a, the model obtained by this methodology could be validated by comparison with an experimental crystal structure analysis.

Treatment of calix[4]arene bis-O-carbamates 4a,b-6a,b with LDA in THF results in the regio- and stereoselective introduction of both axial and equatorial carboxamide groups at the methylene bridges via a homologous anionic ortho-Fries rearrangement to give 7-16. The stereochemical outcome of the rearrangement is dependent on the reaction conditions and the conformation of the starting material. Stereochemical and structural proof has been secured by the X-ray crystal structure of calix[4]arene 10 having only one equatorial carboxamide moiety. The use of this novel class of methylene bridge-functionalized calix[4]arenes is illustrated by the formation of bis--lactone 19, while the enhanced acidity of the remaining hydroxyl groups, owing to the presence of axial carboxamide groups at the methine bridges, followed from the easy propylation of bisrearranged calix[4]arene 7.

3-7 with bromochloromethane. According to X-ray analysis of cavitand 19 and 1-D and 2-D NMR spectroscopy for 18, the cavitands possess a stereochemistry with two adjacent aryl substituents in the axial position and the two others in the equatorial position. The starting methylresorcin-[4]arenes 3-7 were obtained exclusively in the chair conformation in 30-98% yield upon condensation of 2-methylresorcinol with aryl aldehydes.

There is a real need for novel anticancer agents for chemotherapy. In this regard, lignans are an extremely important class of compounds. However, few currently have applications in chemotherapy due to their severe toxicity [1]. Judging by reported applications, etoposide is the most potent lignan known in chemotherapy. It is primarily used in combination chemotherapies, for example chemotherapeutic cycles or pretreatments [2–4]. Often it is applied to treat tumour cells that have developed resistance to previously used chemotherapeutic agents [4,5]. Etoposide is still limited in its applications and common problems found in chemotherapy such as multidrug resistance (MDR) and toxicity problems are also apparent [1,5]. Therefore, the search for novel (lignan) cytostatics continues. This review covers sixteen patents showing some strategies which could potentially enlarge the scope of the use of lignans in chemotherapy.

Fourfold homologous anionic ortho-Fries rearrangement in the twofold bridged tetra-O-carbamate 3 gave the tetrakis(carboxamidomethyl)resorc[4]arene 4 in 68% yield. Compound 3 was prepared by selective carbamoylation of methylresorc[4]arene 1, followed by the bridging of the remaining OH groups in tetra-O-carbamate 2.Key words: resorc[4]arenes, selective functionalizations, homologous anionic ortho-Fries rearrangement.

The bioconversion of the lignan desoxypodophyllotoxin by cell suspensions of Linum flavum and of Podophyllum hexandrum was investigated. The apolar substrate could be easily dissolved in the culture medium at a concentration of 2 mM by complexation with dimethyl-β-cyclodextrin. Growth parameters of the cell suspensions were not affected by either the addition of cyclodextrin itself, or when cyclodextrin-complexed desoxypodophyllotoxin was present in the medium. The complexed lignan disappeared from the medium within 7 days for both cell cultures. Cellularly only small amounts of desoxypodophyllotoxin were found. After feeding of desoxypodophyllotoxin, the cell culture of L. flavum accumulated 5-methoxypodophyllotoxin and 5-methoxypodophyllotoxin-β-D-glucoside. After 7 days a total maximal content of 2.38% on a dry weight basis of 5-methoxypodophyllotoxin was formed. corresponding with 249 mg l-1 suspension. The highest bioconversion percentage of 52.3% was found at day 14. The desoxypodophyllotoxin-fed culture of P. hexandrum accumulated podophyllotoxin and its β-D-glucoside with a maximal content of 2.87% on a dry weight basis after 9 days, corresponding with 192 mg l-1 suspension. The highest bioconversion percentage of 33.2% was also found at day 9.