Occurrence and Chemical Synthesis of Apocarotenoids from Mucorales: A Review.

Apocarotenoids are metabolites originated by degradation of carotenes through the loss of carbon atoms placed at the side chain of their structure as consequence of oxydative reactions. We present here the first review of apocarotenoids in the fungi mucorales Phycomyces blakesleeanus, Blakeslea trispora and Mucor mucedo. This review is divided into two parts: the first one presents their structures and sources, whereas the second part is dedicated to their chemical synthesis.

Synthesis of Stilbene Derivatives: A Comparative Study of their Antioxidant Activities.

A series of structurally simple compounds belonging to thestilbene family were synthesized by means of a Ti(III)-mediated methodology that allows access, in an efficient manner, to derivatives of dihydrostilbene, E-stilbene, and stilbene oxide, with high yields. The antioxidant activity of these compounds has been evaluated by means of two electrochemical assays, which provide complementary information, showing that the majority of these stilbene analogs exhibit significant antioxidant activity dependent on the electronic structure and functionalization of the molecule in each case.

Determination of antioxidant activity of spices and their active principles by differential pulse voltammetry.

The anodic oxidation of mercury in the presence of hydrogen peroxide in differential pulse voltammetry (DPV) was used to determine the antioxidant (AO) character of radical scavengers. Hydroperoxide radical is formed at the potentials of the oxidation peak on mercury electrodes, such radical reacting with the antioxidants in different extension. The parameter C10 (antioxidant concentration at which the peak area decreases by 10%) is used to measure the scavenging activity of the individual antioxidants. To establish the scavenging activity of antioxidant mixtures as a whole, the parameter, µ10 as the reverse of V10, V10 being the volume necessary to decrease the peak area in DPV by 10%, was selected. Higher µ10 values correspond to higher scavenging activity. The studies have been extended to aqueous extracts of some species. The results may be useful in explaining the effect of spices in vitro and in vivo studies.

Isocyanate-functionalized chitin and chitosan as gelling agents of castor oil.

The main objective of this work was the incorporation of reactive isocyanate groups into chitin and chitosan in order to effectively use the products as reactive thickening agents in castor oil. The resulting gel-like dispersions could be potentially used as biodegradable lubricating greases. Three different NCO-functionalized polymers were obtained: two of them by promoting the reaction of chitosan with 1,6-hexamethylene diisocyanate (HMDI), and the other by using chitin instead of chitosan. These polymers were characterized through 1H-NMR, FTIR and thermogravimetric analysis (TGA). Thermal and rheological behaviours of the oleogels prepared by dispersing these polymers in castor oil were studied by means of TGA and small-amplitude oscillatory shear (SAOS) measurements. The evolution and values of the linear viscoelasticity functions with frequency for -NCO-functionalized chitosan- and chitin-based oleogels are quite similar to those found for standard lubricating greases. In relation to long-term stability of these oleogels, no phase separation was observed and the values of viscoelastic functions increase significantly during the first seven days of ageing, and then remain almost constant. TGA analysis showed that the degradation temperature of the resulting oleogels is higher than that found for traditional lubricating greases.

Terpenes and polyacetylenes from cultivated Artemisia granatensis boiss (Royal chamomile) and their defensive properties.

Artemisia granatensis, an endemic endangered plant species from Sierra Nevada (Spain) has been successfully cultivated in artificial systems (plants in artificial soil and transformed in vitro roots) to generate enough plant biomass (aerial and root) to allow for its chemical and biological study and at the same time to provide with methods for the sustainable production of the plant and its metabolites. A eudesmanolide (17) along with six sesquiterpenes (11-16), nine monoterpenes (2-10), one nor-monoterpene (1), three acetylenic spiroacetal enoleters (18-20) and one coumarin (21) have been identified from the aerial plant ethanolic extract. Acetylenic spiroacetal enoleters 18-19 and coumarins 21-23 have been isolated from the transformed root ethanolic extract. These extracts and some isolated compounds or mixtures of them have been tested for their insect antifeedant effects against Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi. Significant antifeedant properties were determined for the aerial plant extract, spiroacetals 19-20 and secoguaianolides 13+14 and 16.

Solid-phase selenium-catalyzed selective allylic chlorination of polyprenoids: facile syntheses of biologically active terpenoids.

Regioselective halogenation of the terminal isopropylidene unit of different acyclic polyolefinic polyprenoids (farnesyl acetate, geranylgeranyl acetate, squalene, etc.) using NCS/catalytic polymer-supported selenenyl bromide is described; good to excellent yields are obtained (68-96%). The first applications of this protocol include the concise synthesis of bioactive terpenoids 1-3.