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Abstract: About 90–98% of native lycopene exists in the all-E form, but 79–88% of the lycopene found in the human body are Z-isomeric forms. Thermally-induced geometrical isomerisation of lycopene occurred within 24h of refluxing in ethyl acetate and the proportion of Z-isomers increased from 5.8% to 49.9%. Accordingly, the concentration of lycopene required to double quinone reductase (QR) activity in Hepa 1c1c7 cells decreased from >100 to ∼22μg/mL following thermo-isomerisation, while cell viability was retained at >87% at levels up to 50μg/mL. The inhibition of nitric oxide (NO) production in activated RAW 264.7 macrophages was 50% at ∼100μg/mL thermo-isomerised lycopene and increased to >80% when the concentration in the medium was increased to 500μg/mL. No significant inhibition of NO evolution by macrophages occurred with native (∼94% all-E) lycopene. Both QR induction and NO inhibition bioassays revealed that the structural changes evoked by thermo-isomerisation were accompanied by enhanced biological functionality. [Copyright &y& Elsevier]

Abstract: Research on the biosynthesis of carotenoid pigments, from diverse points of view, has undergone a considerable boost in recent years due to the large body of studies that highlights their beneficial effects in humans. To obtain valuable information from such surveys, it is of paramount importance to reduce the tentativeness with which some carotenoids are still identified, above all, when they are key compounds for the synthesis of other important metabolites. This is the case for neoxanthin (5′,6′-epoxy-6,7-didehydro-5,6,5′,6′-tetrahydro-β,β-carotene-3,5,3′-triol), an epoxycarotenoid which can be found in the light harvesting apparatus of plants and whose cleavage leads to the formation of xanthoxin and then of the plant hormone abscisic acid, among other compounds. Hence, this paper presents pieces of evidence that may put in doubt the presence of such a carotenoid in orange juice, as a consequence of which we propose that the compound formerly tentatively identified as neoxanthin should be referred to as “unidentified” prior to its conclusive characterization and identification. [Copyright &y& Elsevier]