Current Organic Chemistry - Volume 12, Issue 6, 2008

The 2008 Catalysis/Natural Product Chemistry issue of Current Organic Chemistry contains four contributions from eminent scientists in differend fields. The first subject edited by Bolanos and coworkers deals with some aspects of the chemistry and biological activity of hydroxytirosol, an interesting molecule from the olive tree. Bruno and coworkers provide an overwiew of diterpenoid metabolites of the genus Elaeosldinum (Apiacee) with biological activity. The properties of cyclodestrin system in different dense gas techniques have been reviewed by Mammuccari and Foster with their potential use in dense gas processing. Finally Salvador and coworkers review catalytic epoxidation and syn-dihydroxylation of steroid in order to obtain intermediates for synthetic applications. I would like to express my sincere thanks to all the authors for providing these articles and for the fascinating results described.

Hydroxytyrosol is a phenol found predominantly in the olive tree (Olea europea). It shows a broad spectrum of beneficial effects such as cancer chemoprevention by inducing apoptosis, cardioprotection and anti-atherogenic activity, skin photoprotection and anti-inflammatory activity. These biological properties are based on scavenging of reactive oxygen species by hydroxytyrosol, being more active than antioxidant vitamins and synthetic antioxidants. Its biological activities and beneficial effects on human health has stimulated the development of new methods of extraction and purification from olive mill wastewater, from table olive processing, or from leaves. Different procedures for the chemical and enzymatic synthesis of hydroxytyrosol have been developed from tyrosol, from 3,4-dihydroxyphenylacetic acid and its methyl ester, and from oleuropein. Some hydroxytyrosol acyl derivatives have been prepared by chemical and chemoenzimatic methods in order to increase both stability and solubility in lipophilic preparations. Mechanistic experiments on hydroxytyrosol oxidation and isolation of species formed by oxidation are also reported.

The natural kaurane, beyerane and atisane diterpenoids isolated from the genus Elaeoselinum (Apiaceae) and their semi-synthetic derivatives are reviewed. Published 13C NMR spectroscopic data and biological properties of these diterpenes are also reported.

The use of different dense gas techniques for the manufacture of cyclodextrin systems is reviewed in terms of results and potential. The application of cyclodextrins in dense gas processing is also discussed.

The oxidation of steroidal olefins allows the incorporation of functional groups into their skeleton and accounts for the obtention of valuable intermediates in the synthesis of pharmaceuticals, agrochemical and other fine chemicals. The catalytic epoxidation and syn-dihydroxylation reactions of steroidal alkenes are reviewed.