A new simplex chemometric approach to identify olive oil blends with potentially high traceability.

Olive oil blends (OOBs) are complex matrices combining different cultivars at variable proportions. Although qualitative determinations of OOBs have been subjected to several chemometric works, quantitative evaluations of their contents remain poorly developed because of traceability difficulties concerning co-occurring cultivars. Around this question, we recently published an original simplex approach helping to develop predictive models of the proportions of co-occurring cultivars from chemical profiles of resulting blends (Semmar & Artaud, 2015). Beyond predictive model construction and validation, this paper presents an extension based on prediction errors' analysis to statistically define the blends with the highest predictability among all the possible ones that can be made by mixing cultivars at different proportions. This provides an interesting way to identify a priori labeled commercial products with potentially high traceability taking into account the natural chemical variability of different constitutive cultivars.

Chemical diversification trends in Astragalus caprinus (Leguminosae), based on the flavonoid pathway.

Flavonoid glycosides of Astragalus caprinus (Leguminosae) were investigated; more than 30 glycosides were found in leaf material, based on the aglycones kaempferol, quercetin and their methylated derivatives. Among them 14 compounds were found in significant amounts and showed a contrasting distribution. They could be ordered into three groups: polyglycosides, acylated polyglycosides and methylated polyglycosides. The distribution of these compounds was studied within a large collection of individual plants harvested in Tunisia; the results showed a relationship between metabolic trends and ecological diversification.

Two new glycosides from Astragalus caprinus.

A new glycoside of flavonol (1) and a new glycoside of a cycloartane-type triterpene (2) were isolated from the leaves and the roots of Astragalus caprinus, respectively. Their structures were elucidated in turn by spectroscopic data interpretation as 3-O-[[beta-D-xylopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->6)][beta-D-apiofuranosyl(1-->2)]]-beta-D-galactopyranosyl kaempferol (1) and 3-O-(beta-D-xylopyranosyl)-24-O-(beta-D-glucopyranosyl)-20,25-epoxycycloartane-3beta,6alpha,16beta,24alpha-tetrol (2).